Lucerne for pasture and fodder...5 It is a reliable perennial, capable of producing green feed in most seasons subject to soil moisture and temperature, and often when other pastures

AGFACTSAGFACTSAGFACTS

Agdex 121/13Order no. P2.2.25

www.agric.nsw.gov.au

Agfact P2.2.25, third edition 2003W. McDonald, Technical Specialist (Pastures),TamworthA.Nikandrow, Senior Plant Pathologist, OrangeA. Bishop, Senior Research Scientist, GosfordM. Lattimore, District Agronomist, YancoP. Gardner, Agronomist (Seed Production),DubboR. Williams, Research Agronomist, TamworthL. Hyson, formerly Technical Assistant(Irrigation), Tamworth

Lucerne forpasture andfodder

Order no. P2.2.25 Agdex 121/13

2

Contents Page

Summary 3Introduction 3Uses 4Special features 4Production advantages and nutritive value 5Distribution and climatic limitations 8Soil requirements 8Varieties 9Establishment 11Companion crops 13Seeding rate 14Inoculation and lime pelleting 15Establishing lucerne on acid soils 16Species to grow with lucerne 16Nutrition and fertiliser 17Grazing management 21Livestock health on lucerne 24Haymaking 25Making silage 31Renovation 32Terminating the lucerne phase 32Irrigation 33Salinity 37Growing lucerne for seed 38Weed control 39Pests and diseases 40References and further reading 52

DISCLAIMER

The information contained in this publication is based on knowledge and understanding at the time ofwriting (December 2002). However, because of advances in knowledge, users are reminded of the need toensure that information upon which they rely is up to date and to check currency of the information withthe appropriate officer of New South Wales Department of Agriculture or the user’s independent adviser.

Recognising that some of the information is provided by third parties, the State of NSW, the author and thepublisher take no responsibility for the accuracy, currency, reliability and correctness of any informationincluded in the document provided by third parties.

Warnings/Cautions:Livestock health disordersPasture improvement may be associated with an increase in the incidence of certain livestock healthdisorders. Livestock and production losses from some disorders are possible. Management may need to bemodified to minimise risk. Consult your veterinarian or adviser when planning pasture improvement.

Native vegetationThe Native Vegetation Conservation Act 1997 may regulate some pasture improvement practices whereexisting pasture contains native species. Inquire through your office of the Department of Land and WaterConservation for further details.

ALWAYS READ THE LABEL

Users of agricultural or veterinary chemical products must always read the label and any permit, beforeusing the product, and strictly comply with the directions on the label and the conditions of any permit.Users are not absolved from compliance with the directions on the label or the conditions of the permit byreason of any statement made or not made in this publication.

Lucerne flower

M L

ATT

IMO

RE

Cover:Left: Hay cut in the Narrandera district(Photo: G Johnson); Right: Sheep on lucerne atTamworth (Photo: NSW Agriculture)

3

Figure 1. Area of lucerne in NSW (Source: AustralianBureau of Statistics 1922–97, estimates 1997–2000)

SUMMARY

Lucerne is a temperate perennial legume capableof producing high quality forage throughout theyear, but its main production period falls in thespring, summer and early autumn.

Lucerne is the third most widely grown pasturelegume in New South Wales (after subterraneanand white clover), and is considered the onlyreliable pasture legume for a large area of theState.

It’s wide range of uses, and high adaptability tothe climate and soils of NSW makes it an integralpart of the State’s agriculture, especially in thewheat–sheep zone.

The area of lucerne declined during the 1970’s,coinciding with an increase in cropping and thearrival of the destructive exotic lucerne aphids.The use of improved varieties has largelyovercome the aphid problem and has brought theadded benefit of resistance to a range of diseasespreviously restricting production, as well asbenefits in seasonal production and overallproductivity.

Lucerne is a reliable plant for use as extensivepasture, intensive forage, and fodder underirrigation.

Growing lucerne produces many benefits:

� Economic gains stem from both improvedlivestock production and increases in theyield and quality of subsequent cereal crops.Savings in application of nitrogenousfertilisers to subsequent crops and benefits inthe area of weed control are also significant.

� Environmental benefits can be verysignificant. The ability of lucerne to lowerhigh watertables, thereby reducing thepotential effects of salinity, is outstanding.Lucerne also assists in improving soilstructure and controlling erosion, especiallyas a part of a pasture mixture with grassspecies. Lucerne has also been usedeffectively as a fire-break, and because of itsdrought tolerance it enhances the stability ofpasture swards.

Haymaking techniques have improvedsubstantially in recent years. Better machinery,cubing, recompression of bales and the use ofpreservatives now make lucerne an even moreuseful and profitable species to grow.

The main problems restricting lucerne productionare soil type and soil pH, susceptibility to heavyand continuous grazing, loss of livestockproduction through bloat, diseases such ascommon crown rot, and the need for inexpensiveweed control.

Current breeding programs are investigating bloatprevention, grazing tolerance, improved nutrientcontent, disease resistance and better adaptationto specific situations (for example, croppingrotations). Herbicides are continually being testedin an effort to reduce the costs of establishmentand production.

INTRODUCTION

Lucerne (Medicago sativa L.) is a high-producing,nutritious legume that is well adapted to a rangeof climates throughout the world.

Originating in the Middle East, it was introducedinto NSW before 1806, and in time spreadthroughout Australia. It grows in conditionsranging from tropical to temperate and willtolerate frosty winters.

The area of pure lucerne in NSW in 1996 (fromAustralian Bureau of Statistics data; 1996 was thelast year in which statistics were recorded forsome issues relating to lucerne production) wasapproximately 280 000 ha (64 per cent of thetotal area sown in Australia). Of this area, anunusually high area (40 per cent) was cut forhay in that year (Figure 1); the majority wasproduced under irrigation, with the remainderunder rain-fed conditions. It is also sown inpasture mixtures (almost all rain-fed), with528 000 ha existing in 1996. A study by Hill andDonald (1996), suggested that NSW was also theState with the greatest potential for furtherincreases in area of lucerne.

0

200

400

600

800

1000

1920 1930 1940 1950 1960 1970 1980 1990 2000

Thou

sand

hec

tare

s

Total area

Green feed area

Hay area

4

The area sown has varied markedly over the pasttwenty years. During the 1970s the area declinedbecause of the trend to move away from pasturestowards cropping. This situation was exacerbatedby the arrival of the spotted alfalfa aphid in 1977.However, sowing of pure lucerne stands hasincreased steadily over recent years owing toconfidence in new aphid-resistant varieties andincreased interest in livestock production. Thearea of lucerne increased further following thedrought years of the early 1990, as the benefits oflucerne as a drought-tolerant plant werehighlighted. Approximately 30 per cent of thepure lucerne area and 30 per cent of the mixedlucerne area is resown annually. In 1996, this wasequivalent to approximately 83 000 ha of purelucerne and 153 000 ha in mixed pastures.Although the largest areas of lucerne are grown inthe cropping belt, the heaviest concentrationsoccur along river valleys.

USES

Lucerne may be grown as a pasture for year-round and special-purpose grazing, or for hay,silage, green fodder, pellets, cubes, seedproduction, sprouts or protein fractionation.

The main use of lucerne in NSW is as a pasturefor year-round grazing and in crop rotations.Grown either alone or with other species, itprovides good feed in all seasons, provided thereis adequate soil moisture.

Whether grazed or used as fodder, lucerne has ahigh nutritive value relative to other fodder atcomparable growth stages: it is high in protein,metabolisable energy, vitamins and minerals, allof which can increase animal production. Whensown as a pasture phase, it can improve soilnitrogen levels and control crop weeds such aswild oats and some summer-growing weeds.

Lucerne can also be used as a special-purposepasture to finish prime lambs and beef cattle inlate spring and summer, when other pasturespecies are low in protein and may havedried off.

The traditional role of lucerne in NSW is as a haycrop, with at least 406 000 t produced annually(1998–99). This represents 44 per cent of thelucerne hay produced in Australia. Production isusually on alluvial river flats and under irrigation,although opportunity hay is also made from dry-land grazing stands. Lucerne often gives higher

yields than other pastures and can be made intofirst-class fodder (especially as hay and chaff).Hay yields from well managed irrigated stands arein the range of 10–22 t/ha, with best yields in theorder of 25–27 t/ha under exceptionalmanagement and growing conditions.

Export of lucerne products (hay, cubes and meal)from NSW has declined in recent years, withexport from the southern States increasing. Anumber of factors appear to favour this trend,including freight advantages, more favourableharvesting conditions, domestic demand andcomparatively attractive domestic prices. The totalexport market for lucerne products was 150 000tonnes in 1998–99, most destined for Japan. NSWexports in that year were less than 5 per cent ofthis tonnage.

Normally, lucerne is made into silage only if it isweedy or when the weather is unfavourable forhaymaking. Lucerne can also be harvested andfed fresh to stock as highly nutritious green chop– particularly in feedlots and dairies – but feedingto cattle must be restricted to avoid bloat.

Specialist seed growers produce lucerne seedmost efficiently, although some isopportunistically harvested, usually from grazingstands. A small proportion of the seed crop ismarketed as alfalfa sprouts for humanconsumption.

As well as having a role as a legume ley incropping rotations, lucerne also is used inconjunction with cotton production. Although itsuse is not widespread, a small area of a cottonfield is sown to a strip, border or block oflucerne and managed as it would be for irrigatedproduction. The lucerne strips effectively act asan attractant for some pests and beneficialinsects contributing to integrated pest controlprograms. Associated dryland areas are alsooccasionally sown to lucerne for the samereason as well as to reduce the cost of weedcontrol.

Potential also exists for protein fractionation,which provides products for specialised livestockfeeding and pharmaceutical industries, and forother industrial uses in the area of energy andbiodegradable ‘plastics’.

SPECIAL FEATURES

Lucerne has a number of features that make itextraordinarily versatile and adaptable.

5

It is a reliable perennial, capable of producinggreen feed in most seasons subject to soilmoisture and temperature, and often when otherpastures are dormant. It can respond to rain inany season, so that the risk of extended feedshortages is greatly reduced and the opportunityfor out-of-season production increased.

In suitable soils lucerne develops a long taproot,enabling it to draw on deep soil moisture. Thus, itcan continue to grow long after surface moistureis depleted, shallow-rooted plants have wilted,and many annuals have died, giving it a strongcompetitive advantage over many weeds.

The taproot stores energy that is used toaccelerate the production of new shoots.Established lucerne grows much faster afterautumn rain than germinating annual species,providing quicker autumn feed and allowingmore feed to build up before the onset of winter.This can offset the need for hand feeding.

After the plant is grazed or cut, fresh shootsgrow either from the remaining green stems orfrom buds in the crown (the top part of thetaproot). Heavy grazing damages new buds, butin most varieties these are rapidly replaced. Thecapacity of lucerne to produce buds and shootsfrom the crown at or below the soil surfacepromotes its survival, but continual heavygrazing will kill the plant.

Once nodulated, lucerne can fix nitrogen – that is,it can convert atmospheric nitrogen to a form

available to the plant with the aid of rhizobiumbacteria. This nitrogen allows the plant tomaintain high protein levels and build up soilnitrogen. A good lucerne stand can add in excessof 140 kg N/ha to the soil in one year.

Lucerne may live for up to 20 years, although thelife of an average stand is closer to five years. Asswards age, inappropriate cutting or grazingmanagement, weeds, disease and insects taketheir toll and the plant’s survival declines.

When correctly managed and grown, either aloneor with a perennial grass or annual legumes,lucerne restricts the growth and spread of manyweeds.

The deep taproot can deplete soil watereffectively and lower water tables. This canreduce the effects of salination. Similarly the deeproots can take up leaching soil nitrate, thusreducing the rate of acidification.

PRODUCTION ADVANTAGES ANDNUTRITIVE VALUE

Lucerne is valuable as a year-round special-purpose pasture for finishing livestock. Theprotein and energy levels of well-managed greenlucerne are high enough to maintain and fattengrowing animals. The plant also containssufficient concentrations of vitamins and mostminerals for all classes of livestock. In spring, itcompares very favourably with other pasture

Pasture species Metabolisable energy Crude protein

(MJ/kg dry matter) (%)

mid-Sept mid-Dec mid-Sept mid-Dec

Lucerne 10.8 7.8 24 14

Barley grass 9.6 5.7 13 6

Annual ryegrass 10.8 5.6 10 4

Subterranean clover 10.7 5.4 19 8

Phalaris 10.1 5.9 13 5

Vulpia (Vulpia myuros) 10.4 6.6 15 5

Demeter fescue 10.5 7.5 15 12

Wallaby grass 10.8 5.3 15 10

(Austrodanthonia spp.)

Red grass – 6.8 – 8

(Bothriochloa macra)

White clover 11.3 7.5 25 14

Kikuyu 10.8 7.5 16 12

Weeks of growth 6 12 6 12

Table 1. Metabolisable energy and crude protein levels of some common pasture species in southernNSW (collated by P Cregan)

6

species. In summer and autumn, provided there isenough moisture for it to remain green, it is moredigestible than species that mature and die off.

Comparative metabolisable energy and crudeprotein levels are set out in Table 1.

When lucerne is grown with an annual winter-growing legume, its high summer–autumn feedvalue combines with similar winter–spring feedvalues to give high-quality nutrition throughoutthe year.

Livestock productionLivestock production can be substantiallyincreased by using lucerne. At Tamworth, forexample, fertilised natural clover pastures cancarry 6 dry sheep per hectare, but well managedlucerne can carry up to 15 dry sheep per hectare.At Trangie, with rotational grazing, lucerne hascarried 10 dry sheep per hectare, compared with2.5 dry sheep on naturalised pasture.

Research in the southern districts of NSW hasshown that sheep and cattle production canincrease by 10–20 per cent if lucerne is includedin pastures based on subterranean clover orphalaris. (See Table 2.)

Using lucerne in crop rotationsLucerne has a long record of use in our croppingsystems. In northern NSW it is the most popularlegume, whereas in the central areas lucerne and

annuals such as subterranean clover and annualmedics are of equal importance. In the south,annual legumes have traditionally been the mostimportant legume, but lucerne is still importantfor opportunistic summer feed after rain, andlarger areas are now being sown in the south.

The advantages of using lucerne in croprotations are many:

� Reliable source of quality feed.

� Drought tolerant.

� The complementarity of lucerne-basedlivestock enterprise and winter cereals ishigh, providing a diversification of income.

� Contributes nitrogen to succeeding crops.

� Breaks the disease cycle in many crops.

� Improves soil structure (although much lessthan perennial grass-based pastures).

� Uses soil water to depth, reducing the effectsof rising watertables in cropping systems andthus reducing the risk of salinisation.

� Can effectively control weeds of crops (forexample, wild oats) when combined withgood grazing management.

� Can be effectively undersown in mostdistricts, given good sowing practice.

Table 2. Increases in animal production obtained in experiments from animals grazing lucerne-basedpastures. Collated by E Wolfe and P Cregan (Wolfe 1983)

*In these experiments the production from animals grazing combinations of lucerne and subterranean clover or phalaris was compared with the production fromanimals grazing annual grass and/or phalaris with subterranean clover or, in the case of experiments at Glen Innes, with white clover.

