World agriculture vol 4 no 2

WORLD AGRICULTURE

editorsWorld Agriculture Editorial BoardPatronSir Crispin Tickell GCMG, KCVO

ChairmanTo be appointed

Managing Editor and Deputy ChairmanDr David Frape BSc, PhD, PG Dip Agric, CBiol, FSB, FRCPath, RNutr. Mammalian physiologist

Regional Editors in ChiefRobert Cook BSc, CBiol, FSB. (UK)Plant pathologist and agronomistProfessor Zhu Ming BS, PhD (China)President of CSAE & Seed and food drying and storage engineer

Deputy EditorsDr Ben Aldiss, BSc, PhD, CBiol, MSB, FRES. (UK)Ecologist, entomologist and educationalistDr Sara Boettiger B.A. ,M.A.,Ph.D (USA)Agricultural economistProfessor Neil C. Turner, FTSE, FAIAST, FNAAS (India), BSc, PhD, DSc, (Australia)Crop physiologist,Professor Xiuju Wei BS, MS, PhD (China)Executive Associate Editor in Chief of TCSAE, Soil, irrigation & land rehabilitation engineer

Members of the Editorial BoardProfessor Gehan Amaratunga BSc, PhD, FREng, FRSA, FIET, CEng. (UK & Sri Lanka) Electronic engineer & nanotechnologist Professor Pramod Kumar Aggarwal, B.Sc, M.Sc, Ph.D. (India), Ph.D. (Netherlands), FNAAS(India), FNASc (India)Crop ecologistDr Andrew G. D. Bean, BSc, PhD, PG Dip. Immunol. (Australia)Veterinary pathologist and immunologistProfessor Phil Brookes BSc, PhD, DSc. (UK)Soil microbial ecologistProfessor Andrew Challinor, BSc, PhD. (UK)Agricultural meteorologistDr Pete Falloon BSc, MSc, PhD (UK)Climate impacts scientistProfessor J. Perry Gustafson, BSc, MS, PhD (USA)Plant geneticistHerb Hammond, (Canada) Ecologist, forester and educatorProfessor Sir Brian Heap CBE, BSc, MA, PhD, ScD, FSB, FRSC, FRAgS, FRS (UK) Animal physiologistProfessor Fengmin Li, BSc, MSc, PhD, (China)AgroecologistProfessor Glen M. MacDonald, BA, MSc, PhD (USA)GeographerProfessor Sir John Marsh, CBE, MA, PG Dip Ag Econ, CBiol, FSB, FRASE, FRAgS (UK)Agricultural economistProfessor Ian McConnell, BVMS, MRVS, MA, PhD, FRCPath, FRSE. (UK)Animal immunologist Hamad Abdulla Mohammed Al Mehyas B.Sc., M.Sc. (UAE)Forensic GeneticistProfessor Denis J Murphy, BA, DPhil. (UK)Crop biotechnologist Dr Christie Peacock, CBE, BSc, PhD, FRSA, FRAgS, Hon. DSc, FSB (UK & Kenya)Tropical AgriculturalistProfessor R.H. Richards, C.B.E., M.A., Vet. M.B., Ph.D., C.Biol., F.S.B., F.R.S.M., M.R.C.V.S.,F.R.Ag.S. (UK)AquaculturalistProfessor John Snape BSc PhD (UK)Crop geneticistProfessor Om Parkash Toky, MSc, PhD, FNAAS, (India)Forest Ecologist, Agroforester and SilviculturistProfessor Mei Xurong, BS, PhD Director of Scientific Department, CAAS (China)Meteorological scientistProfessor Changrong Yan BS, PhD (China) Ecological scientist

Advisors to the boardDr John Bingham CBE, FRS, FRASE, ScD (UK)Crop geneticist

Editorial AssitantsDr. Zhao Aiqin BS, PhD (China) Soil scientistMs Sofie Aldiss BSc (UK)Rob Coleman BSc MSc (UK)Michael J.C. Crouch BSc, MSc (Res) (UK)Kath Halsall BSc (UK)Dr Wang Liu. BS, PhD (China) HoriculuturalistDr Philip Taylor BSc, MSc, PhD (UK)

Published by Script Media, 47 Church Street, Barnsley,

South Yorkshire S70 2AS, UK

WORLD AGRICULTURE 3

contentsIn this issue ...

Published by Script Media, 47 Church Street, Barnsley,

South Yorkshire S70 2AS, UK

� Dr Roger Turner obituary 4Robert Cook

editorials:� In This Issue – achieving a Low Carbon Economy 5-6Dr David Frape

� Conflicting Perspectives On GM – Science And Persuasion 7Professor Sir John Marsh

� What do we mean by Sustainable? 8Robert Cook

� Policy And New Technology – Common Policy Problems 9Professor Sir John Marsh

scientific:� Contribution of improved nitrogen fertilizer use to 10-18development of a low carbon economy in ChinaProfessor David Powlson, Professor David Norse, Professor David Chadwick, Dr Yuelai Lu, Dr Weifeng Zhang, Professor Fusuo Zhang, Professor Jikun Huang, Dr Xiangping Jia

� Agroecosystem management in arid areas under climate change: 19-29Experiences from the Semiarid Loess Plateau, ChinaDr Rui-Ying Guo and Professor Feng-Min Li

� Interactions between orogeny, climate and land use in the 30-31Semiarid Loess Plateau, ChinaDr Pete Falloon

� Plastic-film mulch in Chinese agriculture: Importance and problems 32-36Professor Yan Changrong, Dr. He Wenqing, Professor Neil C. Turner, Dr. Liu Enke, Liu Qin, Liu Shuang

� Aquaculture: are the criticisms justified? II – Aquaculture’s environmental impactand use of resources, with special reference to farming Atlantic salmon 37-52Dr C J Shepherd and Professor D C Little

the GM debate:� Pros and cons of GM crops as a source of resistance to insect pests 53-59Professor Helmut van Emden

� GM is a valuable technology that solves many agricultural 60-67problems in breeding and generation of new traits Professor Anthony Trewavas and Martin Livermore

� Response to Professor Anthony Trewavas & Martin Livermore 68-69Dr Helen Wallace

� In defence of GM crops 70-71Professor Anthony Trewavas and Martin Livermore

economics and social:� Mitigation of water logging and salinity through biodrainage: 72-77potential and practice Professor O.P.Toky and Dr R. Angrish

� Scaling Up Technology Adoption Among Poor Farmers: 78-83 the Case of SeedDr Sara Boettiger

� Problems of ‘Scaling up’ new crop cultivars: thoughts of an agricultural 84economist on wider issues in this interconnected worldProfessor Sir John Marsh

� Smart Metrics and Data Management Strategies for 85-86Public Private Partnerships Dr Sara Boettiger

expected futurecontributions:� Dr Penelope Bebeli – Landracesin Greece.� Dr Michael Turner – Seedpolicies in guiding seed sectordevelopment in the ‘post projectera’.� Professor Wallace Cowling –Plant breeding systems for dryland Australia.

If you wish to submit an article forconsideration by the EditorialBoard for inclusion in a section ofWorld Agriculture: a) Scientificb) Economic & Socialc) Opinion & Comment ord) a Letter to the Editorplease follow the Instructions toContributors printed in this issueand submit by email to the [email protected] photo – Overview of salmon farm, Isle ofSkye – note feed barge to the right of the pens(Courtesy of Marine Harvest Ltd., Scotland)

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obituary

Dr Roger TurnerRobert Cook

It is with great sadness that we reportthe death of Roger, one of oureditors since the journal started.Roger made a great contribution to

the technical revolution that sweptthrough arable farming during the lastdecades of the 20th Century.

As a researcher and a researchmanager he not only helped todevelop the industry, but was a greatexponent using technology to improveproduction efficiency and output.

The early part of his career was spentwith Shell Agriculture nearSittingbourne, Kent, where he joinedthe herbicide development team in1967.

He later worked in the Shell centre inLondon and then in the 1980s, wasdirector of their field station inCambridgeshire.

After Shell closed their agriculturalbusiness he became Chief Executive ofthe British Association of PlantBreeders.

He was responsible for a number ofsignificant developments within theseed industry, not the least of whichwas the royalty scheme andarrangements for use of farm savedseed.

As a scientist he was not only wellliked and respected by his colleagues,but also made a significantcontribution to the dissemination of

knowledge as an editor of severaljournals.

He also served on the board ofRothamsted Research for a number ofyears.

In addition to a successful career in

agriculture he was involved in his localcommunity as a churchwarden inMildenhall and was a devoted familyman.

We send or deepest sympathy to hiswidow, children and grandchildren.

Dr Roger Turner

Welcome to new Editorial Board membersOn behalf of my colleagues I shouldlike to welcome fourteen newmembers to our Editorial Board (seepage 2). These are all leaders in theirfields of knowledge who, inalphabetical order, are from: Australia,Canada, China, India, Sri Lanka, UnitedArab Emirates, UK, and the USA.

World Agriculture now has

individuals on its Board with expertknowledge in various fields of botany,meteorology, engineering, nutrition,plant and animal physiology, veterinarymedicine, both animal and humanimmunology, genetics, soil and plant &forest ecology, agroforestry & forestry,forensic chemistry, agriculturaleconomics & sociology, teaching, and

biodiversity. This breadth of knowledge should

allow us to deal effectively with manyof the interactions andinterrelationships agriculturalproduction has with a changingclimate and an increasing worldpopulation.

David Frape

WORLD AGRICULTURE 5

editorials

In this Issue we have internationalcooperation amongst nations of thekind this Journal was designed to

kindle. Experts from China, UK, Australia

and India have integrated and focusedtheir attention on several currentproblems of international concern, thesolutions to which will havewidespread effects, not only foragricultural production, but also forissues of both economy andbiodiversity.

In this Issue we have conducted adetailed survey of many aspects of thesemi-arid Loess Plateau in north-westChina. In four papers the orogeny,climate, greenhouse gases, pollution,population & society and forestry ofthis area are discussed and waysforward are proposed.

We continue our discussion of thevital subject of the nitrogen cycle.Previously in this Journal, ProfessorVaclav Smil (1) concluded thatapproximately seven percent of man-made energy is employed in thefixation of atmospheric N2, as NH3,

by the Haber Bosch process and thatapproximately 40 percent of thehuman race depend on the N-fertilizerindustry for adequate food to sustaintheir lives. Without that industry itwould have not been possible for thehuman race to expand in the way ithas during the 20th century.

We all look forward to the timewhen atmospheric – N can be fixedindustrially by a more direct use ofsolar energy, contributing immenselyto a low carbon economy. Industrialfixation of N2 will have to increase,not only to accommodate anincreasing human population, but tocompensate for a possible decline innatural N-fixation as the poplulationof oceanic phytoplankton declines.

N ferilizers are essential for the cropyields we now expect. Without Nfertilizers it would be impossible tofeed the current human and livestockpopulations of the world.Nevertheless, where the use of theseferilizers is subsidised there is the riskof their excessive use (see Powlson etal. this Issue, pages 10-18). This canlead to pollution of ground water, andthe excessive production of nitrogen

oxides which are the most potent ofgreenhouse gases, in addtion to thewaste of fossil carbon energy in theproduction of NH3. Powlson et al.propose there is an urgent need forthree sets of key changes in China ifthe management of N fertilisers is toincrease significantly, improvingeconomy and reducing both pollutionand GHG emissions:

1. Radical changes in the way thatinformation is communicated tofarmers.

2. Changes in Government policiesrelating to subsidies for themanufacture and use of N fertiliser.

3. Measures to increase farm sizeand professionalism of farmers.

Of these they consider points (2)and (3) to be much more important.

The ecology and loss of theeconomic potential of the arid Loessplateau, of China, as a source of cropsfor food production and for plantgrowth generally, is of very greatconcern to the Government of Chinaand to our scientists and economistsgenerally.This subject is detailed inthis Issue (pages 19-29). From thepoint of view of plant growth, theclimate of this area has beendeteriorating over centuries, owing

partly to the loss of forest trees. Thecauses of this deterioration arediscussed by our meteorologist (pages30-31). We also discuss the use inIndia of planted trees to helpdrainage of water-logged land, byacting as natural water pumps (seepages 72-77).

A polythene mulch to retainmoisture and heat in the soil toextend forward the growing season isa universal agricultural instrument forseveral crops. Whilst increasing yieldsthis procedure has several drawbacks.These have been widely studied,especially in China, where a heavygauge polythene is currently in use.

Thicker material not only costs more,and is an oil-based product, but itpersists longer in the soil pofilecausing pollution and ultimately,following several years of continuoususe, it may cause a depression in yieldof crops. These effects have beenmeasured by Chinese scientists andare discussed with solutions proposedin this Issue (see pp. 32-36 & 19-29).

As a consequence of over-fishing,and with a decrease in O2 tension inthe upper layers of the sea, and alsoas oceans gradually become moreacidic, owing to an increase in the

In This Issue – achieving a LowCarbon Economy

David Frape

Landscape of Shangri-La tibetan village © raywoo – Fotolia.com

6 WORLD AGRICULTURE

editorialspartial pressure of atmospheric CO2,wild fish stocks and fish production willcontinue to decline. This emphasisesthe vital importance of fish farming –which will soon exceed oceanic fishingas a food source for the human race.Moreover, as fish are cold-blooded andare buoyed up by water they haveconsiderably lower maintenanceenergy needs than do land animals.We discuss this subject in detail (seepp. 37-52 for the second paper in theseries).

We are again devoting space to theGM crop debate and include afascinating paper (van Emden, pp.53-59) on the control of insect pests byGM and pesticide means.

It is vital that world-wide decisionand policy makers understand thearguments both for and against GM. Inmy view it is quite irrational, tocondem a whole field of science for

reasons of heresay statements andprejudice, rather than to basejudgements on substansive peer-reviewed evidence and rationaldiscussion.

There can be arguments both for andagainst individual procedures, but notfor an entire field of knowledge.Hence, it is our opinion that theseissues should be aired and that sound,rational conclusions should bereached- a major function of thisJournal.

New cultivars of crops, whether ofGM or traditional origin, must bepurchased by the farmer for sowing.Problems and procedures in the supplychain and scaling up of supply fromthe breeding firm to the farmer arealso analysed in this Issue (pp. 78-83).

Finally, research is becoming moreand more expensive, so that the needfor cooperation between groups is ever

more pressing. The procedures andproblems encountered in Public-PrivatePartnerships of research work arediscussed here (pp.85-86).

In this Issue we are commenting to amuch greater extent, than previously,on our papers to initiate discussion onboth suggested consequences ofconclusions drawn and on the widerimplications of these conclusions.Hence, we welcome sensible commentfrom readers, either as Letters to theEditor, or more formally in our peer-reviewed, Comment & OpinionSection. Please, let us know your views.These should be addressed to theeditor: [email protected]

Reference1. Smil, V. World Agriculture (2011) Nitrogencycle and world food production, Vol. 2, No.1, pp9-13.

Landscape of Shangri-La tibetan village © raywoo – Fotolia.com

WORLD AGRICULTURE 7

editorials

On January 17th 2014 ademonstration took placeoutside the Greenpeace offices

in Hamburg. It was led by a group of scientists

who were protesting againstGreenpeace’s opposition to GoldenRice. This is genetically modified ricethat provides a rich source of VitaminA (as ß-carotene), essential for humanhealth but not sufficiently available inthe diets of many poor people whosestaple food is rice.

Greenpeace’s resistance togenetically modified food has takenthe form of political action which hasresulted in legislation to restrict use ofGM crops and their produce inEurope . Their action is also associatedwith demonstrations against field trialsof some modified crops, some leadingto the destruction of experimentalplots.

It seems that the future forgenetically modified food has becomea contest to manipulate publicopinion. Within the debate both sidesclaim that ‘science’ supports theirposition.

World Agriculture has welcomedauthoritative papers from a leadingopponent of GM technology, DrHelen Wallace and from scientists whoadvocate its acceptance and practicaluse. In this issue we include a criticalanalysis of Dr Wallace’s paper byProfessor Anthony Trewavas andMartin Livermore BA (Oxon), Director,The Scientific Alliance and DrWallace’s response.

The issues involved are of globalimportance, especially for poorpeople. Growing population, theprobability that global warming willdiminish the productivity of somemajor food producing areas and thepressure to grow crops for fuel willlimit food supplies. Rising realincomes among some populouscountries where diets are beingupgraded suggest that real foodprices will rise.

For those whose incomes do notkeep pace there is a prospect ofgrowing hardship and for those wholack resources either to grow or buyfood, an increased risk of starvation.The world needs every means at its

disposal to produce a sustainable andsufficient increase in food output.

Those who support GM technologybelieve that its use can make animportant contribution to relievingthis pressure. Several claims areinvolved. It will be possible to produceGM crops that can cope with lessfavourable growing conditions,including higher temperatures, lesswater and shorter growing seasons.

Using the technology plants canresist common pests and diseaseswithout the use of chemicals that canpollute the environment and are, intheir production and application,energy intensive.

The implication is that more foodoutput would be possible using fewerresources than current productionsystems. The modification of plantsmay also improve their nutritionalquality, for example in golden rice.Thus, the use of genetic modificationis expected to make a directcontribution to improving humanhealth and wealth.

As with any new technology it isimpossible to know fully the possibleeffects it may have, especially in thelonger term. In this area, as in allothers, our knowledge is provisionaland will be enlarged by later researchand analysis. Given so potent a newtechnology it is natural that many

wish to proceed slowly rather thanunleash forces that later prove to bedamaging and uncontrollable. Wehave therefore to take seriously thoseanxieties that do surface, whetherthese arise from scientific critiques,from social concerns or because newtechnologies infringe ideologicalconvictions.

In each of these areas of concernserious analysts can honestly come todiffering conclusions. In such asituation it is vital that each exploresthe position of others in order todiscover where the real disagreementoriginates and thereby to understandmore fully the issues at stake.

World Agriculture & Environmentseeks to encourage such a discourse.We are grateful to the contributors tothis edition for setting out theirpositions with clarity. It moves thedebate from the barricades to a morerational and more productive form ofdiscourse.

We would welcome furthercontributions that take the discussionfurther. Such a conversation is helpfulto those who are not themselvesexpert in genetic modification orinvolved in its commercial exploitationbut have to take decisions which willdetermine our capacity to cope withthe looming problem of global foodshortage.

Conflicting Perspectives On GM –Science And Persuasion

Professor Sir John Marsh

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editorials

What do we mean by Sustainable?Robert Cook

Should we not in editorials pose areas in which solutions might lie and indicate theproblems associated with their implementation?

In the last issue we published someestimates of how the world might beable to avoid mass starvation without

reducing biodiversity (destroying theenvironment,), by use of balanced andconstructed vegetarian diets.

That article demonstrated that theworld could feed itself in 2050,assuming the population changesenvisaged by the UN. It alsodemonstrated that it is possible todevelop more sustainable foodsystems, although the diets wouldinevitably be rather bland anduninteresting to the consumer. But itwould mean a greater extent of foodredistribution from temperate totropical regions?

The article demonstrated that largeamounts of external energy would stillbe needed to produce the fertilizersneeded for crop production. It madeno estimates of the energy needed forother tasks such as cultivations or cropprotection, whether provided by manor machine, or of needs for transport,refrigeration or marketing. In order todevelop a fully sustainable system,these energy needs should be metfrom replaceable systems.

However, things are not as simple asthis. If we assume economies continueto grow demand for more anddifferent foods will increase. That willput further pressure of foodproduction. One of these changeswhich might be anticipated is thatpeople will wish to eat more meat.That will also increase demand on thefood production system, simplybecause the energy and waterrequirements of livestock productionare so great.

Modern life is complex andsophisticated. The infrastructure of thefood chain enables Western consumersto have a wide choice of producethroughout the year. However, inlarge parts of the world humans arealready in food deficit, simply becauseof production constraints, irrespectiveof conflict. It suggests that alreadyone might be able to argue that anysystem which limits the output per unitarea might be unethical or immoral.

We have constructed acommunication system which providesinstant, detailed information about

diverse issues. Presentations in themedia often seek to contrast thedifferences which emerge in complexdebates, rather than inform of thecomplexities or attempt to findcommon ground.

Climate change provides an excellentexample. This is a complex subject.Subtle changes to the earth’satmosphere and orbit, as well as solaractivity, have significant impacts, thefull effects of which may take hundredsof years to develop, so climates changeover time. The consensus of informedscientific opinion recognizes that subtlechanges to the atmosphere, made byman over many centuries, also affectthe earth’s heat balance, leading togeneral recognition of anthropogenicimpacts.

How we respond to these changesattracts significant debate, not justbecause there are economicimplications, but also because anyadaptations to our life style or activityneeds to be universally acceptable tohave any chance of reducing theeffects of so called global warming.This is the big problem – “I’m alrightJack”. There is no universal overlordinstructing countries what they mustdo to offset potential problems forwhich the level of risk of theiroccurrence is uncertain, until it will betoo late to take effective action – thataction could mean a lower standard ofliving at present in order to prevent apossible catastrophic effect on living

standards for some future generations– it is nigh impossible for any singledemocratic government to institute astate of affairs that would be politicalsuicide and put a country at aneconomic disadvantage vis à vis othercompeting countries, e.g. greenenergy policy.)

Debates about feeding the world aresimilarly complex. Factors such as landavailability, changing climates, humannutrition and agricultural technologyhave fundamental impacts individuallyand when considered in concert. Theproblem associated with these factorsshares with climate change the factthat each of the factors interacts withone another so it becomes difficult tocommunicate not just the complexityof the problem but also the multiplelevels of interactions*. This makes itdifficult for the informed specialist topresent the facts in simple, readilyunderstood ways, not only to policymakers but also to the general public,who need facts to help themunderstand ‘the big picture’.

*Examples are: “are the currentfloods/storms in the UK caused byclimate change?”

“Is climate change man made”.Therefore if we stop using fossil fuelswill these storms be a thing of the past– Yes of course they will never occuragain ah?

This journal highlights these issuesand helps readers to comprehend thecomplex factors and we hope

© frank peters – Fotolia.com

WORLD AGRICULTURE 9

Editorials

This edition of WA includes apaper by Powlson andcolleagues that looks in depth at

the use of Nitrogenous fertiliser inChina.

Its conclusions are of immediaterelevance to improving both theefficiency of Chinese agriculture andits impact on the environment. Thepaper also illustrates some generalproblems that apply to agriculturalpolicy in China and in Europe.

Subsidies and the creation of adependent clientele. Fertilisersubsidies seem a good way toencourage its use, especially where forfarmers it is a new technology.

However they can lead to a situationwhere agriculture comes to dependon continued support, even if fertiliserapplications are excessive. Not onlyfarmers but also fertilisermanufacturers, distributors andadvisors become clients of the supportsystem. A reduction or withdrawal ofsubsidies then generates social andpolitical problems. Jobs may be lostand incomes fall, since markets willnot reward current rates of us.

Employment in most agriculturalcommunities is dispersed making itdifficult, especially in remote areas, tofind alternative work within reach ofthe homes of displaced farmers andfarm workers. Support initially givento encourage output, as with the CAP,becomes difficult to remove becauseof its social and politicalconsequences.

New technologies demand structuraladjustment. Innovative technologylowers costs of production for anindustry but businesses that cannotuse it efficiently becomeuncompetitive.

Traditional farming is labourintensive and in most places a familyenterprise. New technology usuallyreplaces labour by capital. It alsoincreases the scale and geographicrange of markets.

Small, independent, scatteredholdings cannot reduce labour costsor deliver the volume of product largemarketing organisations seek to buy.

This study shows how in China theuse of contractors to deliver and apply

fertiliser has been used to counteractsome of the limitations of small-scalefarming. However, viability of suchfarm businesses depends onemployment off the farm. Where thisis not possible technologicaldevelopment needed to make anation’s agriculture more productivemay impoverish remote, small farms.

Where farming becomes only asubsidiary source of incomehusbandry standards are unlikely tobe maintained. Structural adjustmentthrough farm enlargement dependsgreatly on the ownership of the landand prevailing systems of tenancy.For family farms it is often a painfulprocess. At a national level it lagsbehind the pattern needed to obtainmaximum economic benefit fromcurrent technology

Policies relating to technologicaldevelopment have to be assessed interms of social costs and benefits.Innovation will be profitable for thefarmer if additional costs are less thanreturns. Such calculations determinethe decision to invest, but usuallyignore costs or benefits that do notfigure in the farm’s financial accounts.Farmers, themselves, are ofteninfluenced by such non-market costs.

They may want to find work for afamily member. They may value aparticular landscape feature or simplyenjoy being farmers. For society as awhole such non-market costs andbenefits have been increasinglyrecognised. Environmentalists havedeplored the impact of some modernfarming practices on biodiversity,wildlife, water quality and thelandscape. Pressure groups have madeit clear that these are real costsalthough they do not figure inmanagement accounts. There areother types of social costs.

The costs per unit of providingservices such as education and healthrise, as people have to move to findemployment. The informal supportgiven to the elderly within traditionalcommunities may disappear asfamilies are separated.

Conceptually the principaljustification for policy intervention isto make social costs and returns

influence the decisions of farmers andconsumers.

In practice this is difficult.Recognition of non-market costs andreturns often depends on theexistence of articulate pressure groupsrather than on the impact of policieson the whole community. Powerfuland well-informed pressure groupscommand a hearing when nationalpolicies are debated. Organisationssuch as RSPB*, RSPCA** and CPRE***have widespread support and claimattention for the interests theyrepresent. Local activists may beregarded as NIMBYs, and carry littleweight on national policies. Somesocial costs and benefits such as theloss of village schools and shops, orthe state of rural roads attract muchless organised campaigns.

Even when costs and benefits areidentified there is seldom an objectiveor agreed means to measure them.The outcome is that policy tends toreflect the concerns of organisationsthat can claim to speak for a largenumber of members.

Such membership is largely urban orsub-urban. There is less interest infarming as a business and more onthe countryside as an amenity.

Traditional literature and visualattractiveness in television programstake precedence over present farmbusiness reality. Such concerns havestimulated policies to prevent huntingwith dogs, to give ramblers rights ofaccess and to impose restrictions onthe use of GM technology. It is arguedthat such policies are justified becausethe non-market benefit to thecommunity is larger than the costs,financial and non-market, they imposeon the industry.

The debate on such issues, and ingeneral the uptake of newtechnology, may depend less onscientific analysis or economic benefitthan on the political clout ofinterested parties.

* Royal Society for the Protection ofBirds

** Royal Society for the Prevention ofCruelty to Animals

*** Campaign to Protect RuralEngland.

Policy And New Technology –Common Policy Problems


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scientific

Contribution of improved nitrogenfertilizer use to development of a

low carbon economy in ChinaProfessor David Powlson1, Professor David Norse2, Professor David Chadwick3,

Dr Yuelai Lu4, Dr Weifeng Zhang5, Professor Fusuo Zhang5, Professor Jikun Huang6, Dr Xiangping Jia6

1 Rothamsted Research, UK. 2 UCL Environment Institute, University College, London,UK. 3 Bangor University, UK. 4 University of East Anglia, UK.

5 China Agricultural University, China. 6 Centre for Chinese Agricultural Policy, Chinese Academy of Sciences, China.

Introduction

China has been extremelysuccessful in achieving foodsecurity through a set of

government-initiated measuresintroduced over several decades.

For many years there was a de facto

policy of aiming at close to 100% self-sufficiency in basic food crops: in 1996the policy was modified and a target ofat least 95% self-sufficiency in grainswas formally adopted.

The measures adopted during the last30-40 years to achieve food securityhave included provision of new crop

cultivars to farmers, installation ofinfrastructure such as irrigationschemes, subsidies to fertilisermanufacturers to limit the price offertilisers to farmers, and varioussubsidies to farmers to enable them topurchase inputs such as fertilisers,pesticides and machinery.

SummaryThe use of nitrogen (N) and other fertilisers has been one of the keys to achieving food security in China. Grain productionalmost doubled in China between 1980 and 2010, yet total fertiliser use increased more than four-fold in the same period.This disparity is partly due to changes in cropping, with a large increase in the area devoted to horticultural crops(vegetables and fruit trees) that are given large rates of fertiliser, especially N. But it also reflects the extremely high rates ofN application given to a wide range of crops, including cereals. There is overwhelming evidence that rates of N applied tomany crops in many regions of China are greatly in excess of the rates required to achieve maximum economic yield. Theseexcessively high rates, combined with inappropriate fertiliser management practices such as timing and method ofapplication, have led to very inefficient use of N and considerable losses to water and air with numerous adverseenvironmental impacts. A key reason for much of the inappropriate fertiliser management is that many farmers are part-time, with more lucrative income from off-farm work. Thus farm operations are given a low priority, with little incentive tochange practices if these involve additional costs, or labour, that interferes with the off-farm work. In this article we reviewthe current situation regarding N fertiliser in China, with an emphasis on the reductions in greenhouse gas emissions thatare achievable through changes in both manufacturing and agricultural use. We argue that, although technical innovationshave a role, these are only likely to be widely adopted in practice if policy changes are implemented to promote changes infertiliser manufacturing and on the farm. Necessary changes in policy include changes to the subsidy, originally developedto make fertilisers affordable to farmers in the period before rapid economic development in the country. At the farm level,policies to promote greater professionalism in farming through increasing the size of farms will facilitate more rational use ofN. This is possible as large numbers of former farmers move to other work in cities; the Chinese government has policyinitiatives in this area through changes in land rental arrangements. Another welcome change would be measures topromote more farmer-oriented approaches to the delivery of technical advice such as the farmer field-school approach, anddevelopment of a contractor sector for fertiliser application.

Key wordsChina, fertilisers, nitrogen, pollution, nitrate, nitrous oxide, greenhouse gas emissions

Abbreviations GHG greenhouse gas; IPCC Intergovernmental Panel on Climate Change; Mt million tonnes; Tg tera grammes, equal to1012g or 1 Mt

GlossaryEmission factor (EF): is a measure ofthe average emission rate of a givengreenhouse gas (GHG) from a givensource material in a given context. Inthis article it is used to describe the

proportion of the nitrogen (N) fromsources including fertiliser, manure orbiologically fixed N that is converted tonitrous oxide (N2O) when applied tosoil. EFs are always expressed asproportion of the source substanceconverted to the GHG in question, so if

1% of applied fertiliser N is convertedto N2O the EF is 0.01.Eutrophication: a dense growth ofaquatic plant life caused by excessiverichness of nutrients in a lake or otherbody of water, frequently due to run-off from the land.

WORLD AGRICULTURE 11

scientificThe use of fertilisers, especially

nitrogen (N), has been a major factorin achieving food security – so thepolicies to make it available andaffordable have been successful. Butthere is now overwhelming evidence ofN fertiliser being applied at excessiverates and in ways that lead to itsinefficient use and large losses to theenvironment, with a wide range ofdamaging environmental andeconomic impacts.

These excessive rates are a majorcause of agriculture overtaking industryas the main source of pollution (1),and this is estimated to be causing areduction in national GDP of about1%. The situation could be termed an“overshoot”; policies that were entirelyappropriate in the past have servedtheir purpose, successfully, but are nolonger helpful and are havingunintended and perverseconsequences.

This paper briefly reviews theevidence for current over-use andmisuse of N fertiliser in China and theenvironmental and economic benefitsto be gained from a move to a morerational use. We emphasise thereductions in greenhouse gas (GHG)emissions to be derived from reduceduse because this aspect has previouslyreceived less attention than has waterpollution. We conclude that changes inpolicy are urgently required if a morerational use of N fertiliser is to beachieved – improved training offarmers is necessary, but is generallyinsufficient to alter behaviour,especially if not accompanied byappropriate policies and economicmeasures. A particular requirement isfor a change in the current subsidyregime affecting N fertiliser. There are

strong moves in China to develop agreener economy, with lower GHGemissions per unit of production, or ofeconomic output, but the large andvery cost-effective contribution that ispossible from agriculture is often notrecognised.

Nitrogen fertiliser use –present situationFigure 1 shows the increase in totalproduction of grain (wheat, maize,rice) and the use of fertilisers (total ofN, P and K) between 1980 and 2010.Grain production increased to 170% ofits 1980 level but the correspondingincrease in fertilizer use was 438%.

In part this is a reflection ofincreasingly inefficient use of fertilisersbut it also results from a major changein cropping patterns over the period.There has been a large increase inproduction of horticultural crops(vegetables and fruit), both in openfields and under plastic.

Table 1 shows changes in theamounts of fertiliser (total of N, P andK) applied to different classes of crop

over the ten year period, 1998 to2008. The amount applied tovegetables almost trebled and that tofruit crops doubled; this partly reflectsthe greatly increased area of thesecrops and partly the very large rates offertiliser (especially N) applied to them.

There is a particular issue with Nfertiliser being applied at rates inexcess of that required to achievemaximum yield. There are numerousexamples of this for all major crops inmost regions of China. Over-application, and a range ofinappropriate management practices,have led to very inefficient use of Nfertilizer by crops in China.

Figure 2 shows the partial factorproductivity for N (PFPN) of graincrops in China over the period 1980 to2005. PFPN is the ratio of grainproduced to N applied so a largernumber represents a more efficient useof N fertiliser. During the 25 yearperiod shown, the value of PFPNdecreased by half from 34 kg grain kg-1 N applied when N rates were low inthe early 1980s to about 15 kg grainkg-1 N in recent years. Forcomparison, the PFPN for maize in theUSA increased from about 40 to almost60 kg grain kg-1 N between 1980 and2000 (2).

Fortunately, there is widespreadevidence that reduced application of Nfertilizer, often combined with changesin timing or other managementfactors, can achieve the same cropyields as current excessive applications.In one study, two major croppingsystems of great importance to China’sfood security were investigated: therice-wheat system as practiced in theYangtze River basin in Jiangsu Provinceand the maize-wheat rotation in theNorth China Plain. (3).

The authors concluded that currentcrop yields could be maintained withreductions of 30-60% in N fertilizerapplications.

Figure 1. Changes in total fertiliser use (total of N+P+K) (grey) and grainproduction (total of wheat, maize and rice) (yellow) in China between 1980 and2010. Values in 1980 set at 100.

Table 1. Fertiliser used (total of N+P+K) on different crops in China: changesbetween 1998 and 2008. Values shown are quantity of fertiliser applied to eachgroup of crops and this quantity expressed as a percentage of the total used onall crops.


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Another study on rice in 20 farms inthe Yangtze basin, this time inZhejiang Province, showed that in oneyear N applications to rice could bereduced from 300 to 150 kg N ha-1

with no loss of yield (4). In other years and sites reductions of

about 30% were more common. In theNorth China Plain a study on Nfertilisation of winter wheat (5) showedthat by basing N applications onmeasurements of mineral N in soil totalapplications could be reduced to 55-65kg N ha-1, with no loss of yield, insteadof the farmers’ practice of 300 kg Nha-1. This dramatic result was becauseof large residues of nitrate in the soil,unused from previous years which arenormally ignored, or are lost due toexcessive irrigation. Such large savingsare unlikely to be sustained indefinitely,but reductions of 30-50% compared tocurrent common practice, as shown inother studies, are considered

sustainable in the long term.Management practices such as timingare also important for increasing theefficiency of use of applied N; in thestudy previously cited (5) it was foundthat, with current rates of N, cropyields could be doubled comparedwith farmers’ yields through a set ofmanagement changes.

Single year experimentsdemonstrating that yields aremaintained with reduced N applicationcan, correctly, be criticised as being areflection of nitrate accumulated in thesoil over many years and thus notrepeatable in future years. However,long-term experiments clearly showthat high yields can be sustained withN rates that are significantly lower thancurrent common practice. Forexample, at one site in HenanProvince, in the North China Plain(part of an 8-site national network ofexperiments), yields of wheat in the

wheat-maize double crop rotationwere sustained at 6-8 t ha-1for 15 yearswith an annual N application of 165 kgN ha-1. This rate is far lower thancommonly observed in the region, thatare well in excess of 200 kg N ha (6).

Table 2 (from Norse et al., (7))summarises results for a range of cropsin various regions of China whichdemonstrate that substantial savings ofN fertiliser can be made. Not only iscrop yield not decreased, there is oftena modest yield increase. A smallincrease in yield compared to cropsreceiving excessive N fertilizer is notunexpected because it well known thatcrops over-supplied with N are moresusceptible to pests and diseases (8),so a more rational N managementshould lead to decreased use ofpesticides with wider benefits for theenvironment and human health, inaddition tofinancial gain for the farmer.Crops over-supplied with N can also bemore prone to “lodging” where cropsfall over, due to weakness of the stems,making harvesting more difficult, andso leading to loss of grain. In addition,research at China AgriculturalUniversity has shown than maize plantsreceiving a super-optimal amount of Nfertiliser have a smaller root systemthan that of correctly fertilised plants(Figure 3).

Over-use of N fertiliser in China hasserious impacts on land, water and airat the local, regional and global level.

Figure 2. Changes in annual N fertiliser consumption, grain production andpartial factor productivity of N (PFPN) in China between 1980 and 2008. PFPN isthe ratio of grain produced to fertiliser N consumed expressed as kg grain kg-1 N.

Table 2. Examples of N fertiliser over-use for various crops in different regions ofChina (from (7)).

Figure 3. Effect of N fertiliser over-application on growth of maize roots.(a) Roots of over-fertilised plants. (b)Roots of plants given a rational rate ofN fertiliser. (Photo by C.J. Li, ChinaAgricultural University, Beijing).


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Soil acidification has doubled over thepast 30 years, to which N fertilizer hascontributed about 60% (9). Much ofthe acidification stems from the highinputs of ammonium-based N fertilizersuch as urea and the uptake andremoval of base cations rather thanfrom acid rain.

However, in view of the rapidincrease in animal numbers in recentyears, ammonia emissions frommanure and other livestock wastes maybecome of increasing importance. Thecrop yield and food security impacts ofacidification include suppression ofrhizobial activity and reducedavailability of micro-nutrients, inaddition to direct impacts ofacidification on crop growth. Theoutcome is a threat to thesustainability of Chinese agriculture.

In the case of surface waters, nitrateentering rivers and lakes (together withphosphate, often derived from poormanagement of manure) leads to algalblooms, the growth of water weedsand widespread eutrophication. Morethan 50% of China’s major lakes arenow eutrophic and for most of themthe situation is getting worse (10).

The incidence of algal blooms hasincreased several-fold since the 1990sand agriculture is responsible for 25-80% of N inputs to major rivers which,in turn, are damaging to fisheries andso damage food security in a differentsector. With both surface waters andground waters, nitrate not taken up bycrops leads to high concentrations inwater used for drinking, which oftenexceed WHO guidelines for drinkingwater. Algal blooms themselves alsopose a health threat to animals andhumans due to production of potent

toxins by the cyanobacteria (alsoknown as blue-green algae) thatcomprise the blooms. The impact canbe direct through drinking of the water(11, 12) or through the food chain,especially via shellfish (13) and theoccurrence of cyanobacterial blooms islikely to increase under the influence ofclimate change (14).

Finally there is the important impacton air quality, particularly the emissionsof ammonia that lead to particulateformation with resulting implicationsfor human health (15), eutrophicationof natural and semi-natural aquatic andterrestrial systems, soil acidification asdescribed above and to thegreenhouse gas emissions examined inthe next section.

Figure 5a illustrates the situation

regarding high rates of N fertiliserapplied to horticultural crops. The dataare from a survey of farmers growingtomatoes under plastic in so-called“sunlight greenhouses” of the suburbsof Xi’an city in northwest China (16).

The greenhouse structure is coveredwith plastic for part of the year toprovide a protected environment andincreased temperature for growing arange of horticultural crops includingtomatoes, cucumbers, courgettes(zucchini), aubergines (egg plant) andpeppers that have a high value. Theplastic is removed from the structuresduring summer, when rainfall isrelatively high and the highertemperature is not needed. Saltsaccumulated in the soil are leached outof the topsoil during this period.

Figure 4. Lake eutophication and algalgrowth caused by run-off of nitrateand phosphate from agricultural land.

Figure 5. Results from a survey of “sunlight greenhouses” in a region near Xi’ancity in northwest China. These are greenhouses used for growing a range ofhigh-value horticultural crops under plastic, often two or three crops each year.The plastic is removed during the summer rainy period to expose the soil torainfall so that accumulated salts are washed out. Results are mainly fromgreenhouses growing tomatoes, 116 being surveyed to determine rates of Nfertiliser applied by the farmer and 43 being measured for nitrate accumulated insoil. Data plotted show the frequency distribution of (a) N fertiliser applicationrates and (b) residual nitrate (kg nitrate-N ha-1) in soil to a depth of 1m. Bothare expressed as a percentage of the total number of greenhouses surveyed(From 16).


scientificOf the 116 greenhouses surveyed in anarea near Xi’an city, 65% of farmerswere applying in excess of 400 kg Nha-1 with a quarter applying >800 kg Nha-1. These rates are extremely high byinternational standards and were inaddition to large annual manureapplications estimated to be supplyingalmost 1000 kg N ha-1. Not surprisinglythese management practices led tovery large residues of nitrate in soil.More than 60% of sites where soil wasanalysed contained >350 kg N ha-1 asnitrate-N in the soil to a depth of 1m(Figure 5b). The issue of inefficient useof nutrients from manure has recentlybeen reviewed and proposals made foraddressing the problem (17), asmanure applications are generallyignored when farmers make decisionson application rates of fertilizer.

Greenhouse gas emissionassociated with nitrogenfertiliserNitrogen fertiliser inevitably has a largegreenhouse gas footprint withemissions from the following sources:1. Carbon dioxide (CO2) emittedduring manufacture, especially fromthe ammonia production stage usingthe Haber-Bosch process because thisrequires a large amount of energy toachieve the necessary hightemperature and pressure. The energyis provided largely by fossil fuels,usually natural gas or coal. In Chinacoal is the dominant energy source.2. Emissions of nitrous oxide (N2O)when N fertiliser is applied to soil.Typically the quantity evolved is small,1% or less of the N applied, but N2O isa very powerful greenhouse gas; eachmolecule is almost 300 times morepowerful in global warming than amolecule of CO2, so even smallemissions have large impacts.Emissions of N2O from the field whereN is applied are termed “directemissions”. Emission can vary widelyaccording to climate, soil type andenvironmental factors. The gas can beproduced from two separate processesin soil, nitrification and denitrification.Nitrification is the conversion ofammonium to nitrate and is adominant process in most soils exceptthose that are water-logged (as inflooded rice cultivation), or in soils thatare very acid. Denitrification is thereduction of nitrate to a mixture ofN2O and nitrogen gas, normally insoils under wet conditions in whichoxygen is limiting. It is often the mainsource of N2O from soils, but in the

dry conditions of north China there isevidence that nitrification is the majorpathway (18, 19).3. “Indirect emissions” of N2O. Thesearise from transformations of N thathas moved from the site of fertiliserapplication. For example, nitrateleached from surface soil to deeperlayers or to waterways can bedenitrified later. Ammonia volatilisedfrom the soil surface after applyingurea is redeposited onto soil and waterelsewhere and undergoes nitrificationand denitrification.

The IPCC derived an average value of1% of N applied for the directemission of N2O at the site of fertiliseror manure application, based on areview of world literature (20). This istermed the “emission factor”, EF. Laterreviews (21, 22) have suggested an EFvalue that takes into account totalN2O emissions (direct + indirect) inthe range 2-5% of applied N. Widely accepted values for the totalgreenhouse gas impact of N fertilisers,combining emissions from bothmanufacture (under Europeanconditions) and agricultural use are10.5 kg CO2-equivalent per kg N inurea and a corresponding figure of 8.4for ammonium nitrate (23). A clearimplication of this large value is that itis essential to use N fertiliser efficiently,so that emissions are no larger thanabsolutely necessary.

Some might argue that a strategy ofeliminating all use of N fertiliser wouldbe an effective way of decreasingemissions from agriculture, but thiswould have a devastating impact onglobal food security. One estimate (24)is that agricultural systems using nochemical fertilisers could, on optimistic

assumptions, feed only 4.2 billionpeople or 60% of the current worldpopulation and less than 50% of thepopulation expected by 2050. Theconcept of “yield-scaled N2Oemissions” has been introduced as away of expressing the N2O efficiencyof a cropping system (25).

A global meta-analysis of non-leguminous annual crops showed thatN2O emissions expressed as aproportion of crop N uptake (thisbeing used as a proxy for yields acrossthe diverse crops included) were at aminimum at N fertiliser applicationrates of approximately 180–190 kg Nha-1 and emissions increased sharplyafter that – for example 3-fold greaterfor applications rates > 300 kg N ha-1

(25). N applications that are very low or

near zero give increased values foryield-scaled N2O emission becauseyield is low. The N application rategiving a minimum value of yield-scaledN2O emission was often about thesame rate as recommended formaximum economic yield and therewas a negative relationship between Nuse efficiency and yield-scaled N2Oemissions. These findings furtheremphasise the importance of aiming atrational N fertiliser rates as a means ofdecreasing GHG emissions – but theydo not lend support to the idea ofeliminating N fertiliser. And evenwhere fertiliser can be replaced bymanures or biologically fixed N, N2Oemissions still occur (22. 21, 22).

