U N I V E R S I T Y O F A A R H U S Faculty of Agricultural Sciences The role of soil science in optimization of soil resource management Per Schjønning University of Aarhus Faculty of Agricultural Sciences NJF Congress June 27-29 2007, Copenhagen
Dec 26, 2015
U N I V E R S I T Y O F A A R H U S
Faculty of Agricultural Sciences
The role of soil sciencein optimization of
soil resource management
Per Schjønning
University of AarhusFaculty of Agricultural Sciences
NJF CongressJune 27-29 2007, Copenhagen
Plan for presentation
• Values in science and the Soil Quality concept
• Risk Assessment (Soil Framework Directive)
• Tools for analysing and regulating the system
Change in agricultural research
-> 1980
• Productivity• Efficiency• Breeding of new varieties• Pest control• Fertilization
1980 ->
• Effects on the environment• Biological diversity• Animal welfare• Soil degradation• Food quality
The sustainability issue
Focus areas
Change in agricultural research
Science interaction with society
Interested parties
-> 1980
• Farmers
1980 ->
• Farmers• Politicians (national and EU)• Consumers• NGO’s (the general public)
Change in agricultural research
-> 1980
• Organic manures• Light traffic• Low-energy tillage• Diversified crop rotations
1980 ->
• Mineral fertilizers• Heavy traffic• High energy input in tillage• Monocultures
Soils at stress
Soilmanagement
The sustain
ability is
sue
Science interaction with society
Soils at stress
The modern soil scientist at work
Focus areas
Interested parties
Actual managem
ent
The SSSA SQ definition
Soil quality is the capacity of a specific kind of soilto function, within natural or managed ecosystemboundaries, to sustain plant and animal productivity,maintain or enhance water and air quality,and support human health and habitation
(Agronomy News, June 1995)
Soil quality
Minimum Data Set (MDS)
Analogue with human medicineE.g. blood pressure, body temperature etc.
(Larson & Pierce, 1991)
Potential indicators in MDS
Nutrient availabilityTotal organic CLabile organic CParticle sizePlant-available water capacitySoil structureSoil strengthMaximum rooting depthpHElectrical conductivity
Scoring(indexing 0-1)of some selectedsoil quality indicators
Andrews et al. (2002)
Soil Function Soil Function Soil Function
Management Goals
Minimum Data Set
Indicator Indicator Indicator IndicatorIndicator
score score score score score
Index Value
Soil Function Soil Function Soil Function
Management Goals
Minimum Data Set
Indicator Indicator Indicator IndicatorIndicator
score score score score score
Index Value
Soil Function Soil Function Soil Function
Management Goals
Minimum Data Set
Indicator Indicator Indicator IndicatorIndicator
score score score score score
Index Value Karlen et al. (2004)
Caution!
Indexing is a very effective wayof hiding information!
Values in science
”No subsoil compaction is the criterion for sustainability regarding traffic in the field”
Medvedev & Cybulko (1995); van den Akker & Schjønning (2004)
”Subsoil compaction should not create physical conditions that would reduce the saturated water conductivity beyond 10 cm d-1”
Horn (2006); Lebert et al. (2007)
Fact:Several investigations have shown that compaction of soil below ~50 cm depth is persistent for decades or centuries
Two different statements by soil scientists:
Soil quality is how wellsoil doeswhat we want it to do
The scientist (the subject) is part of the system (object) studied
Systemic science
Alrøe & Kristensen (2002)
Reflexive objectivity
The ability to perform sciencewith full awarenessof the values in play
Based on Alrøe and Kristensen (2002)
Reflexive objective- some implications
• Beware of the overall purpose of your research
• Present the results together with your own priorities
• Identify potential precautionary actions,- but present them separately
Plan for presentation
• Values in science and the Soil Quality concept
• Risk Assessment (Soil Framework Directive)
• Tools for analysing and regulating the system
Resistance = capacity to resist change
Resilience = capacity to return to pre-stressed situation
Stability of soilproperties and functions
EU Soil Framework Directive
Five threats to soil quality• Erosion• Organic matter decline• Compaction• Salinization• Landslides
Three major commitments (at the national level)• Identify risk areas• Set up risk reduction targets • Programme of measures for reaching those targets
Extract from the EU Soil Framework Directive(COM(2006) 232 final)
Risk Assessment
Two EU projects preparing the risk assessment
• ENVASSO• RAMSOIL
Risk Assessment
The politician: Is this biological system at risk?