Experiment Livestock Product Production increase from lucerne (%)*

Canberra 1967–68 Lambs and weaners Wool (per fleece) + 10Lamb (growth per head) + 46

Wagga 1969–72 Ewes and lambs Wool + 10

Lamb growth + 43

Wagga 1969–73 Dry ewes Wool + 12

Temora 1969–73 Ewes and lambs Wool + 21Lamb growth + 15

Canberra 1972 Steers Steer (growth per head) + 103

Canberra 1973–75 Steers Steer (growth per head) + 9

Wagga Wagga 1975 Steers Steer growth + 11

Wagga Wagga 1976 Steers Steer growth + 128

Wagga Wagga 1977 Steers Steer growth + 11

Glen Innes 1984–87 Weaners Lamb + 6Wool + 6

Canberra 1981–85 Weaners Lamb + 21

7

� Reduces the leaching of nitrate nitrogen tothe subsoil, thereby reducing the risk of soilacidification.

� Maintains levels of vesicular arbuscularmicorrhiza (VAM) for subsequent crops.

� Improves soil fauna and ground coverrelative to continuous cropping.

There are a number of issues that managersneed to take into account where lucerne is theprimary species used in rotations, especially inextensive cropping areas. Fortunately, soundmanagement can reduce the potential impact ofmany of these issues. The issues are:

� Livestock disorders, for example, bloat.(See Livestock health on lucerne.)

� Lucerne dries out the soil profile, oftendisadvantaging the following crop. Removelucerne early enough to make nitrogen andmoisture available to the following crop.

� Limited herbicide options are available forlow-cost weed management. Plan for weedcontrol during the cropping phase and usesound grazing management to reduce manyweed problems.

� Infrastructure (watering and fencing) shouldbe such that lucerne can be rotationallygrazed, or rested strategically to allowreplenishment of root reserves. Low-costelectric fencing can be used to effect.

� Lucerne is less effective in building soilstructure than grass-based pastures.Therefore, include other species where soilstructure or erosion is a particular concern.

� Lucerne can be difficult to remove to provideweed-free fallow. Early planning andstrategic timing of herbicides will allowgreater flexibility.

� Leaf drop occurs under severe moistureshortage. Diversification of pasture types anduse of forage crops and fodder conservationcan be used to reduce the impact.

Nitrogen (N)Lucerne nodules fix adequate nitrogen for theplant and also add nitrogen to the soil. Thecontribution of nitrogen to the soil is directlyrelated to the amount of above-ground plantmaterial produced. The duration of the lucernephase can also have an effect, as can themanagement of lucerne.

Approximately 15–25 kg N is fixed for everytonne of dry matter produced. A similar amountis fixed below ground. While 25 kg N/ha/t maybe fixed under ideal irrigated conditions, it isevident that under our wheatbelt conditions thecontribution is of the order of 15–20 kg N/ha/tof dry matter. Lower rates of fixation have,however, been recorded in drier parts of thewheat belt (for example, 9 kg N/ha/t in theTrangie and Condobolin districts).

As soil nitrogen levels increase, lucerne will usesoil nitrogen itself, in preference to fixingnitrogen. The benefit to soil nitrogen willdepend on the productivity, plant density, weedcontent, management (for example, nutrition,grazing/cutting regime) and the duration of thelucerne pasture.

Research at Tamworth has shown that a lucernephase of two and a half years in a croppingrotation can improve grain yields and proteinlevels because of added nitrogen from lucerne.These improvements are considered adequate tosupport two to three wheat crops on red-brownearth soil and three to five wheat crops on blackearth soils, depending on the background soilnitrogen present. In addition, an improvement

Figure 2. Effect of a lucerne phase on the subsequent yield and grain protein percentage of wheat followinglucerne compared with continuous wheat at Tamworth (Source: G Crocker, NSW Agriculture)

(a) GRAIN YIELD: Effect of including lucerne in crop rotations on 2 soil types at Tamworth

0

0.5

1

1.5

2

2.5

After lucerne on black soil

After wheat on black soil

After lucerne on red soil

After wheat on red soil

Whe

at y

ield

(t/h

a)

(b) GRAIN PROTEIN: Effect of including lucerne in crop rotations on 2 soil types at Tamworth

8

9

10

11

12

13

14

After lucerne on black soil

After wheat on black soil

After lucerne on red soil

After wheat on red soil

Whe

at p

rote

in (%

)

8

exceeding two percentage units in grain proteincan be expected (Figure 2), depending on yieldand seasonal influences. Benefits are directlyrelated to the amount of forage produced bylucerne, so that management decisions thatenhance production (for example, grazingmanagement and nutrition) help the nitrogeninput into the system.

The same trials examined the amount of bagnitrogen needed to grow wheat of similar yieldand quality on these two nitrogen-deficient soiltypes. The equivalent amount of nitrogen neededto equal the effects of a three-year phase of well-managed lucerne ranged from 55 kg/ha to125 kg/ha of nitrogen per season.

To get the maximum benefit from lucerne in arotation, stands must be sufficiently dense,inoculated, relatively weed free, rotationallygrazed and maintained in a healthy condition.Selection of a suitable variety and maintenance ofsoil nutrients can be important factors.

Similarly, in rotation with sorghum, largebeneficial effects from lucerne have beenmeasured in both grain yield and protein contentfor at least four years following well-managedlucerne (3.5-year phase). As with wheat, theeffects have been more pronounced on blackearth soils than on red-brown earth soils.

DISTRIBUTION AND CLIMATICLIMITATIONS

Apart from rainfall, climatic limitations on thegrowth of lucerne in NSW are few it is otherfactors, such as soil type and pasturemanagement, that restrict establishment andproduction.

The western limit of lucerne under rain-fedconditions corresponds to the western limit of thecropping zone. This approximates to the 350 mmlong-term average annual rainfall isohyet insouthern districts and the 400-mm isohyet in thefar north of the State. As rainfall decreases, sodoes the potential for lucerne production.

The major growing areas are on the slopes andnear plains, where lucerne is usually grown inassociation with crops. To the west, productiondeclines owing to low rainfall. To the east, lesssuitable soil types and poor drainage, and on thecoast, a higher incidence of disease, reduce thepotential for high production.

The potential yield of lucerne is generally higherin northern inland areas than in southern districtsbecause of higher summer rainfall and a slightlylonger growing season.

The best temperature for lucerne growth isaround 25°C. Reasonable production occurs inthe range 10°C–30°C, but below 10°C, productioncan be significantly lower (for example, oncooler, elevated tablelands). Marked yieldreductions are likely in western districts whentemperatures reach around 40°C, despite thepresence of adequate soil moisture (the so-called‘summer slump’). Lucerne will germinate over awide range of temperatures with an optimum of19°C–25°C.

Lucerne is tolerant of frost, but there may be leafdamage to actively growing plants, especially ifthey have not been conditioned by a period oflow temperatures before frost. ‘Frost lift’ andsubsequent seedling death is not uncommon withlate autumn-winter sowings on the tablelands.Lucerne can survive under snow when dormant.

The higher rainfall and humidity in coastaldistricts generally create greater weed and diseaseproblems. These can be partly overcome by usingdisease-resistant varieties.

SOIL REQUIREMENTS

Lucerne will grow on a variety of soils, but doesbest on deep, well-drained soils of medium tolight texture where the pH (Ca) of the topsoil liesbetween 6.0 and 7.0, with very low levels ofexchangeable aluminium in the soil (less than5 per cent). For best results, a good supply ofcalcium is also required. Other nutrients are alsorequired. (See also Nutrition section.)

Rich alluvial soils are ideal, but lucerne alsothrives on most of the red earths, red-brownearths, and well-drained black and grey soilsfound throughout the cropping zone. Nativetimbers like white box (Eucalyptus albens),yellow box (E. melliodora), bimble box(E. populneum), and kurrajong (Brachychitonpopulneum) indicate good drainage and deepsoils that are not too acid. Skeleton weed is also asign of deep, well-drained soil.

Established lucerne tolerates saline soilsmoderately well, but seedlings are less tolerant.Because of this tolerance it has a role inreclamation of slightly saline areas by loweringwatertables.

9

Poorly drained soilsAlthough healthy, established lucerne can survivea brief period of flooding in moving water (twoor three days), waterlogging often kills orweakens lucerne plants, particularly whentemperatures are high. These high temperaturescan increase plant death (a condition known as‘scald’).

The presence of one or more of the followingfeatures indicates areas less suited to the long-term survival and production of lucerne:

� boggy seepages

� impermeable clay subsoil

� light-coloured surface soil with yellow or greyclay subsoil and ironstone concretions

� valley floors prone to frequent flooding – theproblem is compounded if the soil is heavyand subject to surface sealing

� smooth-barked eucalypts (gum trees) onpoorly drained soils

� rushes and sedges.

When sowing in these conditions, select varietieswith high resistance to root rot, and eitherconsider improving soil drainage or accept ashorter stand life. Gypsum can improve waterinfiltration where high soil sodium levels areresponsible for poor structure.

Acid soilsLucerne is not as well adapted as subterraneanclover and some other clovers to acid soils,especially those with a pH (Ca) less than 5.2.

Acid soils are usually deficient in calcium andmolybdenum, and hence inhibit nodulation androot growth. Highly acid soils may also have toxiclevels of aluminium and manganese, a problemmagnified by fluctuations in moisture andtemperature.

On soils with an acid topsoil and a satisfactorysubsoil, lucerne can grow satisfactorily providedspecial techniques are used in the establishmentphase. (See the section on Establishing lucerne onacid soils.)

The growing and removal of lucerne hay has anoverall acidifying effect, and the need to correctpH should be monitored over time andameliorated with lime when appropriate.

VARIETIES

There are now more than 30 varieties of lucerneavailable.

These varieties have a wide range of pest anddisease resistances and growth patterns. Choosinga lucerne variety is a matter of matching thepaddock to be sown with the intended use of thestand.

When selecting a variety, you should consider:

� the desired stand life

� aphid and disease resistance

� growth pattern and yield

� availability and price of seed.

Stand lifeThe lifespan of a stand is determined by theinteractions between pests, diseases,environmental factors and management practices.

Where ley farming is practised, a stand life ofthree or four years is usually adequate andattainable, unless severe disease or pest problemsare encountered.

When longevity is important, variety selection iscritical, as is good management (for example,rotational grazing of lucerne). Likely pest anddisease problems must be identified beforesowing. If in doubt, consult your agronomistabout possible problems, as the use of pest-resistant varieties can reduce losses and improvepersistence. Pests and diseases of lucerne aredescribed in the final section of this Agfact.

The dormancy characteristic of varieties is alsoimportant. Semi-dormant varieties with adequate

The distorted roots on this plant emphasise the needfor deep well drained soils. Plough pans can beparticularly troublesome.

NSW

AG

RIC

ULT

URE

10

resistance to disease and insects persist longerunder harsh grazing than similarly pest-resistanthighly winter-active varieties. Some winter-activevarieties, however, combine the benefits of winteractivity with the better persistence of semi-dormant varieties.

Aphid resistanceResistance to the spotted alfalfa aphid (SAA) andblue green aphid (BGA) is essential. The oldvariety Hunter River is not recommended, as it isextremely susceptible to SAA and BGA.

Growing varieties that are susceptible to aphidsallows aphid numbers to build up, increasingdamage. This in turn adds to the cost ofproduction and increases the rate of developmentof insecticide resistance. It also increases the riskof aphid strains developing that can damagevarieties currently resistant to aphids.

Disease resistanceThe need to select for disease resistance dependsvery much on the paddock characteristics.

It is essential to select a variety with resistance toPhytophthora root rot if you are sowing into soilsthat are poorly drained or occasionallywaterlogged. Root rot resistant varieties shouldalso be selected if you intend to irrigate. There isno variety resistant to waterlogging. It is desirableto have resistance to anthracnose, as occasional

damage occurs from the crown rot form of thisdisease (Colletotrichum crown rot) on the coastand in central and northern NSW, especially inhumid environments.

Unfortunately, there is no lucerne variety that isresistant to common crown rot, a damagingdisease that is widespread.

Resistance to the less widespread diseases,bacterial wilt and stem nematode, is important onthe coast and in some inland river valleys.

Your local agronomist can advise you whetherthese diseases are likely to be a problem.

Unfortunately there is very limited resistance tothe range of leaf diseases that cause damage,especially in the autumn. There are, however, anumber of varieties with resistance toStemphyllium leaf spot. Many highly winter-activevarieties tend to be particularly affected by leafdiseases in the field under humid conditions.

Growth pattern and yieldLucerne varieties span a wide range of growthpatterns, from highly winter-active to winter-dormant. However, all varieties grow best fromlate spring to early autumn.

Examples of varieties are:

� highly winter active: CUF101, Aquarius

� winter active: Aurora, Trifecta

Varieties do make a difference. In this 10-year-old trial at Cooma, the highly winter active variety to the left did notsurvive the management and growing conditions, unlike the dormant variety to the right.

W M

CD

ON

ALD

11

� semi-dormant: Venus, Hunter River

� winter dormant: Prime, Pioneer Brand 54Q53.

Highly winter-active and winter-active varietiesare generally more productive than semi-dormantand dormant varieties during the first three years.They have more vigorous seedlings, and recoverfaster after cutting or grazing. However, they losequality relatively quickly when they are toomature, and they are less persistent under heavygrazing, particularly where disease is prevalent.

Winter-dormant varieties, having lower seedlingvigour, are not well suited to late autumn–wintersowings in cooler districts. They are generally notsuitable for dryland sowing because they do notgrow well in times of feed shortage (autumn–early winter). They have, however, performedwell in the colder areas of the SouthernTablelands, especially on the Monaro, and forspecialist irrigated hay production. Winterdormant varieties, once established, tend todisplay excellent persistence.

In southern districts semi-dormant varieties out-yield highly winter-active varieties in the hay-cutting season, whereas highly winter-activevarieties yield better than semi-dormant varietiesfrom late autumn to early spring. Total yieldsfrom these groups are similar.

In northern districts (which are favoured by alonger growing season), well-adapted, highly

winter-active varieties have shown greater overallyield potential (in the order of 12 per cent) thansemi-dormant varieties. However, managementneeds to be at a high level to take advantage ofthis gain.

The extra winter production from winter-activeand highly winter-active varieties has provedvaluable to livestock production in the coolermonths.

Winter-active varieties have proven popularthroughout much of the lucerne-growing area ofthe State, as they combine some of theadvantages of both the highly winter-active groupand the semi-dormant group of varieties.

Consult the NSW Agriculture web site or youragronomist for the latest information on varietyavailability and disease and pest resistance.

Current breeding programs in Australia aim todevelop varieties that are more tolerant ofgrazing; resistant to leaf diseases; higher yielding;targeted at specific uses (such as ley rotations);less likely to cause bloat; and able to producemore wool from the same quantity of lucerne.

ESTABLISHMENT

Sowing timeFour main factors determine sowing time:

� moisture: enough moisture must be availablefor germination and seedling development inthe spring

� temperature: there must be enough time for astrong seedling to develop before frosts andlow temperatures or hot, dry weather sets in

� competition: competition from weeds andcover crop (if used) must be low

� companion species: consider the sowingrequirements of a companion crop (if used)and companion pasture species.