In a recent study by Zhang et al. (26)a life cycle approach was taken toquantify the GHG emissions associatedwith N fertiliser in China; the resultsare summarised in Table 3.

Table 3. Greenhouse gas (GHG) emissions associated with the N fertiliser chain inChina including manufacture, transportation and agricultural use of N fertiliser(adapted from (26)).


scientificThe total GHG emission associatedwith N fertiliser (both manufacture anduse) was estimated at 452 Mt CO2-equivalent in 2010, representing 7% ofemissions from the entire Chineseeconomy (26).

Emissions per kg of N fertilisermanufactured and used in China (13.5kg CO2-equivalent kg-1 N) are higherthan corresponding values fromelsewhere in the world such as Europe(10.5 kg CO2-equivalent kg-1 for urea-N) for two main reasons. First, coal isthe dominant source of energy used inN fertiliser manufacture in China,accounting for 86% of energy use(26). CO2 emissions per unit of energyare greater for coal than for natural gaswhich is the main source of energy forfertiliser manufacture in Europe andmost other regions. In addition to CO2emitted from the fertiliser plant, thelife cycle approach means that thesignificant methane emissions from themining of coal should also be includedin the accounting. Second, 64% offertiliser manufacture in China occursin small plants using old technology(26); for any energy source (coal, oil ornatural gas) these plants are lessefficient and give larger emissions perunit of N fertiliser produced than largerplants utilising modern technology.

Options for decreasingGHG emissions connectedwith N fertilisers in ChinaFertiliser manufactureWhen seeking to identify opportunitiesfor decreasing GHG emissions fromagriculture, especially those associatedwith N fertiliser, it is common to focussolely on management practices atfarm level.

Whilst these are extremely important,the results in Table 3 show clearly thatit is also appropriate to consideremissions at the manufacturing stage;in China these account for over 60% ofthe total emissions from the N fertiliserchain (or 38% if methane from coalmining is excluded). A complete switchfrom coal to natural gas is not apractical option because China haslarge reserves of coal but a shortage ofdomestically sourced natural gas.Consequently changes in the fertilisermanufacturing sector will have to focuson the following:1. Phasing out small factories whichmay often cause local air pollution withnegative impacts on human health aswell as being large GHG emitters.2. Upgrading technology in existinglarger factories.3. Consider installation of “carbon

capture and storage” (CCS) at thelargest coal fired factories.

All of these measures will requiregovernment action in the form ofchanges to subsidies (27), includingremoval of support for small scaleplants and incentives to upgradeothers, but the potential impact isconsiderable. A set of scenarios wereconstructed in the study of Zhang etal. (27) to explore the decreasespossible by 2020 and 2030 comparedto “business as usual” (scenario 1) inwhich it was assumed that N fertiliseruse would continue to increase in linewith projected population increase.This showed that even withoutimprovements in N use at farm level,improvements in the efficiency of theN fertiliser manufacturing processalone (scenario 2), could decreaseGHG emissions by 20-30% comparedto “business as usual” (Figure 6; thesevalues did not assume majorinfrastructure installations such asCCS). Even if only a fraction of theseGHG savings can be achieved, due topractical constraints, the analysisdemonstrates that considerablesavings, which are often overlooked,are potentially possible from fertilisermanufacture in China. Additional issuesregarding the present subsidy regimeare discussed later.

Technical approaches to improvefertiliser management at farm levelResearch in China has identified arange of management practices atfarm level that would increase theefficiency of use of N fertiliser and/or

decrease N losses to the environment(27). These include the following:� Adjust N application rate to arealistic assessment of crop needs,based on previous yields and takingaccount of the likely supply of N fromsoil. The latter includes N mineralisedduring the cropping season, residualnitrate in the soil profile andN fromprevious manure applications. Asdiscussed above, there is a vast body ofdata showing that very significantsavings of N can be made with no lossof crop yield – and in some cases smallyield increases.� Adopt sub-surface application of Nfertiliser because surface application ofurea, which is currently normalpractice, frequently leads to large Nlosses to the atmosphere as ammonia.In one experiment conducted by ChinaAgricultural University, this applicationmethod decreased ammonia losses atthe time of urea application from 27%to 8%.� In many situations it may be possibleto alter the timing of N fertiliserapplication such that a greaterproportion is given during the maingrowth period instead of at sowing, ortransplanting in the case oftransplanted paddy rice.� Where farmers consider itimpractical to adjust the timing of Napplication (often due to labourconstraints at mid-season because ofoff-farm work use of either slowrelease forms of N fertiliser or formscontaining inhibitors of eithernitrification or urease activity in soil.(28, 29).

Figure 6. Greenhouse gas (GHG) emissions (expressed as CO2-equivalent) associ-ated with the manufacture and use of N fertiliser in China. Emissions shown inunits of Tg CO2-equivalent (1Tg = 1012g or 1 million tonnes). Emission estimatesfor 2020 and 2030 are for 4 scenarios. Scenario 1: “business as usual”; N fertiliserproduction and use increases in line with projected population increase, nochanges in manufacturing processes or agricultural practices. Scenario 2:improved manufacturing technologies. Scenario 3: improved manufacturing tech-nologies plus controlled N use on crops. Scenario 4: improved manufacturingtechnologies plus reduced N use on crops using all available methods (from 26).


scientific� In regions where soil andenvironmental conditions lead tosignificant emission of N2O throughnitrification in soil use nitrate-basedfertiliser instead of urea.� Improve management of animalmanures and other organic inputs suchas residues from anaerobic digestion(the process used for producingbiogas) at all stages in order todecrease N losses and maximiserecovery of manure-derived N by crops(17). Taking account of manure-derived N, decreasing fertiliser Napplication accordingly, is especiallyimportant where vegetable crops orfruit trees are grown, as these tend toreceive large doses of manure. Inregions where there is an excessivequantity of manure due to large animalnumbers promote production oforganic fertiliser products using aerobiccomposting and transport these toother regions as a partial substitute forinorganic fertilisers. Because of the costof the composting process, thisrequires government subsidies to makeit viable.� Where irrigation is used, adopt“fertigation” in which nutrients aredissolved in irrigation water anddelivered to crops during the growingperiod as this can greatly increase theefficiency of crop utilisation ofnutrients. The practice is already usedby some farmers growing horticulturalcrop under plastic but there is a needfor greatly improved delivery of adviceto ensure that the maximum benefit isobtained. There are also opportunitiesfor extending the practice to irrigatedcrops grown in open fields, thoughadditional engineering innovationwould be required together withdelivery of appropriate technicaladvice.

Innovations necessary to facilitatechanges in N fertiliser managementThe benefit of many of the changes inN fertiliser management listed abovehas been known for many years andthe changes have been proposed byresearchers – yet very few have beenadopted by farmers and, in the main,the situation of over-use, mis-use andinefficient use of N fertiliser in Chinahas become progressively worse. Why?

We suggest three sets of key changesthat are required if the management ofN fertiliser is to improve significantly:1. Radical changes in the way thatinformation is communicated tofarmers.2. Changes in Government policiesrelating to subsidies for themanufacture and use of N fertiliser.

3. Measures to increase farm size andprofessionalism of farmers.

We consider that the second two by farthe more significant but we considereach in turn.

Communication of fertilisermanagement information to farmersIt is often stated in China that the keyto improving fertiliser management isto improve the delivery of technicaladvice to farmers. We consider this tobe partially true, but certainly not thefull answer. China has a large andestablished national extension systemand in the past it has been effective inassisting farmers. But in recent years,for a range of organisational reasons, ithas become ineffective: the reasonshave been documented in detailelsewhere (30). It is now understoodthat extension messages delivered inthe traditional mode of “expert tellsfarmer” are often ineffective. Forexample, a study based on householddata collected from 813 maize farmersin Shandong Province showed thatwhile training on rational fertiliser use(termed: integrated nutrientmanagement, INM) could lead tosome reduction in farmers' rates of Nfertilizer application, training alone wasnot sufficient to change practicessignificantly and farmers only partiallyadopted the recommended INM (31,32).

An alternative model is the farmerfield school in which “farmer tellsfarmer”, albeit facilitated by an“expert” or advisory agent. Evidencefrom around the world, as well as inChina, demonstrates that this can bemore effective. Although it has beenapplied in China with respect topesticide use, as yet it has been littleused for fertiliser management.Identifying early adopters andinnovators would be key to adoptionof these techniques.

Changes in government policiesregarding subsidies affecting fertilisermanufacture and useSubsidies to keep down the cost offertilisers were introduced to makethese vital inputs affordable for smallfarmers. This policy has clearlysucceeded and is no longer necessary.We propose that the general subsidyon fertilisers be removed and replacedby more targeted payments that arerelevant to the current situation (10,27).

A major and positive innovationwould be a scheme to promote therole of contractors in applying fertilizer.Virtually all the technical innovationsdiscussed above have either an

economic cost (e.g. equipment forsub-surface application of urea), orrequire additional labour for applyingN during the course of the growingseason. Because so many farmers areengaged in off-farm work, that isusually far more lucrative than theincome from farming a small area, theyhave no incentive to adopt practicesthat increase efficiency of N use.Reorganising subsidies such that afarmer had a payment for the use of acontractor, instead of for the cost offertiliser, could make a majorcontribution to the improvedmanagement of N and other nutrients.

It would be worthwhile for acontractor to purchase machinery forsub-surface fertilizer applicationwhereas it is not so for an individualsmall farmer. And a contractorspecialising in this work would be ableto make timely applications,unhampered by labour shortages atkey times, as often occurs for the part-time small farmers. There are alreadyagricultural contractors operating inChina, often using small combineharvesters and in some cases applyingpesticides, so the extension to fertiliserapplication is not unreasonable –provided the policy and subsidyenvironment is arranged specifically tofacilitate and promote the change.

A similar approach could beextremely useful in promoting theefficient use of nutrients in manure, interms of transportation andmechanised spreading (17). It wouldneed to be cost-neutral for the farmerand ideally be attractive through aspecific payment, at least initially. Inpractice contractors (termed“professional service providers” inChina) are usually innovative farmerswho decide to specialise in a specifictype of work to increase their income.

A further advantage of promotingthis contractor sector is that itrepresents a cadre of moreprofessionally skilled agriculturaloperators. They are more likely to beinfluenced by training programmesthan the part-time farmers, who haveoff-farm priorities.

Also, because their numbers wouldbe smaller than the total of all farmers,the task of delivering relevant technicaltraining is more tractable. However,there are challenges to this approach.For example, it is essential that afarmer has confidence in his or hercontractor and trusts their judgmentand honesty.

Monitoring the performance ofcontractors is difficult under currentconditions in China: development of


scientificcertification or accreditation schemeswill be an important development,possibly learning from the FACTSscheme for training and accreditationof fertilizer advisers in the UK whichhas backing from governmentagencies, fertiliser industry and farmersorganisations (33).

Measures to increase farm size andfarmer professionalism The importance of off-farm work forfarmers presents challenges to goodagricultural practice, as discussedabove.

But it also presents opportunitiesthrough the possibility of thosewishing to concentrate on other workrenting their land to neighbours whowish to specialise in farming. (In Chinait is a matter of land rental rather thansale because all land is owned thestate). This trend leads to a gradualincrease in farm size, termed “landconsolidation”. It has been occurringfor some years in China, initiallythrough informal arrangements butlater with official encouragement.

There is evidence that farmers with alarger area use slightly lower rates of Nfertiliser (31, 32), presumably becausethey are making farm managementdecisions in a more professional way. Arecent Chinese government documenton agricultural polices includesstatements on measures “to speed upthe transfer of rural land and offermore subsidies to family farms andfarmer's cooperatives … in an effort todevelop large-scale farming” (33).Policies of this type may well be thekey to moving towards more rationaluse of N fertilisers and other desirablefarm practices.

ConclusionsRapid changes in China, affecting boththe general economy as well aspractices within farming, have led toexcessive N fertiliser use.

The amounts applied to crops inmany situations are now considerablygreater than those required formaximum economic yield. Thesituation is particularly severe in thehorticulture sector but even with themajor cereal crops (wheat, maize, rice)it has been clearly demonstrated thatreductions of 30% or more are oftenpossible – with no loss in yield andoften a small increase. In addition toexcessive quantities being applied,management factors such as timingand method of application are ofteninappropriate and lead to inefficientuse of N by crops, large losses to theenvironment and decreased profit to

farmers. There are numerous and wellknown technical approaches toimprove the situation but these areunlikely to be adopted unless theirpromotion is accompanied by changesin policy and infrastructure to create amore professional approach tofarming.

These measures include changes tosubsidy regimes, that were introducedto promote fertiliser use at a timewhen farmers could ill-afford suchinputs, encouragement of a contractorsector for fertiliser management (toovercome labour shortages affectingmany part-time farmers involved inmore lucrative off-farm work) andmeasures leading to increased farmsize through encouragement of theland rental market. Althoughimproving delivery of advice tofarmers, based on up-to-date scientificunderstanding, is important this willhave limited impact if notaccompanied by appropriate changesat the policy level.

Improved management of N fromfertilizers and manures is often seen asa means to improve water quality inChina.

The potential to cut greenhouse gasemissions and contribute to a lowcarbon economy, a goal of the Chinesegovernment, is often overlooked.Recent research shows that cuts inemissions equivalent to between 2 and6% of total emissions from the wholeChinese economy are possible througha combination of improvements infarm practice and N fertilisermanufacture.

References1. National Pollution Survey Bulletin (2010)http://www.stats.gov.cn/tjsj/tjgb/qttjgb/qgqttjgb/201002/t20100211_30641.html (in Chinese).Reported in The Guardianhttp://www.theguardian.com/environment/2010/feb/09/china-farms-pollution 2. Cassman, K G, Dobermann, A, Walters, D T(2002) Agroecosystems, nitrogen-use efficiencyand nitrogen management. Ambio 31: 132-140.3. Ju, X T et al (2009) Reducing environmental riskby improving N management in intensive Chineseagricultural systems. Proceedings of the NationalAcademy of Sciences, USA 106 (9): 3041-3096.4. Wang, G, Zhang, Q C, Witt, C, & Buresh, R J(2007) Opportunities for yield increases andenvironmental benefits through site-specificnutrient management in rice systems of Zhejiangprovince, China. Agricultural Systems 94: 801–806.5. Chen et al (2011) Integrated soil–crop systemmanagement for food security. Proceedings of theNational Academy of Sciences, USA 108 (16): 6399-6904.6. Zhao, B-Q, Li, X-Y, Li, X-P, Shi, X-J ,Huang, S-M,Wang, B-R, Zhu, P, Yang, X-Y, Liu, H, Chen, Y,Poulton, P R, Powlson, D S, Todd, A D & Payne, RW (2010). Long-term Fertilizer ExperimentNetwork in China: crop yields and soil nutrienttrends. Agronomy Journal 102: 216-230.

http://dx.doi.org/10.2134/agronj2 009.01827. Norse, D, Powlson, D S. & Lu, Y (2012).Integrated nutrient management as a keycontributor to China's low-carbon agriculture. InClimate change mitigation in agriculture (eds E.Wollenberg, A. Nihart, M-L. Tapio-Bistrom & M.Grieg-Gran) pp. 347-359. Earthscan, Abingdon.8. Cu, R M, Mew,T W, Cassman, K G., & Teng, P S(1996) Effect of Sheath Blight on yield in tropical,intensive rice production systems. Plant Diseases89: 1103-1108.9. Guo, J H, Zhang, Y, Shen, J L, Han, W X, Zhang,W F, Christie, P, Goulding, K W T, Viyousek, P M,& Zhang, F S (2010) Significant acidification inmajor Chinese croplands Science 327: 1008-1010.10. Sun, B, Zhang, L, Yang, L, Zhang, F, Norse, D,& Zhu, Z (2012) Agricultural Non-Point SourcePollution in China: Causes and MitigationMeasures. Ambio 41: 370-379. 11. Cheung, M Y, Liang, S, & Lee, J (2013) Toxin-producing cyanobacteria in freshwater: A reviewof the problems, impacts on drinking water safety,and efforts for protecting public health. Journal ofMicrobiology 51: 1-10.12. Zhu, L, Wu, Wu, Y L, Song, L & Gan, N (2014)Ecological dynamics of toxic Microcystis spp. andMicrocystin-degrading bacteria in Dianchi Lake,China. Applied and Environmental Microbiology 80:1874-1881.13. Zhang, F, Xu, X, Li, T, & Liu, Z (2013) Shellfishtoxins targeting voltage-gated sodium channels.Marine Drugs 11: 4698-4723.14. El-Shehawy, R, Gorokhova, E, Fernandez-Pinas,F, & del Campo, F F (2012) Global warming andhepatotoxin production by cyanobacteria: Whatcan we learn from experiments? Water Research46, Special Issue: 1420-1429.15. Sutton, M.A. and 22 others (2013) OurNutrient World: The challenge to produce more foodand energy with less pollution. Global Overview ofNutrient Management. Centre for Ecology andHydrology, Edinburgh on behalf of the GlobalPartnership on Nutrient Management and theInternational Nitrogen Initiative.www.gpa.unep.org/gpnm.html16. Zhou, J-B, Chen, Z-J, Liu, X-J, Zhai, B-N &Powlson, D S (2010). Nitrate accumulation in soilprofiles under seasonally open 'sunlightgreenhouses' in northwest China and potential forleaching loss during summer fallow. Soil Use andManagement 26: 332-339.http://dx.doi.org/10.111 1/j.1475-2743.2010.00284.x17. Chadwick, D, Chen, Q, Tong, Y, Yu, G, &Shen, Q (2012) Improving manure nutrientmanagement towards sustainable intensification inChina. SAIN Policy Brief No. 6.http://www.sainonline.org/SAIN-website(English)/download/SAIN_%20Policy_Brief_No6_EN.pdf18. Ju, X, Lu, X, Gao, Z, Chen, X, Su, F, Kogge, M,Römheld, V, Christie, P, Zhang, F (2011) Processesand factors controlling N2O production in anintensively managed low carbon calcareous soilunder sub-humid monsoon conditions.Environmental Pollution 159: 1007-1016.19. Hu, T et al. (2014) Ammonia-oxidation as anengine to generate nitrous oxide in an intensivelymanaged calcareous Fluvo-aquic soil. ScientificReports 4: 3950.20. Intergovernmental Panel on Climate Change(2006) IPCC Guidelines for NationalGreenhouse Gas Inventories, Prepared by theNational Greenhouse Gas InventoriesProgramme, eds Eggleston H S, et al. (Institute forGlobal Environmental Strategies,Hayama, Japan).21. Crutzen, P J, Mosier, A R, Smith, K A, &Winiwarter, W (2008) N2O release from agro-biofuel production negates global warmingreduction by replacing fossil fuels. AtmosphericChemistry and Physics 8: 389–395.


scientific22. Davidson, E A (2009) The contribution ofmanure and fertilizer nitrogen to atmosphericnitrous oxide since 1860. Nature Geoscience 2:659–62.23. Brentrup, F, & Palliere, C (2008) GHGemission and energy efficiency in Europeannitrogen fertilizer production and use. Proceedingsof the International Fertilizer Society, 639, 25 pp.24. Connor, D J (2008) Organic agriculture cannotfeed the world. Field Crops Research 106: 187–190.25. van Groeningen, J W, Velthof, G L, Oenema,O, van Groeningen, K J, & van Kessel, C (2010)Towards an agronomic assessment of N2Oemissions: a case study for arable crops. EuropeanJournal of Soil Science 61: 903-913.26. Zhang, W-F, Dou, Z-X, He, P, Ju, X-T, Powlson,D S, Chadwick, D R, Norse, D, Lu, Y-L, Zhang, Y,Wu, L, Chen, X-P, Cassman, K G. & Zhang, F-S(2013). New technologies reduce greenhouse gasemissions from nitrogenous fertilizer in China.Proceedings of the National Academy of Sciences,USA 110: 8375-8380.27. Powlson, D S, Zhang, F S, Zhang, W F, Huang,J, Norse, D, Chadwick, D R., & Lu, Y (2012)Policies and technologies to overcome excessiveand inefficient use of nitrogen fertilizer: delivering

multiple benefits. Sain Policy Brief No. 5.http://www.sainonline.org/SAIN-Website(English)/download/PolicyBrief%20No%205%20Feb%202012.pdf 28. Kottagoda, N Munaweera, I, Madusanka, N,Sirisena, D, Amaratunga, G A J, & Karunaratne, V(2012) The advent of nanotechnology in smartfertiliser. World Agriculture, 3 (1): 27-31.29. Watson, C J, Laughlin, R J, & McGeough, K L.(2009) Modification of nitrogen fertilisers usinginhibitors: opportunities and potentials forimproving nitrogen use efficiency. Proceedings ofthe International Fertiliser Society, 658, 40 pp.30. Hu, R, Cai, Y, Chen, K Z., & Huang, J (2012)Effects of inclusive public agricultural extensionservice: Results from a policy reform experiment inwestern China. China Economic Review 23: 962-974.31. Jia, X P., Huang, J K., Xiang, C, Hou, L K,Zhang, F S, Chen, X P, Cai, Z L. & Bergmann, H(2013) Farmer's adoption of improved nitrogenmanagement strategies in maize production inChina: an experimental knowledge training.Journal of Integrative Agriculture 12: 364-333.32. Huang, J, Xiang, C, Jia, X & Hu, R (2012)Impacts of training on farmers’ nitrogen use in

maize production in Shandong, China. Journal ofSoil and Water Conservation 67: 321-327. 33. FACTS scheme for training and certification ofadvisers in plant nutrient management in the UK.https://basis-reg.com/facts/default.aspx34. Xinhuanet (2014) FACTBOX: China's 11 No.1central documents on agriculturehttp://news.xinhuanet.com/english/china/2014-01/19/c_133057374.htm

AcknowledgementsThis work was mainly derived from acollaborative China-UK project fundedby the UK Foreign and CommonwealthOffice and co-funded by the ChineseMinistry of Agriculture. Some aspectswere derived from projects funded bythe Chinese Academy of Sciences andthe UK Biotechnology and BiologicalSciences Research Council (BBSRC)through grant-aided support toRothamsted Research.

Longji rice terraces, Guangxi province, China © air – Fotolia.com


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Agroecosystem management inarid areas under climate change:

Experiences from the SemiaridLoess Plateau, China

Dr Rui-Ying Guo, Professor Feng-Min Li*State Key Laboratory of Grassland Agro-ecosystems, Institute of Arid Agroecology,

School of Life Sciences, Lanzhou University, Lanzhou 730000 China.Corresponding author: Feng-Min Li, E-mail: [email protected]

SummaryThe Loess Plateau is the cradle of ancient Chinese civilization and a place where dryland agriculture originated; it is also oneof the world’s most vulnerable ecological systems with the most serious soil erosion problems. The plateau has supported apopulation of more than 100 million and over 70% of which are rural and are relatively weak. Dryland agriculture hasplayed a key role in providing sufficient food for the inhabitants, as well as , environmental conservation and economicdevelopment of the Plateau over the history. It is now facing a considerable challenge from climate change with drier andwarmer environment. In order to reverse the serious ecological degradations, especially the significant water loss and soilerosion, the Chinese Government initiated a series of major ecological engineering projects to control the environment. Thefour significant ecological engineering included 1) a terracing system as a vital tool for agricultural production; 2) a checkdam system, constructed in loess gullies to block and collect sediment to prevent its loss to downstream and for croplandimprovement; 3) an integrated small watershed control system including dryland farming techniques, water and soilconservation system, and animal husbandry; and 4) the Grain-for–Green project in the plateau, returning slope croplands tograssland or forest to increase vegetation coverage and control water loss and soil erosion since 2000. Rainwater harvestingtechnologies in various forms are becoming the central dryland farming model to improve the efficient use of precipitation,which includes limited irrigation system and ridge-furrow mulching technologies. The grain yield and local farmer incomehave been increasing rapidly since 2000 due to the efficient rainwater use technologies, especially in recent 5 years. Theincreasing migration of rural residents to cities for jobs, with rapid urbanization in the recent decades, has alleviated thepopulation pressure in rural areas. With less cropland needed to produce food for the residents, greater amounts ofcropland have been returned to grassland or natural vegetation. Therefore, dryland farming technologies, and urbanizationindirectly, have benefited the sustainability of the semiarid Loess Plateau.

Key wordsDryland agriculture, Loess Plateau, low cost, climate change, sustainable development

Abbreviations RFMTs ridge-furrow mulching technologies; RFRRH ridge–furrow rainwater-harvesting system; LPR Loess Plateau Region;NH Northern Hemisphere

GlossaryIsohyets: This refers to a line drawn ona map connecting points that receive

equal amounts of rainfall.Orogeny: This refers to forces andevents leading to a large structural

deformation of the Earth's lithosphere(crust and uppermost mantle) due tothe engagement of tectonic plates.

Introduction

The Loess Plateau in China is oneof regions where drylandagriculture originated to meet

the food requirements of a growingpopulation (1).

It is one of the areas with serious soilerosion, which is closely related to theextensive operation of drylandagriculture. Thousands of years ago,the main landforms of the LoessPlateau were expansive flat plateauswith few gullies, and where the forest

cover was up to 53% (2-6). Withpopulation growth, large areas ofnatural vegetation (forest, shrub andgrassland) had to be converted tocultivation to increase grainproduction, and eroded sloping areasincreased greatly. Forest coverage wasreduced from over 50% about 2000years ago to 33% about 1500 yearsago and then to 6.1% by 1949 (3).Soil erosion accelerated as a result ofthe loss of nature vegetation.

For a long period, agriculturalproduction of the Plateau was weak

and unstable which, together withpopulation increase, in caused foodshortages and impoverishment of thepeople. Since the founding of the P RChina in 1949, the CentralGovernment has made unremittingefforts, promulgating a series ofpolicies and measures to boost localrestoration of degraded ecosystemsand improve the livelihoods of thepeople. In the last decade, with therapid development of urbanization, alarge number of local peasants havemigrated to cities for work, which to .


scientificsome extent has reduced ruralpopulation pressure. At the same time,the development of low-costintegrated dryland agriculturetechnology, mainly aims at efficientusage of precipitation, has resulted insignificant improvement of agriculturalproduction and the standard of living.

The recent Grain for Green Programimplemented by the CentralGovernment has led to significantchanges in environment and farmingproduction on the Plateau and broughtabout sustainable ecological restorationand improvement of production (7-8).The conceptual change on theagriculture in the Plateau representsthe development in dryland areas ofChina in the last 60 years, especiallythe development paradigm of theLoess plateau from productivity toecological function(9).This papersummarizes agricultural techniques,patterns, and models of the Plateau,describes the evolution of drylandagriculture with the uniquecharacteristics of traditional methodsand modern progress and discuss thepotential link between drylandagriculture and climate change. Itfocuses on two aspects: (1) therelationship of environmentalmanagement and dryland agricultureof the Loess Plateau of China over thelast 60 years and (2) the interactionbetween ecology and production inseeking sustainable development.

2 Regional backgrounds2.1 The formation and geomorphologyof the Loess PlateauThe Loess Plateau is located on theNorth central region of China, atlatitude 34°~40°, longitude 103°~114°.

The plateau stretches over 1,000 kmfrom east to west, and about 700 kmfrom north to south, including theareas west of the Taihang Mountains,Northeast of Tibetan Plateau, north ofthe Qinling Mountains and south ofthe Yinshan Mountains. The plateauoccupies parts of Shanxi, Shaanxi,Gansu, Qinghai, Ningxia, InnerMongolia, Henan and some otherprovinces, a total area of about640,000km2 (Fig. 1), with theelevation range from 800 to 2,400 m.

The formation of the Plateau and theHimalayan orogeny are closely related(10). The Himalayan orogeny led notonly to the formation of the TibetanPlateau, but also to the uplift of theQinling Mountains, hindering thenorthwest cold air mass fromspreading south, and the southeastwarm wet snap from spreading north.The Himalayan orogeny caused the

gradual strengthening of the northwestwind during the winter, and in Springit blew dust up to more than 3,000 min altitude to inland arid desert regionsof Central Asia, causing the southeastwind drift. Owing to interference ofthe southeast monsoon and the barrierand interception of the QinlingMountains, Liupan Mountains, LvliangMountains and Taihang Mountains, thewind was dissipated, depositing itsdust along the Yellow River and henceforming the thick loess (11). Duringthe Pleistocene (from about 2,588,000to 11,700 years ago), the TibetanPlateau rose to its current height andeventually formed the northwest aridregion. As the climate became drierand cooler, Malan loess accumulatedmore rapidly by wind action,eventually creating the total area of640,000km2 of loess in northern Chinaand a spectacular Loess Plateau alongthe middle reaches of the Yellow River(12).

Apart from a few rocky mountains,the Loess plateau is covered with thickloess that has a thickness between 50to 80m, and even up to 150 to 180m.The texture of loess is exquisite anduniform, and the particle size is only1~10mm. The Plateau is an area ofcracked-terrain land, which is mainlydivided by ravines and hills. Thisterrain accounts for about 90% of thearea covered by Loess. In the centre ofthe thickest loess area, there are severalrelatively flat plateau surfaces betweenthe rivers Jinghe, Luohe, Marin and afew sections of the Puhe. The topsurface of the plateau is relatively flat,but some areas are eroded to thevalleys with steep sides. The tablelandarea of Plateau has reduced by soil

erosion to less than 10% of the totalarea of Loess Plateau (13).

2.2 Climatic characteristics anddistribution of dryland farming of theLoess PlateauThe southeast monsoon frequents thenorthwest arid area of the ChineseLoess Plateau (14) and the annualaverage temperature is 8.8°C (spring10.0°C; summer 20.9°C; autumn 8.8°Cand winter -4.6°C) (13).

From 1957 to 2009, the averageannual precipitation of the LoessPlateau region was 434 mm (15), witha general trend of more precipitationin the south than in the north, andmore in the east than in the west, anda decrease progressively fromsoutheast to northwest (Fig. 2) (15).Most rain falls in the summer (June toAugust), accounting for 50%~65% ofthe annual precipitation. Autumn(August to November) accounts for13%~23%, spring (March to May)accounts for 18%~32% and winter(December to February) is the least-about 5% (16). The rainy season (Mayto September) accounts for 78%~92%of the total annual precipitation (16).

Arable land of the Loess Plateaucovers about 1 458.159 x 104 ha (17).Data for the year of 2008 showed thatfarmland with slopes greater than 5°accounted for 31.21% of the totalcultivated area, in which areas with5~15° inclines accounted for 42.14%,15~25° accounted for 19.38%, and>25° for 7.27% (17).

The irrigated farmland covers only25.2% of the total arable land, mainlydistributed in west Inner Mongolia andWeihe river plain areas.

Figure 1. Maps showing location and coverage of the Loess Plateau.


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The rainfed agriculture sectoraccounts for more than 70% of thecultivated area, mainly distributed inthe semi-arid hilly areas withprecipitation range 250~550 mm peryear.

2.3 Changes in the Climate of theLoess PlateauBased on the dataset of 224 weatherstations on the Loess Plateau, from1961 to 2010, the averagetemperature increased significantly(1.91°C/50yr), a greater increase thanin the overall northern hemisphere(18). By 2030, the temperatures inNorthwest China may be further raisedby 1.9~2.3°C (19). However, theoverall change in precipitation over theLoess Plateau has not been significant,whereas the precipitation significantlydecreased by 47.6 mm per 10-year inthe southeast region. According to therainfall data of 89 weather stations onthe Plateau, the precipitation over theentire Plateau fell by 49.1 mm over the52 years from 1957 to 2009 (Table1)(15).Spring, summer and autumnexhibited no significant difference indecreasing trend of precipitation, withan average reduction rates of -0.09mm/a, -0.57 mm/a, -0.19 mm/a,

respectively (16).Since the 2nd century B.C., a trend

of increasing drought has been themain climatic observation (20). Thefrequencies of drought years haveconsistently increased in the Plateau. Inthe Sui and the Tang dynasties in the6-9th century, the proportion of dryyears was less than 17%. From then onthe probability increased progressively:27% in the 10th~14th century; 43% inthe 15th~17th century; 46% in the18th century, and >51% since the1830s (11). An increasing arid climatictrend is bound to have a significantimpact on the ecosystem of thePlateau.

2.4 Ecological degradation and povertyin the Loess PlateauThe Plateau is the cradle of ancientChinese civilization and is one of theworld’s most vulnerable ecologicalenvironments. The area of soil erosioncovers 45.4x104km2 and accounts for60% of the total Plateau area (of whichwater erosion covers 337,000 km2, andwind erosion 117,000 km2) (21). Theannual loss of soil is estimated a to be2,000 - 2,500 tons km-2 (22). Themain reasons for the soil erosion onthe Loess Plateau are drought, heavy

rain in the summer, steep terrain, loosesoil and sparse vegetation (23). In thisenvironmental context, over-exploitation and unsustainableagricultural practices included bypopulation growth, such as farming onsteep slopes, deforestation,overgrazing, has led to severeecological degradation. The lost inecological function of waterconservation has led to further erosion(6, 23) and decrease of fertility (24-25). According to the Loess Plateauforest distribution map in differenthistorical periods, the coverage offorest declined from 53% (770B.C.~221B.C.) to 42% (221B.C. ~A.D.8), to32% (A.D.618~A.D.279) and to 4%(A.D.1386~A.D.1911) (26). Somespecies disappeared with thedestruction of vegetation by humanactivity over nearly 600 years (27).

Ecological degradation exacerbatedthe impoverishment of people living inthe Plateau. According to 2008statistics, the total population of thePlateau was 108 million, of which therural population was 73.33 million(17). The population density of thePlateau was 167 people per squarekilometer, equivalent to 1.229 times ofthe national average. The GNP of thearea was 1.85 trillion RMB, and ruralper capita net income was 3,196 RMB(17). In 2001, the State Councilapproved a national poverty alleviationand development plan for 592counties, of which the Loess Plateauregion accounted for 115 counties(17). In order to survive, people haveto reclaim land, and as a consequence,enter a vicious cycle of ‘the poorer, themore cultivated; the more cultivatedand the poorer.’ Therefore, how toreduce soil erosion, and improve thequality of soil and environment, is atask that must be confronted andsolved in the Plateau.

3 Four ecologicalengineering constructionson the Loess PlateauResidents and governments have madetremendous efforts to reduce soilerosion in the Plateau region, promoteecosystem restoration andreconstruction, and promote acomprehensive development ofagriculture, forestry and animalhusbandry.

Through an accumulated wealth ofexperience, the major ecologicalprojects include terracing, constructionof a check dam, small watershedmanagement, and Grain for Green

Figure 2. The distribution of mean annual isohyets from nearly 830 mm in thesoutheast of the Loess Plateau to nearly 100 mm in the northwest in 1957-2009(Wan et al., 2013)

Table 1. The variations in annual precipitation (mm) in different decades acrossthe Loess Plateau, China (Wan et al., 2013).


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project (Returning farmland to forestand grass). These projects and valuableexperience have played important rolesin promoting sustainable developmentin the region.

3.1 TerraceTerrace is a kind of farmland built on ahill, which in general is divided intofour types in the Plateau, namelysloping terrace, interval terrace, flatterrace and back-slope terrace (Fig. 3)(28). Terrace in the watershed of theYellow river has a long history. There isterraces dating documented andverifiable, back to the Ming and Qingdynasty (1368~1840), and there arehundreds of thousands of terracedhectares of historical legacy. After the

founding of New China, governmentsof all levels have paid attention to theconstruction of terrace over the last 60years. Before 1958, the terrace wasmainly built on the hill; after 1958,mainly constructed as level terrace,and since 1990, mechanized levelterracing has been adopted andconstruction efficiency was greatlyimproved (29). The statistics of 2008showed that the area of terracedlandscape on the Plateaucovered325.6x104 ha, accounting for22.33% of the total arable land area(1458.159x104 ha) in the Plateau (17),and it is expected that over the periodof 2010~2030, 260.8x104 ha of landwill be terraced (17).

Terracing is the primary step forfarming on the Plateau. Terraced slopecan be altered to reduce the slopelength and increase rainfall infiltrationrate, enhancing soil water storage,improving the efficiency of water andnutrient use (4, 6, 30-32). From 1951to 1995, retention of water of theYellow River basin by terrace reached19 billion m3, which accounting for23.4% of the total storage capacity ofsoil and water conservation (81.27billion m3) (29).

A large number of tests have shownthat terraced water efficiency and soilconservation benefit could haveattained 86.7% and 87.7%,respectively (Table 2). Effects of waterand soil conservation by terraces havea very close relation with theprecipitation. For example, when thesingle rainfall integrated parameters,annual rainfall and flood flow rainfallwere less than 2010 mm2/min, 350mm and 125 mm, the benefits of thesoil and water conservation by theterraces could reach 100% (33-34). Forexample, when the rainfall synthesisparameter PI, rainfall in flood period,annual rainfall of runoff generationwere less than 20.0 mm2/min, 350mm and 125 mm, respectively, thebenefits of the soil and waterconservation by the terraces couldreach 100% (34). However, theconservation benefits of terraces wouldbe lower when rainfalls were larger.

Figure 3. Diagrammatic map of four types of terrace in the Loess Plateau

Table 2. The benefits of soil and water conservation of flat terrace on the Loess Plateau (Wu et al., 2004).


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Terrace level also affects the quality ofsoil and water conservation.

The terraces on the Plateau may bedivided into three quality categoriesaccording to their soil and waterconservation benefits (35). Category 1is best quality, in which soil and waterconservation benefits are 87% and90%, respectively; Category 2 is goodquality, the both benefits are 82% and85%, respectively; Category 3 is poorquality with both the benefits of 76%and 78%, respectively (35). Theconstruction of terraces greatlyincreased crop yields (Table 3)(36,37,38). Terraces not only increaseconventional crop yields but alsoaccelerate the development of cashcrops, including vegetable, fruit andpotato production on the Plateau, andincrease per capita income (Fig. 4)(37). Due to agricultural developmenton terraces, the population carryingcapacity of the Plateau also increasedfrom the 148 people/km2 to 374people/km2 (37). The construction ofterraces also provides convenientconditions for the optimization offarming technology and has aprofound impact on regional

sustainable development.

3.2 Check dams in the Loess PlateauA check dam is considered the mosteffective way to reduce soil erosion inthe river (39-40).

Soil erosion in the Plateau is mainlyderived from the slopes and riverbanks. In the loess gully region, theproportion of the total sedimentdeposited from the river banks is 90%,i.e. 9 times the amount deposited fromthe slopes (41-43).The check damblocks the transport of sediment to thedownstream area and collecting thesediment. The check dam raises thebase level of slope’s bottom, reducesthe soil erosion, and effectivelyprevents the soil of cutting. The checkdam prevents the gully bank’s erosion.Check dams block the sediments effluxfrom slopes area to the gully area (44).Dams have a history similar to that ofthe terraces, dating to the MingDynasty. Renowned water resourceexpert, Li Yizhi, who advocated the‘Gouxu’theory to manage the YellowRiver, and introduced check dams aspart of a strategy to govern the River.In 1945, China invested in the first

‘government-run’ check dam (29).Since 1949, the construction of checkdams has reduced the water and soilloss of the Plateau (45-46). In the last50 years of the 20th century, morethan one hundred thousand of checkdams have been built in the Plateau(5). In 1983, the ‘Key conservation ofsoil and water in the Gullies’ projectconducted a three-year experiment todevelop appropriate planning, andtechnical specifications and regulations(Table 4) (44). Since theimplementation of this ‘Key Gully Plan’in 1986, 1,118 of check dams wereestablished since then till 1999 on thePlateau (45). However, it is expected totake another 100 years to completethe remaining construction ofapproximately 130,000 check dams(5).Dams constructed in the Yellow Riverregion (1951~1952) held back 9.6billion m3 of water accounting for11.8% of the total impeded byconservation measures. The effect ofintercepted sediment and reducedrunoff is closely related to the height ofeach check dam. According to thestatistics of 4,877 check dams, thosewith heights of 5~10, 10~15, 15~20,20~25 and 25~30m, had sedimentinterception efficiencies of 13.5%,27.9%, 38.3%, 42.0% and 48.4%respectively, and efficiencies of runoffreduction of 1.97%, 4.63%, 7.26%,6.37% and 7.73%, respectively (33). Check dams have become a uniquecharacteristic of the Chinese LoessPlateau. They play an important rolenot only ecologically, but also in grainyield. Dams produce high fertility andsoil moisture (5, 47). Grain output istypically increased the by 8~10 fold (5,41)and even up to 16 fold (48) that ofthe hilly farmland. Planting around 1ha of dam is equivalent to planting on2~3 or 5~6ha of terraced slopes (48).

Table 3. Crop production and increases compared with yields in sloping fields >10o on terraced land constructed indifferent years (Liu et al., 2011).

Figure 4. Farmers income per capita (Yuan) during 1985-2005 in ZhuanglangCounty, Gansu Province, China. (Construction of large-scale terracing across theentire Zhuanglang County started in the 1960s, and in 1998 almost the entirecounty was terraced. The terraced fields accounted for 95% of the total arableland) (Liu et al., 2011).


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A study of the World Bank LoanProject for Yan River WatershedManagement (1994 to 1996) showedthat the input rates of dams, terraces,irrigated agricultural land were 3.3, 2.4and 4.2 times that of hilly land,respectively, while their net benefitswere 12.8, 5.1 and 13.2 times that ofthe inclined land, respectively (29).Although the check dam has asignificant role in reducing gullyerosion and increasing agriculturalproduction, it is still controversial. Fourreasons are for this point. (1) Checkdam construction requires a substantialinvestment in financial and humanresources. (2) Due to insufficientfunding, the construction quality of amajority of check dams is poor, so thecollected sediment is unlikely toprevent flooding and may evenexacerbate soil erosion. Owing to thispoor quality, following a prolongeddrought, in 1977 and 1978 they weresubject to frequent rainstorms, and itwas estimated that more than 80% ofthe dams were destroyed (5), leadingto fulminant and serious soil erosion.(3) Following dam construction,agricultural production is facingenormous challenges. Because of poordrainage of new farmland near dams,nearly 33.3%~50% of the dams innorthern Shaanxi and western Shanxisuffered from salinization, causinggrain losses of 50 million kg. (4) Thelong-term ecological impact and roleof this large-scale human check dam’sintervention in the Plateau is unclear(5). Therefore, the large-scalepromotion of check dam constructionneeds careful consideration fromengineering, technical and ecologicalangles for farming. In more recenttimes during China's economicdevelopment, the materials andtechniques of check dam constructionhave been developed considerably and

can effectively prevent storm erosion.Nevertheless, check dam constructionrequires a lot of human resources, andit continues to be an enormousfinancial burden (49).

3.3 Integrated management of smallwatersheds in the Loess PlateauThe integrated watershed control ofsoil erosion is a summary of longexperience, and lessons learned.

Early comprehensive treatment ofwatersheds was applied in manycountries during the 19th century (50-52), and proved to be a practicaltechnology which could reduce soilerosion and enhance ecosystemresilience (53). The integratedwatershed system is considered a smallwatershed as a unit, according to thecharacteristics and patterns of soilerosion, local conditions, farmlandfortification, engineering measurestaken, plant measures combined withagricultural technical measures,comprehensive management oflandscape, farmland, forest and roads,rational use of rainwater and landresources, optimizing structure ofagriculture, forestry and animalhusbandry (23).There are more than one million smallwatersheds in Yellow River Region, andeach watershed is from a wholegeographical unit, where thegeneration of sediment transport froma small basin. There is a need toconsider all of the major factorscontrolling soil erosion for ‘integratedwatersheds’. These include farmlandconstruction, commercial forestry, fuel,protection of woodland planting, soilconservation, adjustment ofagricultural structure and needs oflocal people (23). It combine reductionof soil erosion with local economicgrowth, applying a variety of effectiveecological engineerings (terracing,check dams and soil reservoirs) and

environmental managementtechniques (contour farming and strawmulch) (5). These measures started inthe 1980s, coordinated the ecologicalrestoration and increase of productivity(54). By 2000, these projects havebeen carried out in more than 5 000basins (5). The CAS Institute of Soiland Water Conservation and otherrelevant organizations in ShaanxiProvince have built 5 models, and 11comprehensive managementdemonstration areas, achieving goodeconomic and social benefits. The totalloss of soil in 11 typical watershedsreduced by 50%~90%, and crop yieldsincreased significantly.Nevertheless, the implementation ofintegrated small watersheds in thePlateau presents problems. First, thisproject will require substantial externalfinancial, material and humanresources (5). Second, there are morethan a million small watersheds in thePlateau that has been costly. Thus,although small watershedmanagement in the area has gainedremarkable success, it has been tooslow to relieve environmentaldeterioration. Thus, at present theecological status of the Loess Plateau isstill deteriorating overall, despite some‘partial improvements’ (55).