The scientist: Let’s do a lot of measurements on the system to find out
! ? !
Risk Assessment
Disturbingagent
(management/climate)
Soil
Risk Assessment
”A process intended to calculate orestimate the risk to a given target organism, system or sub(population), including the identification of attendant uncertainties, following exposure to a particular agent, taking into account the inherent characteristics ofthe agent of concern as well asthe characteristics of the specific target system”
OECD (2003)
Askov-trial(110 years)
UNF NPK FYM
1.07 1.15 1.30
Case-study(cash crop<>forage
crop)
Cash crop Forage crop
1.45 1.97
Tilth class:
AcceptablePoor
Organic C in soil,- what is the critical threshold? g C 100 g-1 soil
(Munkholm et al. 2002;Schjønning et al. 2002)
Threshold ~1.1?
Threshold ~1.6?
Indicatorthreshold
(soil type 1)
Indicatorthreshold
(soil type 2)
Indicatorthreshold
(soil type 3)
Indicatorthreshold
(soil type 4)
Indicatorthreshold
(universal [indexed])
Soil indicator thresholds
Management thresholds
Managementthreshold
(non-universal)
Soilfunction
(soil type 1)
Soilfunction
(soil type 2)
Soilfunction
(soil type 3)
Soilfunction
(soil type 4)
Knowledge ofsoil/management
interactionFor soil organic matter, a management threshold may be e.g. some characteristic of the crop frequency
Plan for presentation
• Values in science and the Soil Quality concept
• Risk Assessment (Soil Framework Directive)
• Tools for analysing and regulating the system
Researcher
NGO-representative
Governmentofficer
Farmer / consultant
The scientistin a modern network society
Diagnosis / prognosis
Is the system sustainable?
Proces control in agriculture”DADD”
NB: Explicit definition of sustainability!
Description of the system
Management details(soil, crops etc)
Analysis of the system
Research resultsGeneral knowledge
Data from monitoring (indicators)Models
Decision on the most effective response
(control)
Researcher
NGO-representative
Governmentofficer
Farmer / consultant
The scientistin a modern network society
Research chains
Bouma, 2001
Large scale
Small scale
Mechanistic
Empirical
QuantitativeQualitative
Johan Bouma (1997) about traditional agricultural research: ”Too many answers were generated for questions that were not raised, while no adequate answers were provided for some acute problems”
Mec
han
isti
cE
mp
iric
al
Qualitative Quantitative
The soil compaction problemResearch topics and research chains
Yield response,drainage
Soil-tyreinteractions
(stress distribution)
Trafficsystems
Stresstransmission
Soil strength;stress-strain
relations
Strain (deformation)effects on soil functions
Researcher
NGO-representative
Governmentofficer
Farmer / consultant
The scientistin a modern network society
The DPSIR concept
Driving forces
Pressures
State
Impact
Responses
The DPSIR concept- exemplified for the soil compaction problem
Driving forces
Pressures
Status
<Yield
More fertilizer
Driving forces
Pressures
Densesoil
<Yield, >Erosion
Subsoiling
The DPSIR concept- exemplified for the soil compaction problem
Driving forces
Size of machinery, tyre
typesDense
soil
<Yield, >Erosion
More axles, better tyres
The DPSIR concept- exemplified for the soil compaction problem
Economy, profitability
Size of machinery, tyre
typesDense
soil
<Yield, >Erosion
Market regulation
(economics)
The DPSIR concept- exemplified for the soil compaction problem
Drivingforces
Size of machinery, tyre
typesDense
soil
<Yield, >Erosion
Regulation(e.g. EU SFD)
The DPSIR concept- exemplified for the soil compaction problem
Soil function
Stability - resistance - resilience
Thresholds - soil indicator - management
But not indexed!
Reflexive objectivity
Reflexive objectivity
The DPSIR concept Research chains
Risk assessment• Hazard identification• Hazard characterization• Exposure assessment• Risk characterization