Autumn and spring are the best times to sowlucerne. Avoid winter sowing in colder, wetlocalities, especially if the variety is winter-dormant. Sowing in early spring is suited only ifyou are sowing under irrigation or in districtswhere the spring rainfall is reliable.

The ideal time to sow in the wheat belt is mid-April to mid-May in the south of NSW, extendingto mid-June in the north. Establishment has, ofcourse, been successful outside these periods,with earlier sowing in the south and sowing often

The low crown of a winter dormant variety on the leftcontrasts with the erect crown of a highly activevariety on the right.

W M

CD

ON

ALD

12

extending into July in the north. Winter sowingmay have more reliable soil moisture forgermination, but earlier sowing give seedlingsmore time to establish before the onset of coldweather and provides a better chance of survivalin a dry spring. The slow growth following wintersowing leaves plants prone to damage by insectsand disease, as well as being less competitiveagainst weeds. An effective fungicide seedtreatment is available to reduce effects of diseaseon emerging seedlings.

When a dense hay stand is required, sowing inearly spring (late August–early September) oftenproduces good results. However, there must beenough moisture to maintain seedling growthuntil late spring. Seedlings grow faster in springthan in autumn, as long as moisture is adequateand there is no competition from companioncrops or summer weeds (for example, nutgrass,barnyard grass and wireweed). Spring sowingalso reduces the risk of damage from earth mitesand lucerne flea. If summer weeds are likely tobe a serious problem, it may be best to sow inautumn.

On the wetter slopes and tablelands, springsowing avoids slow winter growth and prolongedwaterlogging, which is particularly damaging onacid soils. However, spring-sown seedlings maybe at risk if high temperatures and or dryconditions are encountered.

Varieties and time of sowingVarieties differ in seedling vigour, particularlywhen sown in winter. Generally, the seedlings ofwinter-dormant varieties grow more slowly, sovarieties should be sown as early as possible inautumn or in spring. The winter-active varietiesestablish rapidly from a late autumn–wintersowing, except in very cold districts.

Preparing the seedbedThe ideal seedbed for lucerne is of reasonablyfine tilth, free of weeds, and well compacted (firm2 cm below the soil surface). This allows for goodseed to soil contact. Most failures result frominadequate, hasty preparation. However, failurecan also result from overworking a seedbed. If apre-emergent herbicide is to be used, allow forthe incorporation cultivation. Do not overworkthe seedbed.

Ideally, plant one or two crops before sowinglucerne into newly cleared country or afterpasture or lucerne. This helps to control weeds,diseases and insect pests and gives a cleaner

seedbed. Sowing lucerne into loose soil androlling before sowing will give better control ofthe depth of sowing.

If you are sowing lucerne with a companion crop(usually a winter cereal), a well-prepared seedbedtilth suited to cereals is generally a reasonablecompromise. Ensure, however, that the lucerne issown shallow (see below), and level the seedbedwith a levelling bar in front of where the lucerneseed in sown.

Fallowing helps to store soil moisture and controlweeds. It increases the chance of success in thedrier parts of the wheat belt, and is necessary forgood, consistent establishment of lucerne in thewestern sections of the central and northernwheat belt.

SowingAim to place the seed in the best environment forgermination and establishment. Techniques varywith soil and topography. If surface moisture islikely to last, a sowing depth of 1 cm is ideal.Under quick drying conditions sowing deeper (to2–2.5 cm) may be a compromise, but a poorerestablishment may result. Always aim to sow asnear as possible to the ideal depth, adjusting forsoil type, moisture content, sowing time andfertiliser placement (described later). Sowing toodeep can result in unsatisfactory establishment.(See Figure 3.)

Combine or drill sowingThe most common method is to drop the seedonto the soil surface from a small pasture seedbox attached to a combine or drill and then coverit using light trailing harrows. This method issatisfactory when the topsoil is likely to remainmoist until seedlings emerge.

Figure 3. The effect of sowing depth (cm) on thepercentage of lucerne emergence in different soiltypes (Sund et al. 1966)

0

10

20

30

40

50

60

70

80

1.25 2.5 3.75 5

Depth of sowing (cm) and soil type

Emer

genc

e %

SandLoamClay

13

For better results, smooth the soil surface with alevelling bar in front of the down-tubes from thesmall seed box, and trail a set of light harrows ora piece of mesh to just cover the seed. A bandseeder attachment places seed more accurately.

Where the surface soil dries out quickly (as withearly autumn or late spring sowings, or in thedrier western part of the wheat belt), drilling2–2.5 cm deep on a firm, moist bottom andcovering with harrows helps the seedlings toestablish.

On deep sands and self-mulching soils, where itis often difficult to keep the soil around the seedmoist, use the furrow-sowing technique. In thistechnique the seed is directed through tubes fromthe small seed box to behind the rear cultivatingtines. It is then placed on the firm, moist bottomof the furrow made by the tines and covered withup to a maximum of 2.5 cm of soil. Trailingharrows are not used. Subsequent movement ofvehicles and machinery is not greatly impeded, asthe furrows level out in time.

Using a roller after sowing can improveemergence if moisture at sowing depth is barelyadequate. Do not roll soils that are prone tocrusting. The use of press wheels aligned withsowing tines or band seeder tubes gives asignificant improvement, and is advantageousbecause weed seeds between sown rows are notencouraged to establish.

Sowing lucerne with an air seeder has resultedin many failures because of deep sowing (Fig.3). Modifications to air seeders to ensure shallowsowing, trailing a independent band seeder intandem, or sowing as a separate operation witha band seeder are common ways to overcomethe problem.

Sowing lucerne seed into a dry seedbed andirrigating or waiting for rain is usually successfulonly if the seedbed is free of weed seeds thatmight establish and compete.

After sowing, make regular thorough inspectionsfor earth mites. (see the section on Pests anddiseases.) Spray immediately with a registeredinsecticide if mite numbers are high or seedlingsare damaged. If lucerne is sown after a longfallow or a stubble burn, it is usually necessary totreat only a strip around the perimeter of thepaddock to stop mites migrating fromsurrounding areas.

Direct drillingSowing lucerne into an existing pasture ispossible. This normally involves preventingcompetitive annual weeds from seeding in thespring and controlling pasture growth until theautumn. Competition from the existing pasture isusually controlled with herbicides just beforesowing. Sowing is best done with a minimum-disturbance machine and the seedlings managedto ensure establishment.

Direct drilling lucerne into old lucerne to improvedensity has met with variable success. (Seesection on Renovation.)

Old lucerne stands have the disadvantage of abuild-up of weeds, lucerne pests and diseases.Furthermore, the older lucerne plants will out-compete the seedlings if moisture becomesscarce.

Surface sowingLucerne has been established successfully bysurface sowing on non-arable tableland country,where it is usually mixed with perennial grasses.Use the same management techniques as thoseused for direct drilling. Sow only where lucernecannot be sown into prepared seedbeds or bydirect drilling and where herbicide drift is not aproblem. Where native vegetation is involved,consult the Department of Land and WaterConservation to ensure compliance with theNative Vegetation Conservation Act 1997.

COMPANION CROPS

Lucerne should be sown by itself for bestresults. Sowing with cover or companion cropsincreases the risk of a poor establishment andweakens lucerne plants so that survival throughthe first summer can be jeopardised.

Companion crops have nevertheless been usedvery successfully over a wide area of the State.Failures tend to be greater where spring rainfall isunreliable, where lucerne is not well adapted (forexample, acid soils, shallow soils), where lucerneis sown late, where the cover-crop sowing rate orrow spacing is inappropriate, or where acombination of these factors is present.

Crops such as cereals, linseed, sunflowers, lupins,Japanese millet, canola and turnips have beenused, with cereals being by far the most popular.Companion crops do, however, compete withlucerne seedlings for moisture and nutrients; theycan also deprive the lucerne plants of sunlight if

14

sown too densely. Sowing the crop and lucernein alternate rows is a successful method ofestablishing a companion crop in the wheat belt,but additional attention may be needed to controlweeds and reduce erosion risk on some slopingcountry.

If a cereal crop is used, there are three mainpoints to consider:

� Choose a short-strawed, erect variety ifpossible. Short, two-row barleys are best,followed by short-strawed wheats, taller-growing wheats, triticale, grain oats, andgrazing barley or grazing oats.

� If rain delays the grain harvest and promotesthe growth of lucerne seedlings (especiallywith the highly winter-active varieties), thegreen lucerne may cause harvestingdifficulties with the shorter-growing cereals.

� The poorest companion crops are the cerealsthat tiller most (for example, forage oats), astheir profuse growth overshadows theundersown pasture.

Use low seeding rates for companion cropsSow cereal companion crops at about 50–75 percent of the recommended rate for grain crops inthe district. The lower the seeding rate, thegreater the advantage to lucerne in seasons ofaverage to below average rainfall.

Sow earlyLucerne is best sown early (before the middle ofMay), so the companion crop should be suited tosowing at the same time. Rather than delaysowing until a better companion crop can besown, it is sometimes preferable to sow lucerneearly with a reduced seeding rate of thecompanion crop, and to graze it lightly in winter.

Harvesting a cereal companion cropWhen harvesting a heavy-strawed companioncrop there is a risk that straw residue will smotherthe lucerne, so use a header straw-spreader toscatter the straw evenly. Also as mentionedabove, tall green lucerne plant material caninterfere with harvesting.

SEEDING RATE

Always use good quality certified or qualityassured seed that is true to type. Hard seed isunlikely to contribute to stand density.

Imported seed is usually of certification standard.However, it is still advisable to check a recent

germination test, since correct seeding ratescannot otherwise be determined.

There are about 440 000 lucerne seeds perkilogram; at a seeding rate of 1 kg/ha this gives44 seeds/m2. Under good field conditions, 20–25plants/m2 will normally establish from thisquantity. However, losses from disease and weedscan reduce this figure further.

The initial density of lucerne grown for goodquality irrigated hay production needs to be atleast 130 plants/m2. Higher rates give higheryields and better weed control in the first year butlittle yield advantage in later seasons, although aquality advantage may persist for some time.Yields tend to drop significantly when lucernedensities fall below 50–60 plants/m2.

Highly winter-active varieties have fewer stemsthan the larger-crowned dormant lucernes, anddensity is more critical, as they may not make thesame compensatory growth as the winter-dormantvarieties when density declines. A sparse swardwill not give top yields, and stems will becometoo thick and woody (although the density isoften suitable for seed crops).

The choice of seeding rate also depends largely onthe care taken at sowing, the climate, and thecondition of the soil at sowing time. Under idealconditions low seeding rates can be very

Band seeders mounted on the rear of combines havesuccessfully increased the reliability of establishment.

P C

REG

AN

15

successful. When using companion crops, increasethe seeding rate of lucerne by 25 per cent.

The following suggestions are for seed with agermination rate above 80 per cent.

Pure lucerne for hay and occasional grazingFor full irrigation 12–15 kg/ha is adequate. Higherrates (up to 20 kg/ha) are used by some farmers.The main benefit is in the first year, withincreased yield and better weed control.

Seeding rates of 4–6 kg/ha are suitable in highrainfall and favourable dryland areas. However, inmost dryland situations high seeding rates arewasteful, as the plants rapidly thin out duringperiods of moisture stress. A rate of 4 kg/ha oflucerne seed is usually adequate. On good creekor river flat soils, where moisture is quite reliable,this can be increased to 6–8 kg/ha.

Lucerne pasture for year-round grazingA satisfactory pasture for year-round productionin the more reliable areas of the wheat belt hasin excess of 30 plants/m2 at establishment, with15–20 plants/m2 remaining the following winter.In the marginal cropping areas, productivelucerne pastures tend to have densities in therange of 7–12 plants/m2.

In southern and central NSW, lucerne for grazingis sown as a mixture with other species,especially subterranean clover. In this case it isusually sown at 2 kg/ha and subterranean cloverat 5 kg/ha. With good sowing techniques,however, the amount of lucerne in this mixturecan be reduced to 1 kg/ha. If a perennial grass isneeded, add it at the rate of 1–2 kg/ha.

In northern and parts of central NSW, grazinglucerne is more often sown as a pure stand. Aseeding rate of 1–2 kg/ha is satisfactory in drierareas. To the east of the State, as rainfallincreases, raise the seeding rate to 2–3 kg/hawhere the annual rainfall is around 600 mm, andto 3–4 kg/ha where the annual rainfall is 750 mmor more. Again, in the wheat belt, an initialdensity of 30 plants per square metre indicatesexcellent establishment, with the pasture thinningto around 15–20 plants in the following seasonand thus providing optimum production. Ifsowing lucerne with tropical grasses, keep theseeding rate of lucerne low (0.5–0.75 kg/ha) toreduce the effects of lucerne out-competing theperennial grass.

In the drier, western margin of the wheat belt, adensity of 5–8 plants/m2 is regarded as

satisfactory for optimum production under thedrier conditions.

Seed standsSpecialised stands for seed production underirrigation are sown at a maximum of 1 kg/ha.However, many seed production areas are dualpurpose (grazing/cutting) and sown at a rate of2–3 kg/ha.

INOCULATION AND LIME PELLETING

Lucerne, like all legumes, obtains its nitrogenfrom the air with the help of bacteria (Rhizobia)that form nodules on the roots. On old lucerneplants nodules are usually difficult to find, as theyoccur on fine roots. Nodules on inoculatedseedlings at the three- or four-leaf stage should beeasily visible clustered on the main root justbelow ground level. Effective nodules are pinkinside. Plants that nodulate without the additionof inoculant tend to develop more widelyscattered nodules.

The nodule-forming bacteria live on nutrientsfrom the plant. In return, they provide nitrogen ina form the plant can use. There are many strainsof these bacteria, each specific to a particularlegume or group of legumes and needing certainconditions for survival.

The more acid the soil (that is, the lower the pH)the less likely it is that the required number ofbacteria will be present to form nodules quicklyand fix nitrogen. Molybdenum, often deficient inacid soils, plays a vital role in nitrogen fixation.

When buying the inoculum make sure it is thecorrect one for lucerne (group AL). Somepesticides used for seed treatment can kill thebacteria.

In some situations, inoculation has not given alarge response. For example, where the soil pH(Ca) is more than 5.5, and where healthy lucerneand/or annual medics have been grown recently.Generally, though, inoculation should be aroutine procedure, as it is inexpensive insurance.It is essential on soils with inherently low fertilityor after extended cropping, which seriouslydepletes the nitrogen level, or on soils where thepH (Ca) is less than 5.5.

If there is any doubt as to the need to inoculate,then inoculate and pellet. Directions for thisprocedure are readily obtainable on inoculantpackets or in Agfact P2.2.7 Inoculating and

16

pelleting pasture legume seed, available from NSWAgriculture web site (www.agric.nsw.gov.au)

After inoculation, sow seed as soon as possible(always within 12 hours). Keep inoculated seed ina cool, shady place until you are ready to sow. Ifseed has also been lime-pelleted, it can be storedin this way for up to a week. However, evenunder these conditions many of the bacteria willdie, so whenever possible avoid storing treatedseed.