3.4 Grain for Green projectGrain for Green project is a largeecological engineering aiming atecological restoration and soil erosionreduction in China (56).

According to regulations, thefarmland in slope with the gradient>25° for southwest and >15° fornorthwest in China, respectively,should be replaced with grasses andtrees. Farmers participating in theproject receive grain, treeing seedlings,grasses seeds and cash ascompensation provided by thegovernment (57).

The pilot project of Grain for Greenwas carried out in 1999 in Sichuan,Shaanxi and Gansu provinces, andformal project began from 2002. Theproject involved 25 provinces and1897 counties in China. Till now, Grainfor Green project is an ecologicalengineering with strongest policy andbecame the world's largest ecologicalengineering (56).Grain for Green project has changedthe local employment and incomestructure (58). For example, in WuqiCounty, the proportion of the laborforce engaged in the cultivation beforethe ‘Grain for Green project’ was87.82% in 1998, fell to 19.16% in2006 (58).

Table 4. Scheme for the check-dam systems, including numbers of key projectsand check dams in the Loess Plateau (Huang, 2000)


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The proportion engaged in animalhusbandry raised from 6.3% to 24.6%,but there´s a significant decline in herdsizes, because the grazing leads tohigher costs of feeding and raisingforage shortages. The main laborreduced from agriculture moved to therelatively high income industries suchas building construction, catering,transportation and other non-agricultural industries. After returningfarmland, the compensation incomebecomes the main source of income oflocal farmers, followed by familiesoperating income and subsidy ofreturning farmland to forest, the ratiowere 48.31%, 27.39% and 24.30%.The grassland area increased 20.3%,the forest area increased by 13.786times (58).

The main three factors guarantee thesuccessful implementation of Grain forGreen Project are. The first one isgovernment's high-handed policy,there’s a huge investment for thisproject. The second is the rapiddevelopment of China's economy andurbanization; this provides anopportunity for farmers who migrateto cities, they can get a higher incomethan farming at home, the land is nolonger their main income source. Thethird is great progress of drylandagriculture technology; it provide aguarantee to achieve enough food andhigher economic benefit in limitedlands (59). According to the projectplan, the government subsidies ofGrain for Green project will end in2018 (60). Thus, although thesustainability of Grain for Green Projectremains to be seen, but on the whole,it ought to help keeping thevegetation coverage, rural industrialstructure adjustment, in order to

promote the ecosystem reconstructionand sustainable development (60).

4 The development ofdryland agriculture in theLoess Plateau4.1 The significance of drylandagricultureDryland Agriculture is the main system,charged with the task of self-sufficiencyin the Plateau (42, 61).

Since China's central governmentimplemented the grain-for-greenproject in the plateau in 1999, thecultivated land area declined by 10.1%from 1996 to 2007, including adramatic decline of 15.15% from 1996to 2003 (62). From 2003 to 2007, thecultivated area increased by 5.95%compared with that in 2003. Between1996 and 2007 grain productivitydecreased by 3.76%, a lesser declinethan that of the cultivated area (62). Adramatic decrease of total grainproduction in Loess Plateau was about8.73% from 1996 to 2003, whereasbetween 2003 and 2007, grainproduction increased by 5.45% overthat in 2003, owing to an increase inthe area cultivated (62). In Gansuprovince, following the Grain-for–Green project, total grain yield, thegrain yield per unit area and the grainyield per capita all increased fairlyuniformly (Fig. 5). The improvement ofdryland tillage techniques increasedoutput per unit area (63-69).

Despite China’s grain productionpolicy, it was planned to restore theecology of western China while theprice of grain fell (70). However, anychange in grain production throughimplementation the policy shouldinclude local self-sufficiency (62), as

the people of the Plateau were verypoor (42). The Grain-for-Green projectprovides Government subsidies as amain income source for each farmhousehold but only until 2018. Aninvestigation of livelihoods indicatesthat 37.2% of farmers may re-cultivatethe ‘returning land’ in the Plateau (8).Therefore, improvement of drylandagricultural techniques relates to bothregional and China’s food safety, to thelivelihood of local people, to the pastachievement of Grain-for-Green Projectand to the ecological restoration of theLoess Plateau.

4.2 The development of drylandagricultural techniques in the LoessPlateauThe key to dryland agriculture isutilizing limited rainfall efficiently (71).

In a typical semi-arid region of thePlateau, the precipitation overfarmland distributes as follows:evaporation loses 50%~60% of rainfall;plant transpiration used 30%~40%rainfall; and about 10% rainfall lost asrunoff or by other routes (72). Theannual precipitation over the entirePlateau is about 3000 billion m3,which is equivalent to five times theamount needed in this area (72).Water-harvesting eco-agriculture is themain tillage mode to increase theefficiency of use of precipitation in thesemiarid Loess plateau (73).

A series of tillage techniques aredesigned for rainfall harvesting atminimal cost. These techniques aresuccessful examples for improvinggrain productivity in dryland ofdeveloping countries (74). The systemis based on traditional terraces andhorizontal trenches to gatherprecipitation. Either the rainwater isgathered into a underground cistern tosupplement irrigation at the criticalperiod of crop growth, or therainwater is drained into the cropplanting zone by the rainwaterharvesting surface, e.g. a plastic filmmulched ridge-furrow system, whichcan enhance the water supply in plantgrowth zone (75-77). The techniquecan improve rainfall utilizationefficiency in dryland.

4.2.1 Limited (supplementary)irrigation technique of the drylandLoess PlateauSupplementary irrigation was mainlydue to the farmer’s requirement of lowcost and a growing shortage of groundwater resource (78).

Limited irrigation achieved goodresults in the Midwest Great Plains inthe U.S., where the rainfall is about480mm annually.

Figure 5. The dynamics of total area of cropping land (104 ha), total grain yield(107 kg), grain yield per hectare (102 kg ha-1)and grain yield per capita(kg Hd-1)in the dryland area of Gansu Province (from 1993 to 2011, which included theYuzhong County, Huining County, Tianshui region, Pingliang region, Qingyangregion and Dingxi region) (the data are from Gansu statistical yearbook).


scientificExperiments showed that continuouscultivation of dryland is possible whenlimited irrigation (about 150mm) iscarried out at the critical stage of acrop’s water requirement.

Grain production could be increasedby over 60%, and water efficiencydoubled compared with an adequateirrigation treatment (78). In China,according to the local situation, someexpert defined the limited irrigation as‘according to the amount of availablewater resource in local area and waterrequirement of local crop, the managerconduct the lowest water supplyingbased on the natural rainfall condition’(72). In the hilly region of the Plateau,the irrigation water relies mainly onrainfall. Underground water tanks canbe established to collect rain andprovide supplementary irrigation at thecritical stage of crop growth.

In Gansu province, a typical semiaridregion of the plateau, a so-called ‘121’rainwater harvesting project had beeninitiated by the local government in1995. The government supported theconstruction by each household, onearea for water collection, two storageareas and one to plant cash crops (71).

This project has successfully provideddrinking water for 1.3 million peopleand their 1.18 million livestock. In1997~1998 a rainwater catchment andirrigation project was instituted toprovide supplemental irrigation waterwith a highly efficient method. Thisproduced higher crop yields (79-80)and full utilization of natural rainfall tosupport dryland agricultural withwater-saving irrigation (from 1997 to

2010). The system of water-harvesting has

been greatly improved developed anew water-tank system with low costspecifically for the semiarid LoessPlateau (81). Meanwhile, the water-harvesting technique was usedtogether with micro-irrigation,increasing the crop’s water useefficiency (34, 82). In addition, asimple supplemental irrigation, withlow cost such as wet sowing and holeirrigation with mulching, could furtherimprove the crop water use efficiency(71). Nevertheless, limited irrigationcould not be used widely for graincrops in the semiarid Plateau, becauseof the small quantities of rain collectedand the high cost of establishing thesystem (80). In order to benefit fromthe cost of an increase in supply ofunavailable water, it is recommendedthat supplemental irrigation should beused mainly for cash crops, e.g.potatoes and other vegetables.

4.2.2 Ridge-furrow mulching technolo-gies in the Loess Plateau Ridge-furrow mulching technologies(RFMTs) were proposed and innovatedby a local research worker in Gansuprovince (83).

In the central area of the Plateau inGansu province, the yields of wheat,oat, potato and pea are low andunstable (the spring wheat yield is2,250~3,000 kg per ha). In order toimprove farmers’ livelihoods, RFMTSare used to extend planting of maize inthe semi-arid Plateau. These RFWHSare based on the concept of gathering

and using rain in-situ (Fig 7). Bymodifying the micro-topography offarmland, limited rainfall is retained inthe furrow- the location of the croproot zone. Rain is redistributed in spaceat the field level (84). It is aninnovative technique for boosting cropproductivity in semiarid rain-fedenvironments (85).A field is cultivatedwith a wide ridge and a narrow ridge(‘double ridge’) before spring orautumn sowing, and then the entiresoil surface is covered by plastic film.The seeds are sowed in the furrowbetween broad and narrow ridges(Fig.6).

Maize grain yield on RFMTS couldreach 7 500~9 000 kg ha-1, higherthan other traditional crops, e.g.wheat, oat, pea and maize without filmcovering (86). RFMTS increase maizeyield by 30%~90% compared withnormal cultivation (86), and wheatyield by 100%~150% (75). In thecooler region of northwest China,maize cannot attain reproductivedevelopment in time to produce aviable cob, but with a plastic filmmulching the crop can be plantedearlier and it emerges earlier so thatreproduction is not compromised (67,86-87). The increased quantity ofmaize straw assists local livestockbreeding (88) and reduces grazingpressure on natural grassland. As aconsequence of the tremendousincrease in yield, the areas over whichRFMTS are used has graduallyincreased, and they have beenadopted for crops such as wheat andpotato (89-91).

Figure 6. Sectional view in ridge–furrow rainwater-harvesting system (RFRRH).


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From 2008, use of RFMTS has beenextended by the Ministry of Agricultureto Qinghai, Inner Mongolia, Ningxia,Shaanxi and Shanxi provinces.

Through long-term research andpractice, the best ratio of ridge, furrowand plastic covering time has beendetermined for various climates, soiltypes and crop water requirements(84, 92-93). Increased yields withRFMTS should be attributed to threefactors: (1) inhibiting waterevaporation from the soil surface andincreasing soil water content duringcritical stages of crop growth by theplastic film mulching (67,83,85); (2)increasing soil temperature, and henceaccelerating seedling emergence andearly growth in cooler locations (85,94) and (3) improving soil nutrientavailability, especially nitrogen (81).RFMTS contribute to rain use and cropyield where the annual precipitation isin the range of 230~440 mm (95).

RFMTS increase crop yield but withexcessive soil utilization (96). As aresult of increased soil temperature andmoisture content, soil microbial C andN biomass, soil enzyme activity, soilrespiration rate and nitrogenmineralization rate are all increased(92, 97-98). Thus, Li et al (99) reportedthat in an upland rice system soilorganic matter and total N could bereduced by 8.3%~24.5% and5.0%~22.0%, respectively, with filmcovering in contrast to that withoutthe film. Therefore, it is proposed thatthe application of RFMTS should becombined with increasing soil organicmatter content (100). The ‘white’pollution (plastic mulching waste) hasled to dispute in dryland application ofRFMTS. A few studies have focused onthe effect of plastic film residues oncrop yield and soil quality. It isestimated that about 45kg ha-1 yr-1 ofplastic film residues occur. Weconducted a pilot field experimentwith 10-year, 30-year and 60-yearaccumulative residue of plastic film in

Zhonglianchuan and Xiaguanying,Yuzhong County, Gansu province. Thecorresponding amount of plastic filmresidue was 450kg ha-1, 1,350 kg ha-1

and 2,700 kg ha-1, respectively. Thefilm was shredded and incorporatedinto the field. The preliminary resultshowed that this residue has nosignificant influence on maize yield incontrast with the treatment withoutfilm incorporation (Table 5,unpublished data). But further researchshould be conducted on the effect offilm residue on crop yield and soilquality over extended periods.

5 ConclusionsThe two key driving forces ofecological degradation in semi-aridareas of the world are nothing morethan climate change and unsuitablehuman activities.

Climate change has resulted in drierand warmer in the Loess Plateau. Thisleads to a decline in vegetation andthen to a series of environmentalissues. Unsuitable human activitiesimplies that in order to increase foodproduction or land income for riddingthe local poverty, the people have tocultivate and over-graze more land,which results in damage tosustainability of the ecosystem, andthen in its further degradation.Ecological degradation enlarges thegap between demands of local peopleand ecosystem services. This leads tofurther aggravated predatory landreclamation, and a vicious cycle ofecological degradation occurs.

The primary way to overcome theecological problems is to increase unitland productivity so that a fewer areaof cultivated land meets the needs ofthe local population. This procedurealleviates the ecological pressure,providing the space for its ecologicalrestoration.

The Loess Plateau Region is a uniquearea with an historic accumulation ofloess. Excess land reclamation and

over-grazing for food productionresulted in an extensive environmentaldegradation, causing widespreadpoverty that has plagued the localgovernment and people for manydecades. Since P R China was foundedin 1949, the Central Government andsocial organizations have paid muchmore input to the development of theplateau, and taken a series of measuresincluding the application of ecologicalengineering and improvement ofagricultural techniques. However, thisregion was still impoverished andecological deterioration continuedbefore the turn of the new century.

From the year 2000, dryland farmingproductivity on the plateau hasincreased significantly and livelihoodgreatly improved with the farmingdevelopment of new techniques ofhigh rainfall use efficiency. Meanwhile,the progress of China’s economy haspromoted a rapid urbanization andmore and more local young residentsmove to cities to find jobs. Bothmovements are the main driving forcesto land use change and ecologicalrestoration. The local people can useless land than before to feedthemselves and improve their livingstandard. A greater area has beenreturned to grassland or naturalvegetation. The area of vegetation hasincreased while the climate hasbecome drier and warmer.

The change of the pattern of land useshows a new promise for the LoessPlateau, and it contributes to thestrategy of “large land for ecologicalrestoration and small land for farmingproduction” in the Loess Plateau.However, there is still a long way to gofor dryland farming development ofthe Plateau owing to uncertainty andfuture challenges of climate changes.More research and further positivemeasures should be taken to establishnew complex ecosystems and realizethe harmony of production andenvironment in the context of climatechange.

AcknowledgementThe authors are grateful to Dr FrapeDavid for his patient advices and to DrPete Falloon for his valuablecommentary. This research wassupported by program of ChineseMinistry of Science and Technology(2011BAD29B04), MOST InternationalSci-Tech Cooperation Program(2010DFA32790), ‘111’ Project(B0751), and the FundamentalResearch Funds for the CentralUniversities (lzujbky-2010-k02,860974).

Table 5. The effect of plastic film residue into soil on maize production (kg/ha)(unpublished data from Li’s group of Lanzhou University), modeling after 0 to 60years by F0, F10, F30, F60, measured during two years (2012, 2013)


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scientific61. Liu, C. A., Zhou, L. M., Li, F. M., Jin, S. L.(2009). Effects of plastic film mulch and tillage onmaize productivity and soil parameters. EuropeanJournal of Agronomy. 31(4): 241-249.62. Zhou, L. M., Li, F. M., Jin, S. L., Song, Y. J.(2009). How double ridges and furrows mulchedwith plastic film affect soil water, soil temperatureand yield of maize on the semiarid Loess Plateauof China. Field Crops Research. 113(1): 41-47.63. Zhao, H., Xiong, Y. C., Li, F. M., Wang, R. Y.,Qiang, S. C., Yao, T. F., Mo, F. (2012). Plastic filmmulch for half growingseason maximized WUEand yield of potato via moisture- temperatureimprovement in a semi-arid agroecosystem.Agricultural Water Management. 104(1): 68-78.64. Zhou, D. C., Zhao, S. Q., Zhu, C. (2012a).TheGrain for Green Project induced land coverchange in the Loess Plateau: A case study withAnsai County, Shanxi Province, China. EcologicalIndicators. 23: 88-94.65. He, M. J., Zheng, S. F., Li, H. (2008). Analysison rural economic restructuring after rehabilitatingplough to forest (grassland)-based on WuqiCounty in Shaanxi province. Journal of Northwest A& F University (Social Science Edition). 8(4):21-26.66. Li, L. (2007a). Economic post-evaluation of "1-2-1" Rainwater Harvesting Project in GansuProvince. China Rural Water and Hydropower. 9:50-52.67. Shan, L. (2002). Development Trend ofDryland Farming Technologies. Scientia AgriculturaSinica. 35(7): 848-855. 68. Li, F. M., Xu, J. Z. (2002). Rainwater-collectingeco-agriculture in semi-arid region of LoessPlateau. Chinese Journal of Eco-Agriculture.10(1):101-103.69. Gosar, B., Baricevic, D. (2011). Incorporationof a ridge-furrow-ridge rainwater harvestingsystem with mulches in high-value plantproduction. Irrigation and Drainage. 60: 518-525.70. Li, F. M., Guo, A. H., Wei, H. (1999a). Effectsof Plastic Film Mulch on the Yield of SpringWheat. Field Crops Research. 63(1): 79-86.71. Zhang, Y. F., Wang, Y. F., Liu, L. X., Hou, X. Y.(2002). Research progress on arid-land agriculturein northern China. Geographical Research. 21(3):305-312.72. Zhao, X. N., Wu, P. T., Feng, H., Wang, Y. K.(2009). Advance in research of supplementalirrigation of collected rain water for eco-agriculture in semi-arid Loess Plateau of China.Scientia Agricultura Sinica. 42(9): 3187-3194.73. Steward, B. A. (1983). Yield and water useefficiency of grain sorghum in a limited irrigation-dryland system. Agronomy Journal. 75: 629- 634.74. Zhu, Q., Li, Y. H. (1998). On rainwatercatchment and utilization. Proceedings of theInternational Symposium and 2nd NationalConference on Rainwater Utilization. Xuzhou,China.75. Li, F. M., Zhao, S. L., Duan, S. S., Gao, S. M.,Feng, B. (1995). Preliminary study on limitedirrigation for spring wheat field in semi-arid regionof loess plateau. Chinese Journal of Applied Ecology.6(3): 259-264.76. Wang, G. Z., Gao, J-En., Xiao, K. B., Fan, H.H., Yang, S. W., (2008). Monitoring analysis onwater quality change of a new kind of rubber-plastic cellar. Agricultural Research in the Arid Areas.26(2): 150-153.77. Hou, X. Y., Wang, F. X., Han, J. J., Kang, S. Z.,Feng, S. Y. (2010). Duration of plastic mulch forpotato growth under drip irrigation in an aridregion of Northwest China. Agricultural and ForestMeteorology. 150: 115-121.78. Zhao, H., Wang, R-Y., Ma, B-L., Xiong, Y-C.,Qiang, S-C., Wang, C-L., Liu, C-A., Li, F-M.(2014). Ridge-furrow with full plastic filmmulching improves water use efficiency and tuberyields of potato in a semiarid rainfed ecosystem.Field Crops Research. 161: 137–14879. Li, S. Q., Li,F. M., Song, Q. H., Wang, J. (2001). Effects of

plastic film mulching periods on the soil nitrogenavailability in semiarid areas. Acta Ecologica Sinica.21(9): 1521-1526.80. Gan, Y. T., Kadambot H. M., Siddique, Turner,N. C., Li, X. G., Niu, J. Y., Yang, C., Liu, L. P., Chai,Q. (2013). Ridge-Furrow Mulching Systems—AnInnovative Technique for Boosting CropProductivity in Semiarid Rain-Fed Environments.Advances in Agronomy. 118: 429–476.81. Hai, L. (2010). Effects of plastic-film mulchingon maize yields and soil quality in the semi-aridLoess Plateau of China. PhD thesis, LanzhouUniversity.82. Jin, S. L., Zhou, L. M., Li, F. M., Zhang, G. Q.(2010). Effect of double ridges mulched with wideplastic film on soil water, soil temperature andyield of corn in semiarid Loess plateau of China.Agricultural Research in the Arid Areas. 28(2):28-33.83. Zhang, W. S., Li, F. M., Xiong, Y. C., Xia, Q.(2012). Econometric analysis of the determinantsof adoption of raising sheep in folds by farmers inthe semiarid Loess Plateau of China. EcologicalEconomics. 74:145-152.84. Wang, Q., Zhang, E. H., Li, F. M. (2004a).Runoff efficiency and soil water comparison ofplastic-covered ridge and ridge with compactedsoil at different rainfall harvesting stages insemiarid area. Acta Eologica Sinica. 24(8): 1816-1819.85. Wang, X-L., Li, F-M., Jia, Y., Shi, W-Q. (2005c).Increasing potato yields with additional water andincreased soil temperature. Agricultural WaterManagement. 78(3): 181- 19486. Tian, Y., Li, F. M., Liu, X. L. (2007). Effect ofdifferent ridge-furrow planting patterns of potatoon soil evaporation in semiarid area. ChineseJournal of Applied Ecology. 18(4): 795-800.87. Song, Q. H., Li, F. M., Liu, H. S., Wang, J., Li,S. Q. (2003). Effect of plastic film mulching on soilmicrobial biomass in spring wheat field in semi-arid loess area. Chinese Journal of Applied Ecology.14(9): 1512-1516.88. Wang, Q., Zhang, E. H., Li, F. M., Wang, X. L.(2005b). Optimum ratio of ridge to furrow forplanting potato in micro-water harvesting systemin semiarid areas. Transactions of the CSAE. 21(1):38-41.89. Wang, Q., Zhang, E. H., Li, F. M., Li, F. R., Xu,C. L. (2005a). Effect of generation characters ofmini-size water collection by ride sand furrows insemiarid area of Loess plateau and related potatoplanting techniques. Chinese Journal of Ecology.24(11): 1283-1286.

90. Ren, X., Chen, X., Jia, Z. (2009). Ridge andfurrow method of rainfall concentration forfertilizer use efficiency in farmland under semiaridconditions. Applied Engineering in Agriculture. 25:905–913.91. Wang, J., Li, F. M., Jia, Y., Li, S. Q., Song, Q. H.(2004c). Effects of plastic film mulching and pre-sowing irrigation on yield formation of springwheat. Journal of Desert Research. 24(1): 77-82.92. Li, F-M., Song, Q-H., Hao, J-H., Jjemba, P. K.,Shi, Y-C. (2004b). Dynamics of soil microbialbiomass C and soil fertility in cropland mulchedwith plastic film in a semiarid agro-ecosystem. SoilBiology and Biochemistry. 36(11): 1893-1902.93. Bu, Y-S., Miao, G-Y., Zhou, N-J., Shao, H-L.,Wang, J-C. (2006). Analysis and comparison of theeffects of plastic film mulching and strawmulching on soil fertility. Scientia Agricultura Sinica.39(5): 1069-1075.94. Li, X., Shi, H. B., Chen, M. J. (2007). Effects ofthe supplemental irrigation of harvested rainwateron the growth and yield of maize. Transactions ofthe CSAE. 23(4): 34-38.95. Zhou, L. M., Jin, S. L., Liu, C. A., Xiong, Y. C.,Si, J. T., Li, X. G., Gan, Y. T., Li, F. M. (2012b).Ridge-furrow and plastic- mulching tillageenhances maize-soil interactions: opportunitiesand challenges in a semiarid agroecosystem. FieldCrops Research. 126: 181-188.96. 1.Wang, J., Li, F. M., Jia, Y., Li, S. Q., Song, Q.H. (2004). Effects of plastic film mulching and pre-sowing irrigation on yield formation of springwheat. Journal of Desert Research. 24(1): 77-82.97. Li, F-M., Song, Q-H., Hao, J-H., Jjemba, P. K.,Shi, Y-C. (2004). Dynamics of soil microbialbiomass C and soil fertility in cropland mulchedwith plastic film in a semiarid agro-ecosystem. SoilBiology and Biochemistry. 36(11): 1893-1902.98. Bu, Y-S., Miao, G-Y., Zhou, N-J., Shao, H-L.,Wang, J-C. (2006). Analysis and comparison of theeffects of plastic film mulching and strawmulching on soil fertility. Scientia Agricultura Sinica.39(5): 1069-1075.99. Li, X., Shi, H. B., Chen, M. J. (2007). Effects ofthe supplemental irrigation of harvested rainwateron the growth and yield of maize. Transactions ofthe CSAE. 23(4): 34-38.100. Zhou, L. M., Jin, S. L., Liu, C. A., Xiong, Y. C.,Si, J. T., Li, X. G., Gan, Y. T., Li, F. M. (2012).Ridge-furrow and plastic- mulching tillageenhances maize-soil interactions: opportunitiesand challenges in a semiarid agroecosystem. FieldCrops Research. 126: 181-188.

Rice terraces. Yunnan, China © silver-john – fotolia.com


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Interactions between orogeny,climate and land use in the

Semiarid Loess Plateau, ChinaDr Pete Falloon

Met Office Hadley Centre, Fitzroy Road, Exeter, EX1 [email protected]

Guo and Li (2014) present afascinating study of the historyof agriculture in the Chinese

Semiarid Loess plateau, andsuggestions for sustainable futuremanagement options.

The region, and Guo and Li’s studyare particularly interesting from aclimatological perspective because ofthe two-way interactions betweenorogeny and land use and the climatein this region.

Himalayan uplift created the QinlingMountains, with several beneficialclimatic effects. The mountainsprevented the Northwest cold snapfrom spreading southwards into theLoess plateau, and also prevented thewarm snap from the Southeastspreading further north, ensuring amore temperate climate in the region.Wind drift from the Southeast blewdust towards the region in spring,while the Southeast Monsoon and thebarrier effect of the mountains meanthat the winds deposited their dustalong the Yellow River basin, resultingin thick loess deposits. The existence ofthese thick loess deposits, and themore moderate climate, werefoundations for fertile rain-fedagriculture in the region.

However, subsequent agriculturalexpansion in the region also had along-term negative impact onproductivity, through knock-on effectsof severe deforestation. The Loessplateau was 50% forest 2000 yearsago, but only 6.1% of forest coverremained by 1949, leading tosignificant soil erosion. Since 1949, aprogramme to restore degradedecosystems attempted to reverse thistrend. In the last decade rapid

urbanization has also led to lowerpopulation pressures in the region,drawing people from rural areas toregional centres. The “Grain for Green”initiative meant that cultivated land inthe region declined by approximately15% from 1996-2003 although therewas been a small increase between2003 and 2007. The current focus onagriculture has been on low-costdryland technologies to make moreefficient use of limited precipitation.This has been particularly importantgiven a long-term trend towardsdrought, and heavy summer rains.

It is estimated that 50-60% offarmland precipitation is lost byevaporation, 30-40% through planttranspiration and 10% through runoff.(Some is retained, especially by greencrops.)There is limited potential forwidespread irrigation in the region.Timing water supply to meet cropneeds is a critical issue in the Loessplateau. Land management in theregion, and the key to a sustainable,productive future therefore focuses onintegrated watershed managementand water harvesting techniques.These include terracing and checkdams to reduce soil and water loss,and increase fertility and soil moisture,and ridge furrow mulching with plasticfilms; although the latter may havesome negative impacts through lowersoil C and N contents due to warmer,wetter soils.

The human-driven changes in landcover (LCC1) and land management(LMC2) in the Loess plateau over thelast 2000 years may have led toimpacts on climate themselves (e.g.Betts et al., 2007; Raddatz, 2007;Pongratz et al., 2010), potentially by

altering biogeochemical processes(e.g. C and N cycling) and biophysicaleffects (such as surface albedo3,surface roughness andevapotranspiration).

Deforestation to agriculture orgrassland (e.g. Davin and De Noblet-Ducoudre, 2010; Lee et al., 2011)tends to reduce evapotranspirationrates, with a warming effect onclimate. The brighter crops have ahigher albedo, potentially cooling theclimate. A further significant impact ofagricultural expansion is during winterand spring in climates where snowcover is significant, as the bare soilallows a much brighter, snow coveredsurface with higher albedo than theforested regions, to have an additionalcooling impact. Overall, deforestationin cool regions may cool local climatebecause the effect of increased surfacealbedo tends to be dominant, whileincreases in cool-region forest area mayhave the opposite effect (Falloon et al.2012). Outside the tropics, impacts ofLCC and LMC on precipitation areoften less pronounced (Falloon et al.2012). Recent climate modellingstudies have indicated that warmingresulting from large-scale mid-and-highlatitude afforestation may be altered byenhanced transpiration (Swann et al.,2010) and water vapour export(Swann et al., 2011), triggerringfurther feedbacks and changes tocirculation patterns.

For instance, large-scale afforestationin Northern Hemisphere mid-latitudes(45o to 60oN) may warm the NorthernHemisphere and alter the Hadleycirculation leading to a northwarddisplacement of tropical rain bands(Swann et al. 2011).

GlossaryLand cover change: the replacement ofone land cover type by another, e.g.,due to expansion of croplands, defor-estation, or a change in urban extent.Land management change: a change

in how humans treat vegetation, soil,and water for a specific purpose – forinstance the use of fertilizers andpesticides, irrigation, use of introducedgrass species for pasture, the treespecies used in reforestation and

livestock movement.Albedo: is the fraction of solar energy(shortwave radiation) reflected fromthe Earth back into space. It is ameasure of the reflectivity of theearth’s surface.


scientificSwann et al. (2010) found thatafforestation with deciduous trees atNorthern Hemisphere high latitudesled to stronger climate impacts fromgreater transpiration compared to theeffect of albedo changes; warmingfrom increases in atmospheric watervapour content melted sea ice,triggering a positive feedback viaocean albedo and evaporation.

It is therefore possible that historicdeforestation in the Loess plateau mayhave cooled the local climate,depending on the balance betweenalbedo and evapo-transpiration effects,although such impacts may be difficultto detect in observational climaterecords. The more subtle recentchanges in LMC to prevent soil andwater loss and preserve fertility mayalso have effects on climate. Althoughthe climate effects of LCC have beenmuch more widely studied than thoseof LMC, Luyssaert et al (2014) showthat LMC may have impacts on surface

temperature of a similar magnitude tothose of LCC.

The story of the Loess plateau, andfuture prospects described by Li (2014)tell us that the key to futuresustainable food production inchallenging environments is to harnessour knowledge of how land use, soil,water, and climate interact with eachother (Falloon & Betts, 2010) to makethe best use of limited naturalresources.

ReferencesDavin, E. L. and de Noblet-Ducoudre, N.: Climaticimpact of global-scale deforestation: radiativeversus non-radiative processes, J. Climate, 23,97–112, doi:10.1175/2009JCLI3102.1, 2010.Falloon, P. D., Dankers, R., Betts, R. A., Jones,C. D., Booth, B. B. B., and Lambert, F. H.: Roleof vegetation change in future climate under theA1B scenario and a climate stabilisation scenario,using the HadCM3C Earth system model,Biogeosciences, 9, 4739-4756, doi:10.5194/bg-9-4739-2012, 2012.Falloon, P., and Betts, R. (2010). Climate impacts

on European agriculture and water managementin the context of adaptation and mitigation: theimportance of an integrated approach. Science ofthe Total Environment 408(23): 5667-5687.Lee, X., Goulden, M. L., Hollinger, D. Y., Barr, A.,Black, T. A., Bohrer, G., Bracho, R., Drake, B.,Goldstein, A., Gu, L., Katul, G., Kolb, T., Law, B. E.,Margolis, H., Meyers, T., Monson, R., Munger, W.,Oren, R., Paw U, K. T., Richardson, A. D., Schmid,H. P., Staebler, R., Wofsy, S., and Zhao, L.:Observed increase in local cooling effect ofdeforestation at higher latitudes, Nature, 479,384–387, 2011.Li, F (2014) Climate change and agro-ecosystemmanagement in arid areas: experiences from theSemiarid Loess Plateau, World Agriculture (inpress)Luyssaert S et al. (2014), Land management andland-cover change have impacts of similarmagnitude on surface temperature, NatureClimate Change, doi:10.1038/nclimate2196Swann, A. L., Fung, I. Y., Levis, S., Bonan, G., andDoney, S.: Changes in Arctic vegetation inducehigh-latitude warming through the greenhouseeffect. P. Natl. Acad. Sci. USA, 107, 1295–1300,doi:10.1073/pnas.0913846107 , 2010.Swann, A. L. S., Fung, I. Y., and Chiang, J. C. H.:Mid-latitude afforestation shifts general circulationand tropical precipitation, PNAS, 109, 712–716,doi:10.1073/pnas.1116706108 , 2011.

Shanxi Loess Plateau road © Kemo – Fotolia.com


scientific

Plastic-film mulch in Chineseagriculture: Importance

and problemsProfessor Yan Changrong1, Dr. He Wenqing1*, Professor Neil C. Turner2,

Dr. Liu Enke1, Liu Qin1, Liu Shuang1

1 Institute of Environment and Sustainable Development in Agriculture, CAAS/KeyLaboratory of Dryland Farming Agriculture, MOA, No.12 South Street

Zhongguancun, Beijing, 100081, P.R. China; 2The UWA Institute of Agriculture andCentre for Plant Genetics and Breeding, M080, The University of Western Australia, 35

Stirling Highway, Crawley, WA 6009, AustraliaTel:86-10-82106018; Fax:86-10-82106018

E-mail:[email protected]; [email protected]

1. The application ofplastic-film mulch inagriculture

The use of plastic-film mulch isnow widespread in agriculture,particularly in cold, arid and

semiarid regions of China. The mulch has numerous functions,

including increasing the soiltemperature, intensifying sunlightpenetration , reducing soil evaporationand maintaining soil water content;also improving fertilizer-use efficiency,soil conservation, and reducing andeliminating weeds (1, 2, 3, 4). Over thepast three decades, the amount ofplastic film applied and area coveredhas increased dramatically from 6000 tin 1982, to 1.2 Mt in 2011, a 200-foldincrease (Figure 1) (5). The area ofcrops with plastic-film mulching hascontinued to increase from only 0.12Mha in 1982, to 4.9 Mha in 1991,11.0 Mha in 2001 and 19.8 Mha in2011(6).

Plastic-film mulch is widely applied,from the arid and semiarid regions innorth China to the mountainous, coldregions in south China, such as theprovinces of Inner Mongolia,Shandong, Henan and Hebei in northChina, Xinjiang and Gansu in

northwest China, and Sichuan andYunnan in southwest China.Shandong, Xinjiang and Sichuan arethe leading provinces in the use ofplastic-film mulch, using 148,100 t,121,200 t and 71,000 t, respectively in2008 (5).

SummaryPlastic-film mulch is widely used to increase the productivity of crops, vegetables and fruit trees in cold and arid or semiaridregions of China. Use increased from 6000 t, covering 0.12 million ha, in 1982, to 1.2 million t, covering almost 20 millionha, in 2011. The thin (4-8 µm) polyethylene film used in China is slow to degrade, easily damaged, difficult to reuse for asecond season and difficult to remove. Residual plastic in the top 0.3 m soil layer is now estimated to vary from 72 to 260kg/ha, depending on number of years use, percentage of ground covered and film thickness. Research results showed thatplant growth was affected when residual plastic exceeded 37.5 kg/ha in the soil; the emergence of winter wheat seedlingdecreased by 25% and the tiller number decreased by 17%. Cotton yields were reduced by 4%, 8%, 12% and 19%,respectively when the amount of residual plastic in the soil was 80, 170, 280 and 370 kg/ha. Use of photo- and bio-degradable plastics is currently considered to be too expensive for agricultural use in China, but we suggested that use ofthicker (15 µm) and stronger film that can be reused for two or more years, together with planters that can collect theresidual plastic while (planting) sowing, the seeder should be developed.

Keywordsplastic residues, soil pollution, yield decline, degradable plastic film, China

Figure 1. The amount of plastic-film mulch used in Chinese agriculture from 1982to 2011.


scientificThe plastic film utilization intensity

index (kg/ha/yr), calculated bydividing the application quantity (kg)of plastic-film mulch by agriculture (hacovered) of the province or city,reflects the use of plastic-film mulch inthe region. Xinjiang had the largestutilization intensity of plastic-filmmulch with 34.8 kg/ha/yr in 2011 as aresult of the special climate andagricultural activities in the region (5,

6). In Xinjiang, irrigation, especiallydrip irrigation under the plastic film, iswidely utilized in agriculturalproduction, resulting in a rapidincrease in the quantity of plastic filmused. Shanghai and Beijing also hadhigh plastic-film utilization intensity forvegetable and fruit production in theperi-urban and urban areas. Theprovinces with significant agriculturalproduction like Shandong, Hebei,Henan, Sichuan and Gansu, all hadhigh (above 10 kg/ha/yr) use intensityindexes of plastic film. From 1991 to

2011, the intensity in all the provincesand cities had increased by 3 to 8 -fold(Table 1).

Plastic-film mulch has been widelyused in the production of grain,cotton, oilseeds, sugar, vegetables,melons, fruit and tobacco, to improvecrop yields, save water, enable earlierharvesting, and reduce herbicide andpesticide use (4, 7). The crop with thelargest use of plastic-film mulching ismaize, especially in arid mountain

region (Figure 2). In 2011,the area ofplastic-film mulch for maize andvegetables was about 6.7 Mha, cotton,3.4 Mha and peanut and tobacco,about 1.0 Mha.

2. Pollution by plastic-filmresidueThe plastic films used in China are amacromolecule hydrocarboncompound made from polyethylene(PE) by adding antioxidants.

They are of high molecular weight,highly stable and may persist in thesoil under natural conditions. Theplastic-film residue arising from large-scale use is considered to be a riskfactor for sustainable agriculture inChina. Over the past three decadesabout 20 Mt of plastic film have beenapplied(5), and 2 Mt of plastic-filmresidue remain in the soil. The thin (4-8 µm) plastic film is extremely difficultto recycle because of the high labourrequirement. Farmers have to harvestthe film by hand or with machinerybefore sowing the subsequent crop(Figure3). In Xinjiang and Gansu, thelarge quantity of plastic-film residueremaining in the soil has affectedagricultural activities and crop growth.

The amount of residual plastic in thesoil varies with the number of years ofmulching, film thickness, sheet width,and the percentage of soil covered bythe film in the treated area (themulching ratio). Our results showedthat Xinjiang had the maximum filminput of 61 kg/ha and that Hebei hadthe minimum of 33 kg/ha. In Xinjiang,Gansu and Ningxia in northwesternChina, the mulching ratio was high upto 80%, while in the southwestmountain areas and in northern Chinathe mulching ratio was only about40% (Table 2). According to theMinistry of Agriculture of China (5), theagricultural residual plastic-film in the17 provinces averages 60 kg/ha overthe 10-year period of application in the1990s(8). The average plastic-filmresidue in farmland soils was 90 to 150kg/ha, the severest pollution occurred

Table 1. The plastic-film utilization intensity index (kg/ha/yr) of Chineseprovinces and cities.

Figure 2. Hillsides in rainfed areas covered with plastic-film mulch (Photo byZhang Yajian, 2012)


scientific

in the cotton fields in Xinjiang with theaverage residue of 259 kg/ha (Table 2),and with the maximum plastic filmresidue of 381 kg/ha.

On average, the residual pieces ofplastic film in the soil are 1-2500 cm2

in area, with most pieces being 4-25cm2. The percentage of pieces >25cm2 is 16% to 25%, the percentage ofthat from 4-25 cm2 is about 44%-54%, while the pieces <4 cm2

accounts for 21%-40% of the total.Depending on agricultural activitiesand usage, the residue exists as flakes,curled pieces or cylindrical andspherical balls distributed horizontally,vertically or at any angle in the soil.71.9% of the pieces are deposited in0-0.1 m, 21% in the 0.1-0.2 m, 4.8%in the 0.2-0.3 m and 2.3% below0.3m soil layer (Table 3) (Figure4). Ingeneral, The number of years use ofplastic film was proportional to thedepth at which residues were found(9,

10, 11, 12, 13).

The plastic-film residue is consideredto be a risk for sustainable agricultureas there are several adverse effects onthe soil. The most important one is

that the residue can prevent thepenetration and flow of water withinthe plough layer and surface layer ofsoil, reducing infiltration and affectingthe water absorption of the soil (15, 16,

17, 18, 19, 20).

The plasticizer, diisobutyl phthalate

(DIBP), added to the plastic film duringthe production process is volatile, maydiffuse into the mesophyll cellsthrough the stomata of the plant, todamage the chlorophyll and limit itsformation(2, 17), and thereby affectplant growth. When the quantity ofplastic-film residue in the soil reached37.5 kg/ha, the seedling numbers ofwinter wheat decreased by 25% andthe tiller number decreased by 17%.Plastic-film residue may also limit thegrowth of the root systems of maize,eggplant, cabbage and peanut. Cottonyields were reduced by 4%, 8%, 12%and 19%, respectively when theamount of residual plastic in the soilwas 80, 170, 280 and 370 kg/harespectively (15, 16).

Plastic-film residue not only affectsthe soil and growth and developmentof crops, resulting in a decrease in cropyield, but has other adverse effects.One is the death of cattle followingingestion of plastic film mixed withthe stover used as cattle feed, whileanother is the aesthetic pollution fromplastic-film residue deposited byroadsides, in ditches and along fences.It also binds around the wheels of aseeder or the teeth of a plough, andhinders the cultivation operations(Figure 5)(9, 10, 18).

3. Reducing plastic-filmresidue pollution3.1 Use less plastic filmTo save and reduce the input of plasticfilm in the field, a technique has beendeveloped, which is called the

multipurpose plastic- film technique(Figure 6), that is, the use of plastic-film mulch of medium thickness (15µm), increased toughness, and highresistance to damage.

After harvesting, it can be collectedand reused for a subsequent crop orcrops, which not only reduces theuseof plastic film, but also saves timeand labour and protects theenvironment.

Figure 3. Removing plastic-film residue in Gansu and Xinjiang (Photo by YanChangrong, 2008).

Table 2. The use of plastic film and the residues of plastic in five representativeregions

Table 3. The plastic-film residues in soil profile (depth, m) after 10-20 years usedin four representative regions (%)

Figure 4. Plastic-film residue pollution in crop fields in Xinjiang (Photos by HeWenqing (Left, 2006) and Zheng Jiaming (Right, 2014).

Soil depth Chengan Shihezi Tongchuan Zhengning Mean


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In Gansu during 2013, the techniquewas shown to reduce the mulchingratio from 80%-100% to 50%-70%while maintaining a high crop yield(Table 4).

3.2 Use of degradable plastic filmPhotodegradable and biodegradableplastic to replace PE plastic film (21)

would have the advantage ofreducing residue pollution (22).

Cost of degradable plastic film is themain obstacle to its use in China. Aneconomic assessment of biodegradableand PE plastic film for cottonproduction showed that the price ofbiodegradable film was double,although the total input costs ofbiodegradable film with differentthicknesses increased by only 12%,41% and 69%, respectively, because ofexclusion of the cost of collectingbiodegradable residues (14) (Table 5).Considering the environmental effect,biodegradable film has a greatpotential for agricultural application inthe future.

3.3 Mechanization of residual plasticrecycling technologyIn developed countries, plastic film isgenerally used in vegetable, fruit andother cash crops.

In these countries, the plastic film has15 µm thickness, and is easy to reclaim

by machine. In China, the plastic filmmulch for agricultural use is very thinwith only half of thickness of that usedin developed countries, fragile andeasily damaged, and thus not easilyreclaimed by the machines.

Nevertheless, several kinds ofreclaiming machines, such as roller andrake types are available and highlyefficient in reclaiming plastic residues.We propose that a planter with afacility for reclaiming plastic residuefrom the previous crop is the key tofuture development (23, 24, 25).

4. ConclusionsThe continuous use of thin stable PEplastic-film mulch for improving cropproduction in cold and dry regions ofChina has led to large quantities ofplastic residue building up in the soil. It

Figure 5. Some side effects of plastic residues pollution in China

Table 4. The economic analysis of Multipurpose plastic-film mulch technique forcrops in Gansu

Table 5. Annual economic assessment of biodegradable and PE plastic film incotton production

Thickness (µm)

Colour Transparent Transparent

Price (RMB yuan/kg)

Amount of plastic film (kg/ha)

Cost of plastic film (RMB yuan/ha)

RMB yuan/ha

Total costs (RMB yuan/ha)

Percentage cost increase (%)

Items PE plastic film Biodegradable plastic film


scientificIt has begun to reduce crop growthand yields, particularly in cotton whichhas the longest term use among crops.For sustainable agriculture, thecontinuous use of plastic-film mulchneeds to be reduced in the future. Thedegradable plastic, thicker andstronger plastic film for multiple-yearuse, a reduction in the mulching ratioand the use of cultivators/seedingequipment that can pick up plasticresidue are recommended for reducingplastic pollution. These techniquesneed to be explored.

AcknowledgementWe thank two reviewers and Dr. DavidFrape for their valuable suggestionsand comments, which led tosubstantial improvements of this paper.

This study was partially supported bythe Chinese National ScientificFoundation (No. 31370522), the 12thfive-year plan of National KeyTechnologies R&D Program (No.2012BAD09B01) and “948” projectfrom Ministry of Agriculture (2014-Z6).Dr. He Wenqing is correspondingauthor.

References1. Li Fengmin, Wang Jun, Xu Jinzhang, Xu Huilian(2004) Productivity and soil response to plasticfilm mulching durations for spring wheat onentisols in the semiarid Loess Plateau of China. Soiland Tillage Research 78, 9-20.2. Yan Changrong, He Wenqing, Mei Xurong(2010)Agricultural application of plastic film andits residue pollution prevention . Beijing: SciencePress. pp. 76~86.3. Wang Hanbo, Gong Daozhi, Mei Xurong, HaoWeiping (2012) Dynamics comparison of rain-fedspring maize growth and evapotranspiration in

plastic mulching and un- mulching fields.Transactions of the Chinese Society of AgriculturalEngineering 28 (22), 88-94.4. Gan Yantai, Siddique K H M, Turner N C, Li X-G, Niu J-Y, Yang C, Liu L, Chai Q (2013) Ridge-furrow mulching systems - an innovative approachfor boosting crop productivity in semiarid rain-fedenvironments. Advances in Agronomy 118, 429-476.5. Ministry of Agriculture P. R. China. Chinaagricultural statistics yearbook, Beijing: ChineseAgricultural Press. 6. Rural Society Investigation Department ofNational Statistical Bureau. China Rural StatisticsYearbook. Beijing: China Statistics Press, 2002,2012.7. Scarascia-Mugnozza G, Sica C, Russo G (2011)Plastic materials in European agriculture: Actualuse and perspectives. Journal of AgriculturalEngineering 42 (3), 15-28.8. Wang Xiaofang, Shen Maoxiang (1998)Farmland plastic film-Hope and dawn of Chineseagricultural development. Countryside Scienceand Technology Department of Science of China.9. Yan Changrong, Mei Xurong, He Wenqing,Zheng Shenhua ( 2006 ) Present situation ofresidue pollution of mulching plastic film andcontrolling measures. Transactions of the ChineseSociety of Agricultural Engineering 22 (11), 269-272.10. Yan Changrong, Wang Xujian, He Wenqing,Ma Hui, Cao Silin, Zhu G (2008) Study on theresidue of plastic film in cotton field in Shihezi,Xinjiang. Acta Ecologica Sinica 28, 3470-3484.11. Ma Hui, Mei Xurong, Yan Changrong, HeWenqing , Li Kang ( 2008 ) The residue ofmulching plastic film of cotton field in NorthChina. Journal of Agro-Environment Science 23,570-573.12. He Wenqing, Yan Changrong, Zhao Caixia,Chang Ruifu, Liu Qin, Liu Shuang (2009) Study onthe pollution by plastic mulch film and itscountermeasures in China. Journal of Agro-Environment Science 28, 533-538.13. He Wenqing, Yan Changrong, Liu Shuang,Chang Ruifu, Wan X, Cao Silin, Liu Qin (2009)The use of plastic mulch film in typical cottonplanting regions and the associated environmentalpollution. Journal of Agro-Environment Science 28,1618-1622.14. Zhao Caixia, He Wenqing, Liu Shuang, YanChangrong , Cao Silin (2011) Degradation of

biodegradable plastic mulch film and its effect onthe yield of cotton in Xinjiang region, China.Journal of Agro-Environment Science 30, 1616-1621.15. Zhao Surong, Zhang Shurong, Xu Xia, XuLichao, Zhang Donghe, Zhang Xinmin , WangJinfeng, Xu Ligong , Qi Ying ( 1998 ) Study on theagricultural plastic sheeting residue pollution.Agro-environment and Development 3, 7-10.16. Cheng Guihua, Liu Xiaoyang, Liu Yuanjun, JinWeixu, Mu Luming, Yan Zhonghui (1991) Studyon permissible value of plastic residual piece infield soil. Soil and Fertilizer 5, 27-30.17. Nan Dianjie, Xie Honge, Gao Liangsheng,Zhang Dongmei , Zhao Haizhen, Ren Pinghe ,Chai Shiwei (1996) Study of the influence of theresidue film on soil and cotton growth in thecotton fields. Acta Gossypii Sinica (now CottonScience) 8 (1), 50-54.18. Gao Qinghai, Lu Xiaomin, (2011) Effects ofplastic film residue on morphology andphysiological characteristics of tomato seedlings.Journal of Tropical and Subtropical Botany 19, 425-429.19. Chang Ruifu, Yan Changrong (2012) Researchreport on overall current situation on agriculturalplastics residuals pollution and itscountermeasures. Beijing: China AgriculturalScience and Technology Press, pp. 13-15, 41.20. Lu Shengzeng, Zhou Zhenfeng, Yan xishi(2013) Environmental problems and control waysof plastic film in agricultural production. AppliedMechanics and Materials 295, 2187-2190.21. Ammala A, Bateman S, Dean K, Petinakis E,Sangwan P, Wong S, Leong KH (2011). Anoverview of degradable and biodegradablepolyolefins. Progress in Polymer Science, 36(8),1015-1049.22. Kyrikou I, Briassoulis D (2007) Biodegradationof agricultural plastic films: a critical review. Journalof Polymers and the Environment, 15(2), 125-150.23. Cao Silin, Wang Xujian (2008) The researchstatus of plastic film residual pollution control andthe patent strategy. Agricultural Machinery 20, 77-78.24. Cao Silin, Wang Xujian, Shen Congju, Lu Bing(2000) Patent analysis on mechanizationtechnology of retrieving the used plastic film.Chinese Agricultural Mechanization 4, 48-50.25. Cao Silin, Wang Xujian, Wang Min, HeYichuan, Liu Yun (2012) Design and experimentalresearch on 1LZ series combined tillage machine.Acta Agriculturae Boreali- Occidentalis Sinica. 21,

Chinese agricultural farm worker © Kadmy – fotolia.com


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Aquaculture: are the criticismsjustified? II – Aquaculture’s

environmental impact and use ofresources, with special reference to

farming Atlantic salmonDr C J Shepherd BVSc, MSc, PhD, MRCVS and

Professor D C Little BSc, MSc, PhD, FSB* Address for correspondence: Prof D C Little,* Institute of Aquaculture,

University of Stirling FK9 4LA, UK. Email: [email protected] farming is the most highly developed form of large scale intensive aquaculture owing to its productivity growth andtechnological change. The fundamental questions are how farmed salmon compares to other food production systems andprospects for its improved sustainability. This paper reviews the criticisms of Atlantic salmon farming, in particular thoserelating to its ecological and environmental record. Compared with terrestrial livestock, fish are better suited for farming,being cold-blooded (ectothermic) with neutral buoyancy in water, which enhances production efficiency, and farmed fishare more productive than wild fish as they use less energy and lack predators.Some of the criticisms of salmon farming are entirely erroneous (e.g. that hormones or growth promoters are used). Othersare unfounded today due to the rapid advances made since the industry started in the 1970s (e.g. that antibiotics areoverused; that health risks exist from eating salmon due to the presence of contaminants; that using fishmeal and fish oil isunsustainable and threatens wild fisheries; that salmon farm effluent threatens the coastal ecosystem). It is concededthatinfestation of salmon (Lepeophtheirus salmonis) by sealice and the risk of salmon escaping from farms remain validconcerns. Sealice numbers can readily build up in salmon farms and, even if satisfactorily controlled in the cages, infectiousstages of the parasite may leave the cage and potentially infect adjacent wild salmon populations. Escaping farmed salmonmay contribute to this, but can also potentially breed with wild salmon and affect the native salmon gene pool. However,there is no convincing evidence that the salmon farming industry is responsible for the widespread decline in wild salmonand sea trout populations, which began to decline before salmon farming was established.Life cycle analysis suggests salmon farming and cod fishing are comparable. However, catching cod prey species (e.g.capelin) to use as salmon feed ingredients is a far more efficient way of supplying nutrients for human consumption thanleaving such prey in the sea and harvesting the resulting cod. Recent detailed studies of the salmon farming industry inNorway have shown that it is a more efficient way of producing nutrients for human consumption than either pig orchicken farming, as demonstrated by its climate impact, area of land occupation, and use of non-renewable phosporusresources. Farmed salmon retain nutrients more efficiently and are better converters of feed nutrients to nutrients for humanconsumption than the most efficient land animal production. There is no evidence that the progressive replacement of marine protein and oil by plant protein and oil is more sustainablethan salmon farming based on wild-caught fish (or their by-products). At the same time it causes the farmed salmoncontent of long-chain polyunsaturated fatty acids (PUFAs) (especially Eicosapentaenoic acid or EPA and Docosahexaenoicacid or DHA) to fall with negative implications for consumers (pending availability and consumer acceptance ofcost-effective alternative PUFAs), unless they compensate by consuming more oil-rich fish or take PUFA supplements.The salmon farming industry continues to innovate and prioritise to improve its sustainability, to improve seawater survivaland to find cost-effective alternatives to the limited supply of fish oil, which is currently the only practical source of EPA andDHA. A subsequent paper will consider the extent to which the improved environmental track record and resourceefficiency of Atlantic salmon farming is duplicated by other aquaculture species. Although it has been shown that much ofthe criticism of salmon farming is false or exaggerated, the industry is small in a global aquaculture context. Do these (orother criticisms) hold true, for example, with the farming of warmwater shrimp or carp? Such questions are relevant whenconsidering aquaculture’s global role in food security and how best to guide its sustainable development.

Keywordsaquaculture; eco-efficiency; environmental impact; life cycle analysis; productivity; salmon farming; supply chain;sustainability.


scientificAbbreviations FAO Food and Agriculture Organisation; FCR Food conversion rate; FIFO Fish-in, Fish-out ratio; GM Genetic modification; PCB Polychlorinated Biphenyls; PPR Primary Productivity Requirement; EPA Eicosapentaenoic acid; DHA Docosahexaenoicacid; DNA Deoxyribonucleic Acid; PUFA Polyunsaturated Fatty Acid; HACCP Hazard Analysis Critical Control Point; EFSA European Food Safety Authority; HCH Hexachlorocyclohexane; LCA Life Cycle Analysis.

GlossaryA coproduct is a product producedjointly with another product; anepizootic is a disease that appears asnew cases in animals at a substantiallyelevated incidence rate and is ananalogous term to ‘epidemic’ appliedto human populations; eutrophicationis the ecosystem response to theaddition of artificial or naturalsubstances (e.g. nitrates andphosphates through fertilizers orsewage) to an aquatic system; Tofallow an aquaculture site meansleaving it empty of fish for a periodwithout restocking in order to allowthe seabed to return to normalcondition and to restore the site’sproductivity; feed conversion rate =(kg feed fed)/(kg bodyweight gain);fish-in fish-out ratio (when usedabout aquaculture) refers to the inputof fish materials (usually fishmeal andfish oil) as feed ingredients comparedto the resulting output of farmed fish;fishmeal trap is a term denoting the

concern that increased demand forfeed by aquaculture will increasefishing pressure on wild stocks andhence threaten the sustainability of theassociated capture fisheries; a gadoidis a soft-finned marine fish which is amember of the family Gadidaeincluding cod; a genome is thecomplete set of DNA within a singlecell of an organism and genomics isthe genetic discipline that sequences,assembles, and analyzes the functionand structure of genomes; geneticmodification (GM) (e.g. of a fish or aplant) results in a genetically modifiedorganism (GMO), which possesses anovel combination of genetic materialobtained through the use of modernbiotechnology; life cycle analysis(LCA) is a technique to assessenvironmental impacts associated withall the stages of a product's life fromstart to finish; an oil adjuvant is animmunological vehicle for enhancingthe potency of a vaccine, eg byemulsification in mineral oil;

Organoleptic properties are theaspects of food or other substances asexperienced by the senses, includingtaste, sight, smell, and touch; apoikilotherm is an organism with aninternal temperature which varies,usually in response to changingenvironmental temperature and issometimes known as an ‘ectotherm’or ‘cold-blooded’; a reduction fisheryis a fishery that ‘reduces’ its catch tofishmeal and fish oil and is also knownas a ‘feed’ fishery or a ‘forage’ fishery;salmonids are fish which are membersof the Salmonidae, or salmon andtrout family, which belong to the orderSalmoniformes; a smolt is a juvenilesalmon in freshwater or estuarineconditions which has become silvery incolour and is ready to go to sea;triploid fish have three sets ofchromosomes instead of the normaltwo (‘diploid’), usually because the eggis physically shocked shortly afterfertilisation occurs, resulting in sterilefish.

Figure 1. Global production of farmed Atlantic salmon 2000-2013 (tonnes x 1000)Source: Kontali Analyse (2013)


scientific1. Introduction

Aquaculture is a more variedactivity than land animalfarming, encompassing a range

of systems for rearing finfish, molluscs,crustaceans, and aquatic plants, infreshwater or seawater.

From 1980 to 2010 world food fishproduction by aquaculture hasexpanded almost 12-fold at an averageannual rate of 8.8%, although slowingto an average annual rate of only 6.3%over the last decade to reach 63.6million tonnes in 2011 (excludingaquatic plants).1 The contribution ofglobal aquaculture to world seafoodproduction for human consumptionhas risen from 9% in 1980 to 47% in2010.

The hunting of fish and the problemof static or declining fish stocksrepresent an uncertain and erratic wayto meet demand consistently on along-term basis.

The high price and seasonal supply ofwild salmon helped to encouragepioneering investment in farming ofAtlantic salmon (Salmo salar) in the late1960s and the industry took off inNorway and the UK in the 1980s,

followed by North America and thenChile, as retailers and food servicecompanies found they were able toplace contracts for year-round supplyof consistent product. Thedevelopment of salmon farming hasbeen characterised by progressiveindustrialisation and commoditisation.However, aquaculture, especially thefarming of carnivorous fish like salmon,has attracted intense and oftenmisinformed criticism. This has beenlinked mainly to the use of dietscontaining fishmeal and fish oil orminced wet fish, – the subject of aprevious paper2 in World Agriculture.At the same time improvements in dietformulation and feeding systems haveresulted in feed conversion rates (FCR)improving from almost 3.0 in 1980 tojust over 1.17 in 2012,3,4 meaning thatthe quantity of feed needed per unitliveweight gain has reduced byapproximately 60% over the period.

Global production of farmed Atlanticsalmon reached 2.0 million t (wholeround, bled weight) in 20125 which issmall (ca. 3%) in relation to estimatedtotal global aquaculture production.1Fig. 1 shows global production ofAtlantic salmon has increased from

2002 to 2013 (estimated) by mainproduction regions, whereas Fig. 2shows a stagnating wild fish catchcompared with aquaculture supplysince 2000, with a forecast to 2020.Atlantic salmon farming is recognisedas the most highly developed form ofintensive fish cultivation. Accurateinformation is also available enablingdetailed analysis of its efficiency,especially for the Norwegian salmonfarming industry, which dominatesglobal salmon production and is thetechnical model for intensivecage-based aquaculture.

This paper surveys the main criticismsof aquaculture, with special referenceto Atlantic salmon. When assessing thevalidity of such criticisms, thefundamental question with respect tosalmon aquaculture is how farmedsalmon compares to other food itemsand production systems and ifdevelopments in the salmon industrywill lead to improved sustainability.The answers to such questions haveimplications for other forms ofaquaculture and may help assess thepotential role for global aquaculture infuture food production and foodsecurity.6,7

Figure 2. Global fishery and aquaculture production, 2000-2011 (tonnes x million)Source:FAO Fisheries and Aquaculture Statistics and Information Branch 2013. Capture production 1950-2011. Aquacultureproduction 1950-2011.Available at http://www.fao.org/fishery/statistics/en

Total capture

Total aquaculture

Total world


scientific2. Suitability of fish forfarmingCompared with warm-bloodedanimals, cold-blooded ‘poikilotherms,’such as fish, are more efficientconverters of feed energy tobodyweight, especially under farmingconditions. Firstly they have lowermaintenance and respiratory costs.8

Their protein metabolism uses lessenergy since they excrete ammoniadirectly into the environment insteadof excreting urea or uric acid. Alsotheir neutral buoyancy in water savesenergy by avoiding the need for aheavy skeleton to counteract gravity. Ingeneral this means a greaterproportion of the fish carcase is ediblecompared with land animals; this isespecially the case for carnivorous fishwhich have a shorter digestive tractcompared with fish species moreadapted for a vegetarian diet.Compared with fish in naturalenvironments, farmed fish showimproved growth and nutrientretention because they are protectedfrom predators and utilise less energyin accessing food.9

Compared with intensively housedland animals, it is difficult to maintain acontrolled environment within a fishfarm and maintain biosecurity. This isespecially the case in seawater cagesand will be considered further,together with the prospects formitigation. Most aquatic animals havefar greater reproductive capacity thanterrestrial livestock, but also allocateless resource to reproduction. Althoughmany fish have microscopic larval

stages, the cost of producing salmonfry is low as they produce relativelylarge eggs (with attached yolk sacs),which in turn develop into larvaecapable of feeding readily on inerthatchery diets once the yolk saccontents are fully consumed.

3. Salmon productivitygrowth and technologicalchange Fig 3 shows the development ofNorwegian farmed salmon productionover the period from 1985 to 2011,the average cost of production and theaverage export price. Production hasincreased from 31 177 to 1 005 600 twhile the production costs and salesprices have fallen steeply. Thus in 1986the average production cost was 76.1NOK/kg but it had fallen to 15.5NOK/kg in 2005 (1 NOK or Norwegiankrone equals 0.16 US dollar as of Dec.2013), since when costs have slightlyrisen and prices have fluctuated butthe industry has remained profitable.The price reduction has enabled theindustry to continue expanding intonew markets. This could not havetaken place without lower costs due toincreased productivity andtechnological change.10 This is becausefarmers have become more efficient(i.e. growing larger salmon morequickly with fewer losses) while at thesame time they have benefited fromimproved inputs (including improvedstock, better feed and rearing systems)and have gained economies of scale

from establishing larger farms.Thus improvements in diet and

feeding systems, as well as better fishhealth, have improved FCRs forNorwegian salmon from almost 3.0 kgfeed/kg salmon body weight gain in1980 to just over 1.17 kg/kg in 2012.This is partly due to a marked changein the ratio of protein to oil used infeeds related to the development ofvacuum coating of lipids. Crudeprotein levels of 45% and fat of 18%in the 1980s have changed to 36%and 38% respectively in the2000s.11The salmon farming industryhas been criticised for its supposedreliance on dietary marine ingredients.However, the quantity of wild fish usedto produce the fish meal and oilneeded to rear 1 kg of farmed salmon(i.e. the Fish-in, Fish-out ratio or FIFO)has decreased from 4.4 and 7.2 in1990 to 1.4 and 2.3 respectively in2010; when corrected to take accountof the use of processing by-products ofcapture fishing, the values in 2010were 1.1 and 1.8 respectively.12 Thelimited and fluctuating supply and costof marine ingredients have encouragedthe Norwegian salmon farmingindustry progressively to substituteplant ingredients for marineingredients, and there has been afurther change since 2010, so currentFIFO ratios are probably below 1.0 forfishmeal and close to 1.0 for fish oil.These developments have progressivelychallenged the criticism thataquaculture of ‘carnivorous species’(e.g. salmonids) is unsustainable (see4(i) below).

Figure 3. Norwegian farmed salmon volumes (tonnes x 1,000) compared with production cost and export price(Norwegian Krone) in real terms (2011=1), 1985-2011Source: Norwegian Directorate of Fisheries: Norwegian Seafood Export Council

1,00

0 to

nn

es


scientificFor increasing use of plant ingredientsand other challenges, see section8(viii).

4. The criticisms related toecological impact andenvironmental pollution(i) IntroductionAny production process interactingwith the natural environment canpotentially compromise theenvironment. For instance it has beenclaimed that the use of dietary marineingredients in fish farming causesunsustainable damage to wild fishstocks being harvested for fishmeal andfish oil, and that reduction fisheries willtherefore inevitably becomeoverfished.13 This so-called ‘fishmealtrap’ has not occurred, however, dueto dietary innovation, increased use offish process trimmings, and to theincreasingly responsible managementof reduction fisheries.10,14 Thereforethe criticism is no longer valid exceptin the case of ‘trash fish’ feeding inSouth East Asia.2 However, there is arange of local environmental issueswhich is claimed to have detrimentaleffects on the local and regionalenvironment. Salmon is normallyfarmed in floating cages, hence bydefinition takes place in ‘open’ systemsin which water exchange occurscontinuously with the widerenvironment and economicperformance of the fish in such

systems demands that water qualityremains at an optimum. Theimplications for salmon farming areconsidered below, together with theallied risks of disease transmission tothe wild, farmed salmon escapement,contamination from treatmentchemicals, and effluentdischarge/organic waste.

(ii) Effluent discharge/Organic wasteOrganic waste beneath salmon farmscomprises fish faeces and unconsumedfeed, which can accumulate on theseabed. This may impact on localseabed fauna and increase the risk ofeutrophication with consequentnegative effects on productivity.10

During the 1980s many salmon farmswere located in sheltered sites close toshore to reduce potential stormdamage. As a consequence, so called‘dead areas’ developed on the seabedunder the cages. Since then salmonfarming systems have evolved to usemore exposed locations with strongercurrents and deeper water beneathmore robust cage groups (which areregularly rotated between farm sites toenable fallowing), ensuring wastematerials are flushed to sea and salmonhave optimal water quality.Additionally improvements in FCR havereduced the feed requirement pertonne of salmon produced by around60% since the 1980s. The regulatoryframework has also become moresophisticated, e.g. in Scotland

regulation of benthic impact isexercised through rigorously applieddischarge controls, the use of particletracking models, which predict theseabed footprint, and the ‘steady state’and ‘limiting factor’ principles.15 Arecent detailed NOAA report concludesthat marine cage culture has ‘minimal’impacts to the environment wherefarms are appropriately sited andproperly managed.16

(iii) Antibiotics, chemicals, andhormones, etc. Although the use of antimicrobialgrowth promoters is widespread inintensive production of poultry andpigs, it should be noted that they arenot used in salmon farming at all. Norare hormones used in salmon farmingdespite frequent media commentssuggesting otherwise. Fig 4 illustratesthe rise and fall of antibiotic use inNorwegian salmon farming over theperiod 1980 – 2011.

It can be seen that, after reaching apeak in the 1980s, use of antibioticsfell quickly to very low levels despite arapid and continuing increase insalmon production. This was almostentirely due to the successfulintroduction of oil-adjuvantedvaccinesin controlling bacterial diseases.Antibiotics are only allowed onveterinary prescription and the amountused per kilo of meat from terrestriallivestock in Norway is 20 times theamount used for farmed salmon.7

Figure 4. Annual use of antibiotics (kg) in Norwegian salmon production, 1980-2011Source: Norwegian Directorate of Fisheries

Salm

on

pro

duc

tio

n (

ton

nes

x 1

000)

An

tib

ioti

c (k

g)


scientificThere has been a similar reduction inthe use of medicines to control sealice(Lepeophtheirus salmonis) infestation(e.g. azamethiphos; cypermethrin),and in the use of antifoulants to reducebuild-up of algae on cages (e.g. usingcopper-based paints). In the case ofsealice, an integrated pestmanagement approach hasincreasingly become the norm,resulting in much diminished severityof infection in recent years despite thedeclining effectiveness of individualdrugs.

Treatment of affected fish has beenby means of either in-feed antiparasiticdrugs (emamectin benzoate;teflubenzuron) or by adding medicinalproducts applied as baths (e.g.peroxide) to the water in the cage.Treatment of affected fish by means ofin-feed or bath treatments in someinstances is only partially successfuldue to the emergence of resistance.There is also increasing use ofbiological control by the introductionto salmon cages of wrasse of variousspecies (e.g. Labrus bergylta) orlumpsucker fish (e.g. Cyclopterus spp.),which feed directly on the liceattached to salmon skin; this approachhas obvious environmental attractionsand is now stimulating an interest incultivation of these so-called ‘cleaner’fish to supply to the salmon farmingindustry.

A key issue is the cost-effectiveproduction of disease-free juvenilecleaner fish and their management incommercial systems based on fishbeing stocked and harvested on ‘all-in,all-out’ principles.

Use of antibiotics can never beeliminated entirely for reasons ofanimal welfare and the possibility ofemerging bacterial diseases. However,there are continuing problems incontrolling sealice infestation and it isestimated that during 2012 around45% of Norwegian salmon farmingsites were treated for sealice, with eachbeing treated on average 2.5 timesover the production cycle. There isincreased recognition of theimportance of husbandry measures,such as zonal management amongneighbouring salmon farm units(taking account of industry codes ofgood practice), and selective breedingfor increased resistance. The morerecently established Chilean salmonfarming industry continues to strugglewith disease problems and lags behindthe effective control achieved inNorway, Scotland and North Americawithout large scale use of medicinalproducts.

(iv) Transmission of disease agents toand from wild stocksThe early growth of salmon farmingwas severely challenged by epizooticsof infectious disease, in particularbacterial septicaemias, such asfurunculosis (due to Aeromonas spp.)and vibriosis (due to Vibrio spp.).Routine vaccination of smolts byinjection prior to seawater transfer wasfound to be highly effective. Anexception is Salmon RickettsialSyndrome in Chile due to Piscirickettsiasalmonis for which a satisfactorycontrol method is so far lacking,although vaccines are under trial. Anincreasing range of viral diseases hasbeen found to affect farmed salmonand can cause severe losses, althoughviral vaccines against InfectiousPancreatic Necrosis and PancreasDisease are now in routine use. Thesources of such infections are notalways clear but there is increasingevidence that most if not all thecausative organisms have been presentin wild fish populations since beforethe start of salmon farming. Thepresumption is that they rarely causedisease in wild populations, but can betransmitted to adjacent farmed stocksin hatcheries or cage farms whereclinical disease can spread quickly inunprotected salmon under conditionsof high stocking density.

Whereas bacterial and viral diseaseepizootics in farmed salmon may causeshedding of pathogens into theenvironment, there is little evidencethat this causes clinical disease inadjacent wild fish, apart fromoccasional mortalities seen in wildgadoid fish, e.g. saithe (Pollachius

virens), which have gained access tothe salmon cage. However, parasiticinfestations of wild Baltic strains ofAtlantic salmon with the skin flukeGyrodactylus salaris caused severelosses in susceptible Atlantic salmonpopulations when infected fish weretransplanted to Norway and releasedinto the wild. In the same way there isconcern that sealice infestation infarmed salmon (in Europe due mainlyto L. salmonis and in Chile due mainlyto Caligus rogercresseyi) potentiallythreatens wild salmon populations.Sealice occur naturally in the wild and,long before salmon farming started,sealice epizootics caused mortalities ofwild Atlantic salmon in Canada17 whilethe presence of a few sealice on wildsalmon has traditionally been acceptedas a positive indication of freshly sea-run fish. However, under farmingconditions these crustacean skinparasites can multiply rapidly andinfectious stages swim actively to find asuitable host elsewhere within thecage, or potentially leave the cage andmay infest migrating wild salmon inthe vicinity. For this reason, treatmentaims to prevent the development ofsexually mature breeding lice, in orderto reduce infection pressure for bothfarmed and wild salmonid populations,rather than just for farmed fish welfare.

Salmon farming does not appear toprejudice wild salmon populations withthe possible exception of the effects ofsealice. However, new problems willemerge and continuing vigilance isneeded to control fish movements andhence limit the spread of fish diseaseorganisms.

Freshwater production of salmon smolts – note use of underwater lights forphotoperiod control of smoltification (Courtesy of Marine Harvest Ltd., Scotland)


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(v) The effect of salmon farming onwild stocks The number of Norwegian farmedsalmon reported as escaping each yearis relatively low and fairly stable (Fig. 5)when compared with the increasingproduction, although it remains acontinuing problem.

Escaped fish are likely to competewith wild salmon and may breed withthem, hence affecting the gene pool(so-called ‘genetic pollution’).Although the outcome of escapee-wildfish interactions varies withenvironmental and genetic factors,modelling suggests they may benegative for wild salmon18 and thatgene flow from escaped farm fish tonative wild fish may lead to geneticand behavioural changes in wildpopulations in the direction ofdomesticated salmon. It is also possiblethat wild populations may sufferdepressed productivity caused byecological interactions with escapedfarm salmon and their offspring.19 Atthe same time a concern is thatescaping farmed salmon could transmitdisease organisms to wild populations,especially sealice (see 4(iv) above).Compulsory tagging of smolts prior totheir being stocked in salmon cages isbeing considered by the Norwegianauthorities for greater traceability offarmed salmon should theysubsequently escape, in order to aidpolicing and the ability to penaliseoffending farms. Other than adoptinggenetically modified (GM) technology

(should approval be granted), the useof triploid salmon is the only way torear sterile salmon in order to avoidany risk of genetic pollution fromescaped fish (see 8(iv)), whereas thecost of on-shore tank production islikely to remain prohibitive in mostcases. Notwithstanding the aboveconcerns, there is little scientificevidence to support the claim thatsalmon farming has caused thewidespread decline in wild salmonfisheries in Europe and North America.Mismanaged capture fisheries, habitatdestruction, and excessive mortalityfrom fishing have resulted in wide-scaleextirpations, depletions and loss ofbiodiversity in both Atlantic and Pacificsalmon (Oncorhynchus spp.); thisoccurred long before commercialsalmon farming started in the1970s.20,21 For Norway there seemsto be no measurable impact at thenational level of salmon farming on thewild salmon stocks in Norwegianrivers7. In Scotland anglers continue toblame salmon farming for the collapseof the west coast populations ofAtlantic salmon and sea trout (Salmotrutta) in the 1980s. Thus sea troutanglers blame salmon farming for thedemise of the Loch Maree sea troutfishery22 and claim that by 1980 thefishery was in decline, although thescientific evidence for this stock statusin 1980 is not clear cut.23 There seemsno doubt that the fishery wascollapsing in the late 1980s by whichtime salmon farming was established in

the area. It therefore remains apossibility that the effect ofneighbouring salmon farms (e.g. dueto sealice) exacerbated the decline of afishery that was already under stressdue to environmental factors, such asthe effect of freshwater acidification. Amore likely explanation for thistimetable of events at Loch Maree22 isthe introduction of legislation in 1984(Inshore Fisheries Act), which openedup the zero to 3 mile coastal area to allmobile fishing gear. The fact thatfarmed salmon has brought down theprice and largely replaced wild capturesalmon in the market, is probablycontributing to the rebound of somesalmon stocks for both Atlantic andPacific salmon.6

(vi) Contaminants from marine feedingredients entering the food chainThe use of fishmeal and fish oil willtend to concentrate contaminantspresent at low levels in forage fish andhence result in potentially elevatedlevels in farmed fish.

This has raised concern about thehuman health risks from consumptionof farmed salmon and particularprominence was given to a report24

highlighting the presence of low levelsof dioxins and PCBs in farmed salmon.However, subsequent studies haveshown the risks were greatlyexaggerated (if they existed at all) andthat any possible risks are in any eventgreatly outweighed by the resultinghealth benefits.25

Figure 5. Number of escaped salmon in relation to Norwegian salmon production, 1993-2012Source: Norwegian Directorate of Fisheries

Salm

on

pro

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tio

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000)

Ind

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scientificMore recent data showed that farmedsalmon and trout contained onaverage lower levels of dioxins andPCBs than wild caught salmon andtrout, at least for Europe.26

This may reflect the requirementsince 2005/2006 for fishmeal and fishoil in the EU to be routinely tested forcontaminants prior to manufacture.27

It is of interest that fish oilmanufactured within the EU fromforage fish caught in the Baltic isnormally above the required maximumlevels for certain contaminants andcan only be sold after furtherpurification steps under EU control;whereas wild-caught Baltic salmon maybe legally offered for sale without anysuch control.

The permitted maximum levels ofcontaminants set by the EU for thosecontaminants perceived as undesirablein feeds and foodstuffs are laid out inDirective 2002/32/EC (undesirablesubstances in animal feed) and inRegulation EC No 466/2001(maximum levels for certaincontaminants in foodstuffs); theseregulations cover dioxins, PCBs andheavy metals (e.g. mercury, cadmium,lead, arsenic), as well as pesticides (e.g.toxaphene, HCH isomers, endrin,endosulfan, aldrin and dieldrin). In anyevent it seems clear that theprogressive reduction in levels ofdietary marine ingredients due tosubstitution by vegetable ingredientshas also served to reduce the contentof certain contaminants in raw marinefeed materials, and hence trace levelsof any such substances that may bepresent in the salmon product.

5. Comparison withconventional fishingIn 2011 global capture fish volume was93.5 million tonnes of which 67.2million tonnes was of food fish, ascompared with 63.6 million tonnes of

world aquaculture production of foodfish.28

It seems probable that by 2015, orearlier, world food fish production forhuman consumption by aquaculturewill for the first time exceed food fishproduction for human consumptionfrom capture fisheries.29 Capturefishing shows an overall global patternof static or declining catch withincreasing marginal costs. Theproblems of overfishing, by-catch,discards and habitat destruction arewell known. The World Bank estimatedthat global fisheries currently run a neteconomic loss of about US$5 billionper year30 and they take in as much asUS$32 billion per year in subsidies;31

the resulting artificial inflation of profitsencourages increased effort regardlessof the condition of the fishery anddiscourages conservation.32

In addition to the use of fish processtrimmings, the marine ingredients usedin salmon diets rely on capture of smallpelagic species usually occurring intight shoals which are caught usingpurse seines without impacting theseabed and with very low by-catchlevels. Also it is recognised that most ofthe assessed forage fisheries operatewithin the limits that would beconsidered consistent with currentgood industry practice in the contextof single species managementregimes.14

Comparisons of aquaculture withcapture fishing are not straightforwardas the energy transfer betweendifferent trophic levels is not welldocumented, but farmed fish areinherently more efficient due to theirbeing protected from predators andnot needing to forage for food (section2).

Accepted theories on energy andmatter flow between trophic levelsindicate that farmed salmon (andcarnivorous marine finfish culturegenerally) appropriate less oceanprimary production than commercial

capture fishing.33 Assuming a 10%energy flow between trophic levels,producing 1 unit of predatory fish(such as wild salmon) requires 10 unitsof food (largely small pelagic fish), ormore if by-catch values are taken intoaccount.34 Even when compared withthe 2 – 5 units of pelagic fish formerlyneeded to produce one unit of farmedfish,35 there was a clear ecologicaladvantage in favour of farmed salmon.Today, the comparison is even more infavour of farming due to thedominance of plant ingredients insalmon feed.

The evidence clearly indicates thataquaculture can be a more efficient useof living marine resources thancommercial fishing33 if sustainablyproduced marine ingredients are used.This has been well documented in thecase of farmed Norwegian salmon ascompared with capture fishing of wildcod (Gadus morhua). It was shown thatharvesting fish higher in the marinefood chain, such as cod, is far lessefficient in providing marine nutrientsfor human consumption compared toharvesting capelin (Mallotus villosus) tomanufacture fishmeal and oil used insalmon production.

Capelin is an important food sourcefor cod, but using the capelin resourceto produce salmon gave nearly 10times more marine protein, 15 timesmore energy and 6 times more EPAand DHA for human consumption(including the cod liver oil), whencompared with harvesting the codresource.12

Whereas farmed salmon and wild-caught cod are comparable whensubjected to life cycle analysis (LCA) inorder to compare their environmentalimpacts, it is of interest that thenutritional output of marine proteinand essential fatty acids for humanconsumption from these twoalternative ways of using the capelinresource is very different.36,37

Close up view of salmon farm in Western Isles – note use of circular plastic pens with overhead anti-predator nets and cen-tral supports (Courtesy of Marine Harvest Ltd, Scotland)


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6. Comparing salmonfarming with land animalfarmingEstimated 2011 global production ofbeef, pork, chicken, and fish (capturefisheries and aquaculture) is given inFig. 6 (note FAO production data forland animal meat and for fish are notreadily comparable being expressed intwo different product forms: meat incarcass weight and aquaculture/capture in live weight equivalent;FAOSTAT data38 on production of landanimals is given in tonnes as carcassweight, but there is no comparablefigure for live weight equivalent).

It is likely that by 2012 annual globalaquaculture production will haveexceeded global beef production.

Table 1 compares harvest yield,edible yield, energy retention, proteinretention and energy retention in theedible parts of Atlantic salmon, pig,chicken, and lamb, as well as FCR.39 Itcan be seen that the processing yieldof Atlantic salmon is high comparedwith domesticated land animals,reflecting a relatively low skeletalweight.40

Comparing the amount of protein inedible parts to the amount of proteinfed to the animal, salmon retain themost protein (31%) relative to pig,chicken and lamb; salmon also retainthe most energy (23%) in the edibleparts39. The FCR data show that themost efficient converter is farmedsalmon compared with land animals.Although not included in the table,among the least efficient is wildsalmon with an FCR of ca.10.4

The willingness of the Norwegiansalmon industry to divulge accurateand comprehensive data has enabledrigorous analysis by the Norwegian

Institute of Food, Fisheries andAquaculture Research (NOFIMA) andSINTEF of its resource utilisation andeco-efficiency for the year 2010.

Thus Fig. 7 charts the carbonfootprint and land occupation byNorwegian farmed salmon and how itcompares with Swedish pig andchicken production (when comparingthe surface area of the net pen andland use of the salmon feed inputswith the surface area of the land usefor the land animal feeds, butexcluding the sea primary productionarea associated with the origin of themarine ingredients).41

Fig. 8 is an overview of nutrient flowsand energy use for Norwegian salmonin 2010.12

Key findings were as follows:� The carbon footprint of Norwegiansalmon was 2.6 CO2e/kg edibleproduct compared with values of 3.4and 3.9 for Swedish chicken and pigrespectively. � The land occupation per kg of edibleproduct for Norwegian salmon was3.32 m2/kg compared with values of6.95 and 8.35 for Swedish chicken andpig respectively.

� Changing the diet composition from85% plant ingredients to 88% marineingredients resulted in almost the samecarbon footprint, while excludingmarine ingredients from South Americaand the Mexican Gulf from the 2010diet increased the carbon footprintby 7%. � Cumulative energy demand for theNorwegian 2010 salmon was 25.3MJe/kg , edible product; the ratio ofindustrial energy input/energy outputin salmon product was 3.6/kg live-weight and 6.2/kg edible productrespectively. It should be noted that‘edible product’ here excludes salmonheads, frames etc., which can be usedto produce other forms of edibleproduct or eaten directly by someAsian communities. � Producing 1kg of edible chicken andpork requires 2-3 times morephosphorus (as fertilizer) comparedwith salmon, which retain aroundtwice as much dietary phosphorus.� Retention of EPA and DHA was 58%in the whole salmon and 26% in fillet,whereas overall retention of proteinand energy was 26% and 21%respectively in the edible part ofNorwegian salmon in 2010 (net oflosses in feed and salmon production). � The NOFIMA study shows clearlythat salmon farming in Norway is amore efficient way of producingnutrients for human consumption thanchicken and pork production. Farmedsalmon retain nutrients more efficientlyand are more efficient converters offeed nutrients to human food thanpigs and chicken.At the same time it should be noted

that LCA of global salmon farmingsystems showed impacts in mostcategories were lowest for Norwegianproduction and that the most criticalfactor was least-environmental costfeed sourcing.42

Figure 6. Global production for 2011 of beef, pork, chicken and fish (capture fishversus aquaculture) Note: Land animal meat as carcass weight (millions oftonnes): capture fish and aquaculture as live weight equivalent (millions oftonnes) Source: FAOSTAT

Table 1. product yield, energy, and protein retention in edible parts of Atlanticsalmon, pig, chicken and lamb (Source: Bjorkli 2002)(a) Harvest Yield is yield gutted and bled animal(b) Edible yield is ratio of total body weight that is normally eaten, muscle, bodyadipose tissue and liver, lung and heart for pig. Skin is excluded for all animals.(c) FCR = (kg feed fed)/(kg body weight gain)(d) Energy retention + (energy in edible parts)/(gross energy fed)(e) Protein retention = (kg protein in edible parts)/(kg protein fed)

Atlantic salmon Pig Chicken Lamb


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In this connection it appears that theorigin of feed ingredients affects theLCA results and environmental impactsare highly dependent on the reductionfish species used and the energyneeded to catch them.43

Of particular interest was NOFIMA’sfinding that substitution of marine

ingredients by plant ingredients hadvirtually no effect on carbon footprint.The strong trend towards substitutionin salmon feeds is occurring in otheraquaculture feeds and has more to dowith spreading the supply risk andbeing less reliant on limited supplies ofmarine ingredients showing marked

volatility in costs. There is no evidencethat terrestrial agricultural animal andplant feed resources are moresustainable than those from wild-caught marine resources. However, theenvironmental movement isdominated by marine conservationorganisations which pressure fishsupply chains to lower the use ofmarine ingredients for aquaculturediets without considering sustainabilityissues in regard to alternativeingredients (e.g. rain forest impacts ofincreased soya cultivation). In additionto the factors considered in theNOFIMA study, plant productionrequires freshwater, unlike salmonfarming (apart from hatchery smoltproduction), and contributes todepletion of the soil. Most plantingredients can also be used forhuman consumption, and the benefitof substituting marine ingredientsproduced from well managed fisheriessupplying fish species for which thereis little or no demand for humanconsumption is not obvious.44 Theseresults are reinforced by the conclusionof Welch et al.33 that farming salmonincreased production of animal proteinat generally lower land, water, nitrogenand agricultural chemical costs thanterrestrial livestock.

7. Farmed and wildsalmon: supply chainissues, human nutritionalissues, and coproductsIn 2012 global supply of farmedsalmon (dominated by Atlantic salmon)was 2.1 million tonnes (head-on;gutted) compared with approx. 824000 tonnes of wild salmon, mainlycomprising different species of Pacificsalmon.5

Salmon consumption worldwide isover three times higher than it was in1980 and what was once a luxury foodis now among the most popular fishspecies in the U.S., Europe and Japan.

Salmon aquaculture is the fastestgrowing food production system in theworld. To commercial supply chainssalmon is a highly versatile rawmaterial in terms of value addingoptions and product forms (e.g.smoked), as well as having a healthyimage in common with other oily fishspecies linked to its long chain omega-3 fatty acid content.

When compared with the qualityaspects of meat products from landanimals, salmon was rated as beingsuperior in healthiness by Europeanconsumers.45

Figure 7. Carbon footprint and land occupation by Norwegian farmed salmonand Swedish pig and chickenSource: Hognes et al, 2011 SINTEF report (see below)

Comparison of occupation of agricultural land (top axis) and greenhouse gas(GHG) emissions (bottom axis) from production of 1 kilo edible Norwegianaquaculture salmon and Swedish chicken and pig. From project with SIK:

Figure 8. Overview of the nutrient flows and energy use in Norwegian salmonproduction in 2010.Source: Ytrestoyl et al, 2011 NOFIMA report no. 53/2011 ISBN: 978-82-7251-945-1. 65pp

kgCO2e/kg edible product

kg CO2e

m2 land


scientificThese attributes are common to bothfarmed and wild salmon, but does thefarmed product have advantages ordisadvantages in the market placecompared with wild salmon?

Farmed Atlantic salmon products haveproved highly attractive to both foodservice and retail distribution channels.For example in the UK, farmed salmoncurrently represents the mostcommonly stocked fish species onsupermarket shelves, although smallervolumes of wild Pacific salmon are nowbecoming available in the UK, albeit ata price premium to the consumer. Thisreflects the comparative advantage ofaquaculture’s control over productioncompared with wild fish. In particular,wild fish suppliers are unable to matchthe year-round availability of fresh,frozen and processed salmon withconsistent quality from supply chainswilling and able to enter into forwardcontracts for agreed price andquantities. Subjective evidence fromblind taste panels suggests that farmedsalmon is often preferred to wildsalmon; this may, of course, be linkedto farmed salmon containing over 30%more fat than wild counterparts andthe likelihood that panellists are moreacquainted with, and possiblyconditioned to, the organolepticproperties of farmed salmon, which ismore commonly consumed worldwide.