Follow this procedure for pre-inoculated seedproducts as well. Although the shelf life of theseproducts may be enhanced, the survival ofbacteria will be greater the better it is stored andthe sooner it is sown after purchase.

When you are sowing pasture alone, it is oftenmore satisfactory to mix lime-pelleted seed withthe fertiliser and sow shallow.

Lime-pellet inoculated seed before mixing it withfertiliser – otherwise the fertiliser will kill thebacteria. Do not store pelleted seed in closecontact with fertilisers or agricultural chemicals.Note that many growers now add molybdenum aspart of this process. (See under Nutrition.)

Where inoculation failure is evident in a paddock,consult the Agfact mentioned above.

ESTABLISHING LUCERNE ON ACIDSOILS

Lucerne is difficult to establish if the top 10 cmof soil has a pH (Ca) below 5.2 and theexchangeable aluminium level is greater than5 per cent. Acid soils are more common inhigher rainfall zones (those with an averageannual rainfall of 550 mm or more in southernNSW or 650 mm in northern districts), and aremore widespread in the south than in the northof NSW. In drier districts, skeletal ridge countryis sometimes acid.

When checking for soil acidity, take into accountthe pH of the subsoil as well. Correcting acidity inthe surface soil will help lucerne to establish, butan acid subsoil can adversely affect rootdevelopment. Your district agronomist canprovide information on the pH levels of yoursoils.

Overcoming acidity and aluminium toxicityOn mildly acid soils (pH (Ca) of 5.1–5.4)inoculation and lime pelleting or banding withlime and appropriate rates of molybdenum and

phosphorus will assist establishment. Bandingwith agricultural lime has been very successful,especially at pH levels around 5.1; mix 100–250 kg/ha of lime with superphosphate (orequivalent fertiliser) and sow the seed into theband.

If you are applying lime through a combine, mixit with superphosphate first so it will flow freely,or spread bags of each alternately into thefertiliser box and mix. A mixture of lime andsuperphosphate in equal parts is available, butlime is more expensive in this form. On thewetter slopes of southern NSW, some farmershave had more success in establishing lucerne onacid soils by tripling the ratio of lime tosuperphosphate.

On moderately acid soils and on very acid soils(pH (Ca) 4.5) especially where aluminium toxicityis a problem, more than 2.5 t/ha of lime may beneeded (a soil test will indicate quantityrequired). Since lime reacts slowly with soil, andmoves very slowly down the soil profile, work itwell into the soil before sowing (6–8 weeks atleast). This procedure is most successful when itis combined with inoculating and lime-pelletingseed and then drilling it in with a lime-superphosphate mixture.

SPECIES TO GROW WITH LUCERNE

In the wheat belt, where winter active and semi-dormant lucerne varieties are grown for grazing,lucerne can be sown with an annual legume(either subterranean clover or medic). This canresult in better animal weight gains (Table 2) andreduce supplementary feeding.

The winter production of subterranean clover ormedic complements the spring, summer andautumn production of lucerne, especially wheresemi-dormant lucerne varieties are grown asopposed to winter-active varieties (Figure 4).

Combining an annual legume (such as balansaclover or subterranean clover) with lucerne hasan added advantage. In long pasture phaseswhere lucerne density tends to decline, theannual legume can improve in density, ensuringthe presence of a reliable legume component, aswell as improving the winter productivity of thepasture.

Choose the correct variety of annual legume suitedto the soil type, rainfall and intended use. Sow amixture of two or three annual legumes of differing

17

maturity, ranging from the variety normally sownas pure annual pasture to a variety that maturesone or two weeks earlier, to give a mixtureadapted to a wider range of seasonal and paddockconditions. Also, after rainfall in summer or earlyautumn, lucerne grows rapidly and quickly driesout the soil surface. As a result, substantialnumbers of newly germinated clover or medicseedlings will ‘burn off’ if no more rain falls. Selectsubterranean clover varieties with a highpercentage of hard seed, which is more resistant topremature germination in summer–autumn.

Improved medic varieties have a narrow range ofmaturity. The variety best adapted to the localityshould be sown with lucerne. Varieties resistantor tolerant to aphids can prevent build-up beforespring, reducing pressure on lucerne growing inthe area.

Aim for a moderate lucerne density (no morethan 20 well-established plants/m2) to ensure thepersistence of subterranean clover with lucerne.

Adding a perennial grass to the mixtureGrowing a perennial grass with lucerne canreduce the risk of bloat and add stability if a long-term pasture is needed. Erect winter activevarieties of phalaris (for example, Holdfast,Sirosa) are suited to districts with a minimumaverage annual rainfall of 525 mm in the south ofthe State and 675 mm in the north. Varieties suchas Atlas PG, which have a degree of summerdormancy, may be more suited to the driermargins of such areas. In districts with higherrainfall (for example, above average annualrainfall of 700 mm), a wider range of grasses canbe used. Grasses check soil erosion moreeffectively than lucerne, and they also have agreater potential to improve soil structure andimprove water infiltration. They can, however, actas hosts for some diseases of cereal crops.

Under extended dry conditions lucerne cansuppress some perennial grasses like phalaris andfescue. However, lucerne may thin early unlessgrazing management is appropriate.

Direct drilling winter cereals (for example, oats)or forage ryegrass into aging lucerne stands canboost winter production and reduce the bloatrisk. In drier districts this technique can beunreliable, because lucerne dries out the soilprofile over the summer, so that there is often notenough moisture in the soil at optimum sowingtime.

NUTRITION AND FERTILISER

Fertile soil is needed for maximum productionand persistence. Good soil fertility also promotesquicker regrowth after cutting or grazing. A lackof nutrients in the soil can arise from:

� a low natural level of nutrients

� depletion of nutrients by continual removal inthe form of crop, conserved fodder or animalproducts

� an imbalance caused by incorrect use offertiliser.

When high-yielding lucerne is cut for hay, morenutrients are removed from the soil than withgrazed pastures and cereal crops. This appliesparticularly to phosphorus, nitrogen, potassiumand calcium. (See Table 3.) The removal of largequantities of hay also has an acidifying effect.This effect is the equivalent of 70 kg/ha of limefor every tonne of hay removed. Some soils willrequire the application of lime to offset this effect,especially if the paddock is used as a hay orsilage paddock. Monitoring pH by soil testing willindicate if there is a problem.

If lucerne has been effectively nodulated it willnot respond to added nitrogenous fertiliser, butdeficiencies of other nutrients can be corrected

Figure 4. Production of prime lamb carcases (kg/ha)from a spring lambing over four years

Table 3. Quantities of major nutrients removedin 1 tonne of lucerne hay

Nutrient kg removed

Phosphorus 2.5

Potassium 21.0

Calcium 12.0

Sulfur 3.0

0

20

40

60

80

100

120

140

160

180

200

7.4 9.9 12.4 14.8

Stocking rate (ewes/ha)

Car

case

pro

duct

ion

(kg/

ha)

Without lucerneWith lucerne

18

with fertilisers. Do not wait for severe symptomsof deficiency to appear before applying fertilisers– by then, production may have been checked.Use soil tests, tissue analysis and paddock recordsto diagnose likely deficiencies.

The lack of a single element can restrictproduction, even though all other nutrients areplentiful, and growth will not improve until thelevel of the limiting nutrient is raised. Deficiencysymptoms can be misleading, and care is neededin identifying and treating them; in someinstances, where there is an interaction betweenparticular nutrients, a shortage of one may showup as a toxic level of another and vice versa.

Placement of fertiliserDifferent methods can be used, but there aresome basic principles that apply for best results.

For quick, early growth the fertiliser must beplaced where it can be reached by the youngroots soon after germination; banding fertiliser2–3 cm below the seed is best. Subsequently, inareas with an average annual rainfall of morethan 600 mm (or under irrigation), topdressingestablished lucerne with fertiliser gives goodresults (although shallow-rooted weeds canbenefit more than lucerne).

Responses to topdressing are less reliable in drierareas, because the surface 5 cm of soil oftenbecomes too dry for the plant to use the nutrients.In these areas fertiliser should be placed 7–15 cmdeep. The common procedure is to build up soilphosphorus during the cropping phase and then,when the last crop is undersown with lucerne, toplace the appropriate amount of fertiliser at therequired depth. If fertiliser is needed later it isusually top-dressed. The alternative is to return toa crop or a series of crops and repeat the cycle.

Fertiliser requirementsLucerne in NSW is prone to deficiencies inphosphorus, sulfur, molybdenum, potassium,calcium (lime), boron, zinc and nitrogen.

Phosphorus (P)Most soils are low in phosphorus, and usually aphosphatic fertiliser must be used. Applicationrates vary with soil type and fertiliser history.Phosphorus-deficient lucerne (growing withadequate soil moisture) has fine, spindly stemsand narrow leaves. As the plant becomesdeficient, the leaves become bluish green and, insevere cases, purple.

Soil testing can help to determine soil phosphorusstatus and fertiliser requirements.

Establishment. Application of fertiliser atsowing is most important. Generally, soils low inavailable phosphorus need up to 30 kg P/ha(375 kg/ha of single superphosphate orequivalent) in higher rainfall areas, declining to10 kg P/ha in drier districts. Under irrigation up to40 kg P/ha is needed for hay production. Theseamounts can be reduced if the soil is of mediumto high phosphorus status.

Maintenance. Soils in areas under irrigation orwith an average annual rainfall of more than600 mm in southern NSW, or 700 mm in northernNSW, and rated by a soil test as low to medium inavailable phosphorus, will normally respond to10–20 kg P/ha, plus up to 5 kg P/ha (dependingon lucerne yield) for each hay cut or equivalentgrazing by milking cows, applied as an annualtopdressing. In hay stands, remove weeds beforetopdressing. In lower rainfall areas topdressing isusually needed only if insufficient phosphoruswas applied at sowing, or if the stand is morethan four years old. (See Placement of fertiliser.)

Sulfur (S)Symptoms of sulfur deficiency are yellowing andstunting of young actively growing shoots. Sincecultivation releases sulfur for plant growth, thesymptoms tend to deteriorate as the stand growsolder. The recently developed ‘KCl’ sulfur soiltest is a useful tool. Strip tests with gypsum andplant tissue analysis are also useful methods ofdiagnosing sulfur deficiency.

Lucerne growing in soils diagnosed as sulfurdeficient by a surface soil test may not showsymptoms, because the tap root may be gaining

Phosphorus deficiency is common, especially in moreacid soils

EMA

I

19

access to sulfur deeper in the soil. Lucerne maynot respond to sulfur application in this situation.

Sulfur-deficient soils occur mainly on thetablelands. In the north there are large areas thatrequire sulfur fertiliser only. In other districts,where both phosphorus and sulfur are deficient,both must be applied for top yield andpersistence. Increased production from sulfuroften occurs in soils derived from basic rocks (forexample, basalt and limestone), on virgin soils,and on heavier-textured soils, especially at higheraltitudes with more reliable rainfall.

On soils that lack both phosphorus and sulfur,single superphosphate fertiliser has the correctratio of these elements to sustain vigorous growthif used at the recommended rates. High analysisfertilisers like double and triple superphosphatesdo not contain enough sulfur for these conditions.The response of lucerne to sulfur is usually rapid,especially when the sulfur is applied as gypsumand sulfur-fortified superphosphate. Elementalsulfur (a component of many compoundfertilisers) can be equally effective although itworks more slowly, depending on particle size.The plant can use it only after the fine particleshave been converted biologically into a moreavailable form.

Soils low in sulfur on the slopes and tablelandsmay need up to 25 kg S/ha a year to maintainmaximum growth. However, in low rainfall areasof the slopes and on eastern areas of the plains,and where soils have a good fertiliser history,the requirement can be as low as 3–10 kg S/haa year.

Calcium (Ca) and limeCalcium deficiency is uncommon in lucernepastures, but it can occur, because the plant takesup large amounts from the soil. Calcium in theform of agricultural lime reduces soil acidity andthe associated toxic effects of aluminium andmanganese. Of the commonly grown legumes,lucerne is one of the most sensitive to soil acidity,and it is often essential for seedling survival touse lime. In most instances, a pH (Ca) between5.2 and 7.5 is ideal for good yields. Use a soil testto determine whether lime is needed.

Liming can increase the availability ofmolybdenum and phosphorus in the soil, butsometimes too much lime reduces the availabilityof phosphorus, potassium and boron, so it mustbe used carefully.

For further information on using lime see theNSW Agriculture web page(www.agric.nsw.gov.au).

Potassium (K)Potassium deficiency is not widespread, but theincidence is increasing, especially in paddockssubjected to long-term hay production. It showsup as white or yellow spots around the marginsof older leaves and as a yellowing of the leafmargins and tips. Leaf analysis is a usefuldiagnostic guide.

Potassium is present in lucerne in higherconcentrations than other elements obtained fromthe soil (except nitrogen). A deficiency ofpotassium can not only reduce yield but can alsobe associated with increased incidence of leafdisease and premature leaf drop.

Repeated cutting removes large quantities ofpotassium from the soil, and if the supply ismarginal a deficiency soon arises. Mixed lucerneand grass swards, in particular, need enoughpotassium for the lucerne to establish well andpersist.

Analysis of a soil sample (at 0–15 cm depth) isalso helpful for monitoring potassium levels andassessing future requirements. Where a deficiencyis suspected, strip-test actively growing lucernewith muriate of potash (50 per cent potassium) at

Characteristic white spotting of the leaf margins causedby potassium deficiency

I CO

LLET

T

20

rates ranging from 250 to 800 kg/ha. In mostcases 250–375 kg/ha will overcome a deficiency,but there have been instances of such rates beingclearly inadequate. Annual applications ofbetween 125 and 375 kg/ha may becomenecessary where hay is made regularly. Fertilisermixtures containing both phosphorus andpotassium are available.

Boron (B)The upper leaves of boron-deficient lucerne turnyellow, with a reddish-purple tinge. In addition,the growing point and flowering heads aremalformed and often die. Little seed is set. Plantanalysis is the most reliable method of diagnosis.

If deficiency symptoms persist after rain orirrigation, apply 2–3 kg/ha of boron as solidfertiliser or liquid, or as a custom-mixed fertiliser.Do not use more than this rate, as there is a verysmall margin between enough boron and anexcess (sub clover is more sensitive than lucerne).Consult your agronomist or fertiliserrepresentative for the most cost-effectivetreatment for your situation.

Nitrogen (N)If lucerne is correctly inoculated at sowing, or ifthere are enough compatible Rhizobium bacteriain the soil and levels of other nutrients, such asphosphorus and molybdenum are adequate, thennitrogen fertiliser is not necessary for lucerne.

If cold or wet weather is likely to restrict nitrogenfixation, or if the soil is deficient in nitrogen,nitrogenous fertiliser can be used to satisfy theseedling’s initial requirement.

Generally, only small quantities are needed(5–10 kg N/ha). The use of nitrogen fertiliser canencourage weeds, which can be detrimental tothe competing lucerne seedlings. Too muchnitrogen can adversely affect nodulation. Plantswill generally use fertiliser nitrogen before theyfix nitrogen.

Molybdenum (Mo)Molybdenum is a trace element needed in verysmall quantities. However, it is essential forefficient nodulation, plant survival andproduction.