Commercially successful salmonfarming (like broiler chicken farming) isall about management of the supplychain to provide continuity of supply.The key steps include raw materialprocurement, farm management,processing and distribution, while atthe same time other supply chain issuesinclude quality assurance andverification that procedures are beingfollowed, including audited verificationof Good Manufacturing Practice andHACCP. However, due to consumerconcerns about overfishing, a supplychain requirement of growingimportance for both farmed and wildsalmon is independent third partycertification of sustainable sourcing.

In the case of wild salmon, certainretailers and food service channels insistthe source fishery demonstrates it isbeing sustainably managed, either byassessment and certification with theMarine Stewardship Council,46 or withthe FAO-based Responsible FisheriesManagement scheme, which has beenadopted by Alaska Fisheries.47 In thecase of farmed salmon, variousorganisations offer independentverification of responsible practice, e.g.Best Aquaculture Practice,48 and morerecently the Aquaculture Stewardship

Council.49 In addition the supply offishmeal and fish oil is addressed by theResponsible Supply standard of theInternational Fishmeal and Fish OilOrganisation.50

The salmon farming industry in eachof the major producer countries hasestablished representativeorganisations, not only as a politicalvoice, but also in an effort to improvethe quality and sustainability of theindustry. This has close parallels withthe various organisations representingterrestrial livestock industries. Thus inScotland the Salmon Producers’Organisation51 is committed tomaintaining standards in the industryvia the independently audited Code ofGood Practice for Scottish finfishaquaculture (covering food safety andconsumer assurance; fish health andbiosecurity; managing and protectingthe environment; fish welfare and care;and feed and feeding).52 Retailersfocusing on welfare may alsodemand other certifications and it isof interest that approx. 70% of Scottishfarmed salmon is now certified byFreedom Food53 as achieving high fishwelfare standards; this has in turnresulted in higher overall standards offarm practice, while aligning closelywith consumer demands for farmingsystems which strive to care for theanimals’ well-being for both terrestrialand aquatic farming systems.

Unlike broiler chicken farming, forexample, it should be noted thatsalmon cage systems are open to theenvironment, hence inherently less bio-secure. This in turn aligns with theperception of ‘working with nature’ toresolve problems like sealice control,while at the same time supply chainscan claim to be responding toconsumer demand for more ‘natural’food.

The emphasis on environmentalcertifications must not obscure thefundamental objective of producingwholesome and nutritious food in acost-efficient and safe manner. Salmonis an important source of thenutritionally important PUFAs, forwhich there is strong demand from thehuman nutritional sector as well asaquaculture. Man has a limited abilityto elongate and desaturate alpha-linolenic acid (e.g. from oil seeds) andit is generally recognised that the lackof long chain omega-3 fats in the meatof land animals and the presenceinstead of more saturated fats,especially of the omega-6 series, canpredispose to human health problems(e.g. obesity and cardiovasculardisease) if there is inadequate balance

of omega-3 and omega-6 fats54.Traditional poultry and eggs wereone of the few land-based sources oflong-chain n-3 fatty acids, especiallyDHA, which is synthesized from itsparent precursor, but the evidence isthat this has now changed withchickens in the UK market providingseveral times the fat energycompared with protein and muchreduced PUFA levels, hencepotentially negative consequencesfor animal welfare and humannutrition.71 This nutritional healthbenefit of salmon is shared by otherhigh oil fish, hence adding further valueto salmon as a product and acompetitive advantage as against landanimals. The trend towards highenergy salmon diets and the sole use offish oil as a dietary fat source meantthat formerly farmed Atlantic salmon,having a higher fat content than wildsalmon, also had a higher content ofPUFA than wild salmon, especiallywhen oil-rich fish such as anchovy(Engraulis spp.), herring (Clupeaharengus), or sandeel (Ammodytes spp.)were used. Since the progressiveintroduction of vegetable oils as apartial dietary substitute for fish oilfrom around the year 2000, andinfluenced by the growing competitionfor PUFA-rich fish oils by the humannutrition industry, the content of PUFAin farmed salmon has reduced to only athird of what it was before the year2000.55 This may undermine the basisof dietary recommendations for humanconsumption of oily fish; for example,EFSA56 recommends a minimum of 250mg/day of combined EPA + DHA,whereas the UK (Scientific AdvisoryCommittee on Nutrition)57

recommends a minimum of 450mg/day of combined EPA + DHA andconsuming fish twice a week, includingone meal of oily fish. Although differentfarmed salmon are being reared ondifferent combinations of fish andvegetable oil, it is possible that somewild salmon will now contain morePUFA per gram than some farmedsalmon. However, it is clear thatproduct differentiation is now occurringwith some supply chains demandingtheir salmon is supplied with a greaterconcentration of EPA and DHA thanother supply chains. For example,certain UK retailers have focused onmaintaining higher PUFA levels insalmon fillets and Scottish producershave contracted to supply this marketsegment; it is likely that segmentationwill become increasingly apparent toconsumers in terms of product labellingand premium pricing.55


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Given the worldwide scarcity of PUFA-rich fish oil, this situation is likely topertain until such time as new cost-effective PUFA sources emerge fromcurrent research and developmentusing algal production and geneticmodification of oilseeds (see 8 (vi)).

Not all salmon is eaten directly andsalmon coproducts typically representaround 40% of total ungutted carcaseweight; such coproducts includeaquaculture meals and oils for livestockfeeds (which cannot be recycled backinto salmon feed to avoid potentialhealth problems), but also a variety ofvalue-added products for use in thehuman nutritional and pharmaceuticalsectors.58 In general the protein qualityof fish meat is higher than land animalmeat, for example it is higher in lysineand methionine as a proportion of totalamino acids. Table 2 compares theamino acid content in salmon meal andhydrolysate with the requirements ofchickens and humans (adults andschoolchildren).59 Tryptophan seems tobe the only limiting amino acid for alldiets although this may be linked toanalytical problems. Arginine forpoultry seems to be the only truelimiting amino acid in salmon meal, butnot in the hydrolysate where threonineappears marginally limiting. Farmedand wild salmon contain calcium,copper, iron, magnesium, manganese,phosphorus, potassium, selenium,sodium and zinc. Other micronutrientspresent include Vitamins A and D and arange of B vitamins, with farmedsalmon being much higher than wildsalmon in thiamine and folic acid.Clearly the nutritional composition ofwild and farmed salmon reflects theirfeed intake, which reflects the source oftheir feed. In the case of Norwegianfarmed salmon, the marine feedingredients may include fishmeal andoil from locally available fish (e.g.capelin) and process trimmings fromfish for human consumption, as well asimported fishmeal and oil derived from

species such as Peruvian anchovy(Engraulis ringens). The majority ofsalmon dietary ingredients are now ofvegetable origin, such as soya proteinconcentrate and rapeseed oil, and likelyto be imported into the main salmonproducing countries. The efficiencywith which salmon convert these feednutrients to nutrients for humanconsumption and the superior qualityof the output relative to terrestriallivestock have implications for futurefood security, especially given the staticnature of capture fishing.

8. Overcoming technicalconstraints (i) Off-shore productionA possible alternative to the problemsof siting salmon cage farms at inshorelocations is moving the productionunits offshore to deeper and lesssheltered waters, where ocean currentsare stronger.

This avoids the risk that heavily usedinshore sites can become progressivelyunusable despite adopting site rotationand fallowing. At the same time off-shore locations avoid many of theconflicts that occur with other marineresource users in the more crowdedinshore waters, although user conflictsexist offshore too.

This requires sophisticated, capital-intensive cage rearing and feedingsystems capable of withstanding openocean gales; such offshore systems arenow being introduced for marine fishand shellfish farming, but are at anearly testing phase for commercialsalmon farming.

(ii) Recirculation and land-basedsystemsRecirculation technology is showingpotential for intensive aquaculture withminimal water consumption60 and isenabling salmon smolt production totake place under environmentallycontrolled conditions at optimal water

temperatures with minimal bleed-in offreshwater. Marine finfish species arealso now being reared intensively inclosed circuit, land-based, recirculationunits away from the coast, hencepotentially avoiding the problems ofescapement and biosecurity describedin relation to salmon cages, but the keyissue is the cost of energy for suchsystems which may therefore bedifficult to scale up commercially.

(iii) Genetic improvement The relatively long generation time ofsalmon compared with warmwaterfarmed fish (e.g. Tilapia spp.) meansthat selective breeding takes longer.

However, during the last 40 yearsgenetic progress with Atlantic salmonhas markedly improved key productiontraits. For instance, a near doubling ingrowth rate has resulted in a reductionin the length of the production cycleto 1.5 – 2 years;10 the onset of sexualmaturation has been delayed; FCR hasdramatically reduced; higher survivalrates have been achieved (includingincreased resistance to specificpathogens); and fillet quality has beenenhanced in terms of fat and colour.The application to salmon aquacultureof molecular biology techniques(looking at single genes), as well asgenomics (looking at DNAsequencing), is set to offer afundamental approach to solvingspecific problems. The first Atlanticsalmon genome is about to be fullysequenced due to internationalcollaboration61 and early projectobjectives are to identify the genes forsexual maturation, those that code forsealice resistance, and for preferredmeat texture.

(iv) Triploids The use of sterile salmon by farmerswould overcome the risk of escapedfish affecting wild populations and twopossible routes are being considered:triploidy and genetic modification.

Table 2. Comparison of amino acid content in (a) salmonmeal and (b)hydrolysate with requirements of (c) chickens and (d)humans (Ramirez 2007)Sources(a) ww.pesquerapacificstar.cl (b) Wright, 204 (c) Nutrient requirement of poultry, 1994 (NRC) (d) Protein and amino acid requirements in human nutrition, WHO, Technical Report Series [2007(935):1-265]

Amino acids, % of protein

Salmon meal (a) Salmon hydrolysate (b) Chicken (c) Adult human (d) Schoolchild (d)Amino acid


scientificTriploid induction (by shocking theegg shortly after fertilisation) wastested in the 1990s to prevent salmonmaturation prior to harvest, but alsoresulted in poor performance, reduceddisease resistance, and deformities andwas therefore abandoned in favour ofphotoperiod control of maturation. It isnow recognised that growth andsurvival of triploid salmon is stronglyaffected by family. By means of correctselection, triploids were found tooutperform their diploid siblings withminimal deformity rates62 and thefeasibility of using triploid salmon isagain being studied in Norway andScotland.

(v) GM salmon The use of GM salmon is promoted asa sustainable alternative toconventional salmon farming.

Thus trademarked ‘AquAdvantage’salmon are Atlantic salmon with a genefrom chinook salmon (Oncorhynchustshawytscha) reducing the time tomarket by 50%. The owners,AquaBounty,63 intend to grow the fishas sterile, all-female fish in land-basedfacilities. The US Food and DrugAdministration is currently consideringtheir application to approve GMsalmon for human consumption. Ifgranted this would be the firstgenetically modified animal allowed tobe sold to consumers. Consumers inEurope are unlikely to accept theproduct. The largest global salmonfarming company (Marine Harvest) hasrecently issued a statement saying thatit does not support the introduction ofGM salmon and asking for it to bespecifically labelled as such in theevent that it is approved forconsumption. The European salmonfarming industry even avoids the use of(authorised) GM ingredients in the

feed.

(vi) GM feed ingredients The increased scarcity and cost of fishoil has spurred research intomanufacture of long chain PUFAs,especially EPA and DHA, by means ofalgal production (e.g. by fermentation)and by genetic modification of oilseeds,such as soyabean, rapeseed, andCamelina sativa.

Limited quantities of these fatty acidsare already commercially available fromalgal production, while GM materialhas only been producedexperimentally and is some way fromcommercialisation assuming consumerconcerns and regulatory hurdles areovercome. As regards GM soya, canola,and other vegetable protein feedingredients, these are now being usedwidely by the aquaculture industry.However, so far, salmon feeds inEurope have not contained GMingredients due to continuingconsumer concerns.

(vii) Stock losses Currently in Norway one out of fivesmolts stocked in a cage will not reachthe market due to diseases, escapes,and production disorders; reducingthese losses would improve animalwelfare and also reduce the use ofresources.7

The situation in second-placed Chileis substantially worse, due mainly tohealth problems, and the authoritiesare now taking steps to reduce thedensity of farms in a given area and toopen up new ‘clean’ sites. Thereforedisease prevention and controlcontinues to be of major importance insalmon farming and the intenseresearch focus on priorities, such assealice, helped by new techniquesbecoming available, is likely to bring

forward solutions.

(viii) Feeds The main challenges to extendingsubstitution of marine ingredients byfurther dietary inclusion of plantprotein and oils is linked to their lowerprotein and unsaturated omega-3 fattyacid contents and higher starch andfibre contents, unfavourable amino acidprofiles, and the presence of anti-nutritional factors.64

Plant protein and lipid inclusions hadreached 40% by 20107 and are nowexceeding 50% especially in the caseof lipid sources.55 Given the level ofresearch focus by nutritionists and feedformulators, there is little doubt thatinclusion levels of plant materials willincrease and that marine ingredientswill be used more strategically,especially at critical parts of the lifecycle, such as in first feeding and smolttransfer diets.65,66 The limiting marine-based nutrients of most concern forsalmon performance are certain aminoacids (e.g. lysine and methionine) andlong-chain omega-3 fatty acids; thelatter reflecting the increasing scarcityof suitable fish oil until alternativesources become available (see 8 (vi)above). Although the long-chainomega-3 requirement of salmon is lowand likely to be covered in practice bythe dietary fishmeal, even in theabsence of added fish oil,67 theconcern is more about the consumerimpact of low levels of EPA and DHA inthe resulting end-product. Consumerconcerns are also linked to thecontinued resistance within Europe tousing land animal by-products insalmon diets despite the EuropeanCommission recently authorising thereintroduction of processed animalproteins from non-ruminant farmanimals as feed ingredients (c.f. alsoresistance to GM materials). However,increased use of plant materials raisesits own sustainability issues, sincecalculations of the hypothetical arearequired for supplying 100% of all themacro-nutrients from plant sourcesindicate that Norwegian salmonproduction would need around 1.1million hectares (45% of the totalagricultural area of Denmark) in orderto produce 270 000 tonnes of wheat,1.56 million tonnes of soya, and 950000 tonnes of rapeseed7. Much of thesoya would presumably come fromBrazil and further expansion threatensthe southern Amazon basin. Alreadythe soybean trade between Brazil andEurope is creating environmental,social, and economical concerns thathave yet to be fully resolved.68

Interior view of office on feed barge showing monitors for remote cameras anddigital display of temperature and dissolved oxygen” (courtesy of ScottishSalmon Producers’ Organisation)


scientific9. ConclusionsWhereas fishing and land animalproduction have developed overmillennia, large scale intensiveaquaculture has only developed overthe past 30 – 40 years.

Over this same period, issues such asthe use of antibiotics, biodiversity,pollution, and animal welfare, havecome to the fore in regard to landanimal production, especially indeveloped economies. Salmon farmingis the most developed form ofintensive aquaculture but from thestart it has been subjected to constantcritical scrutiny on these issues. That ithas not only survived, but grown to bea highly efficient global industry, ismainly due to innovation and rapidtechnological change enablingincreased productivity, cost reduction,and close control of the productionprocess. These factors have enabledthe industry to resolve most of itsproblems, improve its productivity, andsucceed commercially on a globalscale, while becoming increasinglysustainable.

The criticism that salmon farmingrelies on the unsustainable use ofdietary ingredients of marine originwas reviewed in an earlier paper, whichexplained why the continuingsubstitution of marine ingredients byvegetable proteins and oils in salmonfeed, together with the evidence thatreduction fisheries are not being over-exploited to produce more and morefishmeal and fish oil, make thiscriticism increasingly untenable.

This review has covered otherenvironmental criticisms of salmonfarming, including the impact of itseffluent discharge, the use ofantibiotics and chemicals, thetransmission of disease agents into themarine ecosystem, and the threat towild salmon populations arising fromescaped farmed fish (due either tointerbreeding or to diseasetransmission). During its rapidindustrialisation, the industry has hadto learn how to address theseenvironmental effects and to evolvecodes of good practice in order toavoid reduced productivity, hencereduced profitability, and to complywith government regulations.Improved husbandry knowledge andoperating practices, as well as tighterregulatory frameworks, have largelyhelped the industry to internalise andmitigate these problems in Europe andNorth America,69,70 with the Chileanindustry somewhat lagging behind.Sealice infections and salmon escapesare probably the most serious

environmental challenges in salmonfarming, at least for the dominantNorwegian industry. Intensive researchcontinues to achieve more effectivesealice control, including vaccinationand the use of live cleaner fish tobrowse on lice attached to salmonskin. The long term prevention ofsalmon escapees breeding with wildsalmon depends on consumersaccepting a switch to farming sterilesalmon. Fears that farmed salmon mayconcentrate environmentalcontaminants in the flesh and hencepose a human health risk are false. Noris there evidence to support the viewthat salmon farming has beenresponsible for the widespread declinein wild salmon populations in Europeor North America.

When compared with wild-caughtfish, farmed salmon has a clearecological advantage. Norwegianstudies by NOFIMA have shown that, ifthe objective is to provide marinenutrients for human consumption, it isfar more efficient to harvest pelagicfish for fishmeal and fish oil to rearsalmon than to leave them in the seaas prey for cod and instead harvest thecod resource. Using capelin toproduce salmon gave nearly 10 timesmore marine protein and 6 times morelong-chain omega-3 fatty acidscompared with harvesting the cod,despite farmed salmon and wild codhaving comparable LCAs. Overallsalmon farming is a more efficient useof resources than commercial fishing,especially when taking account offishing externalities. In fact the oceansprovide an under-utilised source ofnutrients for human consumption andsalmon farming offers an efficientmechanism for transforming theseresources into high quality food thatcan be distributed worldwide andavailable all the year round.

The NOFIMA study shows thatsalmon farming in Norway is a moreefficient way of producing nutrients forhuman consumption than chicken andpork production, as indicated by itsclimatic impact, area of landoccupation, and use of non-renewablephosphorus resources. Farmed salmonalso retain nutrients more efficientlycompared with pigs and chicken, butthere is no evidence that terrestrialagricultural animal and plant feedresources are more sustainable forfarming salmon than using feedingredients based on wild-caughtmarine resources.

Although still young, the salmonfarming industry has greatly increasedthe availability and reduced the cost of

supplying salmon to world seafoodmarkets. It has also brought sustainableemployment to many remote rurallocations. The main challenge goingforward will be to continue to growsustainably in step with market andenvironmental considerations. A majorpriority is the reduction in losses overthe production cycle of around 20% offish stocked into a cage. Also sealiceinfestation and escaped salmon mustbe better controlled. A potentiallimiting factor is the availability ofPUFAs due to growing competition forfish oil from the human nutritionindustry. It will be necessary to increasefurther the proportion of plant oil(mainly rapeseed oil) in salmon feed,hence reducing the EPA and DHAlevels in the fillet, which mightadversely impact consumer demand;but in due course this will be solvedwhen cost-effective material becomesavailable either from algalmanufactured oils or from genetically-modified plants.

It will be of interest to considerwhether valid comparisons can bemade between salmon farming andother types of aquaculture, includingless intensive systems, especially asregards environmental impact andresource use. The answers to suchquestions may help us to drawconclusions on the potential role ofglobal aquaculture for future foodproduction and food security.

AcknowledgementsThe authors gratefully acknowledgethe advice and assistance of PetterArnesen, Frank Asche, Ragnar Nystøyl,Randoph Richards, and John Webster.

Special thanks are due to TorbjørnÅsgård and Trine Ytrestøyl (NOFIMA)and to Erik Skontorp Hognes (SINTEF),and their respective colleagues, whosework on the Norwegian salmonindustry features extensively in thisreview.

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Collecting salmon by well boat for harvest – note the net has been pulled up to crowd fish around the pump (courtesy ofIan Armstrong)


the GM debate

Pros and cons of GM crops as asource of resistance to insect pests

Professor Helmut van EmdenSchool of Agriculture, Policy and Development, The University of Reading,

Earley Gate, Reading, Berks., RG6 6AR, United Kingdom

Introduction

The term ‘genetically modified’(GM) has become associatedwith one particular type of GM,

namely direct gene transfer. Rather similar is the way ‘organic

farming’ has become associated withthat type of farming seen as a contrastwith ‘conventional farming'.

I make this point because GM hasbeen around since the dawn ofagriculture, how else did man progressfrom wild grasses to productivemodern cereals? ‘Traditional’ plantbreeding, acceptable to the opponentsof ‘GM’, is certainly GM by anydefinition than other that it does notinvolve direct gene transfer.

Focusing on the technique of genetransfer rather than the properties ofthe gene transferred is well expressedby the following quotation:

“We have recently advanced our

knowledge of genetics to the point wherewe can manipulate life in a way neverintended by nature. We must proceedwith the utmost caution in theapplication of this new foundknowledge”.

The fear of something ‘unnatural’ isclearly behind the opposition to GMcrops. But doesn’t this exactly makemy point that we should concentrateon the gene rather than the method oftransfer? Until recently one could avoidthe ambiguity of GM by calling directgene transfer ‘transgenic’, but recentlythe antonym ‘cisgenic’ has beenproposed for the direct transfer ofgenes amenable to traditional breedingin an effort to find a form of GMacceptable to the ‘organic’ lobby.While this might appear to be retreat,concentrating on the ’naturalness’ ofthe gene may in the end achieveacceptance that the method of transferis not very relevant. After all, it is not

possible to limit the genes transferredby breeding to the one(s) desired;there is associated genetic baggagewhich, if it includes undesirablecharacters, may take many furthercycles of breeding to eliminate; bycontrast cisgenics will transfer onlywhat is intended.

Incidentally, it is salutary to realisethat the quotation above does notrelate to ‘GM’ as we understand ittoday. It expresses the concerns of theagriculturalist Luther Burbank in 1906when he discovered Gregor Mendel’swork with round and wrinkled peaseeds! The first reference I can find tousing transgenic methods to obtainplant resistance to insect pests is in1979 (1), and it is clearly taking longerfor ‘GM’ to be generally acceptablethan applied to Gregor Mendel’s work.‘GM’ crops have now been grown on alarge scale since 1996, and the fear of‘Frankenstein’ consequences does notappear to have any justification.

SummaryCurrent experience of the pros and cons of using GM crops for resistance to insect pests is largely limited to one source oftransgene, the proteins expressing the toxin of Bacillus thuringiensis. Since the gene transferred, and not the method oftransfer, is relevant to the topic of this paper, we can explore what is known from plants traditionally bred for insect-resistance based on similar mechanisms to those likely to be used in GM crops, i.e. on single toxins giving a high level ofcontrol. Across a whole range of potential issues including the development of pest strains tolerant to the toxin and side-effects on natural enemies, crops with resistance mechanisms based on high concentrations of toxins compare badly withcrop varieties giving partial and more broadly-based resistance. Such partial resistance may, however, be fully effective whenintegrated with biological control and selective use of pesticides. However, it must be pointed out that this is not thecomparison that matters, for GM crops will not be used to replace other forms of plant resitance, but instead to replaceinsecticides. In that comparison, the replacement of the spraying machine by a GM crop as the vehicle for delivering toxinshas clear advantages.

Keywordsgenetically modified crops, human safety, insecticide resistance, natural enemies, plant resistance, tolerance, yield loss.

Abbreviations Bt Bacillus thuringiensis; DIMBOA 2,4 dihydroxy 7 methoxy 1,4-benzaxazin-3-one; GM genetically modified; IPMintegrated pest management; USA United States of America.

GlossaryAllelochemical: A chemical producedby a living organism which, when con-tacted by another living organism, hasdeleterious effects on the latter.Cisgene: Transgene transferredbetween organisms not too distantlyrelated.

Secondary (plant) compounds:Complex chemicals made by plantsbut not essential to the life of theplant. Sink (in relation to photosythesis inplants): A function in the plant creat-ing a demand for the products of pho-tosynthesis.

Synthesised gene: A gene with at leastpart of its DNA created artificially.Transgene: Gene transferred from oneorganism to another by any method.Yield drag/penalty: Reduction in cropyield caused by the diversion of photo-synthesis for other purposes such assynthesis of toxins by a plant.

Much of the GM hectarage is plantedto insect-resistant crops expressingBacillus thuringiensis toxins (Bt); thisfirst exploitation of ‘GM’ therefore wasfor resistance to insects. Since then,genes for a number of other insect-toxic proteins (including lectins,amylase inhibitors, trypsin inhibitors,protein inhibitors, chitinases andcytokinins) have been directlytransferred to crop plants, but nocommercialisation has as yet followed.

If we focus on genes rather than thetransfer method, the traditional plantbreeding literature provides a greatdeal of relevant experience about thepotential pros and cons of pest-resistant GM crops. Key to this is thatresistance to pests in GM crops is likelyto be based on toxins, and commercial'GM' varieties will only come to marketif the genes express these toxins at ahigh enough level to give controlequalling that given by insecticides. Sotraditionally-obtained plant resistancecan be directly comparable if it isbased on a strong toxin. Overdosing isnot limited to agrochemicals, anddoing it with genes for plant resistancewill have consequences not dissimilarfrom overdosing with insecticides.

Recently a trial of GM wheat with asynthesised gene (resynthesised frompeppermint to eliminate inhibitorycompounds) expressing the alarmpheromone of aphids (2) was carriedout. The aim was partly to make thepoint that GM crops could involvegenes whose 'escape' from the trial

field could not cause ecologicalmayhem, but such 'behavioural' andtarget-specific possibilities are boundto be extremely rare in comparisonwith toxins.

The advantages of ‘GM’ perceived bythe agricultural industry are thetransfer of single genes without othergenetic material, that it is possible toavoid the crossing barriers that existbetween unrelated organisms and thatthe level of expression can reach virtualimmunity.

Examples from traditional plantbreeding involving toxins show us thatthese advantages also translate topotential disadvantages (Fig. 1) andthis is the theme of this article.

Safety for humansMuch of the history of the geneticmodification of wild plants over pastcenturies, for most of that timewithout any understanding ofMendelian ratios, was to reducedramatically the levels of toxins inthose wild plants to make thempalatable or even safe to eat.

As far as these same compoundsconferred resistance to insects, so thesusceptibility to pests of the cropsincreased and we now go back to thewild ancestors to recover these sourcesof resistance (Table 1 compares thelevels of two toxic chemicals in cropsand related non-cultivated plants)..Good examples are in the Solanaceae,where wild potatoes and tomatoes are

both highly toxic to humans. Safety for humans is paradoxically the

one area of potential concern where‘GM’ crops probably have theadvantage. Because of the ‘unnatural’angle, no one has queried thenecessity for ensuring human safety.The Bt toxin was chosen for the so-called ‘first generation’ GM cropsspecifically for its safety to humansstemming from differences betweenhumans and insects at the cellmolecular level. GM crops are subjectto stringent testing to ensure safety tohumans before they can be marketed.In this they differ from new cultivarsobtained by traditional breeding, andthey have never been required toundergo similar testing before release.A famous example of theconsequences of this is the release inthe USA of the potato variety ‘Lineup’,which contained elevated levels of aglycoaldehyde to confer resistance toColorado beetle (Leptinotarsadecemlineata). Consumers found theflavour of ‘Lineup’ distasteful, andsome showed symptoms of toxicity;the new variety had to be withdrawn(3). With GM crops, the public isprotected against health issues.

A further advantage is that the pestreceives the toxin through the plantand not through a chemical sprayhazardous to the person applying it.

Yield dragIt is hard to think of a mechanism ofplant resistance to insects that doesnot involve some energetic cost to theplant and therefore a potentialreduction in yield.

Gershenzon (4) has quantified thecosts of some compounds involved inplant resistance to insects and, whenexpressed as per cent ofphotosynthesis, some costs appeardramatic. For example, production ofthe triterpene papyriferic acid in birchinvolves a 24.5% cost, and theflavonoid apigenin (in Isocomaacradenia) a cost of 6.9%. Thephotosynthetic costs of othercompounds cited are lower and mostlyrange between 0.1 and 4.8%.

However, the real costs of producingmany of such so-called ‘secondarycompounds’ (or ‘allelochemicals’) arenowhere near as great as Gershenzonand many other authors includingmyself (3) have suggested in the past.Firstly photosynthesis is ongoingwhereas production of allelochemicalsis not, and secondly radiation is mostlysufficient for photosynthesis to be sinkrather than source limited – i.e. thecost of allelochemical production can


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Figure 1. How the perceived advantages (left) of transgenic host plant resistanceto insects have the potential for disadvantageous side effects (right)

Table 1. Quantities of some allelochemicals in cultivated (C) and wild (W)tomatoes and brassicas/

Chemical (units) Plant Quantity Reference

31

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the GM debatebe compensated for by a rise inphotosynthetic rate (4).

Thus, referring back to Table 1, thehigh glucosinolate levels in Sisymbriumofficinale can be achieved in only 7.5minutes of photosynthesis, and thelevels of 2-tridecanone in wild tomatotake less than one hour (4). Such shorttimes would be typical for annualcrops rather than for perennials whichmake lifetime investments in muchmore energy-expensive defencecompounds such as lignin and tanninsthat may accumulate to 20% of drymatter.

It is therefore not surprising that yieldpenalties of plant resistance have beenhard to demonstrate, including for thequite complex molecules of the Bttoxins. Any potential for yield loss willof course be minimised if partial plantresistance is combined with other pestcontrol methods (Integrated PestManagement or IPM) in contrast withthe sole reliance on an allelochemicalas is characteristic of GM.

However, the latter resistance doeshave one advantage. In themodification process it may be possibleto add promoters which result in thetransgenically transferred toxin onlybeing expressed if induced by pestattack. Therefore there can be no yieldpenalty of the resistance in the absenceof the pest.

Tolerant pest strainsIt is a familiar scenario that continueduse of an effective insecticideeventually leads to it losing thateffectiveness because pest strains in thepopulation are selected that aretolerant (resistant).

Such ‘breakdown of control’ is alsovery familiar to plant pathologistsusing resistant varieties to control plantdisease organisms such as rust fungi incereals.

With plant resistance, suchbreakdown is most frequentlyassociated with single major genes forresistance, usually providing only whatis known as ‘race-specific resistance’. Itis therefore only to be expected thatthe high selection pressure on a pestimposed by a single effectivetransgenically transferred toxin willsimilarly result in ‘breakdown’. In astudy of 77 reports from eightcountries in five continents (6), morethan 50% resistance to Bt crops wasfound in five out of 13 pest species in2-011, compared with only one in2005. In the laboratory, it has beenpossible to select one of the cottonbollworms (Pectinophora gossypiella) forresistance to Bt cotton in only 10

generations. The widespreadexpectation of the breakdown of GMpest resistance has led to attempts tocheckmate this development byrequiring farmers to maintain areas ofnon-GM cotton to act as ‘refugia’where moths with some resistance toBt can mate with susceptible ones.With scientific opinion originallydivided on the merits of this approach,this programme was itself anexperiment, but does seem to haveworked pretty well where the strategyhas been implemented. Whereasgrowing Bt cotton with the strategy inArizona has shown sustainedsusceptibility in pink bollworm(Pectinophora gossypiella), controlfailures without the strategy have beenreported in China and India (7).

The danger of breakdown ofresistance with GM crops stems fromthe high selection pressure theexpression of the gene puts on thepest population and so applies equallyto traditional plant resistance based onhighly effective allelochemicals – themode of transfer of the gene isirrelevant! An example of suchbreakdown in traditional plantresistance is that of monogenicresistance in rice to brown planthopper(Nilaparvata lugens) developed at theInternational Rice Research Institute inthe Philippines. One new variety (IR26)was particularly resistant to theplanthopper, but was defeated withinonly 2-3 years by the appearance of astrain that was tolerant to theresistance (8). By contrast, manyexamples of plant resistance which arenot so strong, are multigenic and/orbased on non-allelochemical methodssuch as tissue hardness, have lasted formany years. As an example, therootstocks of the vines of old Frenchcommunion wines, taken to the USAby early settlers from Europe, weregrafted in the early 19th century withscions of vine varieties then current inEurope to deal with the destructionbeing wrought by an aphid(Phylloxera). The resistance thisprovided is still largely effective todayafter 200 years, though a tolerantPhylloxera did appear in a small area inGermany in 1994 (9). Indeed, in areview of the literature in 1996 (3) Iwas only able to find 16 pest species inwhich resistance-breaking strains hadbeen identified; moreover, several wereexamples of selection in the laboratoryrather than in the field. As mentionedearlier, traditional breeding contrastswith GM in resulting in the transfer ofa genetic package which includes thedesired gene amongst others, and so

the resistance may not be monogenicif other unknown genes also confersome resistance. Thus resistance toaphids in cereals, thought to bemonogenically based on just onecompound (the 1,4-benzaxazin-3-oneglycoside DIMBOA), involves otherresistance mechanisms also (10).

Problem tradingOne of the advantages the industryclaims for GM crops with plantresistance to pests is that it isenvironmentally preferable to theheavy use of insecticides it replaces.

Again, there is nothing special hereabout GM; the advantage couldequally be claimed for traditionallybred resistant varieties. However, aninsecticide usually controls more pestspecies on the crop than the onetarget organism, and so another pestmay build up in numbers and becomea new problem once insecticidepressure on the crop is relaxed. Thishas actually happened in Bt cottonwith leafhoppers emerging from littleto major economic importance (11).

Damage to beneficialinsectsWhatever the mechanism of transfer ofa gene conferring high expression of atoxin, natural enemies will lose theirfood supply unless the crop also hostsalternative prey not affected by thetoxin.

In relation to implementing IPM oncrops, there is of course no mileage intrying to combine different methods ofpest control if any one of the methodsis effective on its own. Toxins in plants,whatever their origin or method oftriansfer, are also likely to affect naturalenemies directly if they eat poisonedprey on the plants. There are plenty ofexamples where chemical defence,whether in wild or cultivated plants,also proves toxic to predators and/orparasitoids; some of these are listed byvan Emden (12). Allelochemicals areimportant in soybean varieties bred forresistance to pests and such varietiesare known to affect natural enemiesadversely (13). One interesting case –sadly probably a rare exception –where high levels of allelochemicals areactually less damaging than lowerlevels is that of the aphid-resistancefactor DIMBOA in wheat. At highlevels, the effect on aphids is not acutetoxicity, but to deter their feeding. Theladybird predator Eriopis connexa istherefore not as badly affected as it iswhen eating aphids poisoned on


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cultivars with lower DIMBOA levels(14).

The few toxins so far exploited fortransgenic transfer to crops have ofcourse been tested for any deleteriousside effects on natural enemies offeeding on prey on such plants. Muchof this work relates to Bt, and a reviewin 2004 (15) of some 25 laboratoryand field studies concluded Bt cropswould present few problems, and thishas been confirmed in more recentstudies (e.g. 16, 17). One ratherinconclusive laboratory study didsuggest high mortality of lacewinglarvae when fed caterpillars reared onBt maize (18). In fact, Bt is ratherselective in which taxa it affects, andhoney bees are not affected (19, 20).Also, there appears to be considerabledilution through the trophic levels(21). The concentration of 21.7 µg g-1

fresh weight of a Bt toxin (Cry3Bb 1)in maize reduced to 5.6 µg g-1 inmites feeding on the maize, and wasreduced further to about 4.5 and only1.4 µg g-1 respectively in larvae andadults of a predatory staphylinidbeetle. Other transgenes proposed forpest resistance seem to pose greaterproblems in relation to beneficials. Theladybird Adalia bipunctata fed aphidsreared on the leaves of potatoesexpressing the snowdrop lectinshowed no acute symptoms, butfemale longevity was reduced by halfand fecundity by 20-40% (22). Lectinsare also toxic to bees (20). Amylaseand protease inhibitors proposed forGM legumes against bruchid beetleshave been tested against theirparasitoids with conflicting results (23,24); harmful affects cannot bediscounted.

The high efficacy of pest resistance in

GM crops makes it difficult if notimpossible to exploit the often positiveinteraction between plant resistanceand biological control, whether withindigenous natural enemies present inthe agroecosystem or augmentedartificially (e.g. by release). Theseinteractions include highly specificones such as the switch ofCryptolaemus ladybirds from nectar-feeding to carnivory on cotton varietieson which plant breeding haseliminated the extra-floral nectaries onthe leaves (25) and the improvedpredation of aphids by adult ladybirdson the so-called ‘leafless’ pea varietieswith a profusion of leaf-substituting

tendrils. These substitute for leaves andafford ladybirds a goodgrip, whereasthey frequently fall off the smoothwaxy leaves of normal varieties (26).

However, positive synergism betweenplant resistance and biological controlis a widespread and much moregeneral phenomenon (3) than the twoexamples above might suggest ,though it cannot be taken for granted(e.g. the examples based on toxinscited above).

Positive synergism may arise fromnumerical relationships, i.e. thepredator/parasitoid prey ratio is higheron partially resistant than on morepest-susceptible varieties. This occursparticularly when the natural enemiesuse host plant cues (especially odours)in searching for prey from a distance.Parasitoids often emerge with apreference for the odour of the hostplant (species and even variety) onwhich they themselves developed (e.g.parasitoids of aphids – (27)).Furthermore the plant odour changeswhere sucking insects have probed,which enables the parasitoids to homein on the location of even a few prey(as is only to be expected on resistantplants). Thus biological control inAfrica of the cassava mealybug by itsparasitoid Epidinocarsis lopezi isprimarily achieved when the prey arealready at very low numbers in the dryseason.

More usually, perhaps, the positivesynergism between partial plantresistance and biological control

Figure 2. Some examples of the outcome of combining host plant resistance toinsects with biological control (histograms show the proportion of insects“surviving” the control measures). Histograms in each block from left to right:plant resistance alone (black), biological control alone (checkerboard), predictionof control given by the combination (white), actual outcome (striped). Note: thesecond block of histograms form the left illustrate negative interaction and theexample of diamond-back moth (far right) show simple additivity of the twocontrol measures. More detail of the pest species and sources of the data can befound in (12).

Figure 3. The concentration of different insecticides (listed on left) needed on apartially resistant crop variety to achieve 50% mortality expressed as a percent-age of the concentration needed on a susceptible variety. Key to pests: hoppers(checkerboard), aphids (white), Lepidoptera (black), Coleoptera (x striped). Moredetail of the pest species and sources of the data can be found in (12).

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depends on functional responses, i.e.there is a greater impact per individualpredator on resistant than susceptiblevarieties. The common phenomena(12) appear to be:

1) Prey on resistant plants tend to besmaller – predators will thereforeconsume more before they aresatiated.

2) Smaller prey are also less likely toescape by running away or kicking atthe natural enemy.

3) Disturbance bypredators/parasitoids may cause the

prey to fall from the plant in greaternumbers on resistant than onsusceptible plants (eg. 28).

4) Higher pest densities on the leavesof susceptible plants may leave morewax, faeces, honeydew etc. which mayimpede the movement of naturalenemies or cause them to devotesearching time to cleaning.

A simplistic but nonetheless adequateapproach to measuring synergism isthat of multiplying the survivalcoefficients of the synergisingcomponents. If, in a given timeinterval, biological control reduces apest population by 10% (i.e. survivalcoefficient = 0.9), the population on aplant with 20% resistance (i.e. survivalcoefficient = 0.8) should be 0.9 x .08 =0.72 = 72% of that on the susceptiblevariety without biological control. Fig.2 shows this calculation (expressed aspercentages) applied to a range ofdata from the literature (12).

Thus there is a potential in IPM forexploiting positive synergism betweenplant resistance and biological controlwhich is unlikely to be available withGM crops or with traditionally bredresistant varieties expressing similarlyhigh levels of allelochemicals.

Resistance to insecticidesThe toxicity of insecticides, whether toinsects or humans, is measured as doseof active ingredient per unit bodyweight.

Therefore, as insects on resistant

plants are usually smaller than onsusceptible plants, it would besurprising if the same dose of chemicaldid not kill a higher proportion.

There are many examples illustratingthis phenomenon (e.g. Fig, 3), but theeffect is usually greater than predictedfrom the reduction in body weightalone; a greater ‘physiological’sensitivity also seems to be involved. Infact, Fig. 3 suggests that theconcentration of pesticide applied tosusceptible plants to kill 50% of thepests (LC50) could be reduced bymore than one-third on the comparedresistant plants (12).

However, there are equally exampleswhere pests on resistant varieties haveincreased resistance to insecticides. Theexplanation appears to be thatexposure to allelochemicals in plantsinduces an increase in enzymes whichcan detoxify these chemicals, but alsoother toxins (including insecticides).This effect has been shownconvincingly with the bollwormHeliothis virescens on cotton varietieswith a high gossypol content (29) andby measuring the activity of one suchdetoxifying enzyme (·-naphthylesterase) in armyworms (Spodopterafrugiperda) fed on eight crop plantsknown to contain toxic allelochemicals(30). Finally, there was a reduction inmortality from the insecticide carbarylon resistant (with high levels of 2-tridecanone) compared withsusceptible tomato plants (31), withalmost identical mortalities when thevarieties were replaced respectivelywith artificial diet + 2-tridecanone andstandard artificial diet (Fig. 4).Similarly, addition of the glucosinolatesinigrin to an artificial diet increasedthe tolerance of diamond back moth(Plutella xylostella) progressivelybetween 0 and 0.125 µmol sinigrin g -1 diet (32).

Thus on crop varieties with highlevels of allelochemicals, whethertransgenically or traditionally “bred”,the pests may show resistance toinsecticides should these have to beused as, for example, if individualstolerant to the plant resistance appearin the population.

However, there is a furtherdisadvantage of such varieties inrelation to insecticides. It was pointedout above that, on many pest-resistantvarieties traditionally bred, a lowerdose of pesticide will give the samelevel of control as on a susceptiblevariety. Those lower doses will, ofcourse, achieve a reduction in the killof natural enemies – immediately theselectivity of the pesticide application

Figure 4. Effect of the allelochemical2-tridecanone on mortality ofbollworms (Helicoverpa zea) from theinsecticide carbaryl. Left, comparisonbetween a susceptible (red) and aresistant (red) variety of tomato; right,comparison between two artificialdiets – one without (red) and theother with (red) added 2-tridecanone(data from (31).

Figure 5. Theoretical insecticide concentration/insect mortality response curvesfor a pest (herbivore) and a natural enemy (carnivore) on a susceptible cropvariety (A) and on one where 50% mortality of the pest (LC50H) is obtained atonly 2/3 of the concentration needed on the susceptible variety (B). LC50C,concentration needed to obtain 50% mortality of a natural enemy; striped area,the ‘selectivity window’ (where the proportion of the pest killed is higher thanthat of the natural enemy).


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in favour of the natural enemies willimprove. This is pure IPM!

However, there is more to it thanthat, since this increase in selectivitywill be far greater than one might atfirst envisage. Over 30 years ago, afundamental difference in the responseto insecticides of herbivores andcarnivores was identified (33). Theformer have evolved to cope withallelochemicals in the plants they feedon by producing detoxifying enzymes.Genetically, individuals will differ intheir ability to do this. This will resultin a large difference in the insecticideconcentration required to kill the mostresistant compared with the mostsusceptible individual (Fig. 5A). Bycontrast, carnivores, feeding on preywhich has largely dealt with any toxinsin the plant, have less need for anyarmoury of detoxifying enzymes, and

so there will be less spread in thepesticide concentration needed to killdifferent individuals (Fig. 5A). Fig. 5Bshows how the selectivity window forthe natural enemy increasesdramatically as pesticide concentrationis reduced when only the response ofthe herbivore is affected. However,exploiting this phenomenon will bedifficult in those countries whichlegislate against deviating from themanufacturer’s recommended dose.

The theory behind Fig. 6 has beentested in the laboratory (34), using thecereal aphid Metopolophium dirhodumas the pest with the parasitoid Aphidiusrhopalosiphi and larvae of the ladybirdpredator Coccinells septempunctata asnatural enemies.

Table 2 gives the doses for thepesticide malathion required to kill50% and 90% of the respective insects

on two wheat cultivars, the aphid-susceptible Maris Huntsman and theonly partially resistant Rapier. Not onlywere the doses for the carnivores notreduced by the plant resistance, theywere actually somewhat increased,particularly for the ladybird.

ConclusionsGenetic engineering of plant resistanceto insects has relied on the directtransfer of single genes for theproduction of allelochemicalsdeleterious to plant-feeding pests.tothe point of virtual immunity. It is notdifficult to find potential disadvantagesof this approach, but it must beremembered that insect-resistant GMcrops are only commercial becausethey control serious pest problemseffectively. Therefore it is nonsense, asthe media and public so often do - tocompare them with doing nothing inthe way of pest control – for that ishardly an option.

GM crops do have disadvantages(Table 3) when compared with plantresistance obtained by traditional plantbreeding, especially since the lowercontrol efficacy usually provided bythese can often synergise withbiological control and/or limited use ofpesticides to give grower-acceptablepest control. How can any synergismoccur if one of the methods involvedgives total control on its own? Of 13mechanisms of plant resistancedeveloped by traditional plantbreeding (34), only three involveallelochemicals. Some progress withGM is being made in making theexpression of the allelochemicaldependent on pest attack occurring,and in transferring more than a singlegene for resistance, but the single geneusually giving constitutive protection isstill the norm.

However, in nearly every case, a pest-resistant GM crop will be used toreplace (usually heavy) insecticideapplications. This is therefore the mostimportant comparison, and GM cropsclearly have major advantages (Table3), particularly in terms of humansafety, in selectivity in favour of naturalenemies and less environmentalcontamination. In general, naturalchemical compounds are more easilyand rapidly broken down to harmlesscompounds in the environment thanare synthetic ones. Perhaps pest-resistant GM crops would get a betterpress and be more readily accepted bythe public if they were viewed as analternative to the spraying machine asa way of delivering insecticide!

Table 2. Laboratory estimates of the toxicity of the insecticide malathion to theaphid Metopolophium dirhodum and to two of its natural enemies (the parasitoidAphidius rhopalosiphi and the larva of the coccinellid Coccinella septempunctata)when reared on the aphid-susceptible wheat cv. Maris Huntsman and the partial-ly resistant cv. Rapier. LD50 and LD90, the dose needed to kill respectively 50 and90% of the insects. In each pair of figures, the one showing greater tolerance tomalathion is emboldened.

Table 3. Comparison of transgenic host plant resistance to insects with plantresistance obtained by traditional plant breeding and with the use of insecticide. Comparisons favourable to transgenic resistance are italicised.

9050


the GM debateReferences1. Levin, B R (1979) Problems and promise ingenetic engineering in its potential applications toinsect management. In: Genetics in relation topest management (eds M A Hoy & J M McElvey,Jr), New York, Rockefeller Foundation, pp. 170-175.2. Bruce, T J A, Smart, L E, Aradottir, G J, Martin, JL et al. (2011) Trangenic wheat emitting aphidalarm pheromone. (E)-beta-farnesene, Aspects ofApplied Biology, 110, 112.3. van Emden, H F (1996) Host-plant resistance toinsect pests. In: Techniques for reducing pesticideuse (ed. D Pimentel), Chichester, Wiley, pp. 130-152.4. Gershenzon, J (1994) The cost of plantchemical defense against herbivory. Abiochemical perspective. In: Insect-plantinteractions, vol. 5 (ed. E A Bernays), Boca Raton,CRC Press, pp. 173-205.5. Foyer, C H, Noctor, G. & van Emden, H F.(2007) An evaluation of the costs of makingspecific secondary metabolites; is the yield penaltyincurred by host plant resistance to insects due tocompetition for resources? International Journal ofPest Management, 53, 175-182.6. AFP (2013) ‘More pests resistant to GM crops’:a study<http://www.google.com/hostednews/afp/article/ALeqM5gkQ3lN4hx0r59smxAQgaWzlWKaVg>accessed 10 03 2014.7. Tabashnik, B E, Morin, S, Unnithan, G C, Yelich,A.J. et al. (2012) Sustained susceptibility of pinkbollworm to Bt cotton in the United States(special issue on insect resistance). GM Crops, 3,194-200.8. Panda, N & Khush, G S (1995) Host-plantresistance to insects. Wallingford, CABInternational.9. Anon (1994) Die Rükkehr der Reblaus. Profil,October 1994, 11.10. Gallun, R L (1977) The genetic basis of hessianfly epidemics. In: The genetic basis of epidemics inagriculture (ed. P R Day). Annals of the New YorkAcademy of Sciences, 287, 1-400.11. Steinkraus, D C, Young, S Y, Gouge, D H] &Leland, J E. (2007). Microbial insecticideapplication and evaluation: Cotton. In: Fieldmanual of techniques in invertebrate pathology,2nd edn. (eds L A Lacey & H K Kaya), Dordrecht,Springer, Section VII-6.12. van Emden, H F (1999) Transgenic host plantresistance to insects – some reservations. Annalsof the Entomological Society of America, 92, 788-797.13. Boethel, D J (1999) Assessment of soybean

germplasm for multiple insect resistance. In:Global plant genetic resources for insect-resistantcrops (eds S L Clement & S S Quisenberry), BocaRaton, CRC Press, pp. 101-129.14. Martos, A, Givovich, A & Niemeyer, H (1992)Effect of DIMBOA, an aphid resistance factor inwheat, on the aphid predator Eriopsis connexaGermar (Col.: Coccinellidae). Journal of ChemicalEcology, 18, 469-479.15. Schuler, T H (2004) GM crops: good or badfor natural enemies? In: GM crops – ecologicaldimensions (eds H F van Emden & A J Gray).Aspects of Applied Biology, 74, 81-90.16. Svobodova, Z, Habustova, O, Hussein, H M,Puza, V & Sehnal, F (2012) Impact of geneticallymodified maize expressing Cry3Bb1 on non-targetarthropods: first year results of a field study.IOBC/WPRS Bulletin, 73, 1-8.17. Albajes, R, Lumbierres, B. Madeira, F, Comas,C et al. (2013) Field trials for assessing risks of GMmaize on non-target arthropods in Europe: theSpanish experience. IOBC/WPRS Bulletin, 97,1-8.18. Hilbeck, A, Baumgartner, M, Fried, P M. &Bigler, F (1998). Effects of transgenic Bacillusthuringiensis corn-fed prey on mortality anddevelopment time of immature Chrysoperlacarnea (Neuroptera: Chrysopidae). EnvironmentalEntomology, 27, 1-8.19. Malone, L A, Todd, J H, Burgess, E P J & Philip,B A (2004) Will GM crops expressing insecticidalproteins harm honey bees? In: GM crops –ecological dimensions (eds H F van Emden & A JGray). Aspects of Applied Biology, 74, 114-11820. Hendriksma, H P, Hartel, S, Babendreier, D,Ohe, W & von der Steffan-Dewenter, I (2012)Effects of multiple Bt proteins and GNA lectin onin vitro-reared honey bee larvae. Apidologie, 43,549-560.21. Garcia, M, Ortego, F, Castanera, P & Farinos,G (2012) Assessment of prey-mediated effects ofthe coleopteran-specific toxin Cry3Bb1 on thegeneralist predator Atheta coriaria (Coleoptera:Staphylinidae). Bulletin of Entomological Research,102, 293-302. 22. Birch, A N E, Geoghegan, I E, Majerus, W E N,McNicol, J W et al. (1988). Tri-trophic interactionsinvolving pest aphids, predatory 2-spot ladybirdsand transgenic potatoes expressing snowdroplectin for aphid resistance. Molecular Breeding, 5,75-83.23. Alvarez-Alfageme, F, Luthi, C & Romeis, J(2012) Characterization of digestive enzymes ofbruchid parasitoids-initial steps for environmentalrisk assessment of genetically modified legumes.PLoS ONE, 7(5), e36862.24. Luthi, C, Alvarez-Alfageme, F & Romeis, J

(2013) Impact of alpha AI-1 expressed ingenetically modified cowpea on Zabrotessubfasciatus (Coleoptera: Chrysomelidae) and itsparasitoid, Dinarmus basalis (Hymenoptera:Pteromalidae). PLoS ONE, 8(6), e677857.25. Adjei Maafo, I. K (1980) Effects of nectarilesscotton trait on insect pests, parasites andpredators with special reference to the effects onthe reproductive characters of Heliothis spp. PhDthesis, University of Queensland, Australia.26. Kareiva, P & Sahakian, R (1990) Tritrophiceffects of a simple architectural mutation in peaplants. Nature, 345, 433-434.27. Wickremasinghe, M G V & van Emden, H F(1992) Reactions of female parasitoids, particularlyAphidius rhopalopsiphi, to volatile chemical cuesfrom the host plants of theiraphid prey.Physiological Entomology, 17: 291 304.28. Gowling, G R & van Emden, H F (1994)Falling aphids enhance impact of biologicalcontrol by parasitoids on partially aphid resistantplant varieties. Annals of Applied Biology, 125, 233242.29. Shaver, T N & Wolfenbarger, D A (1976)Gossypol: influence on toxicity of threeinsecticides to tobacco budworm. EnvironmentalEntomology, 5, 192-194.30. Yu, S J & Hsu, E L (1985) Induction ofhydrolases by allelochemicals and host plants infall armyworm (Lepidoptera: Noctuidae) larvae.Environmental Entomology, 14, 512-515.31. Kennedy, G G (1984) 2-tridecanone, tomatoesand Heliothis zea: potential incompatibility of plantantibiosis with insecticidal control. EntomologiaExperimentalis et Applicata, 35, 305-311.32. Hariprasad, K V & van Emden, H F (2014)Effect of partial plant resistance in brassicas ontolerance of diamondback moth (Plutella xylostella)larvae to cypermethrin. International Journal of PestManagement, 60 (in press).33. Plapp, F W Jr (1981) Ways and means ofavoiding or ameliorating resistance to insecticides.Proceedings of Symposia at thr 9th InternationalCongress of Plant Protection, Washington D.C.,1979, 1, 244-249.34. Tilahun, D A & van Emden, H. (1997) Thesusceptibility of rose grain aphid (Homoptera:Aphididae) and its parasitoid (Hymenoptera:Aphidiidae) and predator (Coleoptera:Coccinellidae) to malathion on aphid susceptibleand resistant wheat cultivars. Annales de la 4eANPP Conférence Internationale sur les Ravageurs enAgriculture, Montpellier, 1997, 1137-1148.35. van Emden, H F & Service, M W (2004) Pestand Vector Control. Cambridge, CambridgeUniversity Press.

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GM is a valuable technology thatsolves many agricultural problems

in breeding and generationof new traits

Professor Anthony Trewavas FRS, FRSE, The Scientific Alliance Scotland, 7-9 North St David Street

Edinburgh EH2 [email protected].

Martin Livermore BA (Oxon), Director, The Scientific AllianceSt John’s Innovation Centre, Cowley Road, Cambridge CB4 0WS

[email protected] the last issue of World Agriculture, Vol. 4, No. 1, Dr Helen Wallace of GeneWatch UK wrote a highly critical analysis of therole of GM crops in world agriculture (1) . By selectively quoting only critical sources, Dr Wallace constructed a misleadinglynegative case against a valuable technology. In this review, we examine her case point by point. There are costs andbenefits to every human activity and it is important that all are considered and form the basis of any scientific assessment.Unlike her, we conclude that appropriately approved transgenic events, while by no means a panacea to all problems offeeding a potential nine billion, can make a significant contribution towards a safe, sustainable and secure food supply overthe rest of the 21st Century.

KeywordsGenetic modification, plant breeding, food security, agricultural policy.

Abbreviations DNA deoxyribonucleic acid; dsRNA double-stranded RNA; Bt Bacillus thuringiensis; EFSA European Food StandardsAuthority; GHG Greenhouse Gas; GM genetic modification; IRRI International Rice Research Institute; LEAF LinkingEnvironment And Farming; N Nitrogen; rDNA recombinant DNA; RNA ribonucleic acid

GlossaryCisgenesis – Altering an organism’sgenome using genetic material from aclosely-related species. This differs fromtransgenesis in that the genetic transfercould also have occurred throughnatural cross-breeding because thespecies in question are sexuallycompatible. Some researchers wouldlike cisgenesis to be subject to lessstringent regulation than geneticmodification in which the transfer ofgenetic material could not happen inthe wild.Cry proteins – A class of crystallineproteins expressed by the soilbacterium Bacillus thuringiensis, whichare toxic to some types of insect.Embryo rescue – An in vitro seedbreeding technique which allows theprogeny of diverse parents, whichwould not normally survive, to be

brought to maturity.F1 hybrid – The first generation ofplants produced by crossing twodistinct parental types. The resultingseeds often demonstrate very desirablecharacteristics, but fresh seed has to beproduced each season, as theuniformity is lost in succeedinggenerations.Intragenesis – As for cisgenesis, this is abreeding technique which transfersgenetic material only between closelyrelated species. However, it differs fromcisgenesis in that it allows for the useof new gene combinations created byin vitro rearrangement.Introgression – The transfer of geneticmaterial from one species to anothervia hybridisation and repeated back-crossing.Landrace – A locally-adapted strain of acultivated plant, less geneticallyuniform than a conventional variety.

Mycorrhizae – A symbiotic associationbetween soil fungi and plant roots.No-till agriculture – A method offarming in which crops are drilledstraight into the ground after theprevious crop has been harvested,without disturbing the soil byploughing. This reduces energy use,helps to increase soil organic matterand moisture retention and reduceserosion.Selection pressure – The response of apopulation of living organisms to anexternal negative factor. More tolerantindividuals survive and pass on greaterresistance (to, for example, aherbicide) to future generations.Wildlife – A common Englishexpression covering the non-domesticated animal, bird and insectspecies naturally present in theenvironment.


the GM debateIntroductionThe case made against GM crops

Dr Wallace’s article makes anumber of specific criticisms ofGM crops, which we will

address individually below. These are:The limited range of GM crops

currently available� The reducing effectiveness ofherbicide-tolerant crops, as resistancedevelops.� The patenting of traits, preventingfarmers from saving seed forreplanting.� Possible negative effects on humanhealth.� Cross-contamination and liability.� Negative environmental impact.� Lack of delivery of promised traits inthe next generation of products.� Loss of autonomy for farmers andconsumers.

But first, by way of introduction, weshould appreciate that there are twomain types of objection to GM crops:ideological and those arising from apessimistic world view.

To illustrate the ideologicalcomponent, consider the answersgiven by Lord Melchett (then ExecutiveDirector of Greenpeace UK) toquestions posed in a House of Lordsenquiry (2):

Question 101: ‘Lord Melchett, inrelation to genetic modification, whatdo you object to and why?’

Lord Melchett, Head of Greenpeace,UK: ‘My Lord Chairman, thefundamental objection is that there areunreliable and unpredictable risks.’

Question 105: ‘How far are youprepared to carry your objections tothese developments?’

Lord Melchett: ‘I am happy to answerfor Greenpeace […] Greenpeaceopposes all releases to the environmentof genetically modified organisms.’

Question 107: ‘Your opposition tothe release of GMOs _that is anabsolute and definite opposition? It isnot one that is dependent on furtherscientific research or improvedprocedures being developed or anysatisfaction you might get with regardto the safety or otherwise in future?’

Lord Melchett: ‘It is a permanent anddefinite and complete oppositionbased on a view that there will alwaysbe major uncertainties. It is the natureof the technology, indeed it is thenature of science, that there will not beany absolute proof. No scientist wouldsit before your Lordships and claimthat if they were a scientist at all.’

The attitude of anti-GM activists isnot that this is a technology which

holds promise but needs moredevelopment, but a flat rejection of itspotential. Rather than see well-plannedscientific trials take place to addressconcerns about human andenvironmental safety, they want toclose down R&D and prevent productsgetting to market. Figure 1 shows afield trial being destroyed in a high-profile act which led to the arrest ofthe protestors, including LordMelchett. Such crop-trashing has evenextended more recently to fields ofgolden rice, developed to providemuch-needed Vitamin A in the diets ofthe children of poor farmers in Asia (3)

There is no certainty in life foranything apart from the proverbialdeath and taxes. So the desire forcertainty for GM crops is not a realisticcritique but just an attempt to blocksomething that Greenpeace doesn’tlike. There is no risk-free world, but inthe estimation of risk it is contingenton those who suggest alternatives toestimate the risk of that alternative.Lord Melchett’s responses betray adeep-seated anti-science world viewand an unfortunate pessimism aboutthe human race’s creativity andadaptability. It is undoubtedly the casethat no scientist will claim certainty ofsafety about anything, but thatincludes Melchett’s preferredalternative of organic farming too. In2011 51 people died in northernGermany from eating organic produce,with thousands physiologically injured,possibly for life (4). In a form ofagriculture whose main source of N isvery commonly animal manure,contamination risks will always bepresent. Other similar cases are in themedical literature. All GM productsreceive detailed safety scrutiny and

there is no record of anyone dyingfrom consuming them.

GM technology has advanced wellbeyond the early simple traits ofherbicide resistance and Bt insectresistance. Two transformationtechniques, cisgenesis and intragenesis,have been used successfully to produceplants transformed with geneticmaterial derived only from the speciesitself, or related species that cannormally hybridise with it (5) Foreigngenes are absent in these products.Furthermore, genetic transformationcan now take place at a chosendefined base sequence in the genomewhich is opened and modificationsmade. A number of crops produced inthis way are in field trials, have gainedgood public acceptance and createdproblems for regulators. Are they reallyGM crops? Does the same ideologicalobjection still hold?

The pessimism which began toflourish in the decades after World WarII is encapsulated in this quote: “Thebattle to feed all of humanity is over. Inthe 1970s hundreds of millions ofpeople will starve to death in spite ofany crash programs embarked uponnow. At this late date nothing canprevent a substantial increase in theworld death rate ...” (6) Debilitatingpessimism like this can stifle and thusimpede creativity. It is fortunate thatthis statement by Ehrlich was ignoredby Normal Borlaug (7) and thedevelopment of the Green Revolution.Figure 2 shows how grain yields haverisen steadily since 1960, while thearea cultivated has remained essentiallythe same. While attempting to predictthe future is sensible, strict limitationsmust apply to its usefulness,particularly over the long term.

Figure 1. Greenpeace protestors uproot GM crops in Norfolk (from Greenpeace)(http://www.greenpeace.org.uk/media/press-releases/greenpeace-decontami-nates-gm-field-lord-melchett-arrested)


the GM debate

New technologies cannot by theirnature be predicted and because theworld continues to changeremorselessly what the future contextwould be like for any supposedprojection remains unknown. Statingthe problem and focussing on itusually drives potential solutions andchanges the future anyway. Thepresent buzz word of the Club ofRome is sustainability. But theassumptions that underpin thosesentiments along with theprecautionary principle, a principlelargely used by green organisations tohalt progress, imply a lack of faith infuture generations being able to findadequate solutions to the problemsthey face. Thoughts of sustainability ofa particular activity should be limitedto one or two generations. Beyondthat, it is likely that technologicaladvance will have made the conceptirrelevant.

The Green Revolution harnessedscientific plant breeding and syntheticfertilisers to allow vastly increasedcereal productivity in Asia and LatinAmerica. (8) Now, a global populationof over 7 billion has more caloriesavailable per capita than half thatnumber not much more than 40 yearsago. Nearly a billion people remainchronically malnourished, but this is afunction of poverty, lack ofinfrastructure and poor governancerather than agricultural productivity,and is outside the scope of this review.

The Green Revolution is a particularlyclear example of how technology canand must be used in the agriculturalsector. With the world's population setto rise by a further 2 billion or more bymid-century, farmers need access to alltechnologies available to raise

productivity without ploughing morevirgin land.

The concept of ‘sustainableintensification’ nicely encapsulates thepreferred approach and is now widelyused by stakeholders in the foodsupply chain (9). There are big gains tobe made by bringing best practices tosome of the lowest yielding areas offarmland, but this will not be enoughby itself to guarantee food security in aworld where demand for animalproducts and overall energy willcontinue to grow faster thanpopulation itself. To have the bestchance of achieving this in a waywhich is sustainable in the long term,all available technologies must bedeployed as appropriate. Today,genetic modification is the cuttingedge of agronomic technology,

capable of delivering benefits whichare beyond other more establishedbreeding techniques. Like any othertechnology, it carries risks as well asbenefits, but we cannot afford tobypass it.

The limited range of GMcrops availableNearly all the commercially availableGM crops have one or both of twoimportant agronomic traits, herbicidetolerance and insect resistance.

They are also limited primarily to themajor “broad-acre” crops: soy, maize,oilseed rape (canola) and cotton(10)Nevertheless, as figure 3 shows,these two key traits have led to a largeand sustained year-on-year growth inthe cultivation of GM crops. The mainuse for most of the soy is for animalfeed while the maize goes to the samemarket but, in the USA, is also used forbiofuel production. However, DrWallace implies that the extent of thetechnology’s potential is for farmers inindustrialised countries to supply theanimal feed and biofuels market, withthere being little to offer towardsglobal food security. This most surely isnot the case. Numerous herbicide-resistant crops resistant to a range ofpesticides are available throughconventional breeding. However theproblem with all conventionalbreeding is the difficulty in removingunwanted traits. So it is no surprisethat glyphosate-resistant GM cropshave dominated use. At the levels ofexposure and use, glyphosate isremarkably innocuous to humanhealth, but good at killing weeds.

Figure 2. Rising world cereal yields (right axis) and total production (left axis)while total area planted remains static (left axis) (from FAO)(http://newsimg.bbc.co.uk/media/images/42730000/gif/_42730027_world_cere-als_416.gif)

Figure 3. The evolution of the world market for GM crops (from ISAAA)(http://www.isaaa.org/resources/publications/briefs/43/pptslides/default.asp


the GM debateExtensive use of such crops has led to

the much greater advantageous use ofno-till agriculture. No-till farmingreduces fuel consumption and notonly avoids soil compaction, loss oforganic matter, reductions in microbepopulations and other valuableorganisms like mycorrhizae and largesoil invertebrates, but properly done,virtually eliminates erosion andincreases wildlife populations. Mostcrucially, no-till reduces GHG emissionsto less than one third that of organicfarms and one sixth that ofconventional soils. Continuous no-tillneeds to be managed very differently,but is clearly sustainable in all senses ofthe word. No-till lends itself readily tolarge scale mechanical management oflarge areas of farmland, but could onlyseriously develop with the easy controlof weeds.

Any technology is essentially neutraland it is the socio-economicenvironment which determines how itis used. Genetic modification emergedat a time when existing public sectorbreeders – for example PBI Cambridge– were being privatised, so it wasinevitably the private sector which ledits commercialisation. In addition, thestringent regulatory requirementsencouraged by many environmentalistshave made the approvals process soexpensive that only major internationalcompanies have the resources to bringGM crops to market. Because of theneed to see a return on theirinvestment, they naturally used thetechnology to develop crop varietieswhich would be bought in largevolumes by farmers with the resourcesto benefit from them.

In fact, following the originalintroduction of Roundup Ready™ soyto American farmers by Monsanto inthe mid-1990s, there was a quite rapiduptake of the same crop in SouthAmerica. The development of Btcotton has seen millions of small-scalefarmers in China, India, South Africaand other developing countries alsobenefitting from the technology. This isnot to forget golden rice, finallyapproaching the market after manyyears of development, initially in Zurichbut latterly at the IRRI in thePhilippines (11). Seed will be madeavailable free to small-scale farmers,with all rights to receive patent licencefees waived by the participatingcompanies. For a technology whichhas been commercial for less than twodecades, that is good progress andmore developments aimed atdeveloping-country farmers can beexpected, for example from projects

funded by the Gates Foundation (12).These, too, will be donated free ofcharge to poor farmers.

The reducing effectivenessof herbicide-tolerant crops,as resistance developsHerbicide-tolerant GM crops areessentially all engineered to resisttreatment with glyphosate, anextremely useful and widely usedbroad-spectrum herbicide (althoughthere are other crops resistant, forexample, to glufosinate, which can beused in rotation.

Similarly, pest-resistant crops expressone or more cry proteins found inBacillus thuringiensis. These crops havenot introduced new crop protectionagents to farming, but have allowedtheir use to be extended. Thepossibility to use broad-spectrumherbicides across fields of establishedcrops, to control weeds withoutharming the crop itself, makes weedmanagement much easier. Bt crops, onthe other hand, control certain pestswhich attack them, without harmingnon-target insects. Such crops alsoallow maintenance of a largerpopulation of pest predators.

These traits are very valuable tofarmers, as the rapid and sustainedgrowth in the sales of both shows.However, it is a fact of life that pestsdevelop resistance to crop protectionagents over time, and GM crops are noexception. That glyphosate is soeffective (and environmentally benign)means that its use is quite ubiquitous;Roundup Ready™ crops will likely haveincreased its use to some extent, butfrom an already high baseline.Inevitably, some weeds (in North andSouth America) have become resistant,

but this is part of the continuing cyclewhich requires the constantdevelopment of new herbicides toreplace those which become lesseffective. In practice, any problemweeds can be removed usingalternative herbicides or by hoeing.The practical evidence that suggeststhis is not a big problem for mostfarmers is that sales of glyphosate-tolerant varieties remain high. Farmerswould not pay a premium for a traitwhich did not continue to give them aworthwhile benefit in terms of cropmanagement.

As for pest-resistant crops, the factthat widespread resistance has notdeveloped after a decade, or more, ofexposure of insects to (for the mostpart) a single Bt toxin shows that themanagement strategy (planting arefuge of a certain percentage of non-Bt plants in a field to minimise theselection pressure for Bt-tolerance) hasbeen very effective. The trait, ascommercialised, has been used totarget particular major pests and wasnever intended to give completeprotection from insect attack. Thebenefit of these traits to Americanfarmers is well illustrated in figure 4,which shows how corn (maize)varieties, having both herbicidetolerance and insect resistance, havecome to dominate the market over justa few years. The revolution ingenomics has changed the ease withwhich specific pest species can beselectively controlled. Specific smallsequences of RNA, derived fromdouble-stranded RNA degradation,switch off the expression of specificgenes (13). Pests that ingest a cropengineered with a specific dsRNA havespecific developmental genes switchedoff that are specific to the organism,which then fails to mature.

Figure 4. US market share of maize seed: conventional hybrid (blue); GM InsectResistant (IR, red); GM Herbicide Tolerant (HT, green); GM stacked IR+HT(yellow) (from Seedbuzz.com)(http://www.seedbuzz.com/knowledge-center/article/product-life-cycles-and-innovation-in-the-us-seed-corn-industry)


the GM debateIf Bt ever becomes ineffective,

alternatives are already available.Dr Wallace recognises that resistance

develops in conventional farmingsystems, but views this in a negativelight, as encouraging a ‘pesticidestreadmill’ whereby farmers apply largeramounts of pesticide or turn to moretoxic ones. Although overall pesticideuse is growing, much of this is due tothe adoption of modern farmingpractices in the developing world. Inmany countries, farmers are becomingmore careful about their use ofagrochemicals of all types as theyrealise they can save money andminimise unwanted environmentalimpacts (for example, the greater useof precision farming in industrialisedcountries). Similarly, Dr Wallace seesthe development of a ‘seed treadmill’in which farmers are locked intobuying inputs from off the farm ratherthan being self-sufficient. In fact, aslong as farmers can make an informedchoice and are not dragged intounnecessary debt, their farms are likelyto become considerably moreproductive.

Her argument seems to be moreabout the iniquities of modern farmingrather than genetic modification per se,and is effectively a reformulation of the‘conventional’ (intensive) versus‘organic’ (extensive) debate. Organicfarms almost certainly benefit from thecontrol of pest numbers by proximityto conventional farms.

The patenting of traits,preventing farmers fromsaving seed for replantingClearly, the advent of patented traitsallows suppliers more control of theirtechnology than the pre-existing (andcontinuing) system of plant breeders’rights.

For example, in the UK, farmers arepermitted to save seed for replantingon payment of a fee to the breeder. Inthe case of at least the currentgeneration of GM seeds, the farmerpays a technology fee for thetransgenic trait and enters into acontract which does not permit him tosave and sow seed the followingseason.

However, even where saving seed isan option, it is not always desirable.Farmers who quite legitimately saveseed one year will often buy fresh seedafter a season or two, simply toguarantee freedom from disease or totake advantage of new varieties.Farmers in some developing countries

have often not had the option of highquality seed available to them andhave continued to save seeds of theirown adapted varieties, or landraces, aspart of a cycle of low productivitysubsistence farming. As they becomeable to afford fertiliser, pesticides andbetter tools, so they will be looking tohave more productive crops and wouldbe more open to buying protectedvarieties (including GM).

In developed countries, farmers havebecome used to buying seed each yearas F1 hybrids have entered the market,initially for maize and latterly foroilseed rape and a wide range ofvegetables. The yield advantages ofthese more than offset the additionalexpense of purchase. There is noreason why farmers in the developingworld should not move more towardsa similar model, where more expensiveseed and other inputs are seen asbeing the key to more productive andprofitable cultivation.

Possible negative effects onhuman healthIt is argued that ‘Controversy remainsabout potential unintended effects ofGM foods on human health...’ Inreality, a number of hypotheticalconcerns are raised, for some of whichone-off studies of dubious value arecited as support, for example the workof Ewens and Pusztai (14).

Although such stories continue to bereported from time to time, the greatmajority of plant scientists andtoxicologists do not see any hardevidence that any tests have shownharm to be caused by GM ingredients.Recently, for example, Professor AnneGlover, chief scientific adviser to thePresident of the European Commission,dismissed opposition to GM crops as ‘aform of madness’ (15). The EuropeanAcademies Science Advisory Councilalso published a report in June 2013which supported a move to bringpolicy more in line with the scientificconsensus on the safety and benefits ofgenetically modified crops (16), Thegreat majority of dossiers submitted toEFSA, for example, are recommendedfor approval by the independentscientists who review them, but anumber of Member States routinely failto follow this advice and a qualifiedmajority in favour of approval is neverachieved.

Concerns about the very minorchanges in genomes produced byrDNA technology seem based on amatter of principle (‘unnaturalness’)rather than practical reality.

Opposition by campaigningorganisations such as Greenpeace andGeneWatch is a matter of philosophyrather than science. What is stillreferred to as ‘conventional’ breedingproduces combinations of genes whichare only revealed by their patterns ofexpression and, in the case of non-GMtechniques such as embryo rescue,results in progeny which would not beseen by natural crossing. Mutagenesis,the products of which are happilyaccepted by the organic movement,scrambles genomes to produce arange of undefined mutations. GMtraits, on the other hand, are subject tointense scrutiny and more is knownabout both their genetic makeup andcomposition than of any other cropswe grow.

Cross-contamination andliabilityAgricultural crop varieties inevitably getmixed to some extent, whether bycross-pollination between relatedspecies or by contamination in thesupply chain.

This fact is recognised by itsacceptance along the food chain,subject to specific limits, usually of theorder of a few percent. However,opposition to GM crops has resulted ina much more stringent regime. In theEU, food ingredients must be labelledas GM unless they are certified ashaving less than 0.9% content ofapproved transgenic material. This isachievable, but at a cost. In fact, mostGM crops are used for animal feed,with only co-products – oil, protein,lecithin etc – entering the human foodchain. Although animal feed must belabelled as to its GM content, there isno requirement for meat, milk or eggsto be so labelled.

A problem arises if a grower or tradersuffers economic loss because smallamounts of transgenic material haveinadvertently been mixed in. Forfarmers, this is a rare occurrence, asseparation distances are set tominimise the risk of cross-pollination.Further down the supply chain, cross-contamination can occur, but tradershave systems in place to minimise suchrisks (as for any segregatedcommodities). Risks are insured in thesame way as for other bulkcommodities which do not meet thecustomer’s specification.

The contamination events whichhave occasionally hit the headlineshave been caused by unapprovedtransgenic events entering the supplychain at some point.


the GM debateThese have caused major recalls and

resulted in seed companies paying outlarge sums in compensation. However,the seriousness of such incidents is dueonly to the strict legislation and limitswhich have been put in place; no harmto humans, animals or theenvironment has been caused by suchreleases. This is in stark contrast to theoccasional contamination of foods bytoxins or food poisoning micro-organisms.

Negative environmentalimpactDr Wallace’s article again raisesconcerns about the impact of GMcrops on the environment.

She cites, in particular, the UKgovernment-sponsored Farm ScaleEvaluations (17). These trials have beenthe only reported attempt to study theimpact of farm management systemsin such detail, but their conclusionsapply to the particular herbicideregime used rather than how thespecific tolerance was introduced intothe crop variety. It was widely reportedthat the cultivation of herbicide-tolerant crops – oilseed rape andsugar beet specifically – could reduceweed growth and leave fewer foodsources and habitats for birds andother wildlife. However, this conclusiononly tells part of the story. It is wellknown that cultivated fields are, byand large, not the best places to findwildlife, with most species beingoffered better habitat and more foodsources at field margins and away fromfarmland. Any differences between‘conventional’ management, use ofherbicide-tolerant crops, or of organicmanagement, are in any case,swamped by the differences betweencrops.

The field trials in the UK are,however, a trivial part of an enormousamount of research on GM safetyrecorded by (18). These scientistsconstructed a compilation of 1,783research papers published between2002 and 2012 on crop safety. Theirgeneral conclusion is “that thescientific research conducted so far hasnot detected any significant hazardsdirectly connected with GM crops”. Inbrief the conclusions of this enormoussurvey were:

1. Little to no evidence that GMcrops harm native animal species.

2. The formation of hybrids betweenGM crops and wild relatives certainlyhappens. But this happens all the timewith conventional crops includingmutagenised crops used by organic

farmers. It is the result of growing anycrop in any area with sufficiently closewild relatives where introgression canoccur. The consequence may bereplacement of local wild genotypes,something that of course happensanyway and is called natural selection.

3. No detrimental effect fromconsumption of GM crops by anyanimal has yet been detected.Substantial equivalence placesconstraints on the actual use of GMcrops. They should be nearly identicalin nutrient composition and in thecomplement of natural pesticides, forexample.

4. Every publication that hasexamined the question of potentialincorporation of GM DNA into thehuman, or animal, genome hasrejected it as a potential problem.Humans on average consume a gramof DNA per day containing hundredsof thousands of different genes with noindication of possible transfer throughevolutionary history. This is despiterecent evidence which suggests thatcomplete genes from food may befound in human blood (19). Bacteria inthe soil certainly exchange genes andoccasionally with plants, but again thishas continued for hundreds of millionsof years.

Another problem cited by Dr Wallaceis the potential impact of Bt toxins onnon-target organisms. In fact, the onlyinsects affected are those which beginto eat the crop and so ingest theexpressed cry protein. By this means,any effect on other, more beneficialspecies is avoided. Finally, her paperalso talks of the decline of Monarchbutterflies in North America partly dueto loss of agricultural milkweed (solefood for the larvae), coincident withthe increased use of glyphosate-tolerant maize and soy. However, mostof the milkweed on which the larvaefeed is outside field margins, where itis not treated with herbicide. It is alsoclear that Monarch populations arevery sensitive to weather conditions inMexico, where they overwinter (20).Indeed, populations of butterflies andother insects fluctuate widely and aredependent on a range of factors.

Overall, there is no evidence tosuggest that GM crops offer any morechance of negative impact on theenvironment than conventionally-bredvarieties. All farming, whetherextensive or intensive, itself has amajor impact on the environment. Noform of farming is natural since mostuse the plough. The nearest to naturalconditions is no-till which mimics theannual growth and decay of vegetative

material as seen in all uncontrolledmeadows.

Lack of delivery ofpromised traits in the nextgeneration of productsAs with any new technology, someearly forecasts for new transgenic traitshave been shown to have been over-optimistic.

Salt-tolerance and nitrogen-fixationare quoted as examples of the promiseof GM technology not having beenfulfilled….yet. But progress on both iswell under way. Transgenic cropsrepresent the present best hope forintroduction of such globally-usefultraits, which other breeding techniqueshave failed to do. Because of thecomplexity and cost of bringing a newGM trait to market, companies will notfollow this route if simpler alternativesare available.

Genetic modification is not a magicwand, but it is a tool which allowsbreeders much more scope to developtraits which will minimise our use ofnatural resources while helping toincrease food security. To dismiss itbecause forecasts have provedunreliable is not sensible.

Alternatives to geneticmodificationThe International Assessment ofAgricultural Knowledge, Science andTechnology for Development (21) issometimes cited as a consensus viewby experts on the potential for agro-ecological approaches to improvingyields.

Crop rotation, inter-cropping,improved conventional breeding andwaste reduction are also given asexamples of approaches which canincrease food security without thesupposed risks of transgenics. It isperfectly true to say that all theseapproaches can help. The pitifully lowyields and occasional harvest failures ofmany subsistence farmers can beimproved by even the simplesttechnologies. But this is not an either-or issue: all relevant technologies can,and should, be used in the pursuit ofsustainable intensification. To talk ofalternatives is to create a falsedichotomy. Table 1 shows the yields ofrice and wheat in a number of Asiancountries, with selected high-yieldingcountry data for comparison. There arenot yet any commercially cultivatedGM varieties of either rice or wheat, sothese large yield differences are due to


the GM debate

a range of other factors, includingbetter varieties, optimal fertilizationand irrigation and modern cropprotection. However, futureimprovements will be generated byusing all available technologies, and toignore genetic modification fordoctrinaire reasons would be foolish.

The difficulties presented by themembership of the IAASTD include itspoor lack of balance. These werehighlighted in an article in Science(22). IAASTD is viewed instead ashaving an underlying political agenda,largely against industrial agriculture.

The document cost $12million toproduce and singularly failed torecognise that the only way to savetropical rainforest and other wild landfrom exploitation, arising from thepressures of increased population, is foragriculture on the remaining farmlandto be as efficient as it possibly can be,within the constraints of environmentalmaintenance, including that of wildlife.In its promotion of small farming, in itsultra conservatism, the IAASTD, in itsbroadest extent, represents the desireof a green and reactionary paternalistclass to maintain small farmers in theirpresent state, instead of allowing themthe choice to farm in their own wayand enrich themselves by uses ofwhatever means they see fit to use.

AssumptionsWe quote from a translation of a courtjudgement made in the Philippines onBt aubergine trials from a case broughtby Greenpeace and others.

“The deliberate geneticreconstruction of the eggplant is toalter its natural order which is meantto eliminate one feeder (the borer) inorder to give undue advantage toanother feeder (the humans). Thegenetic transformation is one designed

to make Bt aubergine toxic to its pests(the targeted organisms). In effect, Btaubergine kills its targeted organisms.Consequently, the testing orintroduction of Bt aubergine into thePhilippines, by its nature and intent, isa grave and present danger to (and anassault on) the Filipinos' constitutionalright to a balanced ecology because, inany book and by any yardstick, it is anecologically imbalancing event orphenomenon. It is a wilful anddeliberate tampering of a naturallyordained feed-feeder relationship inour environment. It destroys thebalance of our biodiversity. Because itviolates the conjunct right of ourpeople to a balanced ecology, thewhole constitutional right of ourpeople (as legally and logicallyconstrued) is violated”. (23)

Effectively this judgement states thatpests have a right to destroy cropsplanted and needed for humans tosurvive. The judgement is entirelymisanthropic, anti-science, butrepresents Greenpeace philosophy andindeed most of those that ideologicallyoppose GM crops. It sees the ecologyof everything else as more importantthan its primary species, us. Thosethat promote organic farming,promote the waste of land and in thethird world promote inevitable poverty.

History has seen a progressive changereplacing ideology with pragmatism,folklore with science. There will alwaysbe need for change and improvement,no method of farming is perfect, allhave different problems. At present theaim must be to reduce the area of landunder cultivation, but increase yield.Leaving more land to nature will bebeneficial in terms of emissions and theservices that organisms other thanpests provide. We have alreadymentioned no-till, a method ideallysuited to GM crops. Integrated farm

management as practised by LEAFfarmers (24) seems in our eyes topresent the right combination ofpragmatism with the requirements ofyield and care of local wild life.“Organic” will and should remain aniche agriculture for those that wish tofarm or eat it. Its yields in practice arepoor and its safety must remainsuspect. In our view organic is not ascientific programme, but oneembedded in unrealistic romanticism.

Genetic modification, despite thecriticisms of Dr Wallace and others, is apowerful and valuable tool which,properly applied and regulated, hasthe potential to make a very realcontribution to a secure supply ofaffordable food this century.

References1. Wallace, Helen (2013); What role for GM cropsin world agriculture?; World Agriculture, Vol 4 (1),pp 45-49.2. House of Lords (1998). House of Lords SelectCommittee on European Communities. 2ndReport: EC Regulation of Genetic Modification inAgriculture.3. Science Insider (2013). Activists destroy ‘GoldenRice’ field trial.http://news.sciencemag.org/asiapacific/2013/08/activists-destroy-golden-rice-field-trial4. EFSA (2012); E Coli: Rapid response in a crisis;11 July 2012;http://www.efsa.europa.eu/en/press/news/120711.htm5. Holme, I.B., Wendt, T., and Holm, P.B. (2013).Intragenesis and cisgenesis as alternatives totransgenic crop development. Plant BiotechnologyJournal 11, 395-407.6. Ehrlich, Paul R. (1968). The Population Bomb.Ballantine Books. New York.7. Gustafson, J P, Borlaug, N E, Raven, P H; 2010.World Food Supply and Biodiversity; WorldAgriculture; 2010, Vol. 1 No.2, pp. 37-41.8. Hazell, Peter (2002), Green Revolution: Curse orBlessing?; IPRI.9. The Royal Society (2009), Reaping the benefits:Science and the sustainable intensification ofglobal agriculture; RS Policy document 11/09.10. ISAAA (2013); ISAAA Brief 44-2012: GlobalStatus of Commercialised Biotech/GM crops, 201211. Mayer JE, Pfeiffer W, Beyer P (2008)Biofortified crops to alleviate micronutrientmalnutrition. Curr Opin Plant Biol 11:166-170. 12. http://www.gatesfoundation.org/What-We-Do/Global-Development/Agricultural-Development13. Huvenne H., and Smagghe, G. (2010).Mechanisms of dsRNA uptake in insects andpotential of RNAi for pest control: a review. Journalof Insect Physiology. 56, 227-235.14. Ewen S and Pusztai A (1999), Effect of dietscontaining genetically modified potatoesexpressing Galanthus nivalis lectin on rat smallintestine; The Lancet, Volume 354, Issue 9187,Pages 1353 – 1354, 16 October 1999;doi:10.1016/S0140-6736(98)05860-715. http://www.scotsman.com/business/food-drink-agriculture/madness-of-opposition-to-gm-crops-says-glover-1-310253916. EASAC policy report 21; Planting the future:opportunities and challenges for using cropgenetic improvement for sustainable agriculture;June 2013

Table 1. 2010 yield data for wheat and rice in a number of Asian countries (FAOfigures)


the GM debate17. Squire G R, Brooks D R, Bohan D A et al(2003); On the rationale and interpretation of theFarm Scale Evaluations of genetically-modifiedherbicide-tolerant crops. Philos Trans R Soc Land BBiol Sci; 358 (1439); 1779-1799.18. Nicolia, A., Manzo, A., Vereonesi, F., andRosselini, D. (2013). An overview of the last 10yearsof genetically engineered crop safetyresearch. Critical Reviews of Biotechnologydoi:10.3109/07388551.2013.823595.

19. Spisak S, Solymosi N, Ittzes P, Bodor A, KondorD, et al. (2013) Complete Genes May Pass fromFood to Human Blood. PLoS ONE 8(7):e69805.doi:10.1371/journal.pone.0069805.20. http://www.fs.fed.us/wildflowers/pollinators/monarchbutterfly/migration/21. IAASTD (2009); International assessment ofagricultural knowledge, science and technologyfor development, synthesis report, ed B McIntyreet al.

22. Stokstad, E. (2008). Duelling visions for ahungry world. Science 319, 1474-1477.23. Philippines court of appeal (2013). Decisionon Greenpeace vs Environmental ManagementBureau.http://www.greenpeace.org/seasia/ph/PageFiles/126313/ca-decision-doc.pdf24. www.leafuk.org

A field of tall maize plants © PhotographyByMK – Fotolia.com


the GM debate

Response to Professor AnthonyTrewavas & Martin Livermore

Dr Helen Wallace, Director, GeneWatch UK, 60 Lightwood Road,

Buxton, SK 17 7BB, United [email protected]

Trevewas and Livermore clearlytake the view that the loss ofautonomy for poorer farmers

associated with purchasing patentedGM seeds is justified by a number ofclaimed benefits.

However, in practice, GM farming isin crisis as resistant weeds havebecome widespread in response to theuse of glyphosate-resistant GM cropsand secondary and resistant pests arecausing increasing difficulties forfarmers growing insect-resistant GMcrops. Despite decades of investmentand research, other products have notbeen delivered or have failed to reachthe market place, due to poorperformance and technical difficulties.