A deficiency of molybdenum makes the olderleaves pale – particularly the leaf tips – and alsocauses wilting of petals, restricted flowering, andstunting. Molybdenum deficiency starts to appearwhen the plants are young, and contributes topremature thinning of stands. It is usually patchy,

and becomes marked after fertiliser applicationwithout molybdenum.

Deficiencies occur most commonly in acid soilswhere the molybdenum is in a form that the plantcannot use. The more acid the soil, the morelikely there is to be a molybdenum deficiency.

Use molybdenised fertiliser on all soils with a pH(Ca) of less than 5.0. The rate of molybdenumneeded on most soils is about 50 g/ha every fouror five years, although some soils in high rainfallareas have responded to more than this (forexample, 100 g/ha). Seek advice before usingsuch high rates of molybdenum, as excessiverates may induce copper deficiency.

Superphosphates containing 0.02 or 0.04 percent molybdenum are available. The requiredrate of molybdenum is supplied by applying0.02 per cent molybdenum superphosphate at250 kg/ha. Maintenance dressings of 25–50 gMo/ha may need to be applied every four years,but care should be exercised not to apply toomuch molybdenum, as this can cause a copperdeficiency in grazing animals. Molybdenum isalso available in custom mixes with otherfertilisers.

As an alternative to fertiliser, incorporatemolybdenum trioxiode in the lime when you arelime-coating seed. Molybdenum trioxide containsabout 66 per cent molybdenum, so apply about75 g/ha.

If the deficiency shows up after sowing, therequired quantity of molybdenum can be appliedby topdressing with molybdenisedsuperphosphate or equivalent, as specified above.Alternatively, a foliar spray of ammonium orsodium molybdate can be used.

ZincRecent research in northern NSW has highlightedthe importance of zinc. The application of zincsulfate to lucerne on a deficient soil increasedthe yield and was associated with a lowerincidence of root rot, leaf disease and prematureleaf drop.

Zinc deficiency tends to occur more often onhigh pH soils than on acid soils. Soil tests can beuseful in identifying a problem. Leaf symptomsmay not be present. Strip testing using zincsulfate at 20–25 kg/ha can be used to indicate aresponsive lucerne paddock.

21

GRAZING MANAGEMENT

During establishmentIf lucerne is sown early (for example, in April)with a companion crop, it may be necessary tograze in winter if the crop is dense. This allowslight to reach the lucerne seedlings and reducesthe danger of smothering by early lodging of thecrop. After the companion crop has beenharvested, a brief grazing (10 days, or less if thestocking rate is high) will help to disperse thestubble. It also promotes initiation of new stemsand makes use of grain lost from the header.

The lucerne should then be allowed to flower toreplenish its root energy reserves. However, if adry spell sets in, allow a second short grazingbefore too many leaves drop. Once the lucernehas flowered, begin rotational grazing as outlinedbelow.

Lucerne sown without a companion crop shouldfirst be grazed when in full flower. Earlier grazingor mowing may be necessary if weed competitionhas been severe or if a dry spell sets in. Aftergrazing, allow lucerne to start flowering and thenstart rotational grazing. (When grazing stubbles,be aware of the possibility of grain poisoning.)

Established lucerneThe principlesGrazing management is one of the essentialinputs needed in the production and persistenceof lucerne. It is an extremely important tool, butit must be used in conjunction with varietyselection, good establishment and good soilnutrition for the benefits to be realised.

Lucerne benefits from a grazing system that has aperiod of spelling or recovery, alternated with aperiod of grazing. Spelling allows the essentialroot reserves of energy to be replenished; withoutthis, rapid regrowth after grazing is not possibleand survival through stress periods is threatened.

Research has shown that the essential energyreserves in the roots are at their lowestapproximately two weeks after cutting or grazing(Figure 5). In a traditionally managed stand(based on cutting at 10 per cent flower), theenergy levels are largely replaced by the time thenext cut takes place (for example, one monthlater). Highly winter-active varieties, because oftheir quick regrowth, may not allow these rootreserves to replenish as rapidly as more dormantvarieties and may therefore be more prone todamage from premature grazing or cutting.

It is the spelling time, therefore, that is the mostimportant point to consider in working out agrazing system. During the main growing seasonand under good growing conditions the optimumrecovery time is around one month. The grazingtime needs to be as short as practicable so thatregrowth from the buds at the base of each plantis not grazed prematurely. Under optimumgrowing conditions and during the main growingseason this will range from one to three weeks.

Experience has shown that these principles arethe key to long-term productivity. The bestgrazing system for your lucerne is the one thatcan incorporate these principles into yourenterprises as far as practicable, while allowing aconsiderable degree of flexibility for issues suchas climate variability, low winter growth, lambingrequirements, stock type, labour requirements,and cropping needs with regard to intensivesubdivision etc. Rigid grazing systems are unlikelyto be successful, because of these many practicalrequirements.

Continuous grazing can kill lucerne – the heavierthe stocking rate, the more rapid the decline inthe number of plants, as constant removal of newshoots depletes essential root reserves. Somevarieties exhibit some tolerance to grazing (forexample, semi-dormant varieties compared withhighly winter-active varieties), but still respond torotational grazing to provide good production andpersistence

The height to which lucerne is grazed must takeinto account the class of grazing stock, as well asany possible damage to plant crowns. When most

Figure 5. Root energy reserves in lucerne in relation tocutting time (Boschma and Williams, NSW Agriculture,Tamworth)

81

21

62

02

42

8

UTILISATIONSugars toshoots

STORAGESugars to roots

Root

rese

rves

(% s

tarc

h)

Days after cutting

0 7 14 28 35 42 49

22

of the leaf has been eaten and mostly stemsremain, animal production is likely to decline, butleaving large amounts of stubble can reducelucerne regrowth, as can leaving no stubble.

Livestock with high nutritional requirements, suchas weaners, finishing stock and lactating animals,should be moved off lucerne while there are stilladequate quantities of quality leaf materialpresent. Livestock with lower needs, such aswethers, dry ewes or cows, can then follow toremove the remaining leaf and excess stubble.Similarly, cattle can be grazed before wethers.Observation suggests that lucerne persists betterwhen cattle, rather than sheep, graze lucerne.

Graze small areas of lucerne in association withother feed sources to improve persistence andproduction. As far as is practicable, in thegrowing season, graze lucerne paddocks for up tothree weeks, and then move stock to anothersource of feed and allow the lucerne to recoverfor five or six weeks (or to the 10 per centflowering stage) before returning stock to thepaddock.

During the cooler months spelling periods needto be longer, and alternative pastures based onsubterranean clover are particularly useful. Oats,though of lower nutritional quality, can alsoeffectively fill the winter feed gap.

Stage of growth for grazing/cuttingA number of methods are used that use theseprinciples to indicate when to put stock on tolucerne:

� The early flower or the 10 per centflower stage (when 10 per cent of stemshave commenced to flower) has traditionallybeen the visual indicator as a good time tograze or cut, as it is a good compromisebetween high yield, quality, andreplenishment of root energy reserves. Thetime to flower can be affected bytemperature, moisture stress and variety, sothat the appearance of flowers does notnecessarily indicate that root reserves arereplenished, especially under adversegrowing conditions or with highly winter-active varieties. Grazing later than 10 percent flower has the disadvantage of lowerquality feed and greater chance of leaf drop.This is particularly important if largepaddocks are involved.

� Regrowth from buds is a useful method ofdetermining when to cut or graze. Budregrowth is enhanced by leniently grazinglucerne at a late stage of growth. Theimportant guideline is to reduce damage tothe regrowing buds. As a compromise, grazebefore lucerne bud regrowth reaches 5 cm.Grazing higher, for example with cattle,allows faster regrowth from buds in leafaxils. Cattle generally cause less damagethan sheep.

� Grazing to a time schedule is practical formany producers, as it allows planning forlabour etc. This is satisfactory as long as ittakes into account the principles of restingand grazing over a short period to protectregrowth, and grazing times are altered toaccount for seasonal differences (forexample, 35 days in summer, longer incooler months).

Feed quality considerationsDigestibility, energy and protein are notmaximised at the traditional cutting or grazingstage. There is always a compromise betweenyield, quality and persistence of the stand. Thiscompromise has been satisfactory for mostenterprises, but some are now demanding ahigher level of nutrition.

The dairy industry is a case in point, where unitsoperating at very high production levels needhigher feed quality. There are also certain haymarkets that require cutting at bud or pre-budstage to achieve better quality. The down side tocutting or grazing earlier is that the per annumyield of lucerne will be reduced and,importantly, the stand life is likely to bereduced, increasing the cost per tonne of lucerneproduced.

Depending on relative costs of establishmentand production, as against the cost of additionalsupplementary feed and increased milk yield,grazing earlier (bud or pre-bud stage) may be aproposition.

SubdivisionThe degree of subdivision necessary will varyaccording to the production needed, the requiredlife of the lucerne stand, the reliability of lucerneproduction, the environment, the class of stock,and the likely availability of other feed and otherpractical considerations. Moreover, subdivision isexpensive and rotational grazing requires extra

23

management, and they may not be practicable inmany situations. For example, subdivision maynot be suitable when it is in association with alarge-scale cropping program, although theavailability of low-cost electric fencing hasreduced this problem.

The need for subdivision is greatest wheremaximum use of feed is required, where stockingrates are high, and where rainfall is low or erratic.Where stocking rates are low to moderate, wherea short pasture life (say, three years) isacceptable, or where other species such assubterranean clover are grown with lucerne, lessintensive subdivision is appropriate.

Successful rotation systemsOn the tablelands under reliable rainfallconditions, rotations based on two to fourpaddocks provide good production andpersistence, with rest periods ranging from fiveweeks in summer to eight weeks in winter and agrazing period of up to three weeks. More thanthree weeks’ grazing is possible where growingconditions are favourable and where there is anabundance of other species, such as clover, in thepasture. The persistence of lucerne is reducedwhen grazing periods are extended and youngregrowth continually removed.

On the slopes, under drier conditions, four to sixpaddocks are suited for good production andpersistence, with a rest period of at least fiveweeks and a grazing period of one or two weeks.With low stocking rates, and especially when

Rotational or strip grazing is highly desirable to optimise production and persistence. Use a back fence when stripgrazing.

W M

CD

ON

ALD

other species are sown with the lucerne (forexample, subterranean clover), good productionover three or four years has been achieved byusing three paddocks with rest periods of at leastfive weeks and grazing periods of up to threeweeks.

On the plains, a system of six to eight paddockswith a spelling time of at least five weeks and agrazing period of one week has given maximumproduction and lucerne persistence. Having fewerthan six paddocks and extending the grazingperiod beyond 10 days is likely to reduce plantpersistence dramatically, except under favourablegrowing conditions or low stocking rates, orwhere there is an abundance of other palatablespecies.

Under irrigated conditions, where stockingrates are high, strip grazing or multiple paddocksystems are suitable, with spelling times of atleast five weeks (depending on the feed qualityrequired) and grazing periods of one week orless.

Rotational grazing of a lambing flock can lead tomismothering and reduced lamb survival. Iflambing must occur on lucerne, spread the flockover as large an area as possible to minimisedamage to the lucerne.

When the rotation is relaxed in this way duringthe cooler months it can be difficult to return tothe rotation, as the pattern of feed supply willhave been disrupted.

24

Where it is possible to spell lucerne during thewinter, increased spring and summer productioncan be expected. Excess production during thewarmer months can be conserved as hay orsilage.

Stocking ratesOptimum stocking rates will vary with climate,enterprise and management. Stocking rates thathave been carried successfully under rotationalsystems in trials have ranged from 12.5 wethersper hectare at Trangie, on the plains, through to15 dry sheep per hectare on the slopes at WaggaWagga and Tamworth, to 20 breeding Merinoewes per hectare at Canberra on the tablelands.At higher stocking rates, however, the need forfodder conservation is increased, and theconservation of excess lucerne in spring to feedback in winter needs to be considered, as wasnecessary in some trials. Your local districtagronomist or livestock officer can provideguidelines on suitable stocking rates for yourarea.

Where subdivision is impracticalWhere subdivision to the extent outlined is notpossible, then subdivide as far as practicable androtate stock. Place emphasis on allowing for aspelling period as far as practicable. Even twopaddocks are preferable to one.

Where rotational grazing is not used, thefollowing management practices may reducelosses in production and persistence:

� Ensure that lucerne-based pastures are wellestablished before grazing, and select avariety adapted to the environment (that is, interms of resistance to pests and diseases).

� Ensure soil nutrition is adequate.

� When sowing lucerne, include other species,such as subterranean clover or medic, whichdo not compete to any degree. These willreduce the grazing pressure on the lucerneand provide the basis of a productive pasturewhen the lucerne dies out.

� Use a semi-dormant rather than a highlywinter-active variety. Semi-dormant varietiesare generally more persistent than highlywinter-active varieties, especially when theyare set-stocked.

� Use conservative stocking rates.

� Do not set-stock for long periods, even at lowstocking rates.

� Allow lucerne to flower whenever theopportunity arises (for example, when excessfeed is available elsewhere on the property).If such spells can be timed to precede a stressperiod, such as summer, so much the better.

LIVESTOCK HEALTH ON LUCERNE

There are few health dangers to livestock grazinglucerne. The most serious of them is bloat. Lesserproblems are pulpy kidney, red gut of sheep,nitrate/nitrite poisoning and pizzle rot in sheep,photosensitization in horses and reducedtwinning rates in ewes. Meat tainting can beavoided by moving stock on to an alternativetype of feed for three days before slaughter. Briefnotes on bloat, red gut and reduced twiningpercentages follow. Consult your veterinarian formore detail.

BloatThe risk of bloat must be balanced against thepotential productivity increases from usinglucerne. (See Table 2.) The tendency of lucerne tocause bloat needs to be assessed against theproblems of using alternative pastures, some ofwhich can also cause bloat (for example, clover).Many farmers who successfully stock lucerneyear-round find bloat is a minor problem once allpastures contain at least some lucerne.

Cattle grazing lucerne pastures during the bloatseason (winter and spring) are liable to sufferfrom frothy bloat. Cattle do occasionally sufferfrom bloat in summer or autumn, but at thesetimes the problem is rarely serious.

Sheep are slightly susceptible to bloat, but thisshould not be a deterrent to grazing them onlucerne.

The severity of bloat varies from a slightdistension of the rumen, which causes no distress,to very severe bloat and sometimes death. Deathfrom bloat is generally an isolated occurrence, butlosses are sometimes devastating. Chronic bloatmay also reduce weight gains by 20–30 per centat the peak of the bloat season.

There are a number of ways of reducing the riskof bloat:

� If cattle show symptoms, remove them fromthe pasture. Either graze sheep on the pastureuntil after the bloat season has ended, or savethe lucerne for spring hay.

25

� In a mixed sheep and cattle enterprise, thesheep might graze the lucerne pastures inwinter and spring while the cattle grazeannual pastures, fodder crops, or other non-bloat pastures. In summer and autumn thesheep might be put on dry annual pasture orstubble, for example, while the cattle grazethe lucerne.

� Ensure that cattle are well fed when theyenter lucerne paddocks.

� Mature stands are less risky. Avoid grazingcattle on young and succulent stands.