GM farming in the United States hasnot out-performed non-GM farming inEurope (Heinemann et al. 2013,Hilbeck et al. 2013). In the US, yieldsare falling behind and are morevariable, pesticide use is higher, thenumber of farms is decreasing andthere is greater monopoly control overinputs. The implication that US farmersgrow GM through choice because it issuperior is questionable as seedcatalogues show that the diversity ofseeds on the market in the US hasreduced significantly as a result oftakeovers in the industry, with manyvarieties only available in combinationwith GM traits. In addition, thecapacity to innovate on farm hasreduced significantly.

Although Trevewas and Livermoredescribe GM as a “cutting edgetechnology”, conventional breeding, insome cases enhanced by newtechnologies such as market assistedselection (MAS), has in fact deliveredmore crop improvements much fasterand more cheaply, despite a significantdiversion of resources away fromconventional breeding towards GMresearch (Goodman, 2002; Knight,2003; Jiang, 2013). Organic andresource-conserving agriculture canimprove farmers’ livelihoods, withoutcreating dependency on patented GMseeds and associated chemicals

(Bennett & Franzel, 2013). However,research investment in these areas isrelatively limited. Over-optimism aboutwhat GM can deliver has led tosignificant opportunity costs as otherareas of research have been neglected.

The authors describe glyphosate,which is blanket sprayed on themarket-leading GM crops which aretolerant to glyphosate, as “innocuousto human health” and“environmentally benign”. This claim isnot consistent with evidence in thescientific literature which suggests anumber of mechanisms through whichglyphosate and its commoncommercial formulation RoundUp maydamage human health (see, forexample: Koller et al. 2012; Mañas etal. 2009; Paganelli et al. 2010; Romanoet al. 2010; Samsel & Seneff 2013;Thongprakaisang et al. 2013).Glyphosate accumulates in glyphosate-resistant GM soybeans (Bøhn et al.2013). Regarding environmentalimpacts, there are particular concernsabout impacts on amphibians (Relyea& Jones 2009; Wagner et al. 2013).

Disturbingly, Trevewas and Livermoredownplay the negative effects onwildlife of habitat loss due to blanketspraying, including impacts on iconicspecies such as the Monarch butterfly.Whilst it is clear that other factors (e.g.deforestation) play a role in theMonarch’s decline it is surprising to seethe role of the expansion of GMherbicide-resistant crops dismissedwhen it is widely acknowledged in theliterature (Brower et al. 2012). Inaddition to the negative impacts ofblanket spraying GM crops withglyphosate, further milkweed habitathas been lost due to the large areas ofgrassland and rangeland that havebeen converted to biofuel crops,especially GM maize. Studies haveconfirmed the link between milkweedhabitat loss and glyphosate-treatedfields (Harzler 2010, Pleasants andOberhauser 2013) and the negativeimpact on the butterflies has beenmodelled, providing a convincing link

between the decimation of habitat andloss of fecundity (Zalucki & Lammers2010). Messan and Smith (2011)conclude that herbicide has a largeeffect and that a reduction ofherbicidal spraying is needed tostabilize the monarch butterflypopulation.

Trevewas and Livermore fail toacknowledge the seriousness of theproblem of herbicide tolerant weeds(‘superweeds’) and the harm tofarmers, or the problems associatedwith proposed responses. The spreadof glyphosate-resistant weeds in theUnited States is causing severe weedmanagement problems, with nearlyhalf of US farms affected (Fraser 2013).The dramatic increase in glyphosateuse that caused this would not havebeen possible without glyphosate-resistant GM crops. The proposedresponse includes new GM cropstolerant to more toxic herbicides suchas 2,4-D and dicamba, which willinevitably exacerbate theenvironmental problems associatedwith blanket spraying and create a newcycle of resistant weeds (Mortensen etal. 2012).

Trevewas and Livermore also claimthat widespread resistance has notdeveloped to the Bt toxins expressedby insect-resistant GM crops. However,reduced efficacy of Bt crops caused byfield-evolved resistance has beenreported now for some populations of5 of 13 major pest species examined,compared with resistant populations ofonly one pest species in 2005(Tabashnik et al. 2013; Van den Berg etal. 2013; Jin et al. 2013). Whilst theyconcede that Bt crops were neverintended to give complete protectionagainst pests, Trevewas and Livermoreignore the impact on farmers of anumber of documented increases insecondary pests, which can increasesignificantly in numbers when targetedpests decrease (e.g. Zhao et al. 2011;Tay et al. 2013). As a response to theseproblems, Trevewas and Livermorehighlight research on the use of


the GM debatedouble-stranded RNA to switch off theexpression of specific genes, as a newmeans of pest-control. However, theuse of RNA interference can give rise tounintended off-target effects and itsefficacy and safety is far from beingestablished (Heinemann et al. 2013;Lundgren et al. 2013).

There is no scientific consensus onthe safety of GM crops (ENSSER 2013)and there are limitations to all ratfeeding studies conducted on bothsides of the debate (Meyer & Hilbeck2013). There is also evidence ofcommercial bias in the literature (Dielset al. 2011). Even if there were no suchscientific disagreements, consumershave a right to choose to avoid GMcrops for health, environmental orother reasons, such as objections tothe patenting of seeds. If consumerchoice is to be maintained, theintroduction of GM farming to acountry or region adds the costs ofsegregation to the food supply chain,increasing costs across the board.Failure to plant what consumersdemand or to effectively segregatesupplies means that US farmers havelost markets due to GM farming asexports elsewhere have been reduced(EuropaBio and BIO, 2012). Whilst theindustry argues that the answer is toweaken regulation, the alternativeroute of not planting GM food crops atall still remains open to mostdeveloping countries.

For example, India and China,despite growing GM cotton, are stillrightly hesitant over planting cropssuch as GM brinjal (aubergine) or GMrice. Food security and trade issues area big part of the debate, as countriesseek to avoid dependency on importedGM seeds and associated chemicals.

ReferencesBennett M, Franzel S (2013) Can organic andresource-conserving agriculture improvelivelihoods? A synthesis. International Journal ofAgricultural Sustainability. 2013;11(3):193–215. Bøhn T, Cuhra M, Traavik T, Sanden M, Fagan J,Primicerio R (2013) Compositional differences insoybeans on the market: glyphosate accumulatesin Roundup Ready GM soybeans. Food Chemistry.doi:10.1016/j.foodchem.2013.12.054.Brower LP, Taylor OR, Williams EH, Slayback DA,Zubieta RR, Ramírez MI (2012) Decline ofmonarch butterflies overwintering in Mexico: isthe migratory phenomenon at risk? InsectConservation and Diversity 5(2):95–100.

Catangui MA, Berg RK (2006) Western BeanCutworm, Striacosta albicosta (Smith)(Lepidoptera: Noctuidae), as a Potential Pest ofTransgenic Cry1Ab Bacillus thuringiensis CornHybrids in South Dakota. EnvironmentalEntomology 35:1439–1452.Diels J, Cunha M, Manaia C, Sabugosa-Madeira B,Silva M (2011) Association of financial orprofessional conflict of interest to researchoutcomes on health risks or nutritional assessmentstudies of genetically modified products. FoodPolicy 36(2):197–203.doi:10.1016/j.foodpol.2010.11.016.ENSSER (European Network of Scientists for Socialand Environmental Responsibility) Statement: Noscientific consensus on GMO safety. 21st October2013. http://www.ensser.org/increasing-public-information/no-scientific-consensus-on-gmo-safety/ EuropaBio and BIO (2012) EU-U.S. High LevelWorking Group on Jobs and Growth: Response toConsultation by EuropaBio and BIO.http://ec.europa.eu/enterprise/policies/international/cooperating-governments/usa/jobs-growth/files/consultation/regulation/15-europabio-bio_en.pdf Fraser K (2013) Glyphosate Resistant Weeds –Intensifying. Stratus Research. 25th January 2013.http://www.stratusresearch.com/blog07.htm Goodman M (2002) New sources of germplasm:lines, transgenes and breeders. In: Memoriacongresso nacional de fitogenetica. Saltillo, Coah.,Mexico: Univ. Autonimo Agr. Antonio Narro.28–41.Hartzler RG (2010) Reduction in commonmilkweed (Asclepias syriaca) occurrence in Iowacropland from 1999 to 2009. Crop Protection29(12):1542–1544.Heinemann JA, Massaro M, Coray DS, Agapito-Tenfen SZ, Wen JD (2013) Sustainability andinnovation in staple crop production in the USMidwest. International Journal of AgriculturalSustainability 1–18.Heinemann JA, Agapito-Tenfen SZ, Carman JA(2013b) A comparative evaluation of theregulation of GM crops or products containingdsRNA and suggested improvements to riskassessments. Environment International 55:43–55.Hilbeck A, Lebrecht T, Vogel R, Heinemann JA,Binimelis R (2013) Farmer’s choice of seeds in fourEU countries under different levels of GM cropadoption. Environmental Sciences Europe25(1):12. Jiang G-L (2013) Plant Marker-Assisted Breedingand Conventional Breeding: Challenges andPerspectives. Advances in Crop Science andTechnology. 1(3):e106.Jin L, Wei Y, Zhang L, Yang Y, Tabashnik BE, Wu Y(2013) Dominant resistance to Bt cotton andminor cross-resistance to Bt toxin Cry2Ab incotton bollworm from China. EvolutionaryApplications. 6(8):1222–1235. Knight J (2003) Crop improvement: A dyingbreed. Nature 421(6923):568–570.doi:10.1038/421568a.Koller VJ, Furhacker M, Nersesyan A, Misik M,Eisenbauer M, Knasmueller S (2012) Cytotoxicand DNA-damaging properties of glyphosate andRoundup in human-derived buccal epithelial cells.Arch Toxicol. 86: 805-813.Lundgren JG, Duan JJ. RNAi-Based InsecticidalCrops: Potential Effects on Nontarget Species.

BioScience. 2013;63(8):657–665.Mañas F, Peralta L, Raviolo J, et al (2009)Genotoxicity of glyphosate assessed by the Cometassay and cytogenetic tests. Environ ToxicolPharmacol. 28: 37?41.Messan K, Smith K (2011) Short and Long RangePopulation Dynamics of the Monarch Butterfly(Danaus plexippus). Technical report of theMathematical and Theoretical Biology Institute.http://mtbi.asu.edu/files/MTBIpaper_ButterflyGroup.pdf Meyer H, Hilbeck A (2013) Rat feeding studieswith genetically modified maize - a comparativeevaluation of applied methods and risk assessmentstandards. Environmental Sciences Europe25(1):33.Paganelli A, Gnazzo V, Acosta H, López SL,Carrasco AE (2010) Glyphosate-Based HerbicidesProduce Teratogenic Effects on Vertebrates byImpairing Retinoic Acid Signaling. Chem ResToxicol. 23(10):1586–1595.Pleasants JM, Oberhauser KS (2013) Milkweed lossin agricultural fields because of herbicide use:effect on the monarch butterfly population. InsectConservation and Diversity 6(2):135–144.Relyea RA, Jones DK (2009) The toxicity ofRoundup Original Max to 13 species of larvalamphibians. Environ Toxicol Chem.28(9):2004–2008.Romano RM, Romano MA, Bernardi MM, FurtadoPV, Oliveira CA (2010) Prepubertal exposure tocommercial formulation of the herbicideGlyphosate alters testosterone levels and testicularmorphology. Archives of Toxicology 84(4): 309-317.Samsel A, Seneff S (2013) Glyphosate’sSuppression of Cytochrome P450 Enzymes andAmino Acid Biosynthesis by the Gut Microbiome:Pathways to Modern Diseases. Entropy15(4):1416–1463. doi:10.3390/e15041416.Tabashnik BE, Brévault T, Carrière Y (2013) Insectresistance to Bt crops: lessons from the first billionacres. Nat Biotech. 31(6):510–521.Tay WT, Soria MF, Walsh T, et al. (2013) A BraveNew World for an Old World Pest: Helicoverpaarmigera (Lepidoptera: Noctuidae) in Brazil. PLoSOne 8(11). Thongprakaisang S, Thiantanawat A, RangkadilokN, Suriyo T, Satayavivad J (2013) Glyphosateinduces human breast cancer cells growth viaestrogen receptors. Food Chem Toxicol.59:129–136. Van den Berg J, Hilbeck A, Bøhn T (2013) Pestresistance to Cry1Ab Bt maize: Field resistance,contributing factors and lessons from South Africa.Crop Protection 54:154–160.doi:10.1016/j.cropro.2013.08.010.Wagner N, Reichenbecher W, Teichmann H,Tappeser B, Lötters S. (2013) Questionsconcerning the potential impact of glyphosate-based herbicides on amphibians. EnvironmentalToxicology and Chemistry. 32(8):1688–1700.doi:10.1002/etc.2268.Zalucki MP, Lammers JH (2010) Dispersal and eggshortfall in Monarch butterflies: what happenswhen the matrix is cleaned up? EcologicalEntomology 35(1):84–91. Zhao JH, Ho P, Azadi, H (2011) Benefits of Btcotton counterbalanced by secondary pests?Perceptions of ecological change in China. EnvironMonit Assess. 173:985–994.


the GM debate

In defence of GM cropsProfessor Anthony Trewavas FRS, FRSE, The Scientific Alliance Scotland,

7-9 North St David Street, Edinburgh EH2 [email protected].

Martin Livermore BA (Oxon), Director, The Scientific AllianceSt John’s Innovation Centre, Cowley Road, Cambridge CB4 0WS

[email protected]

Elsewhere in this journal (pages 60-67), we make a critique of thearticle by Dr Helen Wallace

(Wallace, 2013), in which she arguesstrongly that GM crops are bothunnecessary and harmful in variousways.

Dr Wallace has herself responded tothis criticism (pages 68-69) and theeditors have kindly allowed us toprovide an initial reaction, on whichwe hope to expand in the next editionof World Agriculture.

The negative picture painted by DrWallace does not appear to beconsistent with the fact of continuedsteady growth in the penetration ofGM crops in both industrialised anddeveloping countries, with the areaplanted in developing countries nowbeing more than half the global total.

Unless farmers are being deliberatelymis-sold unsuitable crop cultivars byunscrupulous merchants and are insome way prevented from sowingconventionalcultivars in subsequentyears, it is hard to avoid the conclusionthat the majority of farmers are gettingbenefits which outweigh both thehigher seed cost and any negativeimpacts there may be.

Some of her specific criticisms, whichwe intend to address more fully in thenext edition, are addressed below:

1. ‘…GM farming is in crisis asresistant weeds have becomewidespread…’ Inevitably, some weedsdevelop resistance to particularherbicides and it is hardly surprisingthat this is also the case withglyphosate. There were already someresistant species prior to thewidespread use of Roundup Ready™crops – glyphosate having alreadybecome one of the most popularbroad-spectrum herbicides – andfurther resistance will have occurredwith continued use. Resistant weedscan be controlled either withalternative herbicide or by hoeing andthis situation represents the reality offarming rather than a crisis.

2. Dr Wallace compares US farming

unfavourably with Europe, but farmmanagement practices, crops andclimatic conditions are not easilycomparable. She also argues that achoice to revert to non-GM seeds hasbeen made more difficult by theconsolidation of the seed industry andthe lack of diversity. However, there arestill plenty of non-GM cultivarsavailable to both conventional andorganic farmers and it would benormal for any supplier to be able topropagate larger quantities ofparticular cultivars over only a fewseasons if sufficient demand existed.The reduced range of cultivars is morelikely to reflect changing patterns ofdemand than vice versa.

3. According to the critique of ourpaper, ‘conventional breeding… has infact delivered more cropimprovements much faster and morecheaply’. We would not argue thatnon-GM techniques can producecommercial cultivars more quickly andcheaply. Partly, this is a consequence ofthe greater regulatory demands ontransgenic cultivars and partly thatonly a handful of companies have thein-depth technical resources to userDNA techniques and successfullybring transgenic cultivars to market.Nevertheless, despite the barriers,companies continue to develop GMcultivars because they simply cannotuse conventional techniques tointroduce the same traits. We thereforestand by our description of GM as‘cutting edge technology’. In addition,we regard this as an extremely usefulnew weapon in the armoury ratherthan in any way being a replacementfor other breeding techniques.

4. We also consider our use of theterms ‘innocuous to human health’and ‘environmentally benign’ todescribe glyphosate to be justified. Thisdoes mean it is incapable of causingharm, simply that when glyphosate isused according to instructions there isa large margin of safety. Many activeingredients of commercial herbicideshave some environmental impact. Ascientific risk assessment allows any

potential problems to be identified andmanaged. Identifying potentialmechanisms for harm, or havingconcerns, is not the same as providingevidence or demonstrating harm in theenvironment.

5. The issue of habitat loss for theMonarch butterfly and other species isnot one to be taken lightly.Nevertheless, it is fair to point out that,although farmed fields are themselvesrelatively poor in wildlife, overallfarmland management itself providesmany useful habitats. It seems to usthat the criticism is largely one ofmodern intensive farming rather thanGM crops per se. The other side of thecoin is that greater productivity oncurrent arable land reduces thepressure on other natural habitats;pressure on a particular iconic speciesis not the same as an overall regionalreduction in biodiversity.

6. We are criticised forunderestimating the impact of Btexpression. As for any pesticide, somedevelopment of resistance over time isinevitable and this is simply acontinuation of a struggle betweenfarming and pests, which is effectivelyan ‘arms race’. The situation isanalogous to the use of antibiotics,which have been of enormous benefitbut whose efficacy is now sufferingfrom widespread microbial resistance.The answer is to develop new solutionsrather than decry the negative impactsof existing ones. Similarly, the criticismis levelled that secondary pests havebecome more of a problem with thereduction in numbers of the targetspecies. Again, this is an expectedproblem and illustrates that no singlecontrol method is perfect but mustoften be combined with others as thefarmers’ needs change.

7. We take issue with the assertionthat there is no scientific consensus onthe safety of GM crops. In itself, this isan unscientific statement, since all wecan say is that there is no additionalhazard introduced by the particularGM events currently in the


the GM debatemarketplace. Consumers of coursehave every right to choose which foodsthey eat, and the choice to avoid GMfor ethical reasons is easily

accommodated by buying organicfood. These are our first views of thecriticisms and we will provide a more

reasoned response at a later date.

ReferenceWallace, Helen. (2013) World Agriculture, 4, 1, 45-49. What role for GM crops in world agriculture?

© foto76 – Fotolia.com


economics and social

Mitigation of water logging andsalinity through biodrainage:

potential and practice Professor O.P.Toky1 and Dr R. Angrish2,

Department of Forestry1 and Department of Botany and Plant Physiology2,

CCS Haryana Agricultural University, Hisar, India

Dr. O. P.TokyICAR Emeritus Scientist,

Fellow, National Academy of Agricultural Sciences Ex Dean, Postgraduate Studies

CCS Haryana Agricultural University, Hisar-125004 (India)Phone (Residence): ++91-1662-243626

Fax: ++91-1662-234952Mobile: ++91 9896173626E-mail: [email protected]

SummaryOver the past hundred years, vast areas worldwide have been used for intensive agriculture following clearance by removalof deep rooted tree vegetation or by introducing irrigation in arid zones. After decades of profitable returns, many of thesedomains, particularly those underlain with saline aquifers and with poor natural drainage have degraded owing to waterlogging and salinity. Disturbed hydrological balance in the form of sustained percolation of surplus surface rain or irrigationwaters to the saline water table resulted in waterlogged and saline conditions. Surface and sub-surface drainage can be aneffective remedy, but has limited applications in marginal farm lands. During the last two decades, there has beenawareness of the potential for biodrainage to remove surplus soil water. This is typically effected by forming a water tabledepression down slope of a tree plantation or discharge area that may extend up to several meters (around) beyond theplantation. This lowers the water table below the root zone of the (surrounding) crop area. Biodrainage has lowestablishment costs and no effluent disposal problems. Biodrainage systems have been successfully tested worldwide,including India, and a strong case for their large scale adoption can be made. The authors opine a paradigm shift in theapproach of policy makers and drainage engineers in recognizing the role of trees as potent drainage modules. Sensitizationof the affected farming communities to adopt locally suited biodrainage based agroforestry models is also desired.

KeywordsBiodrainage, salinity, water logging, water table, socio-economical, policies.

GlossaryAn aquifer is an underground layer ofwater-bearing (water saturated) areafrom which groundwater can beextracted using water well. Aquifershaving dissolved salts are not fit forirrigation or for potable waterpurposes.Biodrainage is the vertical drainage ofwater table through evapo-transpiration of strategically plantedvegetation, particularly deep rootedtrees. Frequent use of the term

‘biodrainage’ in scientific literature hasbeen only post 2000. Agricultural drainage is a system ofopen channels, subterranean pipesthrough which the water level on or inthe soil of a cropping area iscontrolled. Rio summit is the United NationsConference on Environment andDevelopment (UNCED) held in Rio deJaneiro from 3 to 14 June, 1992. Salinity is the excessive content of salts(generally chlorides and sulphates of

sodium, calcium and magnesium) insoil- or irrigation-water. Salinity is easily measured bymeasuring electrical conductivity ofwater. A conductivity value greaterthan 4000 Siemens per second isharmful for most crops.Water logging of soil agriculturally issaid to occur when the water table ofthe groundwater is too high, so that itsaturates the soil in the crop root zone,resulting in prolonged anoxicconditions.


economics and socialIntroductionBackground:

Over the past hundred years orso, countries throughout theworld have introduced

intensive agriculture on various pristinedomains of nature, each having itsown peculiar ecology.

In many cases, after a few decadesprofits have declined and suchinterventions have not remainedsustainable. In this paper our primaryconcern is the vast area of in arid andsemi-arid land where deeper layers ofsoil had ancient stores of salts. Hereagriculture-led disturbed hydrologicalbalance has resulted in the percolationof water with a gradual rise in salinityin the crop root zone ultimatelyleading to development of salt pansand water logging. These changes inirrigated lowlands due to intensiveagriculture has become critical so thatcertain areas are non-cultivable (1,2,3).

It is a matter of common knowledgethat an engineering drainage system isneeded in such situations to maintain acheck on the salinity-water tablemenace, but our paper deals with thenon-conventional drainage system i.e.biodrainage which has caught theattention of workers throughout theworld. We shall, confine our discussionmainly to the role of trees in drainageof the water from our saturated topsoils of agricultural use. We shall alsobriefly describe the role of trees inareas where groundwater tables havedeclined to abnormally low depths. Weshall also suggest some policies whichshould be adopted.

Soil water use by trees andbiodrainage:Trees can transpire large amounts ofwater, for example, Euperua purpureain Amazonian rainforest was estimatedto transpire 1180 kg/ day of water (4).

Equally noteworthy is the ecologicallevel interaction of deep rooted treeswith groundwater. Thus, as early as1953, Wilde et al. (5) noted that treespecies influence the groundwatertable by acting as biological pumps.FAO (6) highlights the positive andnegative effects of trees like Eucalyptuson groundwater. However, large scalescientific use of trees in ground watercontrol seems to be of more recentorigin. The concept of biologicaldrainage or biodrainage appears tohave originated in the waterloggedagricultural areas where theconventional surface and sub-surfacedrainage techniques were in vogue (7).Biodrainage may be defined as thevertical drainage of water through

evapo-transpiration of strategicallyplanted vegetation, particularly deeprooted trees with the intention oflowering the water table.

Conventional drainage andbiodrainageSuccess and limitations of conventionaldrainage:Conventionally the control of waterlogging and soil salinity has beenobtained through civil engineeringtechniques such as surface drainage,horizontal sub-surface drainage andvertical drainage (8,9,10).

Surface drainage excavation of opentrenches is done to drain surface waterand to prevent pond formation,flooding and consequent damage tothe crops. In the horizontal sub-surfacedrainage removal of soil water belowthe crop root zone is done through anetwork open tile drains. A betteroption is to install a network ofperforated subterranean pipes. Ineither case water or dissolved saltsleach into the tile drains or pipespreventing both water logging andsalinity. In the vertical drainage systembore wells are dug and the water ispumped out. If not saline, this watercan be used for irrigation or pumpedinto the adjoining canals to augmentflow. In semi-arid zones, wheregroundwater is saline, a conjunctiveuse helps in irrigation and prevents agradual rise in the water table.

However, these techniques,particularly horizontal sub-surfacedrainage, are costly to install, maintainand sustain (1,2,11). They also havethe problem of effluent control. Ifdischarged into natural drains thesaline effluent pollutes the riversdownstream. If reused, evenconjunctively, salts are redistributed inthe agro-ecosystem and the problemof salinity increases over a period oftime. Ritzema et al.(2) opined that indeveloping countries like Indiafragmented landholdings of marginalfarmers are not suitable for theadoption of these techniques ascompared to more developedcountries, where agriculture is carriedout on an industrial scale.

Advantages and disadvantages ofbiodrainage:Biodrainage is an ecologically attractiveconcept which has the merits low costand environmental friendliness.

The limitations are a requirement ofland for tree plantations, slow anduncontrolled lowering of water table,limited evacuation of salts from the

system, and vulnerability of trees tohighly saline conditions.

Recharge and discharge zones:In planning a biodrainage system theneed for recharge and discharge zonesshould be clearly understood.

Recharge areas are locations fromwhere water seeps into the watertable, e.g. leaky canals or tributariesand elevated areas receiving rainfallwith runoff water. However, the mostsignificant recharge areas are theagricultural fields where liberal canalirrigation is applied. The areas wherebiodrainage plantations are raised tooffset the recharge water are known asdischarge areas. On average about10% of land in a waterloggedagricultural landscape is to be markedas a discharge area.

Biodrainage andrepresentative problemareas Perusal of the literature shows that twounique situations exist where largescale field level biodrainage effortshave been made. These are outlinedbelow:

Clearing of deep rooted vegetation inhigh rainfall zones:In Australia the pristine deep rootedtree and heath vegetation overlaidbrackish water aquifers and ancientstores of salt.

This was because the annual rainfallwas intercepted and evapo-transpiredby the native vegetation. Introductionof intensive agriculture necessitated theclearing of this tree vegetation and itsreplacement with shallow rootedannual crop plants. The annual waterconsumption by this vegetation wasless than the rainfall and as result waterpercolated to the underlying salinegroundwater table causing its gradualrise. The twin menace of salinity andwater logging appeared.

Now suitable development ofagroforestry systems incorporatingtrees are expected to reduce thesalinity as the water table recedes fromthe root zone of commerciallyimportant annual crops (13,14,15,16).

This model of ‘ecosystem mimicry’(17) intends to obtain a plant-wateruse scenario that closely imitates thepre-clearing situation. The Australiansystem is the most exhaustively studieddisturbed agro-ecosystem thatunambiguously demonstrates thenecessity of harmony between wateruse by vegetation and aquifers (Fig. 1).

Introduction of irrigation in arid andsemi-arid zones:In semi-arid north west India, thetraditional rain fed agriculture was notaffected by the deep underlying salinegroundwater.

The introduction of canal irrigationand intensive agriculture upset thisbalance. Gradual seepage of theliberally used irrigation water caused arise of the saline water table so thatsoils became waterlogged and saline.For example, in the western zone ofHaryana, average water table depthwas static at about 28 m from theground surface between the 1930s andearly 1950s. Since the commissioningof the Bhakhra canal system in 1956,the water table rose to only 6m fromthe ground surface by 2002 (Fig. 2, 3,4). During the past two decades nearly50% of the area of south-west Haryana

has been critically waterlogged withthe water table rising to <3 m of theground surface during this time(1).The phenomenon is worldwide, butbiodrainage systems are beingconsidered and integrated with theexisting agro-ecosystems for example,in China (18), India (12,19,20,21),Israel (22), Pakistan (23) andUzbekistan (24,25).

Impact of biodrainage ondepression of water tableBiodrainage certainly depresses thewater table immediately underneathplantations, but in an agroforestry theobjective is to lower the water table toa safer depth, well below the crop rootzone in the cultivated area that

surrounds the plantation (7,12). A cone of water table depression with

the lowest point near the cavity of awell is known to develop as a result ofpumping from the aquifer (unconfinedaquifer). Further, if two wells areoperating simultaneously at a suitabledistance, two ‘interfering’ cones ofdepression will be formed. The drawdown effect of two related Eucalyptustereticornis block plantations wassimilar to the combined interactingcones of depression of two pumpingwells (20).

Biodrainage and soilsalinityRemediation of soils waterlogged with(fresh) water is a less commonphenomenon as fresh water can bereadily utilized for both agriculturaland non-agricultural purposes.

A more threatening situation ariseswhere water logging involves a salineaquifer or a soil profile with an ancientstore of salts. In either case interactionof a biodrainage plantation with thesaline waterlogged soil becomesinevitable. It is well established thatphysiologically most of the treesgrowing under saline conditionsexclude salts, especially Na+ and Cl-which are excluded by the root and donot form a part of the transpirationstream.

Theoretically, therefore, these mayaccumulate under the plantation overa period of time. This may result in abuildup of salinity in the root zone andpose a risk to the survival of thebiodrainage system itself. In Australia, a7 year old Eucalyptus plantationsurrounded by an irrigated area therewas a significant lowering of the watertable beneath the plantation ordischarge area but no accumulation ofsalt with respect to the outsideirrigated recharge area. However, after15 years accumulation of salts hadtaken place in the capillary fringeabove the water table areas (14) of thisplantation. Archibald et al. (26)examined the sustainability ofEucalyptus plantations on salinedischarge areas and concluded thatalthough soil salinity develops beneaththe plantations, there was an excellentsurvival of plantations even after 20-25years.

Biodrainage strategiesPit versus ridge planting:Soils waterlogged up to surface orsub-surface zones are anaerobic andthe conventional pit plantingtechnique is not feasible.



Figure 1. Salinization of land afterclearing the forests of Eucalyptus forthe purpose of agriculture in Australia.

Figure 2. Eucalypts (Eucalyptustereticornis) biodrainage system on theboundareis in a high water table areaof Rohtak district of Haryana State innorth India. Paddy is the main cropduring monsoon season.

Figure 3. Eucalypts (Eucalyptustereticornis) biodrainage on the bundsin high water table area of Hisardistrict of Haryana in north India.Wheat is the main crop during winter.

Figure 4. A close view of Eucalyptustereticornis plantation on theboundaries as explained in figure 3.



On such problematic locations soilridges raised up to 0.5 m above thesurrounding soil surface isrecommended (20).

This aids the better establishmentand subsequent growth of seedlingson waterlogged soils as it enables themto withstand anaerobic conditionsproduced by prolonged water loggingor ponding. The ridge plantingtechnique is being successfullypracticed by Punjab and Haryana StateForest Departments in India. Sinceridges are made from the field soil,they have the same salinity. Salttolerant species are therefore,recommended. Eucalyptus, Pongamia,Casuarina, Terminalia, etc can growwhile poplars and bamboos could notsurvive (Table 1). To avoid excess ofsalts accumulation due to surfaceevaporation, ridges can be coveredwith sand to discourage capillaryfringe.

Block plantations:A block of suitable trees is planted in awaterlogged area, which causes a coneof water table depression underneaththe plantation.

However, the extent of lowering ofthe groundwater table around thesurrounding recharge area has beenshown to vary from a radius of 40 m(15) to 730m (20). The vastdifferences may be attributed to thesize and other characteristics of thedischarge plantation block, hydraulicconductivity of the soil and croppingpattern, recharge of the surroundings.In the planning of Australianbiodrainage systems the plantationdischarge areas are confined to salineor degraded areas so that less arableland is lost (26).

Strip plantationsBlock plantations work well, but arenot feasible where land holdings aresmall and fragmented where land

cannot be spared for biodrainage. Here strip plantations on field

boundaries are the only alternative. Inmany Indian states, including Haryana,the standard unit of land with fieldboundaries on all four sides is an acre(0.4 ha) of about 66m length in theeast-west direction and 60m width innorth-south direction. Therefore a‘farmer’s model’ comprising parallelstrip biodrainage plantations in anorth-south direction 66 m apart andwith two rows of trees on each stripraised 0.5 m are recommended (27).This agroforestry model has beensuccessfully tested on a pilot scalearound a village (Putthi) in the districtof Hisar in Haryana. The model isconsidered as best option from thepoint of view of: i) technologicaladoption by the farming community,ii) lowering of the water table to about1 m over a period of 5 years and iii)remuneration to the farmers as timber(27).

The authors (28) compared thebiodrainage potential of ten treespecies planted as per this farmer’smodel (Fig. 5, 6). It was revealed thatabout five years old trees differedsignificantly in their biodrainagepotential in the order: Eucalyptustereticornis clone 10 = Eucalyptus hybrid(clone of E. tereticornis x E.camaldulensis) > Eucalyptus clone–130= Tamarix aphylla > Prosopis juliflora >Eucalyptus clone–3 > Callistemonlanceolatus = Melia azedarach >Terminalia arjuna = Pongamia pinnata.

There are several pockets of landwhere water logging is so acute duringthe post-monsoon months of end-

Figure 5. Farmers model of biodrainage developed in a waterlogged area of CCSHaryana Agricultural University at Hisar, north India. Two rows of Eucalyptustereticornis are raised on the boundareis of the field.

Figure 6. Farmers model ofbiodrainage developed in a water-logged area of CCS HaryanaAgricultural University at Hisar, northIndia. Two rows of mesquite (Prosopisjuliflora) are raised on the boundareisof the field. The vertical column in thecentre of four trees on a two rowedfield bund is the observation well forperiodic measurement of water table.

Table 1. Survival and growth of 8-year old trees in a ‘farmer’s model’ (comprisingof parallel strip biodrainage plantations in north-south direction 66 m apart andwith two rows of trees on each strip on about 0.5 m raised ridges) developed inan area having acute water logging at the campus of Haryana AgriculturalUniversity , Hisar, Haryana State in north western India.


economics and socialOctober to December that the top soilis saturated water so that fieldpreparation/sowing of wheat is notpossible. It is on such locations that thetransfer of raised field bund technologyfor biodrainage is adopted even bymarginal farmers without muchquestioning.

Future scope andconclusions Research and developmentInternational research efforts onbiodrainage have been coordinated byan International Program forTechnology and Research in Irrigationand Drainage (IPTRID) of the FAO ofthe UN (7).

In India the Indian NationalCommittee on Irrigation and Drainage(INCID), operating under the Ministryof Water Resources (MoWR),Government of India, coordinatesnational level biodrainage researchfunding and knowledge synthesis (29).

Adoption constraints:The conduits of surface, sub-surfaceand vertical drainage are essentiallycivil engineering structures andbiodrainage may be a difficult conceptfor civil engineers to consider.

Farmers may also be wary of anynegative effects tree plantations mayhave with their crops. This feelingemerged at a National Level TrainingProgram comprising senior irrigationengineers, agricultural scientists andforesters facilitated by the authors (30).However, once aware of the issuesthese personnel could see thefeasibility and advantages of integratedconventional and biodrainage.

Biodrainage cannot be effectivewhere acute and prolonged flooding,or ponding conditions, prevail. Hereonly surface drainage can be effective.However, where over the years a rise inthe water table is a threat, properlydesigned biodrainage can replace orcomplement subsurface and verticaldrainage. In future there may beincreasing exploitation of trees forbetter groundwater hydrology,agroforestry, forestry, urbandevelopment and a green and cleanenvironment at large.

Creation of livelihood:Widespread adoption of biodrainage islikely to depend upon use of trees withalternative uses, for example, ofpoplars on alluvial plains of north-western India, have improved theincome of farmers (Fig.7).

This is due to the fact that a well

developed marketing system isavailable. Eucalypts can make a similarimpact on waterlogged soils as theyare well adapted to waterloggedconditions. Productivity andprofitability of plantations of Eucalyptushave been revolutionized with thedevelopment of genetically improvedfast growing and high yielding clonalplanting material. Average productivityof commercial clones is about 20-25m3/ ha/ yr. Where World Bank aidedforestry development projects existed,many States in India have adoptedclonal plantations of Eucalyptus. Thishas been very helpful to the farmers. Itis important to note that there is noself propagation of eucalypts in India.

Prosopis juliflora and Prosopis pallida,are excellent biodrainers (21), whichcan be used for plantations onwaterlogged soils. Many of theproblems of Prosopis are a result ofusing unsuitable strains of P. juliflora.Seeds from Peruvian material assumedto be P. pallida is superior to materialof P. juliflora available in India. Prosopispods are high in sugars, carbohydratesand protein and can be used toprepare animal cakes. It fruits annuallyand crops evenly in an adverse climate.P. juliflora produces wood with a highcalorific value of approximately 21MJ/kg (5000 kcal/kg), so that charcoalobtained from the wood of Prosopisspecies is of very high quality. Ten kgof green wood will make 1-2 kg ofcharcoal using traditional earth kilns, in2-4 days. Above ground biomass fromdifferent sites varies from as little as 0.5t/ha/yr to over 39 t/ha/yr. Frequentcutting produces small branches whichare ideal for cooking, so that itprovides two important and integralcomponents for rural communities inin some parts of India, especially

Chambal Valley (Fig. 8 shows transportof Prosopis juliflora near the ChambalRiver).

P. juliflora has immense potential onwater logged soils and promises toboost the economy of poor ruralpeople It is grown to reduce erosion inhilly areas with unstable soils prone tohigh run-off.

Casuarina in coastal belts andbamboos in high rainfall areas, areother very important industrial speciesthat can be used for waterloggedconditions.

In order to boost the economy offarmers, there needs to be closecollaboration with the companiesprocessing and marketing the timber.

Environmental concerns:Trees are a valuable carbon sink. Theyplay a vital role in nutrient cycling andof restoring soil fertility, arresting soilerosion and creating a micro-climatesuitable for micro- flora and micro-fauna.

The permanent tree cover protectssoil from erosion and regulates thewater balance. Further, trees andshrubs are less sensitive to fertilitylevels than food crops and somespecies help to stabilize degraded land.

Socio-economic concerns:Apart from the biological andenvironmental roles, trees also have asignificant social, religious and culturalstatus.

Since the Rio Summit in 1992, globalenvironmental concerns have beenacknowledged as integral componentsof sustainable development. Plantingof trees on wastelands or agriculturallands for industrial and environmentalhealth has been initiated particularly indeveloping countries.

Figure 7. Block plantation of poplars(Populus deltoides) in Yamunanagardistrict of Haryana, north India. Thewater table is high and the aquifer hassweet water due to a canal passingnearby. Wheat, sugarcane and foddercrops are grown in the interspaces ofpoplar trees.

Figure 8. Prosopis juliflora providesfirewood for rural communities insome parts of central India. Theillustration shows firewood transportalong the Chambal River, about 80 kmSouth East of Agra. This plant has beenused to stabilize the sandy soils alongthe river and wood is transportedacross the river, creating a localindustry. (Photo courtesy Mrs PennyCook)


economics and socialFor example, in Sri Lanka perennial

crop-based farming systems supplyover 50% of national timber and 80%of fuel wood needs. Climate change: The rural poor indeveloping countries, are most at riskof adverse effects of climate change.Biodrainage/agroforestry plantationshave the potential to create synergiesbetween efforts to mitigate climatechange and efforts to help poorfarmers from the adverse effects ofclimate change. Fuel wood: A large proportion of thefuel wood for domestic energy in ruralareas is harvested from the debris ofagriculture and from trees growingoutside the forest especially for smalllandholders. It is therefore, vital toplant trees which provide quality fuelwood whenever possible.Fodder: Trees play an important role inlivestock production since they provideshade, shelter and fodder. Acacia,Prosopis, Leucaena, Albizia, Bauhinia,Celtis, and Grewia are some generaof immense value.Non-wood products: Wild fruits,herbs, gums, resins, etc. areabundantly produced by improved treebased systems providing diverseproducts which are linked to socio-economic aspects of society. Women’s role: In rural economies ofdeveloping nations women are moreknowledgeable and skillful to handlesome operations such as collecting fuelwood, lopping fodder, collecting wildfruits and other non-timber treeproducts. There are examples, ofwhole tree based systems, for example,where home gardens are maintainedby the women. The tools required,matching their strength need to bedeveloped, and some training to thisgroup can enhance the profit of thefamily.

PoliciesFor the effective adoption ofbiodrainage agroforestry in the farmingcommunity particularly in developingcountries the following policy pointsshould serve as guide lines: To detect the places wherewaterlogging is expected, or hasalready been revealed and to identifythe affected farming community.� Organize trainings for ruralcommunities that are required toachieve the goal.� Promote local-level processing andmarketing of timber and non-timbertree products relevant to the scale oftheir production. � Integrated development plans

should include agroforestry/biodrainage plantations for woodbased industries and should promotemarket demand for farm growntimber. � Strengthening of farmer groupstechnically and making availablesuperior tree planting stock for thefarmers. Incentives should be providedto farmers growing plantations as treesafford carbon sequestration. � Site specific R&D is required.� Knowledge-based adaptive plansshould be prepared as per theguidelines of World AgroforestryCentre and NationalOrganizations/Institutions.

References1. Kumar, R (2004) Groundwater status andmanagement strategies in Haryana. In:Groundwater use in North-west India. (ed., I PAbrol, B R Sharma & G S Sekhon), Centre forAdvancement of Sustainable Agriculture, NewDelhi, pp 16-26.2. Quershi, A S, McCornick, P G, Qadir, M & Aslam,Z (2008) Managing salinity and waterlogging inthe Indus Basin of Pakistan. Agricultural WaterManagement, 95, 1-10.3. Aleksandrova, M, Lamers, P A, Martius, C &Tischbein B (2014) Rural vulnerability toenvironmental change in the irrigated lowlands ofCentral Asia and options for policy makers: Areview. Environmental Science and Policy (in press).4. Jordan, C F & Kline, J K (1977) Transpiration oftrees in a tropical rain forest. Journal of AppliedEcology, 14, 853-60.5. Wilde, S A, Steinbrenner R S, Pierce, R S,Dozen, R C & Pronin, D T (1953) Influence of forestcover on the state of groundwater table.Proceedings Soil Science Society of America, 17, 65-7. 6. Poore, M E D & Fries C (1985) The ecologicaleffects of Eucalypts. Rome, Food and AgricultureOrganization of the United Nations, Forestry paperNo. 59, pp 1- 97.7. Heuperman, A F, Kapoor, A S & Denecke, H W(2002) Biodrainage – Principles, Experiences andApplications. Knowledge Synthesis Report No. 6.International Programme for Technology andResearch in Irrigation and Drainage (IPTRID), IPTRIDSecretariat, Rome, Food and AgricultureOrganization of the United Nations, pp 1-79.8. Tanji, K K (1996) Agricultural salinity assessmentand management, New York, American Society ofCivil Engineers, 1996, ISBN 9 78 078 4473634. 9. Garg, B K & Gupta, I C (1997) Saline wastelandsenvironment and plant growth, Jodhpur, ScientificPublishers,1997, ISBN 9 78 817 2331584.10. Ritzema, H P, Satyanarayana, T V, Raman, Sand Boonstra, J. (2008) Subsurface drainage tocombat waterlogging and salinity in irrigated landsin India: Lessons learned in farmer’s fields.Agricultural Water Management, 95, 179-89.11. Rao, K V G K, Sharma, S K & Kumbhare, P S(2005) Drainage requirements of alluvial soils ofHaryana. In: Reclamation and Management ofWaterlogged Saline Soils, (ed., K V G K Rao, M CAgarwal, O P Singh & R J Oosterbaan), Central SoilSalinity Research Institute, Karnal and CCS HaryanaAgricultural University, Hisar, pp 36-49.12. Kapoor, A S (2001) Biodrainage – A biologicaloption for controlling waterlogging and salinity.New Delhi, Tata McGraw-Hill Publishing Co. Ltd.2001, ISBN 9 78 007 0402317.13. Heuperman, A F (1995) Salt and waterdynamics beneath a tree plantation growing on ashallow water table. Internal Report Department of

Agriculture, Energy and Minerals, Victoria, TaturaCentre, Institute of Sustainable Irrigated Agriculture.14. Lafroy, E C & Stirzaker, R J (1999)Agroforestry for water management in thecropping zone of southern Australia. AgroforestrySystems, 45, 277-302. 15. RIRDC (1999) The ways trees use water. Waterand salinity issues in Agroforestry No. 5, PublicationNo. 99/37, Wembley, Rural Industries Research andDevelopment Corporation (RIRDC), pp 1-78.16. Crosbie, R S, Wilson B, Hughes, J D,McCulloch, C & King, W M (2008) A comparisonof the water use of tree belts and pasture inrecharge and discharge zones in a saline catchmentin the central west of NSW, Australia. AgriculturalWater Management, 95, 211-23.17. Hatton, T J & Nulsen, R A (1999) Towardsachieving functional ecosystem mimicry withrespect to water cycling to southern Australianagriculture. Agroforestry Systems, 45, 1-3. 18. Zhao, C, Wang, Y, Song, Y & Li, B ( 2004)Biological drainage characteristics of alkalizeddesert soils in north-western China. Journal of AridEnvironments, 56, 1-9.19. Angrish, R , Toky, O P & Datta, K S ( 2006)Biological water management: Biodrainage. CurrentScience, 90: 897.20. Ram, J, Garg, V K, Toky, O P, Minhas, P S,Tomar, O S, Dagar, J C & Kamra, S K (2007)Biodrainage potential of Eucalyptus tereticornis forreclamation of shallow water table areas in north-west India. Agroforestry Systems, 69, 147-65.21. Toky, O P, Angrish, R, Datta, K S, Arora, V,Rani, C, Vasudevan, P & Harris, P J C (2011)Biodrainage for preventing waterlogging andconcomitant wood yields in arid agro-ecosystems inNorth-Western India. Journal of Scientific andIndustrial Research, 70: 639-644.22. Gafni, A & Zohar, Y (2001) Sodicity,conventional drainage and biodrainage in Isreal.Australian Journal of Soil Research, 39, 1269-78.23. Chaudhary, M R, Chaudhary, M A & Subhani,K M (2000) Biological control of waterlogging andimpact on soil and environment. In: ProceedingsEighth ICID International Drainage Workshop, NewDelhi. Vol. II,pp 209-22.24. Khamzina, A, Lamers, J P A, Martius, C,Worbes, M & Vlek, P L G (2006) Potential of ninemultipurpose tree species to reduce salinegroundwater tables in the lower Amu Darya Riverregion of Uzbekistan. Agroforestery Systems, 68,151-56.25. Khamzina, A. Lamers, J P A, Worbes, M,Botman, E, & Vlek, P L G (2006) Assessing thepotential of trees for afforestation of degradedlandscapes in the Aral Sea Basin of Uzbekistan.Agroforestry Systems, 66, 129-41.26. Archibald, R D, Harper, R J, Fox, J E D &Silberstein, R P. (2006) Tree performance and root zone salt accumulation in three dry landAustralian plantations. Agroforestry Systems, 66,191-204.27. Ram, J (2009) Biodrainage potential ofEucalyptus for the reclamation of water logged areas. Ph D. Thesis, Nanital India, KumaonUniversity.28. Rani, C. Toky, O P, Datta, K S, Kumar, M,Arora, V, Madaan, S, Sharma, P K. & Angrish, R(2010) Physiological behaviour vis-à-viswaterlogging conditions in some tree species.Indian Journal of Plant Physiology, 15, 44-53. 29. Anon 2003. Biodrainage: status in India andother countries. New Delhi, Indian NationalCommittee on Irrigation and Drainage (INCID), pp1-47.30. Angrish, R, Toky, O P & Patel, R K (2008)Biodrainage: potential and practice. National LevelTraining Program, Training Report. CommandArea Development and Water Management(CADWM) wing, Ministry of Water Resources,Government of India, New Delhi, 1-6 February,2008, pp 1-5.



Scaling Up Technology AdoptionAmong Poor Farmers:

the Case of SeedDr Sara Boettiger

University of California, Berkeley Syngenta Foundation for Sustainable Agriculture

[email protected] development programmes have a long history of working toward the adoption of improved crop cultivarsamong poor farmers. The potential food security impacts of adopting improved cultivars are well documented and criticaladvances have been delivered by public plant breeding research over the decades. Adoption rates, however, still remain lowand there is increasing interest in understanding why so few improved cultivars have been adopted at scale, by largenumbers of farmers. The international development community has begun to explore these issues of scaling up in greaterdepth, considering how to successfully expand policies, programmes, or projects to impact many more people. This papercontributes to a growing literature that builds on scholarship in technology adoption theory but focuses particularly on howto scale up technology adoption, moving from hundreds of farmers to reach millions. The paper presents a simpleframework for analyzing the wide range of challenges inherent in scaling up the adoption of a product or service amonglow-income communities in developing and emerging market countries. The potential use of the framework is illustratedwith a discussion of the challenges present in seed systems when seeking to scale the adoption of improved cultivars.

GlossaryBottom of the Pyramid: socio-econom-ic description of the 4-5 billion peoplewho live primarily in developing andemerging market countries and whoare “unserved or underserved by thelarge organized private sector (1).” Theterm also defines the field of businessstrategy focusing on reaching this pop-ulation as a market for products andservices. Bottom of the Pyramid ismostly associated with the work of C KPrahalad and Stuart Hart (2).

Cultivar: form of a plant species orcrop plant in cultivation (excludingnaturally occurring varieties) whichneeds to be propagated either by seedor vegetatively. The word 'variety' issometimes used to describe theseforms, particularly in the technologyadoption literature where there termslike ‘modern variety’ and ‘high-yieldingvariety’ are widely used. Impact investing: practice of investingin companies, NGOs, programs, proj-ects, and funds with the explicit inten-

tion of generating both financialreturns on the investment as well associal and environmental impacts.Shared value: business conceptdescribing how a company’s strategyto address social and environmentalproblems can simultaneously add valueto the company. The shared valueframework identifies opportunities forcompanies, civil society organizations,and governments to employ of market-based competition to address socialand environmental issues (3).

1. Introduction

Agricultural developmentprogrammes have a long historyof working toward the wide-

spread adoption of improved cropcultivars among poor farmers indeveloping and emerging marketcountries.

Empirical evidence finds that theadoption of improved cultivarssignificantly impacts a wide range ofhousehold poverty indicators.Particularly in staple crops, manystudies have examined the relationshipbetween poverty reduction and the useof improved cultivars (4, 5).

Promoting the adoption ofhigh-yielding cultivars, as well as thosewith traits conferring resistance toabiotic and biotic stresses, remains a

central goal for agriculturaldevelopment policies, programmesand projects.

Despite demonstrated benefits anddecades of innovative plant breedingto create cultivars that serve the needsof the poor, those cultivars that haveachieved widespread adoption are fewand far between. The most well-knownsuccesses are the wheat and ricecultivars of the Green Revolution. Morerecently, the Pan African Bean ResearchAlliance (PABRA) has reached 18.3million households in a decade withgood quality bean seed (6)1. InBangladesh and India the floodtolerance gene (SUB1A) has beenintroduced into a range of ‘mega-rice’cultivars and there is good reason toexpect scaling up (7).

Maize, more than other crops, often

exhibits higher adoption rates andThailand’s Suwan-1 is an excellentexample of widespread adoption (8).In some African countries, adoption ofmodern maize cultivars has soared. InKenya an estimated 70% of land undermaize is planted to improved cultivars(9). There are many more technologyadoption success stories that have notbeen documented, but there are alsomany failures where improved cultivarshave not been adopted as broadly aswe hoped, or there has been lowadoption, particularly in food insecureregions, where modern cultivars aremost needed.

After decades of innovative plantbreeding and efforts by extensionservices to get better seed to poorfarmers, the lack of adoption isdisconcerting.

1. Discussion of ‘improved cultivars’ or ‘improved varieties’ implicitly limit the discussion to improvements in genetics and not seed quality. In fact,improvements in seed quality, particularly for open pollinated varieties (OPVs), may have larger impacts on successful scaling of adoption. Seed quality isdiscussed in several sections of the paper, but is acknowledged here as an essential component of strategies for scaling up the adoption of improved cultivars.



2010 World Bank data in Tanzaniashowed less than 17% of farminghouseholds were using improved seeds(10). Among a surveyed set ofsorghum farmers in Eastern Ethiopia,only 8% of land was planted tomodern cultivars (11). In Cambodia,modern rice cultivars were planted on41% of rice-growing land, butadoption was concentrated in regionswhere hydrological conditions weremore favorable (12).

Figure 1 shows 2012-2013 figures forthe percentage of maize and wheatland planted under improved cultivarsacross a range of sub-Saharan Africancountries (13).2

Despite poor adoption figures,significant public resources continue tobe invested in research to improvecrops for the global poor, throughorganisations like the CGIARConsortium (for which the annualbudget reached $1 billion in 2013)(14). The large number of cultivarsproduced by the research system thatdo not achieve widespread adoptioncan be seen as an indicator of missedopportunities for increasing theeffectiveness of public investmentsdirected to food security and povertyreduction.., For example 41% of themaize area Ghana was planted underone old and popular open-pollinatedcultivar, Obatanpa.

A further 10% was planted undercultivars released before Obatanpa (i.e.before 1992) and only 1% of maize-growing land was planted to the manyimproved cultivars released since theearly 1990s (15). Evidence of the lackof widespread adoption demandsbetter investigation into themechanisms not just of technologyadoption among the poor, but in thescaling up of adoption.

Defining Successful ScalingTo explore the issues of scaling up theadoption of new cultivars it would beuseful to define specifically whatconstitutes success.

Should we, for instance, view theGhanaian Obatanpa maize cultivar as asuccess? One out of twenty-sevenimproved cultivars released since the1960s took twenty years to reach 41%of the land area (16). Who is to say,however, that this success rate, returnon investment and time frame are notreasonable, given the context in whichthe uptake was achieved? This paperargues for the need to develop a moreprecise definition of scaling up. A gooddefinition, however, must be built on abroader foundation of evidence thancurrently exists. Once we havedocumentation and analysis of agreater number of examples of scale inrecent history, we can begin tounderstand successful scaling and thefactors that contribute to it.

The term ‘scale’ will always be usedby the international developmentcommunity as a general way ofreferencing ‘significant growth.’ Forexample, a working World Bankdefinition of scaling up cited inHartmann and Linn (17) reads:

“Scaling up means expanding,adapting and sustaining successfulpolicies, programmes, or projects indifferent places and over time to reach agreater number of people.”

This definition has many merits. Forinstance, it notes that successful scalingwill require not just expansion, but alsothe means to adapt polices,programmes and projects. It also limitsscale to that which is sustainable overtime. Many examples exist of supply-driven expansion of technologyadoption, where public resources have

been spent on design, development,manufacturing and distribution ofproduct only to see the use of theproduct plummet once the publicsector steps back. Sustainable scaleimplies a more demand-driven scalingthat not only will reach a greaternumber of people but will also delivervalue to them. These are importantdistinctions that distinguish the newliterature on scaling up adoption fromthe old technology adoption andextension services literature.

Underneath the umbrella of thisbroad definition, however, we needcritical analysis of what scale means inthe adoption of technologies amongthe poor, and then with even morespecificity, what defines successfulscaling in an individual class oftechnologies. This paper illustrates theimportance of defining and analyzingscale differently for different classes oftechnologies by examining scaling upthe seed of improved cultivars.

2. Diagnosing Failures toScaleIn addition to a rich body of literaturein economics and internationaldevelopment on technology adoption,new explorations of scaling up relyheavily on business literature.

Much has been written on theintersection between social impact andthe commercial potential within low-income developing country markets.From CK Prahalad’s enthusiasticendorsement of opportunities at the‘bottom of the pyramid’ (18) we havecome to more nuanced views of therole of the private sector in povertyreduction (19). At the same time, inthe last decade, we have seen the riseof impact investing (20), theexponential growth of multinationalsbased in emerging market economies(21), and broad interest in Porter andKramer’s ‘shared value’ model (22).

These and other trends haveproduced a wealth of scholarshipabout market-driven solutions ininternational development, some ofwhich discuss key issues related toscaling up the adoption of agriculturaltechnologies. Common businessmodels for reaching rural markets havebeen explored (23), for example, andthe discipline of rural marketing iscoming into its own, particularly basedon experience in India, but withbroader applications for theinternational development field (24).

Figure 1. Percent of Land Under Maize and Rice Planted With Improved Cultivars.

2. In presenting cultivar adoption data, it is important to note that these data are difficult to collect and often differ considerably across sources. For example,in Ghana (15) 61% of maize land was planted to improved cultivars, considerably more than the 19% estimate in Figure 1 derived from national governmentdata during a similar period.


economics and socialA practical understanding of how to

scale technology adoption demands,however, that we move beyondcommon business models andmarketing strategies. The contributionsfrom business are invaluable, but theymust be combined with rigorousempirical knowledge of technologyadoption, extension models, anddevelopment economics. Additionally,progress in learning how to scale theadoption of technologies among thepoor will require disaggregation; wewill need to consider specific individualclasses of technologies. Scaling the useof vaccines, for instance, requiresentirely different strategies to scalingthe adoption of irrigation pumps.Paying attention to these differencescan critically inform potentialopportunities for the internationaldevelopment community in theirefforts to catalyze scale. In addition toconsidering classes of technologies, it isuseful to disaggregate further bydividing scaling issues into three maincategories.

These categories are derived fromtechnology adoption theory and aresometimes used to diagnose whyadoption failed. Examining scalingissues for a product or service requiresexamination of the technology acrossthese three categories. In order toillustrate how such a simple matrix ofscaling analysis can be used, thissection concludes with an overview ofthese three categories as they relate toscaling the seed of improved cultivars.3Then, Section 3 considers sixfundamental differences in seed as aclass of products and, using the scalinganalysis framework, exploresimplications for scaling up adoption.

Category 1: Value The product did not provide value to alarge number of customers.

Perhaps the greatest failure in scalingthe adoption of technologies acrossany sub-field of internationaldevelopment lies in the fact that weare almost always trying to scale thewrong product. Products ininternational development are toooften developed without attention tothe customers’ needs and desires. Thisis as true in the development of newcultivars as it is for other products.

Among the improved cultivars thatare produced in public plant breedingsystems, there are many documentedmismatches between the value farmersassign to traits and the value plant

breeders do. Formal breedingprogrammes may focus on one trait(e.g. yield) rather than a balance oftraits that are valuable to the farmer. Afarmer’s determination of the value ofnew cultivar might include, forinstance, a balance between yield, thestability of yield, early maturity andperhaps heat tolerance. In addition tovaluing the degree to which thecultivar lends itself to local productionconditions and techniques, a farmer’svaluation also depends on consumertraits that are often overlooked byplant breeding programmes (25).Adoption of sweet potato with highervitamin A, for example, depends onthe cultivar’s taste, ‘mouth-feel’,aroma, and color when fried (26). Thevaluation of traits among farmers isalso diverse and dependent on a widerange of factors. In Uganda, forexample, men valued banana cultivarsthat made better beer and womenvalued those that that had bettercooking quality (27). Public plantbreeding programmes have recognizedand made advances in this area, butmuch more work is needed. Successfulscaling strategies will includesignificantly improving the channelsthrough which farmers’ needs caninform decision-making in public plantbreeding programmes (28).

Another failure in attempts to scaleimproved cultivars relates to theassumption that value for the farmer islimited to the seed’s genetics. In fact,the quality of the seed can be asimportant, or more important to afarmer. Tackling quality issues is a keyto increasing adoption of all improvedcultivars, but it can be especiallyimportant in attempts for openpollinated varieties (OPVs) andvegetatively propagated crops.Availability of high quality seed canmake all the difference in a farmer’sdecision to adopt.

Category 2: Information andKnowledge The spread of information andknowledge related to the product wasinsufficient.

A second major category of failure inscaling the adoption of improvedcultivars lies in the information andknowledge systems that run parallel tothe supply chain. Where marketing,extension and education services donot reach farmers, even good cultivarswill fail to be adopted. Some parts ofthese information and knowledge

systems relate to raising awarenessamong farmers about new cultivars,including demonstrations of the valueof the improved cultivar. Other partsinvolve dissemination of knowledgethat, ultimately, increases the value ofthe cultivar to the farmer. Performanceoften varies dramatically with timing ofplanting, fertilizer use, irrigation andother factors. The gene-environmentinterplay is a pillar of value creation incropping systems, and scaling up anew cultivar depends upon how thesebenefits are communicated to farmers.While there is deserved focus by thoseworking in technology adoption onboth the product and underlyingbusiness model, scaling will fail withoutthis parallel system of information andknowledge.

Category 3: AccessThere were problems in access to theproduct.

The third category, where failuresmay occur relates to a farmer’s accessto the improved cultivar. Typically, thisincludes failures across a wide range ofissues such as distribution networks ofthe seed, which may not bring theproduct to the farmer. Dynamic marketeffects across both formal and informalseed systems may be poorlyunderstood and incorrectly forecasted.The timing of the availability of theseed is sometimes wrong, as farmersoften have a narrow window forplanting. Problems in the supply chainmay cause degradation in the seedwhich reduces quality. Supplies ofessential complementary inputs mayalso fail. Credit is often seen as acomplementary input and also bringsissues of affordability to this category .These are examples of issues whichcan contribute to failure in scalingbecause they inhibit the customer’saccess to the product.

3. Diagnosing Failures inScaling the Adoption ofImproved CultivarsThis section illustrates the importanceof disaggregating technologies intoclasses when considering scalingstrategies and provides examples ofhow to use the diagnostic frameworkdescribed in Section 2. Seed, asproduct, has fundamental differencesin production, distribution, andadoption that set it apart from othertechnologies.

3. Vegetatively propagated crops, such as sweetpotato and cassava, play a central role in poverty reduction. Their scaling issues, however, are significantlydifferent. Scaling the multiplication, transportation, extension, and marketing for vegetatively propagated crops, for instance, deserve separate analysis that liesoutside the remit of this paper.


economics and socialAn understanding of these differencesoffers critical insight for the futurepotential to scale up adoption ofimproved cultivars.

In advanced markets, tools to supportthe seed business have developed overtime to accommodate theidiosyncrasies of the seed market. Fromcredit and insurance instruments, tointellectual property rights, totechnologies facilitating transportation and storage, the seed business indeveloped countries benefits fromenabling laws, policies, technologiesand business practices tailoredparticularly to the industry. Indeveloping countries, however, manyof these tools are the targets ofintervention by the internationaldevelopment community.

These tools can be seen as theenablers of scale. Interventions tocatalyze scale, however, cannot begeneralized across products. Bysummarizing six important differencesin the production, distribution, andadoption of seed, the intention is thatthis paper will remind donors, impactinvestors, policymakers andpractitioners that scaling strategiesdiffer radically across classes ofproducts. In access to finance, supportfor technological innovation, thechampioning of business models,changes to the underlying policyframework and many more areas,different interventions are needed toaddress issues of scale in the adoptionof different types of technologies.

A. Production lags and uncertaindemandUnlike many products, seed productionis characterized by a combination oflong delays and uncertain demand.

The time required for multiplyingseed (from breeder’s seed tofoundation seed to marketed seed)varies from two to as many as sixseasons. This production lag creates amultiplier effect for uncertainty;production problems in any one of theseasons will impact the final volumeavailable for the market. The lagadditionally highlights demandforecasting as a critical element inscaling up the production of seed.Supply decisions today are based onthe forecasted demand for cultivarsand quantities made several yearsbefore.

Also, the production lag hasimplications for scaling that relate toinventory costs. Crops with longproduction times larger stocks of seedkept for longer so more money is tiedup. Business implications for inventory

turnover ratios in the seed industryvary across crops according to bulkrates and perishability. Vegetable seedinventory, of course, is less costly tohold than potato seed inventory. Forindustries with low inventory turnoverratios, scaling strategies may demandinterventions focused on financingneeds accommodating long-term cashflow. When inventories are held overlong periods of time, companies mayreact more strongly to changes in thecost of capital. These, among manyothers, are important clues for theinternational development communityseeking to scale up the production anddistribution of the seed of improvedcultivars. Thoughtful application of theframework for diagnosing failures inscale described in Section 2 of thispaper can provide guidance on policydevelopment, creation of financialtools for seed industry enterprises orprovision of support for better demandforecasting.

B. PerishabilityThis is a second defining characteristicwith critical implications for scaling.

Businesses producing, storing,transporting and delivering perishablegoods are, of course, dependent ongood transportation links and coldstorage facilities. Investments ininfrastructure and storage technologiesmay have especially high returns ifthey reduce quality losses. Productionand distribution of seed also deriveshigh value from access to modernsupply chain technology (liketraceability, sensor, or packagingtechnologies).

Scaling up strategies can also beinformed by the impact perishabilitycan have on pricing strategies for seedproducers. Firstly, financingopportunities for businesses sellingperishable products may differ fromothers. Secondly, production anddistribution of perishable products mayinvolve costs of compliance with wide-ranging regulations.

Market dynamics in perishable goodscan be affected by the implications ofperishability and policies developed tosupport the industry. In developingcountries, for instance, policiesgoverning the export cut flowers mayaffect industry constraints. Seedindustries that are not export-led maynot benefit from similar policies, andthe introduction of these types ofpolicy changes could be a potentialarea for catalyzing scale.

C. Counter-cyclical effect Unlike many products, seed production

suffers from an unusual counter-cyclicaleffect that sometimes sends demandand supply in opposite directions (29).

This occurs because producers andconsumers are affected differently bythe same risks. For example, in a yearwhen maize yields are low seedproduction (for future sales) is reducedand farmers’ have also produced less.Scarcity increases market prices forfarmers selling their maize and theydecide, based on high prices, toincrease the land they plant undermaize for the next season. Demand formaize seed rises at a time when supplyof maize seed has fallen. Conversely, ifthere is a bumper harvest in a goodyear maize floods the market, farmersmay plant less maize for the nextseason, lowering demand in the seedmarket. Those same favorableconditions leave seed producersentering the next year with a higherinventory, but lower market demand.

Understanding this characteristic ofseed as a product should informinterventions for scaling in severalareas. High returns may come frominterventions that enable seedcompanies to have access totechnologies that improve control oftheir production environment, forexample, or access better storagefacilities. This characteristic of seedmarkets also has implications for thefinancing needs of seed producers toensure their long-term survival andgrowth of their enterprises.

D. Responses to disastersA fourth characteristic of seedproduction and distribution relates tohow governments and marketsrespond to disasters.

Seed supply and demand arecritically affected by disasters andsimilarly essential to the recovery. Intimes of disaster and insecurity (forexample, when civil unrest ensues,crops are wiped out by a pest ordisease, or there is a prolongeddrought) farmers may use their seed asgrain, using up stocks that had beensaved for planting in the next season.4

In addition, disasters impact the seedmarket when seed is moved throughnon-market channels to alleviate theimpacts of the disaster. How, whereand over what period of timeemergency seed is distributed,therefore, affect the seed markets.Scaling strategies need to recognizethe dynamics of how nascent seedindustries are impacted by variousresponses to disasters and, wherepossible, use this analysis to informboth emergency relief efforts as well as


economics and socialexplore options for building moreresilience in the seed industry.

E. Information asymmetriesA fifth characteristic of seed as aproduct relates to informationavailability.

It may be difficult to identify the truevalue of the product and therefore, forexample, the seller may have moreinformation than the buyer.

In some products this is relativelyeasily resolved. For example,demonstration of an irrigation pumpor a solar lamp resolves some elementsof the information asymmetry. In otherproducts it is much more difficult. Thevalue of a livestock vaccine, forinstance, may only be demonstrated along time after sale of the productwhen a disease kills non-vaccinatedanimals.

It may take time to demonstrate thevalue of the new cultivar, but it isreasonably easy so to do. Thischaracteristic primarily informs scalingstrategies in category two of thediagnostic tool presented in this paper,focusing on interventions in marketing,extension and education, but it alsoindicates the critical dependencybetween marketing (for example large-scale demonstrations of new cultivars)and production.

Additionally, for some productsbrands become all-important.Strategies for scaling production,distribution, and adoption oftechnologies with informationasymmetries offer opportunities forinnovations to improve branding (forexample packaging or anti-counterfeiting) and marketingstrategies become paramount.

F. Easily reproducible goods andinformal seed systemsThe last characteristic of seedconsidered here relates to itsreproducibility.

Markets for some cultivars of seed aredefined by the fact that they are easilyreproducible. This is not true forhybrids and some crops where viabilityis lost in continued multiplication. Formany crops important for foodsecurity, however, seed for next yearcan be produced from this year’sharvest. Scaling strategies for easilyreproducible goods differfundamentally from those that aredifficult to reproduce. Some policiesbecome commercially important (suchas intellectual property rights) andmarketing strategies fundamentallyshift.

For easily reproducible goods likenon-hybrid cultivars , production,distribution and marketing decisionsare based around the farmer’s decisionto purchase, rather than save, seed. Formany cultivars (including many OPVs),scaling the adoption of seed meansunderstanding that the farmer’sdecision to adopt includesconsideration of factors beyond therelative gain brought by the genetics,including central issues of quality. Forthe farmer, the value that spursadoption might be, for example, seedviability or disease resistance.

For reproducible goods that are notbought each year, there are also timingissues that inform scaling strategies.Forecasting requires assessments ofhow many seasons farmers might saveseed before purchasing new. Otherissues that inform scaling strategiesinclude branding, convenience, quality,price elasticities, aftermarket supportservices and planned timing for theintroduction of the next generation ofimproved cultivars. All of these provideguidance for interventions that canscale up the adoption of the seed ofimproved cultivars.

Perhaps the biggest implication ofthe replicability of seed, though, inscaling up adoption lies in the fact thatscaling strategies must approach bothformal and informal aspects of a seedsystem (30). In the ‘informal’ seedsystem, farmers save seed, cross it withlocal strains or landraces and produceit for themselves and for sale.Interventions by the internationaldevelopment community to scale theadoption of improved cultivars mustaddress the seed system from anintegrated perspective, understandinghow new cultivars flow from formal toinformal systems and how they movewithin the informal system.

ConclusionsThis paper has contributed to agrowing literature on scaling up theadoption of technologies by presentinga simple framework for analysis thatcan be used across a wide variety ofproducts and services to understandcritical issues.

Two elements of disaggregation areadvised. First, potential failures can bediagnosed across three interrelatedcategories. Failures to scale may haveoccurred in the past because: [1] theproduct did not provide value to alarge number of customers; [2] thespread of information and knowledgerelated to the product was insufficient

among customers; [3] there wereproblems in customers’ access to theproduct. Second, there is a need forcaution in adopting generalizedbusiness models and interventions forscale that are common in the currentliterature on scaling. Instead, this paperhas illustrated the benefits ofdisaggregating technologies intoclasses to examine tailored scalingstrategies.

Using the scaling diagnosticframework in this paper to examinethe adoption of seed of improvedcultivars as a class of products, it ispossible to derive practical andactionable issues that deserve theattention of donors, impact investors,policymakers and practitioners. Seedhas intrinsic characteristics that, inadvanced commercial markets, haveled to the development of certainpolicies, financial services andtechnologies that allow the industry tofunction. These same tools can provideguidance for supporting growth in lessadvanced seed systems, ultimatelyimproving the capacity to deliverimproved cultivars to smallholderfarmers.

Scaling up has been a buzzword ininternational development for manyyears, languishing in ambiguity and forthe most part escaping empiricalanalysis. The development of moreprecise definitions of scale ininternational development is necessarybefore real progress can be made, butthis relies on a foundation of detailedanalysis of past successes and failuresin scaling that does not yet exist.

Priority investments can be made bythe international developmentcommunity both in a more rigorousunderstanding of scaling up adoptionas well as at programme-specific levelsusing existing diagnostic frameworks.

References1. Prahalad, CK (2009) The Fortune At the Bottomof the Pyramid, Revised and Updated 5thAnniversary Edition: Eradicating Poverty ThroughProfits. FT Press.2. Hart, S & Prahalad, CK (2002) The Fortune Atthe Bottom of the Pyramid. Strategy+ Business, 26,54-67.3. Porter, M E & Kramer, MR (2011) CreatingShared Value. Harvard business review, 89 (1/2),62-77.4. Kassie, M, Shiferaw, B & Muricho, G (2011)Agricultural technology, crop income, and povertyalleviation in Uganda. World Development, 39 (10)1784-1795. 5. Asfaw, S, Kassie, M, Simtowe, F & Lipper, L(2012) Poverty reduction effects of agriculturaltechnology adoption: A micro-evidence from ruralTanzania. Journal of Development Studies, 48 (9)1288-1305.

4. Authors, however, are divided on the extent to which this occurs.


economics and social6. Sperling, L, Buruchara, R, Rubyogog, JC,Boettiger, S (2013) Getting New Varieties Out toMillions: PABRA & the Power of Partnerships.AgPartnerXChange Case Study.7. Singh, US, Dar, MH, Sudhanshu S, Zaidi, NW,Bari, MA, Mackill, DJ, Collard, BCY, Singh, VN,Singh, JP, Reddy, JN, Singh, RK, Ismail, AM (2013)Field performance, dissemination, impact andtracking of submergence tolerant (Sub1) ricevarieties in South Asia. SABRAO Journal of Breedingand Genetics, 45 (1) 112-131. 8. Le Page, L, Boettiger, S (2013) Lessons forAfrica’s Emerging Seed Sector from Scaling Maizein Thailand. AgPartnerXChange Case Study.9. Mbata, J (2013) Agribusiness Indicators: Kenya.The World Bank.10. Thapa, S (2012) Agribusiness Indicators:Tanzania. The World Bank.11. Cavatassia, R,Lipperb, L & Narlochc, U (2011) Modern varietyadoption and risk management in drought proneareas: insights from the sorghum farmers ofeastern Ethiopia. Agricultural Economics 42 (2011)279–292.12. Wang, H, Pandey, S, Verlarde, O & Hardy B,eds (2012) Patterns of Varietal Adoption andEconomics of Rice Production in Asia. IRRI.13. World Bank (forthcoming) AgribusinessIndicators: Synthesis Report for sub-SaharanAfrica. 14. Stokstad, E (2014) Global research networkraises $1 billion for its centers. Science 3, 343(6166) 17. 15. Ragasa, C, Dankyi, A, Acheampong, P, NimoWiredu, AN, Chapo-to, A, Asamoah, M & Tripp, R

(2013) Patterns of Adoption of Improved MaizeTechnologies in Ghana. IFPRI Working Paper, No36.16. Ibid.17. Hartmann, A & Linn, JF (2008) Scaling up: Aframework and lessons for developmenteffectiveness from literature and practice. In:Wolfensohn Center for Development at Brookings:Working Paper 5, USA, 8. 18. Prahalad, CK (2009) The Fortune At theBottom of the Pyramid, Revised and Updated 5thAnniversary Edition: Eradicating Poverty ThroughProfits. FT Press.19. Simanis, E (2012) Reality Check At the Bottomof the Pyramid. Harvard Business Review 90 (6),120-25.20. Goldman, P (2 December 2013) ImpactInvesting: Harnessing the Power of Business forSocial Good. The Guardian.21. Gaur, Ajai S, Vikas Kumar, and Deeksha Singh(2014) Institutions, Resources, andInternationalization of Emerging Economy Firms.Journal of World Business 49 (1), 12-20.22. Porter, M E & Kramer, MR (2011) CreatingShared Value. Harvard business review, 89 (1/2),62-77.23. Accenture (2013) Masters of rural markets:Profitably selling to India’s rural consumers.www.accenture.com/sitecollectiondocumentsaccessed 22 April 2014.24. Modi, P (2009) Rural Marketing: Its definitionand development perspective. International Journalof Rural Management 5 (1) 91-104. 25. Almekinders, C J M, Louwaars, N P & de

Buijn, G H (1994) Local seed systems and theirimportance for an improved seed supply indeveloping countries. Euphytica, 78, 207-216. 26. Afuape, S O, Nwankwo, I I M, Omodamiro, RM, Echendu, T N C & Toure A (2014) Studies onsome important consumer and processing traitsfor breeding sweet potato for varied end-uses.American Journal of Experimental Agriculture, 4 (1),114-124. 27. Edmeades, S, Smale, M, Renkow, M &Phaneuf, D (2004) EPTD discussion paper no.125: Variety demand within the framework of anagricultural household model with attributes: Thecase of bananas in Uganda. Environment andProtection Technology Division, InternationalFood Policy Research Institute, USA. 28. Boettiger, S & Anthony V (2013) Planning forscale brief #2: Scaling demand. Ag PartnerXChange: http://media.wix.com/ugd/ad2c36_f53dd2f8d7e9472e88235ebd160c1b80.pdf accessed 22 April 2014. 29. Louwaars N.P. & De Boef W.S. 2012.Integrated Seed Sector Development in Africa: aConceptual Framework for Creating CoherenceBetween Practices, Programs, and Policies. Journalof Crop Improvement 26: 39-59.30. Sperling, L, Boettiger, S & Barker, I (2013)Planning for scale brief #3: Integrating seedsystems. Ag Partner Xchange:http://media.wix.com/ugd/ad2c36_b4d1abdff989433092daa54a6e0fbd06.pdf accessed 22 April2014.

An olive farm in Andalucia, Spain © Vibe Images – Fotolia.com



Problems of ‘Scaling up’ new cropcultivars: thoughts of an

agricultural economist on widerissues in this interconnected world


This paper deals with a criticalissue in the uptake of technologyin the developing world.

New technologies are essential toensure the increased production andreduced environmental impactagriculture needs to achieve. Initiationof a new technology often arises fromthe recognition of changes in an areawholly unrelated to the problems of aspecific industry – for example theuptake of IT in farming, marketing andmonitoring outcomes. A currentexample is the wish of some UKfarmers to use drones to improve theprecision of pesticide or fertiliserapplication.

Crop development provides aclassical example. We have ‘new’means of generating new cultivars.They are applicable to secure adiversity of purposes such as pestresistance, drought tolerance,palatability and storage requirements.In all these areas the final test ofsuccess is at the point of consumption

- will the amount bought at the pricesthat exist reward the effort involved indevelopment. For seed the gapbetween the initial decision to seek anew cultivar and its use is extended interms of time and the number of otherbusiness decisions that have to takeplace concurrently if the new materialis to succeed. For example, the abilityof a Supermarket chain to capitalise onthe baseless fears of consumers about anew technology may render all theprevious investment valueless.

The thrust of Dr Boettiger’s paper isthat publicly funded institutions get itwrong and that although successful ingenerating new cultivars these do notpenetrate the market on a scale thatjustifies the resources committed.There is an additional element, in thatsuccess is judged not simply inaggregates but in terms of itsdistributional effect – does it serve theneeds of the poor?

It may be that this is an example ofwhere the development community

puts the cart in front of the horse.Using a model that is over simple butcompelling, poverty results frominsufficient demand for labour. Thus,where labour supply is greater than theamount that can be profitablyemployed people remain without workand depend on entitlements enjoyedeither as members of families and localcommunities or through organisedsocial services.

In reality, an activity that raises realincome anywhere in an economycreates demand for more goods andservices and indirectly for the labourthat produces them. If improved cropsmake agriculture more efficient, itsincome will rise and secondary streamsof demand will emerge. This maycome about even if the new methodsare only directly applicable to thecompetitiveness of relatively richfarmers or businesses. Thus focussingon technologies that are directlyapplicable to the poor may bemisguided.



Smart Metrics and DataManagement Strategies forPublic Private Partnerships

Dr Sara BoettigerUniversity of California, Berkeley

Syngenta Foundation for Sustainable Agriculture

Introduction

Collaborations across public andprivate sectors are needed toaddress the challenges facing

our planet.Increasingly, we are turning to public-

private partnerships (PPPs) to createsocial and environmental changes.Today’s PPPs, though, are far removedfrom those of past decades wheregovernments and companies wouldpartner to build infrastructure orprovide public services. In agriculturaldevelopment, PPPs are foundthroughout the value chain, from inputsupply through to the sustainablesourcing of commodities fromsmallholder farmers. PPPs intelecommunications, banking, and ITare also changing the lives of poorfarmers around the world. Thesepartnerships are becoming morecommon in agricultural development,and they are attracting largerinvestments. Grow Africa, for example,is a US$3.5 billion consortium ofcompanies, public sector organizations,the World Economic Forum, and theAfrican Union, investing in Africanagriculture (2).

The challenges of structuring andmanaging PPPs in agriculturaldevelopment are becoming morefamiliar, but some areas remain

relatively unexplored. Critical gaps inour knowledge relate to the use ofmetrics in PPPs and strategies tomanage data across the public-privateinterface. Questions about what youmeasure, how you measure it and withwhom you share the data areapproached very differently bycompanies and public sectororganizations, and the compromisesreached will have tremendous impacton the course of agriculturaldevelopment.

Why Should We CareAbout Metrics in PPPs?We are all familiar with the old adage,‘you can’t manage what you don’tmeasure.’

Metrics can improve public-privatepartnerships by creating a foundationfor evidence-based decisions to makereal-time changes in operations whenthey are needed. Metrics can improvethe allocation of resources and createincentives that drive behavior in partiesat all levels of the PPP. Improvedmanagement of PPPs through the useof metrics frameworks will lead tomore efficient progress towardagricultural development goals.

In addition to better management ofPPPs, however, metrics are important

for learning. Each partner has thepotential to get better at the craft ofstructuring and managing PPPs, butthose lessons can also be codified forwidespread application through themeasurement of successes and failures.More broadly, we also need evidenceof whether PPPs really are a good wayof realizing social and environmentalimpacts. The champions of PPPs whohail them as an efficient instrument ofdevelopment thus far do not havestrong evidence indicating whetherPPPs really do accomplish publicinterest goals.

Lastly, the management of dataacross the public-private interface isparamount to the future of agriculturaldevelopment. In global business, wehave entered an era where thestrategic use of data is an increasinglyimportant determinant of success (3).Companies with the tools to collect,analyze and create businessopportunities from data are at acompetitive advantage. The powerfulnew uses of data are poised to alsorevolutionize internationaldevelopment.

As it becomes more common forPPPs to generate data, there is a needfor strategic data management toensure these valuable resourcescontinue to support public interestgoals. PPPs may also develop with the

GlossaryImpact investing: The practice ofinvesting in companies, NGOs,programs, projects, and funds with theexplicit intention of generating bothfinancial returns on the investment aswell as social and environmentalimpacts.Private sector: For the purpose of thispaper, the private sector consists oforganizations with private interestgoals (for-profit) rather than publicinterest goals. It is recognized that thelines between public and privatesectors are not definitive. There are, for

example, many hybrid entities thathave elements of both public andprivate interest goals.Public-private partnership (PPP): Thedefinition of this term varies widelyand there is continuing debate aboutwhat constitutes a public-privatepartnership. In this paper, the term isused to describe a collaborationbetween public and private sectorentities in which partners engage inthe activities of the partnership,sharing in the costs, benefits, and risks(1). A distinction is drawn betweenpartners engaged in activities andentities whose sole purpose is

financing; the latter is not considered apartner in a PPP. An NGO’s public-interest project with funding from acompany, for example, is notconsidered a public-privatepartnership.Public sector: This paper uses the termpublic sector to describe anorganization with a public interestmandate, including: universities,foundations, aid agencies, internationalorganizations, NGOs and others. Theterm is used to distinguish thefunctional mandate of an organization,rather than its legal structure.


economics and socialpurpose of accessing sources of dataand analytical tools. We have seen thisfor many years already in plantgenomics PPPs (4). Either way, dataissues are likely to be at the core ofmore and more PPPs in agriculture.

Practical Difficulties inMetrics and DataManagement Strategies Despite the value of good metrics anddata management strategies, thosewho have worked to develop PPPsknow how difficult it can be to reachagreement.

There are many differences in howpublic and private partners approachmetrics and the use of data in PPPs.Private partners in a PPP have concernsthat affect confidentiality of themanagement data and what tomeasure. Cost concerns are differentbetween public and private partners,as are time frames. A public sectorpartner may be familiar with after-the-fact, expensive and in-depthmonitoring and evaluation frameworksfound in the academic world.Companies, on the other hand, mayinsist on real-time data and weigh thecost of obtaining data against thevalue they deliver. These are only a fewexamples in a panoply of differences inhow public and private sectorsapproach measurement and datamanagement strategies.

Also, any previous commitments thepartners have to measurementstandards need to be accommodated.These may come directly fromorganizations like the Global ReportingInstitute, or the Global ImpactInvesting Network’s IRIS or others.Donors or impact investors funding aPPP sometimes attach inflexible metricsframeworks to their investments.Previous commitments may also berooted in a belief in the value of onetype of tool, such as randomizedcontrol trials, or they may derive frompartner’s historical commitment to aparticular measure.

Creating a metrics strategy in a PPPcan be further hindered by a mismatchin the skills of the people engaged.Legal and management staff chargedwith setting up a PPP may not be theright people to craft a creative metricsand data management strategy thatincludes institutional commitments,heeds organizational constraints,complies with intellectual propertyrights policies, acknowledges capacitydifferences, supports partners’ goalsand other factors. Bringing in expertisefrom outside is a possibility. Thecommon decision made byorganizations considering whether toinvest in training staff or hire-inexternal expertise exists here. As apartner engages in more partnerships,it may become worthwhile to developin-house expertise, but newer entrantsand smaller partners will seekconsultants with external expertise.Field experts in monitoring andevaluation or metrics will bring awealth of sector-specific knowledge.They may, however, lack appreciationfor the nuances of the public-privateinterface and, especially, be unfamiliarwith newer models of dual use in datamanagement where partners seek tocommoditize data while also ‘do good’with it.

A Role for DonorsGiven the challenges faced by PPPs asthey try to implement smart metricsand data management strategies,donors in agricultural developmenthave an important leadership role toplay.

Many governments, foundations andimpact investors finance PPPs with thebelief that that they are critical toolsfor accomplishing public interest socialand environmental goals, and thatPPPs provide prudent investments forscarce development funds. Theseclaims, for the most part, have yet tobe corroborated. Donors can take thelead in creating better metrics to assessthe impact of PPPs in agriculturaldevelopment.

The role of donors is broader,though, than their responsibility tomeasure the impact of PPPs. They havea vested interest in improving thequality of PPPs and supporting theirsuccess. For this, donors need to beactive in promoting best practices inthe aspects of metrics strategies thatimprove real-time operations ofpartnerships and create incentiveswithin partnerships. For some donorsthis leadership role will be challenging,requiring the ability to step away fromtheir more public-sector historical useof metrics and embrace the ways inwhich modern companies collect anduse data. Other donors are more at thecutting edge of measurement issues atthe public-private interface.

Perhaps most importantly, donorsneed understand new models of datamanagement for public-privateprojects. In agribusiness, as elsewhere,companies are using data in new waysand on an unprecedented scale.Without leadership from donors, publicsector partners entering into PPPs maymake critical mistakes in datamanagement strategies with far-reaching implications.

Regardless of how they choose totake the lead, the call to action is clear.Donors have new responsibilities tosupport better metrics and datameasurement strategies in theagricultural development PPPs theyfund.

References1. Spielman, D J, Hartwich, F & Grebmer, K(2010) Public–private Partnerships andDeveloping?country Agriculture: Evidence Fromthe International Agricultural Research System.Public Administration and Development 30 (4), 261-76.2. Juma, C (2013) Development: Starved forsolutions. Nature, 500, 148-149.3. Manyika, J, Chui, M et al. (2011) Big Data: TheNext Frontier for Innovation, Competition, andProductivity. McKinsey Global Institute Report.4. Boettiger, S, Anthony, V, Booker, K, Starbuck, C(2012) Public-Private Partnerships in Plant Genomicsfor Global Food Security. IDRC web:http://www.idrc.ca/EN/Documents/Public-Private-Partnerships-in-Plant-Genomics-for-Global-Food-Security.pdf Accessed 27 April 2014.


comments

Sir

I was surprised to see the article “Whatrole for GM crops in worldagriculture?” in the summer 2013edition of World Agriculture.

It is good to present a range of viewson important topics, even if membersof the editorial board do not personallyagree with them. However, Dr Wallacedoes little to address the potentialcontribution of crop biotechnology tofarming in developing countries (as thesummary suggests) but uses the bulkof the article to rehearse the well-wornarguments of activists abouthypothetical safety issues andcorporate control of the food chain.

The author suggests that, becauseearly optimistic statements about thepotential of genetic modification toproduce salt-tolerant and nitrogen-

fixing crops have not yet been realised,it should effectively be written offbecause of the greater advances madethrough conventional breeding. Watshe fails to realise is that there is nosilver bullet offered by any onetechnique, and that researchers (andthe funders of research) should havean open mind about the potentialbenefits of all available technologies.

Readers will be aware of the latestwork from Professor Cocking’s groupat the University of Nottingham on thediscovery of nitrogen-fixing bacteriawhich are capable of colonising allmajor crop plants. This is a verysignificant advance, but the fact that ithas been achieved by non-GM meansis no argument for ignoring the veryreal benefits biotechnology can bringwhen such solutions do not present

themselves. Given the major additionalhurdles to be overcome to get a newtransgenic event approved, companieswill not continue to invest in the area ifthey could achieve as much in otherways.

While I applaud the editorial board ofWA for being willing to publish a widerange of views, I think that in this caseit was not helpful to print an articlewhich attacks the very concept of GMcrops. Criticism is to be welcomedwhen a good case can be made, butdoctrinaire opposition is anothermatter.

Martin LivermoreScientific AllianceSt John's Innovation CentreCowley RoadCambridge CB4 OWSTel: +44 1223 421

A response to the article “What rolefor GM crops in world agriculture?”Letter to the Editor

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