� Dense, pure swards cause more problemsthan thin, weedy swards.

� Feed hay during periods of high risk.

� In small, intensively managed areas such asdairy farms, livestock can be given anti-bloatagents by drenching, by flank application, inroller drums, in drinking water, by sprayingthe pasture, or with anti-bloat capsules.

� Some animals are more susceptible to bloatthan others. It is a good idea to graze animalsthat you know to be susceptible on pasture,where there is a lower risk of bloat.

� Pulpy kidney (enterotoxaemia) is oftenassociated with, or confused with, bloat. Haveall animals fully vaccinated against pulpykidney before they are allowed to grazelucerne.

Drilling a cereal or ryegrass into older lucernestands that are due for removal may reduce theproblem in those paddocks, and set-stockinginstead of rotational grazing during high bloatrisk periods may reduce the incidence.

Red gutThis condition is associated with lush, growinglucerne and continuous grazing of lucerne bysheep. Livestock symptoms are similar to thoseof pulpy kidney. Sheep in good condition areoften affected. Addition of a supply of roughagemay reduce the incidence. Rotating stockbetween lucerne and other pastures – five dayson lucerne and two days off – seems to besatisfactory. (See Agfact A3.9.23 Red gut insheep.)

Reduced twinning ratesA reduction in twinning rates in ewes grazinglucerne has been associated with high levels ofcoumestans (oestrogenic compounds) in theleaves of the plant. The effects in sheep are a

reduction in the rates of ovulation and multiplebirths. The effects on cattle are unknown, buteffects on reproduction have been suspected.

High coumestan levels can occur in all varieties,but only when the leaves are stressed, such as bydisease or insect attack. Leaf disease has beenparticularly implicated. Heavy leaf diseaseinfection occurs more frequently in humid areas.

The effects on livestock are short-lived, and theproblem can be avoided by removing breedinganimals from stressed lucerne pastures fourweeks before and during joining.

HAYMAKING

Properly harvested lucerne hay is a high-qualityfeed with a metabolisable energy (ME) level of upto 11 megajoules per kilogram (MJ/Kg) of drymatter and a crude protein (CP) content ofaround 20 per cent (Table 1). Its quality varieswith such factors as the stage of growth at cutting(Table 5), the ratio of leaf to stem, the haymakingtechnique, the proportion of weeds, the extent ofweather damage, and the presence of mould.

YieldsCommercial yields are generally within the range10–22 t/ha, from five to seven cuts between earlyOctober and late April, although yields of 25 to27 t/ha have been achieved under excellentmanagement and growing conditions.

In northern districts there is potential for anadditional cut by taking advantage of theextended haymaking season and by using highlywinter-active varieties. In cooler environments,such as the upper slopes and tablelands, thenumber of cuts is reduced (by one or two) andthe yield lowered accordingly.

In very hot conditions, which can occur in the farwest of the State, yields may be depressed. Thiscondition is called ‘summer slump’.

Do not budget on all hay cuts being of equalvalue. In the north, typically one cut per seasonmay be unsaleable at good hay prices and one ortwo cuts may be downgraded because of weatherdamage. The first cut of the season may also bedowngraded by excessive weed content.

Grazing hay stands during the winter can alsodepress spring and summer yields of hay.

MarketingHay is produced in a variety of forms: smallrectangular bales, round bales and large square

26

bales. Small rectangular bales have been the mostpopular package for hay, and remain so for thehorse trade in particular, but large round andsquare bales have increased rapidly in popularity.

Hay marketing in Australia has been basedtraditionally on price per bale or per tonne. In theinterest of both the end user and the producer,hay is best traded on a weight basis, withadjustments made for feed quality. The systempromoted by the Australian Fodder IndustryAssociation (AFIA) is one such example (Table 4).It is based on objective measurement of the feedvalue of hay or silage using ME and crude protein(CP). The AFIA system replaces the use ofdescriptive terms such as ‘choice’, ‘prime’,‘medium’ or ‘grassy’ hay, which were based onvisual assessment. Although visual assessment canidentify colour, amount of leaf and impurities, it isnot always a reliable indicator of feed quality.

Hay is generally sold by the tonne or by the bale.

As the efficiency of grazing enterprises increase,producers are becoming more demanding in theirrequirements. Marketing will also become moreobjective, with the price more accuratelyreflecting nutritional value, rather than the weightalone. Additionally, the presence of undesirableweeds is likely to become more of a marketingissue as quality standards rise.

CuttingFor the most profitable long-term returns, lucernehay should be cut at the correct stage of growthand baled at the correct moisture content. Thecorrect stage of growth will vary with productquality requirements, yield and persistencetargets.

Deciding on the best time to cut is a compromisebetween the requirements for high yield, goodquality and stand persistence. The hay is at itsbest quality when lucerne is cut at the bud stage,but routine cutting at this stage may shorten standlife and is not justified unless a price premium is

obtained for very high quality hay. As lucernematures, the quality declines significantly(Table 5).

Cutting at the 10 per cent flowering stage(when 10 per cent of the stems show flower) istraditional and a reasonable compromise foryield, quality and persistence. It is not, however,the best cutting time for very high quality hay.

The basis for cutting or grazing according to theneed for replenishment of root energy reserveshas been outlined in the section on grazingmanagement and is illustrated in Figure 5.

Note that the time of appearance of flowers isinfluenced by a combination of soil moisture,temperature, and day length and variety. In hotweather, especially when soil moisture isinadequate, the 10 per cent flowering stage canoccur much sooner, thus reducing the harvestinterval. Flowering per se does not necessarilyindicate that root energy reserves have beenrestored. Highly winter-active varieties may alsoflower earlier than semi-winter dormant varieties.

Using crown bud length (for example, when 50per cent of crown buds are 1–2 cm long) todecide when to cut is also variable, because boththe time of appearance and the rate of elongationof buds vary with factors such as variety, growingconditions and past management. However,cutting should always occur before new shootsare high enough to be damaged by the cutter bar.

Cutting on a time interval basis is convenientand practical for many producers, as it allows forplanning of irrigation and labour use. This issatisfactory as long as the principles outlinedabove for resting are followed.

Research at Tamworth showed that harvestingirrigated lucerne at intervals of 35 days, regardlessof the winter-activity rating of the lucerne variety,produced high yields of good quality hay andmaintained the density of the stand. Thiscoincided with the 10 per cent flowering stage of

Digestible dry matter Metabolisable energy Crude protein(DDM) (%) (ME) (MJ/kg) (CP) (%)

> 19 14–19 8–13.9 < 8

> 66 > 9.5 A1 A2 A3 A4

60–66 8.7–9.5 B1 B2 B3 B4

53–59 7.4–8.4 C1 C2 C3 C4

< 53 < 7.4 D1 D2 D3 D4

Table 4. AFIA national fodder grades for legumes pasture hay and silage

27

the stand. Cutting on a 28-day cycle caused plantdensity to decline rapidly by the fourth year ofthe stand and was associated with increasinginvasion by weeds.

Cutting later than the ideal stage gives higheryields and possibly better persistence. However,the hay will be of lower quality, especially withhighly winter-active varieties harvested early orlate in the season. A lower leaf to stem ratio andthe possibility of leaf damage and loss fromdisease and moisture stress can reduce quality.

Cutting earlier than the ideal stage is necessary forsome markets. Specialised export markets, forexample, require hay to be free of flower and of agood green colour, and this means cutting at thebud stage. The requirements of processorsundertaking protein fractionation are similar.However, constant early cutting or grazing islikely to shorten stand life and increase weedproblems.

Cut as close to ground level as possible withoutdamaging the crowns. This is particularlyimportant with highly winter-active varieties withhigh crowns, which are easily damaged. A cuttingheight of around 5 cm above ground level issuitable in most situations. Leaving excess stubbleand leaf is unlikely to be of benefit unless theintervals between cuttings are shorter thanrecommended. Keep cutting edges sharp,especially on slasher-type mowers. Blunt edgescan damage the crowns, particularly of erect,winter-growing varieties, and so make the plantsvulnerable to fungal infection.

Cutting newly sown lucerne is best delayed untilearly flowering, at the earliest.

Hay cut in the afternoon is marginally higher innutritive value than hay cut in the morning.However, cooler conditions following cuttingallows respiration to continue, with subsequentlosses in nutritive value.

DryingAfter cutting, the aim should be to removemoisture as quickly as possible to avoidcontinued respiration, nutrient loss fromweathering, and degradation from microbialactivity. As much leaf needs to be retained aspossible during this process. A number of factorswill affect the rate of drying, and managementmust be flexible to account for them. (For thisreason, making hay is often referred to as an‘art’.) These factors are the stage of cut, airtemperature, wind speed, relative humidity, soilmoisture, and the structure and density of thewindrow.

Lucerne hay is usually dried to a moisture contentof around 17–18 per cent, with material of up to21 per cent moisture baled only in hot, dryconditions. Hay with a moisture content of

Stage of maturity Crude protein Metabolisable energy Digestibility

(%) (MJ/kg DM) (%)

Early vegetative 23 10.4 72.9

Late vegetative 20 9.9 70.0

Early bloom 18 9.3 66.5

Mid-bloom 17 8.9 64.1

Full bloom 15 8.4 61.2

Table 5. The effect of stage of maturity of lucerne on its nutritive value (after Moran 1996)

W M

CD

ON

AL D

An irrigated hay stand being cut at the early flowerstage

28

around 15 per cent and below is required forsome markets. Take care when drying to lowmoisture contents, as lucerne stems become verybrittle and too much leaf will shatter and be lost.Uneven curing in windrows should be taken intoaccount when deciding on the best moisturecontent for baling.

Roller-type mower conditioners, which cut andcondition the lucerne by crimping or crushing thestems, give more even and rapid drying; they canshorten drying time by as much as half, therebyreducing leaf drop and the risk of rain damage(Figure 6). However, if rain does fall onconditioned hay, the hay deteriorates faster than itwould if it had been left untreated.

Hay will dry quickest when it is left spread acrossa paddock. It must be raked into a windrowhowever, while leaves are still moist and flexible,to minimise leaf shatter.

Lucerne leaves dry out more rapidly than thestems, and tend to shatter. Raking helps maintainan even drying rate and reduces unevenbleaching of material in the windrow. Dailyraking of freshly cut hay while dew is stillevaporating helps keep a good drying windrowstructure and reduces leaf loss. As hay dries,raking may be extended to every two or threedays. Leaf loss can be minimised by raking beforedew evaporates and reducing tractor speed.Under very dry conditions it may be necessary toturn windrows several times a day to ensure aneven drying rate, but handling operations shouldbe minimised once drying hay reaches 50 percent moisture content. Raking at night assists inreducing losses.

Tedders are occasionally used to ‘fluff up’windrows and enhance the movement of airthrough the windrow. They should be used onlyon high-moisture hay (above 50 per cent moisturecontent) to avoid excessive leaf loss.

Take particular care with hay making machinery,as accidents can readily occur. In particular, stopmachinery before attempting to clear anyblockage.

Hay additives/treatmentsK-hay or chemical conditioning (to hastendrying)To make K-hay, potassium carbonate is used as adesiccant to accelerate drying. The solution isapplied when cutting. The mower is modified byfitting a crop bar to lay the crop over and exposethe stems, and a boom is used to spray thematerial on to the stems just before cutting.

Figure 6 shows the main advantage of using K-hay. Despite this advantage the technique is notcommonly used.

The advantages of using potassium carbonate are:

� The chance of weather damage is reduced.

� There is less damage to regrowth.

� More leaf is retained, and colour improvesslightly.

� The hay-cutting season is extended.

The disadvantages are:

� The machinery has to be modified.

� A large amount of water has to be carried.

� Potassium carbonate is mildly corrosive, somachinery has to be washed after use (Avoidsplashing into the eyes and skin contact.)

� The process does not work on the grasscomponent of pastures.

� Treated hay absorbs more water if rain falls.

� Buyer resistance is occasionally raised as anissue.

Producers intending to use additives need tocheck with their marketing outlets as to theacceptability of the treated product and also needto list treatments on vendor declaration forms.

Preservatives (to inhibit mould)Preservatives (based on ammonium propionate orpropionic acid) are used successfully overseas,and are available in Australia. They are used on

Figure 6. The effect of conditioning and usingpotassium carbonate on the drying rate of hay(Source: Crocker and Lodge 1981)

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60

Hours after cutting

Moi

sture

con

tent

(%)

Mown onlyConditioned onlyMown, conditioned andpotassium carbonate

Common moisture % for making lucerne hay

29

hay that is slightly above the ideal moisturecontent for normal baling to prevent moulds fromforming and spoiling the hay. However, they donot permit material with a moisture content ofmore than 30 per cent to be baled. Low volumesof the liquid are sprayed on to the lucerne as itenters the baling chamber. Use of this material inNSW indicates that it has the followingadvantages:

� Mould is effectively reduced.

� Both the equipment and the product arerelatively cheap.

� It can improve hay colour.

� It allows greater flexibility in haymaking.

� It potentially extends the times when balingcan take place.

� The time from cutting to baling can beshortened, avoiding weather damage.(Treated hay can usually be baled one dayearlier than untreated hay.)

� Preservatives currently available and based onammonium propionate or propionic acid arenot toxic and are safe to use.

The process does, however, have somedisadvantages:

� It does not allow wet hay (above 30 per centmoisture) to be baled; use moisture meters toensure that material to be baled is not toowet.

� It cannot substitute for good haymakingpractices.

� It does not replace potassium carbonatetreatment, and the two materials may be usedon the one haycut.

Although both chemical conditioning and use ofpreservatives can be effective, they are not widelyused at the present time. Producers intending touse additives need to check with their marketingoutlets as to the acceptability of the treatedproduct and also to list treatments on vendordeclaration forms.

Hay inoculantInoculants for use on hay are available and mayimprove the efficiency of haymaking. Experience,however, is limited at this early stage. Research isneeded to ascertain the efficacy of these materialsunder NSW conditions as well as their relativemerit when compared with materials such aspreservatives.

Measuring moistureBalingThe most common bale size is the smallrectangular bale weighing approximately25–28 kg (35–40/t). Round bales are typically 320,500 or 720 kg/bale depending on the diameter.Because little drying out is possible in a tightlypacked bale, hay should be baled at the correctmoisture content and then put under cover assoon as possible.

A reliable moisture meter helps to determinethe moisture content at which to bale (15–18per cent, extending to 21 per cent in hot, dryconditions). The accuracy of meters variesconsiderably, and many are not sealed againstmoisture and dust. Meters need calibrating toensure that readings on hay are reasonablyaccurate.

The use of a microwave oven to check themoisture content of a sample of hay is a usefulmethod, especially if you are unfamiliar with fieldmethods. It is not as accurate as oven drying asused by laboratories for calibration. If you use thismethod, ensure that your sample is representativeof the hay cut in the paddock, that the sample isdried to a constant weight, and that a cup ofwater is present in the oven to preventcombustion. Contact your agronomist forinstructions on using a microwave correctly fordrying pasture samples.

Judging moisture content without a meter comeswith experience. The following tests give anindication of when it is safe to bale:

Equipment for applying hay preservative isinexpensive and easily installed. Note the container,pump and spray line directed over the entry to thebaling chamber.

W M

CD

ON

ALD

30

� Twist a few stems from the windrow; ifmoisture is evident the crop is too damp.

� Scratch the skin of the stalk with a fingernail(the ‘bark test’). The skin will lift if thelucerne is too moist, but not if it is dryenough. If you are still in doubt, make a fewtrial bales and examine them. Their weightand tightness, or the presence of moistureeither along the sides or in the biscuitsthemselves, will indicate their unsuitability forbaling.

Remember, it is too early to bale if the crop wrapsitself on to moving parts of the baler or the balerengine labours heavily, if moisture is detectableon the side of the baler, or the bales are tooheavy. Baling too late is indicated by excessiveleaf shatter or dusty hay, or if the bales are tooloose, even after tightening the baling chamber.

In good, dry haymaking conditions, it is usuallynecessary to cease work with the pick-up balerduring the day to prevent leaf loss. At night andin the early morning the hay is tougher and lesslikely to lose its leaf. However, do not bale inheavy dew.

Finally, bales left to dry in the paddock are safestfrom the weather in stooks or small stacks.

If you have to bale when the moisture content ishigher than ideal, adjust the pressure so that baleswill not be packed too tightly, and use a haypreservative. This will allow some further dryingout. Do not stack hay that is high in moisture.Even small pockets of moisture can make hayoverheat and lead to a fire weeks after stacking.

Using a round balerBaling losses (particularly leaf) can occur whenusing a round baler. This mainly occurs in thebaling chamber owing to vigorous handling of theforage with belts and rollers. These losses can bereduced by forming large windrows andmaintaining a higher ground speed. The foragewill then feed more quickly into the baler. Thiswill reduce loss and increase digestibility andprotein content, but bale weight will be reducedowing to lower bale density.

Cubes and recompressed balesAn export market for lucerne cubes andrecompressed bales exists, and there is also adomestic market for these products. The qualityrequirements for these products differ from therequirements for traditional rectangular bales. An

advantage of cubing is that mobile cubers canpick up windrows in the heat of the day.

Hay cubes are dense, bite-sized units of choppedhay about 30 mm square and 50–80 mm long.They are produced by a mobile cuber that picksup hay from the windrow, or by feeding baledhay through a stationary machine. The marketrequires that cubes be made from leafy lucernewith a protein content of at least 15 per cent, amaximum moisture content of 12 per cent, and ofa good green colour with no flowers. Higherquality cubes (24 per cent protein) can beachieved by using mobile cubers.

Recompressed or ‘double-dumped’ bales (tworectangular bales pressed into one, or onereduced to half the normal size) have the samequality requirements as cubes. However, themoisture content of bales for double dumpingneeds to be below 12 per cent.

Moisture content and storageThe ideal moisture content for safe storage oftraditional lucerne hay bales in open-sided farmsheds is 17–18 per cent. The risk of storageproblems increases if the moisture contentexceeds 22 per cent. Hay stored in closed shedsor containers must be drier. Round bales are morelikely to heat in the centre than conventionalbales, and should be stored drier as well.

Take care with hay made from unevenly curedwindrows, as pockets of high-moisture hay maymould, heat up, and even combust.

Hay heating in storageWhen hay is stored, the temperature of the stackis likely to increase, depending on a number offactors. At the extreme, spontaneous combustionis possible. The important points to keep in mindare:

� If hay is baled and stored at below 22 percent moisture slight heating can be expected,but hay will normally return to airtemperature after a short period.

� Where moisture content is above 25 per centor hay has been wet through rain or flooding,further heating is possible and care should beexercised.

� If stack temperatures rise to 70°C, a rapid risein temperature is possible if oxygen isavailable. Spontaneous combustion can thenoccur.

31

Direct-cut lucerne is high in moisture and too lowin sugar to allow an effective silage fermentationto occur. Being a legume, lucerne is also high inprotein and calcium, which buffers any changesin acidity.

Wilting to remove excess moisture has the effectof concentrating the plant sugars, allowing abetter silage fermentation. A mixed pasture thatincludes grasses with lucerne is easier to ensile,because grasses such as ryegrass have more sugarfor fermentation.

Despite these limitations, lucerne can besuccessfully ensiled if it is wilted to a dry-mattercontent of at least 30 per cent (70 per centmoisture) – preferably 35–45 per cent dry matter(55–65 per cent moisture) – before being pickedup by the forage harvester, or 40–50 per cent drymatter (50–60 per cent moisture) if it is to bepicked up with a baler.

Baling drier than 50 per cent dry matter (50 percent moisture) can increase losses in the field. Inaddition, the drier material is more difficult tocompress. Ineffective compression allows moreair to remain in the bale and will, in turn, result inincreased ensiling losses.

It may take from 24 to 48 hours of wilting to getthe lucerne to the correct stage, depending on theweather.

� Heating can occur because of the presence ofmoist pockets of hay in a stack. Avoid storingunevenly moist hay. Rake and bale to avoidthe formation of moist pockets of hay.

� Stacks of large bales, because of their sizeand density, can be more prone to heatingproblems.

� Heating can cause extremely high losses inboth the protein and energy content of hayand can reduce the feeding valuedramatically.

� If you have any doubts about hay heating ina stack, test the stack with a crow bar (or ahollow pipe that allows for a thermometer tobe lowered in) to determine whether there isa high temperature problem. (Most problemsoccur two to seven weeks after storage.)

� As a guideline, if the temperature within thestack is approaching 70°C you can touch thebar only briefly, and if it is over 70°C youcannot hold the bar.

� If the temperature is above 70°C the stackshould be dismantled. Ensure that allnecessary precautions to handle a fire are inplace before you move the hay.

� Never climb on top of a stack that is showingsigns of heating, such as condensation, mouldgrowth or acrid fumes.

(From: Mickan F (1999) What happens when hayheats? Agriculture Notes AG0206, VictorianDepartment of Natural Resources and theEnvironment, www.nre.vic.gov.au)

Transporting and handling hayStacked hay can be dangerous, and care needsto be exercised to prevent injury from fallingbales. Similarly, handling bales can pose a threatto health and safety. Note that loadingrequirements exist in respect to transporting hay.These requirements and information on safelyloading your truck can be obtained from yourRoads and Traffic Authority office or the RTAwebsite (www.rta.nsw.gov.au).

MAKING SILAGE

Lucerne can make high-quality silage provided itis wilted quickly before ensiling. Silage isproduced when an anaerobic (no oxygen)bacterial fermentation uses plant sugars toproduce lactic acid, which preserves the forage.

A C

ROSS

Using a moisture meter to check the moisture contentof hay about to be stored

32

When ensiled correctly, lucerne produces verypalatable and nutritious silage – a valuable feedfor both cattle and sheep. Less forage is lost inmaking silage in the field than in making hay.Silage is usually more digestible and higher incrude protein than hay made from the samematerial.

Lucerne may be stored as bulk, chopped silagestored in a pit or bunker, or it may be stored inround or large square bales that are wrapped inplastic to exclude air. In all cases silage must becompacted to remove air and then sealed to keepair out.

If the compaction and sealing are effective, thensilage fermentation will occur naturally. There is arange of silage inoculants available that can beused to ensure that the best silage bacteria arepresent and plentiful and to promote theproduction of good silage, but results from usingsilage inoculants have been variable. In somecases there has been little benefit. They do notovercome problems of poor quality forage beingharvested or poor wilting and compaction.However, good quality inoculants have beenshown to further improve the quality of well-made silage.

Silage inoculants do not remove the need forwilting. In wet environments additives such asformic acid can be used to preserve silage whenadequate wilting is not possible. This practice isnot common in Australia.

Wrapped large square or round bales of lucernesilage have become popular in some areas,especially when weather conditions make haydrying unreliable. Although plastic-wrapped balesilage is relatively expensive, it can be justified bythe convenience in making and feeding out. Aswith round bale hay, these silage bales are traded,unlike conventional silage. The life of the silage isshort (one year), as puncturing or deterioration ofthe plastic can occur, allowing air into the silageand spoiling it.

Wrapped silage is usually made at a higher drymatter content of 40–50 per cent (50–60 per centmoisture). This is done for convenience and costreasons (lighter bales to handle). The quality ofthese bales has been acceptable where they arebaled tight and sealed well.

RENOVATION

Renovation is the practice of cultivating lightly torejuvenate old, thinning lucerne stands.

Improvement varies in degree, but it is usuallyshort-lived and is often accompanied by crowndamage and plant thinning due to infection bycrown rots and bacterial wilt.

Seed is sometimes over-sown during renovationin an attempt to improve the density of the stand.This is usually unsatisfactory because ofcompetition from established plants. Over-sowinginto fertile self-mulching soils under goodseasonal conditions or irrigation is occasionallysuccessful.

The frequent failure of these attempts and theoccasional failure of sowing lucerne back into oldlucerne country is often attributed to alleleopathy(the suppressing effect one plant has on anotherthrough the action of plant chemicals). It hasbeen demonstrated overseas that exudates fromthe leaf and, to a lesser extent from the roots, canreduce the emergence of plants from new seedssown shortly after ploughing out. Competition formoisture, however, is a common factor in ourlucerne-growing districts that readily preventsestablishment. The presence of insect pests anddisease can similarly cause failure.

With thin lucerne stands, you should first identifythe reason for plant loss before consideringrenovation or re-sowing. If, for example, root andcrown rots are active, renovation is unlikely tosucceed. It would be better to crop the area andthen sow a variety with good resistance to thedisease. Similarly, the activity of white-fringedweevils can thin stands, and renovating or re-sowing such stands is a waste of money.

Occasionally, renovation is useful to reduce run-off and allow rain to soak in, or to incorporateother species (oats, ryegrass and subterraneanclover) or fertiliser into the sward. Renovate onlywhen the soil is moist, and use a tined implementfitted with narrow points to minimise damage toestablished lucerne plants.

Take care not to keep low-density lucerne-basedpastures for too long, as the potential benefits tolivestock and following crops may not berealised. For example, weeds that respond to highnitrogen levels, such as barley grass, encroach onthe pasture, depleting soil nitrogen and causing abuild-up of diseases that may affect cereal crops.

TERMINATING THE LUCERNE PHASE

Two of the major disadvantages of growinglucerne, especially in a cropping situation, are the

33

difficulty of removing lucerne from the croppingrotation and the extraordinary ability of lucerne todry out the soil profile. If the situation is not wellmanaged, this may lead to reduced yield in thefollowing crop.

As a general rule for crop production, the lucernephase needs to be removed while it is stillrelatively productive and seasonally in time formoisture and nitrogen to be available for thefollowing crop. There are, however, other factorsthat need to be considered, such as cropsequencing requirements, weed levels, livestockrequirements, machinery commitments and,importantly, relative returns from enterprises.

In consideration of soil water and nitrogenavailability, in dry climates lucerne is bestploughed out well before sowing time to allowsoil moisture, particularly at depth, to bereplenished for the following crop. This maymean ploughing in spring to ensure that summerrain is collected and weeds are prevented fromseeding down. Similarly, ploughing early allowsnitrogen a greater chance to become available forthe succeeding crop. The optimum time of theyear to terminate a lucerne stand for thesucceeding crop will vary with the locality in theState. Check with your local agronomist oradviser.

The success of control of lucerne in crop fallowswith herbicides has been variable, andwidespread dissatisfaction has been common.Research in both southern and northern districtshas resulted in the registration of two herbicidesthat provide reasonably good control of lucerne.

Herbicide effects may be enhanced if soilmoisture is good in the two weeks beforetreatment and if the lucerne is not grazed, cut ormown for two weeks after application.

Decisions about replacing lucerne stands are bestbased on profitability rather than on such factorsas ‘lucerne plants per square metre’ or theamount of grass invasion.

IRRIGATION

Lucerne growth is very responsive to water, andunder irrigation dry matter yields of up to 25 t/ha are achievable. However, highly productivelucerne hay stands can have high water use.Irrigation can also promote problems ifmanagement is neglected. Lucerne is susceptibleto waterlogging, root and crown diseases and

scald (root damage due to waterlogging in hotweather). Good irrigation management practicescan increase yields and quality, save on watercosts, ensure stand persistence and help to avoidenvironmental problems associated withirrigation.

The main prerequisites for irrigating lucerne are:

� profitable markets

� well-drained soil

� good irrigation and drainage layout

� varieties resistant to root and crown diseases.

Deep, sandy-loam soils are ideal for irrigatedlucerne, but clay soils can be utilised providedthat the internal and surface drainage isadequate. Irrigated lucerne generally uses waterfrom the top 1 m of soil, but if the roots canreach the watertable (for example, in lighter soilsin irrigation areas or river flats) this cansupplement irrigation.

Limitations to irrigated lucerneIrrigated lucerne is prone to a number ofproblems that can limit dry matter yields andstand persistence.

Poor establishmentAcid, saline or sodic soils, hard pans, poor landpreparation, mismanagement of sowing orirrigation, or failure to control pests, diseasesand weeds, can produce thin, unproductivelucerne stands.

DiseaseRoot rots are common under flood irrigation.Crown rots are encouraged by hay cutting andtraffic, and leaf, crown and root diseases are allpromoted by dense stands and warm humidconditions.

WaterloggingLucerne is very susceptible to waterlogging.Temporary waterlogging during irrigation canstop plant growth; prolonged waterlogging dueto poor drainage kills plants. Early symptomsinclude general reddening of the plants,followed by yellowing and plant death.

ScaldLow soil oxygen levels due to ponding of waterand high temperatures can cause rapid root andcrown damage and death of lucerne plants.Rotted, foul-smelling plants can be easily pulledout of the soil within a few days of flooding inhot weather.

34

Inadequate water supplyLucerne avoids moisture stress by reducing itsleaf area (leaf drop and slower growth),channelling energy into growing deeper rootsand inducing a state of temporary dormancy inthe plant. Weaker plants are lost throughcompetition for moisture and light. All thesefactors may reduce dry matter yield and standdensity.

Shallow water penetration into the soilWhere surface soil structure is a problem,inadequate water infiltration will reduce rootgrowth, available stored soil water and hayyield.

WeedsDodder and other weeds can be spread throughirrigation water.

Irrigation methodsLucerne can be irrigated by spray, flood, orsubsurface drip systems.

Spray irrigation is reasonably efficient (up to85 per cent), but machinery and pumping costscan be expensive. It is popular along rivers andcreeks, in small irregular shaped paddocks or onlighter undulating land. For small areas, hand-shift or travelling-gun irrigators can be used,whereas centre pivots, linear-move andtravelling low-pressure booms are suited tolarger areas.

Surface flood irrigation (up to 70 per centefficient) occurs on flat grades and heavier soils.Layouts must be designed to ensure fastwatering and drainage. Raised beds allow quickdrainage in large fields with very flat grades, butmachinery needs to be modified to suit thelayout.

Sub-surface drip irrigation (SDI) is suited toloams and clay soils and is the most efficient (upto 95 per cent) method of irrigating lucerne, butinstallation costs are high and the life of the driplines may be limited.

Factors that should be considered whenselecting and designing your choice of systemare:

� Soil type. The soil water-holding capacity,infiltration rate and any soil structuralproblems are important factors.

� Peak water requirements. Provision ofadequate soil moisture for germination and

supply of water six to 10 days aftergermination if the soil surface dries out areimportant. You must be able to meetmaximum daily or maximum monthlyrequirements, schedule irrigations to avoidplant stress, and water efficiently.

� Distribution uniformity (DU). Water needs tobe applied evenly to the entire irrigation area.

� Source of supply. Water quality must besuitable for lucerne and the soil type, and thevolume required must be sustainable.

� Pump selection. The pump selected shouldbe the most efficient available for the dutyrequired. This will minimise pumping costs.

� System selection. When you select a system,take into account the topography, runningcosts, labour requirements, capital cost andyour lifestyle needs.

Further details on these issues can be obtainedthrough the Waterwise program – inquire at yournearest NSW Agriculture office.

Water requirementsThe object of irrigation is to supply enoughwater to replenish the soil profile before plantgrowth and yield are reduced.

Too little water will reduce yield and quality.Too much water is wasteful and expensive. Itcan also cause problems with disease,waterlogging, summer weeds, soil compaction,nutrient leaching, rising watertables and salinity.When water is limited lucerne can survive withless frequent irrigation, but plant production willbe reduced.

Centre-pivot spray irrigation systems are efficient andsuited to large areas.

M L

ATT

IMO

RE

35

Lucerne generally requires 40–70 mm of water toproduce l tonne of hay. This equates to 7–13ML/ha of irrigation water for a highly productiveirrigated hay stand during a full irrigation season.

Lucerne is irrigated from mid-August to late Aprildepending on the location and climate. Itgenerally requires 10 to 15 waterings (two orthree irrigations between each hay cut, with fourto six weeks between cuts). This can meanwatering every seven to 10 days in mid-summer.Good management is needed to coordinatecutting and watering.

When to irrigateIrrigation scheduling allows more efficient wateruse and helps to avoid waterlogging. The timingof irrigation will depend on the stage of growth,the water-holding capacity of the soil, theirrigation layout and the weather. Regularmonitoring and observation of soil moisturelevels is required. This can be done in a numberof ways.

1. Soil-based observationMost of the soil water used by lucerne isextracted from the top 1 m, so it important tomonitor the moisture in that zone. The soil’swater-storage capacity (and structure) affects thenumber of irrigations required. Greater soil waterstorage requires less frequent irrigations.

The depth of water penetration can be checkedwith a push probe (a 10 mm diameter springsteel rod, with a 12 mm pointed tip) hand-driveninto the soil one day after irrigation.

A soil auger or shovel can also be used tosample the soil at different depths, so thatmoisture can be assessed by hand texturing(squeezing a soil sample between with yourfingers and the palm of your hand). Irrigation isrequired when:

� (for loams and clay loam soils) the soilcannot be rolled to form a thick ribbon25–75 mm x 3 mm

� (for sandy soils) the soil will not holdtogether when pressed into a ball.

A more accurate method is to determine thereadily available water (RAW); namely the soilmoisture that plants will use before moisturestress occurs. The RAW is roughly 50 per cent ofthe moisture-storage capacity of the soil and iscalculated for each layer of soil and summed.The soil moisture level needs to be kept withinthe RAW to minimise plant stress. Below this

amount, plants must use excess energy to extractmoisture, and production losses will occur. TheRAW depends on the soil type and the rootingdepth of the plant. The RAW for lucerne with arooting depth of 1 m in various soil types isshown in Table 6. If the rooting depth is lessthan 1 m, soil water-storage capacity will bereduced and more frequent irrigation will berequired. Growers need to estimate the RAW andto refill the soil with the same amount of water.For example, for a loam soil, irrigate before theRAW reaches 85 mm (at 60 kPa if using atensiometer) to maintain maximum production.

Various other instruments can also be used toaccurately assess soil moisture, includingtensiometers, neutron probes and electronicmonitoring systems. Many of these are nowquite affordable, and contractor services are alsoavailable. The important thing is to choose asystem to suit your level of management and toprovide the information you need for yourirrigation scheduling system.

2. Weather-based observationsCrop water use or evapotranspiration (Et) canbe used to create a progressive soil water budgetto determine the level of soil water depletionand to predict the time to irrigate. In establishedlucerne, the soil profile to 1 m depth is the soilwater ‘bank account’, with crop water usedrawing down the ‘account’, and irrigation andrainfall adding to it. When the crop has used theamount of water equivalent to the RAW, withoutcontributions from rainfall, then it is time toirrigate.

Generalised Et0 (evaporatranspiration from a

reference crop) values can be calculated fromtemperature, wind and radiation measurementstaken from automatic weather stations installedby the weather bureau and governmentagencies. Daily figures are often presented in the

Soil type Plant-available soil RAW to 1 m (mm)water to 1 m (mm)

Clay 145 55

Medium clay 160 55

Loam 150 85

Sandy loam 115 65

Sand 60 35

Table 6. Soil water storage capacity of varioussoil types to 1 m depth, and correspondingreadily available water (RAW) value for lucerneat –60 kPa

36

local news media, such as NSW Agriculture’sWater Watch service, which operates in southernNSW.

To calculate specific crop Et0 at different stages

of plant development, multiply the generalisedEt

0 figures by correction factors (crop

coefficients). These range from 0.4 just aftercutting to 1.2 for a dense stand at earlyflowering, with an average of 0.9.

For example, to calculate the daily water use ofa lucerne crop when evapotranspiration (Et0) is9 mm/day, with no rainfall, with lucerne at theearly flowering stage, multiply by 1.2:

Daily crop water use = 9 mm x 1.2 = 10.8 mm.

Pan evaporation can also be used to estimatecrop water use. This is simply the change inwater depth (mm) in a wide, open container. Toconvert open container evaporation to ageneralised Et

0, multiply by a modifier called the

‘pan factor’ and then by the appropriate cropcoefficient. Pan factors may vary from 0.6 to 0.9.If the factor is unknown, 0.8 will give a goodestimate.

For example, for lucerne at early flowering withevaporation of 10 mm and no rainfall:

Scald damage caused by irrigation mismanagement onpoorly drained soils

L TU

RTO

N

Daily crop water use = 0.8 x 10 mm x 1.2 =9.6 mm.

Time between irrigations can vary significantly,depending on the time of year, the location, soiltype and weather.

3. Plant-based indicatorsTypical symptoms of moisture stress in lucerneinclude a dull green or bluish colour, wilting ofthe foliage, leaf drop, early flowering and slowregrowth after cutting. To maximise yields,irrigation should occur before stress symptomsappear in the crop. This can be difficult, as soiltypes can vary considerably across paddocks, soobservation of stress on the areas with thelowest water-holding capacity could be used tosignal when irrigation is needed.

4. Computer programsPrograms are available to help growers irrigateas efficiently as possible. One such program,Haymaker utilises weather and soil data toimprove irrigation efficiency in lucerne. Its useby spray irrigators in northern NSW hassignificantly increased the yield and efficiency ofhay production.

The final irrigation before harvest should betimed to allow adequate drying of the soilsurface to prevent soil compaction by harvestingmachinery. (This is less important with SDI.)However, adequate subsoil moisture shouldremain to allow quick regrowth after harvest.This can be two to seven days before cutting,depending on the soil type and the weather.Under flood irrigation, rapid regrowth isessential to minimise the risk of scald damageduring hot weather. Ensure that plants haveregrown some leaf before the first watering aftercutting.

Key points on management of differentlucerne irrigation systems1. Spray irrigationWell-managed spray irrigation should yieldlucerne hay at a rate of 15–25 t/ha. The mainbarrier in achieving these yields is usually theinability of the system to satisfy the peak waterdemands of the crop. A spray irrigation systemmust be well designed to ensure its economicfeasibility.

Pressure is required in spray systems, and thehigher the pressure required the more expensivethe system is to operate. In recent times low-pressure spray irrigation systems have become

37

popular. These systems have reduced operationcosts but usually have a high instantaneousapplication rate and are not recommended forsoils with low infiltration rates.

2. Surface flood irrigationGood management of flood-irrigated lucerne isessential on heavier soils to avoid damage to thestand and to maximise yields and quality.Growers should aim to provide the best drainagepossible and to avoid any moisture stress bywatering efficiently.

Key features of flood irrigation systems are:

� Root rot resistant varieties are essential.

� Good layout and drainage are essential toavoid waterlogging.

� Irrigation and drainage should be completedwithin 8 hours.

� Ensure that water penetrates to 80–100 cminto the profile.

� To avoid scald after cutting, do not wateruntil regrowth appears.

� Water at night in hot weather.

3. Sub-surface drip irrigation (SDI)

SDI is an extremely efficient system and hasgained popularity in recent years with therealisation that our water resources are limitedand therefore valuable.

SDI has the ability to optimise soil moisture forplant growth by irrigation frequently with smallquantities, as labour is not a problem. Thissystem also has the ability to deliver waterevenly to the entire irrigation area (highdistribution unifomity). Some labour may berequired to fix blockages or leaks caused byvermin attack (for example, by mice or crickets).

Improving water infiltrationWater infiltration of a soil can be improved byincorporating organic matter from precedingcrops and pastures or, on sodic soils, byapplications of gypsum. Typical application ratesfor dispersive clay soils are 2.5–5 t/ha, but lowerrates can be applied in irrigation water. Thesoil’s sodicity should be reassessed every fewyears.

Groundwater pumps and subsurface (tile) drainsmay be used to improve internal drainage of thesoil profile. For each paddock, the high costs of

Laying sub-surface irrigation tape. This system isefficient and can deliver water evenly over the targetarea.

PEEL

IRRI

GA

TIO

N A

ND

WA

TER

SUPP

LIES

such works should be carefully consideredagainst the long-term benefits.

FertigationThis is a technique for supplying dissolvedfertiliser to lucerne through the irrigation system.It has been used successfully in pressurisedspray irrigation systems such as SDI, centre pivotand lateral move systems.

Continuous application using fertigation has thefollowing advantages:

� savings on the labour needed to spread solidfertiliser

� reduction in the compaction caused byconventional machinery

� placement of fertiliser by SDI into the rootzone, where it can be used more efficiently

� more rapid uptake than solid fertiliser.

Further information on irrigation can be sourcedfrom Irrigation Officers of NSW Agriculture.

SALINITY

Lucerne seedlings are very susceptible to saltdamage, but mature plants are moderatelytolerant relative to other agricultural plantspecies. Lucerne as a species is more tolerantthan either white clover or subterranean cloverbut less tolerant than balansa or Persian clover.Lucerne has a particular role in reducing salinitybecause of its ability to lower watertables.

38

Saline waterUse of saline water can reduce lucerne yields,increase soil permeability and raise salt levels inthe soil surface. Ground water and re-use watersuspected of being saline need to be salt testedbefore being used on lucerne.

Flood irrigation and saline waterWhere irrigation is used to establish lucerne, useonly low salinity water (< 0.8 dS/m.) Maturelucerne can occasionally be irrigated with watercontaining salt at levels up to 2.4 dS/m (orl500 ppm). However, repeated irrigations withthis level of salt over two or three years willreduce yields significantly. Occasional use ofbetter quality water is required to leach salt fromthe topsoil.

Spray irrigation and saline waterIf water is moderately saline, it is best to avoidirrigation on hot days to prevent saltconcentrating on the leaves and causing leafburn. Frequent light irrigations should beavoided, as they do not assist leaching.

Saline soilSoil salinity (EC

e) levels of < 2.0 dS/m should

have little or no significant effect on lucerneyields on well drained soils. At 2 dS/m up to a10 per cent yield reduction can be expected.A 25 per cent loss can be expected at 5.4 dS/m,and levels > 6 dS/m can cause even larger yieldreductions. Expected losses on poorer drainingsoils are greater, with a 10 per cent lossexpected at 1.3 dS/m, and a 25 per cent loss at3.5 dS/m. If EC

e > 2.0, a chloride test can be

used to confirm the presence of harmful salts.

Establishment issues on saline soilsSoil salinity levels should be tested down theprofile before sowing. Fertiliser and gypsumshould not be applied before you take samplesfor soil testing, because they will interfere withthe measured salt levels.

Although mature lucerne is moderately tolerantof salt, it will achieve maximum yields only onthe best soils. Saline soils should be leached ofsalt by growing an irrigated annual salt-tolerantcrop such as millet or barley, followed by anapplication of gypsum. The gypsum providescalcium to displace sodium from the soil andmaintains a high electrolyte level, which helps toprevent soil crusting and maintains a porousstructure. This improves infiltration and allowsdeep wetting and better leaching of harmfulsalts.

GROWING LUCERNE FOR SEED

The market for lucerne seed is very competitive,and seed production has become specialised.Opportunity cropping of grazing or haycuttingstands for seed production has become lessattractive, but it can be a useful sideline whenseasonal conditions permit.

Control of insect pests, pollination and irrigationwater scheduling is critical for efficientproduction of seed.

Insect pests, such as thrips, heliothis and lucerneseed wasp, damage developing seeds and needdaily monitoring. Thrips attack the flower budsat or just before flowering and need to becontrolled early. Heliothis generally attacklucerne flowers, burrowing into the developingseed pod and eating the seed. Spray with aregistered insecticide when heliothis numbersexceed about five to eight insect larvae per 10sweeps with a sweep net.

Lucerne seed wasp attacks green seed pods forabout 10 days after flowering. Seed wasp can becontrolled with good management practices suchas removing volunteer lucerne plants, reducingseed residues over winter and cutting thelucerne stand for the seed crop as early aspossible to avoid the increase in wasp numbersthat occurs after January. Regular use ofinsecticides to control pests like heliothis shouldkeep seed wasp numbers low.

Seed crops need adequate insect pollination, anda minimum of three hives of active bees perhectare is normally adequate. Pollinating insectssuch as honey bees should be introduced intothe crop just before first flower. Insect pests canbe controlled during flowering only by late-evening application of those registeredinsecticides that have low efficacy against bees.Never apply insecticides in the morning duringflowering.

Adequate control of irrigation water shouldallow the crop to grow without inducing severewater stress. Well-watered seed productionstands should have a short flowering periodlasting about two weeks.

Lucerne is generally ready to harvest about90 days after cutting or about 60 days after firstflower, when 80 per cent of the pods haveturned brown. Desiccation with a registeredherbicide improves seed recovery. More than60 per cent of seed can be lost by inappropriate

39

harvester set-up. Be prepared to adjust harvestersettings throughout the day as the temperaturesand moisture levels of the crop change. Consultthe manufacturers for correct set-up for differentoperating conditions.

Seed yields vary from about 100 kg/ha foraverage dryland stands up to about 800 kg/hafor well-managed irrigated stands with goodinsect pest control, adequate pollinating insects,excellent water management and favourableweather conditions throughout the growing andharvest period.

Seed of varieties registered under Plant BreedersRights (PBR) can be sold only by the owner ofthe variety.

In NSW small quantities of seed are used for theproduction of alfalfa sprouts. The industry favoursregular deliveries of smaller quantities of highlywinter-active varieties with low hard-seed contentand germination in excess of 90 per cent.

CONTINUED:

Agfact P2.2.25 Lucerne for pastures and fodder

For the second section of this Agfact on

� Weed Control,

� Pests and Diseases

� References

Please follow this link to the second section.