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CROP REMOVAL RATES | SOIL TESTING | PLANTS AND/OR TISSUE TESTING FOR NUTRITION LEVELS | NITROGEN | PHOSPHORUS | POTASSIUM | SULFUR | ZINC | MANGANESE | COPPER WESTERN SECTION 5 NUTRITION AND FERTILISER OATS FEBRUARY 2016

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Page 1: NUTRITION AND FERTILISER - GRDC · Nutrition requirements for nitrogen (N), phosphorus (P) and potassium (K) in oat grain crops are similar to those recommended for wheat or barley

CROP REMOVAL RATES | SOIL TESTING | PLANTS AND/OR TISSUE TESTING FOR NUTRITION LEVELS | NITROGEN | PHOSPHORUS | POTASSIUM | SULFUR | ZINC | MANGANESE | COPPER

WESTERN

SECTION 5NUTRITION AND FERTILISER

OATS

FEBRUARY 2016

Page 2: NUTRITION AND FERTILISER - GRDC · Nutrition requirements for nitrogen (N), phosphorus (P) and potassium (K) in oat grain crops are similar to those recommended for wheat or barley

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SECTION 5 OATS - Nutrition and fertiliser

1Know more. Grow more.

February 2016

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5

SECTION 5

Nutrition and fertiliser

Oats have traditionally been considered a low input crop and have generally been grown onpaddockswithlowersoilfertility.Thedevelopmentofhigheryieldinggrainandhayvarietiescombinedwithgreateremphasisongrainandhayqualityfrombothexportanddomesticmarketsmeansthatnutrientmanagementhastobemorecarefullyconsideredwhen growing oats.

Most oat varieties grown on poor soil (e.g. low in nitrogen) could develop red-tipping on the leaves and this may result in below-optimum yields.

Nutritionrequirementsfornitrogen(N),phosphorus(P)andpotassium(K)inoatgraincropsaresimilartothoserecommendedforwheatorbarley.

Itisimportantforgrowerstousebothsoiltestingandtissuetestingtoensurethecropnutrientstatusisadequateforplantgrowth.Asperothercereals,nutritionalinputsshouldbebasedonsoiltestdataandyieldpotentialofthecrop.1

Applyfertiliseratabovethenormallyrecommendedratestocropsusedforgrazingandgrain,astheyhavealongerproductiveperiodthangrain-onlycrops.

5.1 Crop removal ratesTable 1: Nutrients removed (kg) per tonne of grain production 2

Crop type Nitrogen Phosphorus Potassium SulfurWheat 21 3.0 5 1.5

Triticale 21 3.0 5 1.5

Barley 20 2.7 5 1.5

Oats 17 2.5 4 1.5

5.2 Soil testingSoiltestinformationcanbeusedtosupportdecisionsaboutfertiliserrate,timingandplacement.Soiltestingistheonlyquantitativenutrientinformationthatcanbeusedtopredict yield response to nutrients.

Soilsamplesshouldbetakenbeforesowingsothatresultsandrecommendationsareavailableintimetoordertherightfertiliserproduct(s).Cropnutritioncanbemonitoredbytissuetestingtochecktheavailabilityofsoilandappliednutrients.

Choose a laboratory that has the Australasian Soil and Plant Analysis Council certificationfortheteststheyoffer.NationalAssociationofTestingAuthoritiesaccreditation is also desirable.

1 DAFWA(2015)Oats:fertilisersandplantnutrition,https://www.agric.wa.gov.au/oats/oats-fertilisers-and-plant-nutrition

2 AgricultureVictroia(2008)Establishingforagecereals,http://agriculture.vic.gov.au/agriculture/dairy/pastures-management/forage-cereals/establishing-forage-cereals

FAQ

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SECTION 5 OATS - Nutrition and fertiliser

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Regular soil testing using the same GPS locations in paddocks (e.g. every three years) allowsmonitoringoffertilitytrendsovertime.3

Themostcommonsoilsamplingdepthfornutrientanalysisis0to10cmforbroadacrecrops.Thislayerwaschosenbecausenutrients,especiallyP,andplantrootsareconcentratedwithinthislayer.Toobtainmorecomprehensivesoildata,includingnutrientdata,samplingbelow10cmshouldbeconsideredforsomenutrients.4

5.3 Plants and/or tissue testing for nutrition levels

Figure 1: Oats crops remove significant quantities of all major nutrtients. (Photo: DAFWA)

TheagriculturalareasofWesternAustraliaaredominatedbysandysoils.Theycontainlowamountsoforganicmatterandarepooratretainingwaterandnutrients.Aswithwheatandbarleycrops,oatcropsgrowpoorlyifnutrientsaren’tadded.ThemajornutrientsrequiredforhealthygrowthareN,P,KandS;andthemicronutrientsCu,Mn,Mo and Zn.

Oatcrops,particularlyoatenhay,removesignificantquantitiesofallthemajornutrients.Itis,therefore,importantforgrowerstousebothsoiltestingandtissuetestingtoensurethecropnutrientstatusisadequateforplantgrowth.ApplicationofnutrientsisrequiredtooptimiseproductioneitheronanannualbasisfornutrientslikeNandPorlessfrequentlyforthemicronutrientslikeCuandZn.

Thecontinuedlossofnutrientsfrompaddockswithoutreplacementbecomesparticularlyimportantwhenthesoilsarealreadymarginalordeficientinnutrients.Continuallydepletingnutrients,particularlyK,fromsoilwithadequateamountsofthatnutrientwilleventuallyreducesoilKsupplyanddecreasetheproductivityandqualityofproduce.RemovingnutrientsfromthesoilmayalsoreduceitspH.Astheplantmaterialisremovedfromthepaddock,thereisanetexportofalkalinitywhichleavesresidualhydrogen ions in the soil to maintain electrical balance. As this process is repeated over time the soil becomes acidic. 5

While oats have a higher tolerance to acidic soil and high aluminum levels than barley andwheat,economicresponsestolimingarestillachieved.Thereforeitisimportanttomonitortop-andsub-soilpHlevelstodetermineiflimingisrequired.

3 GRDC(2013)Betterfertiliserdecisionsforcropnutrition,http://grdc.com.au/Resources/Factsheets/2013/11/Better-fertiliser-decisions-for-crop-nutrition

4 GRDC(2014)Soiltestingforcropnutrition(NorthernRegion),http://grdc.com.au/Resources/Factsheets/2014/01/Soil-testing-for-crop-nutrition-North

5 DAFWA(2015)Oats:Fertilisersandnutrition,https://www.agric.wa.gov.au/oats/oats-fertilisers-and-plant-nutrition

i More information

Soiltestingforcropnutrition (Northern Region)

Betterfertiliserdecisionsforcropnutrition

i More information

CSBP Soil and Plant Analysis Laboratory

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5.4 Nitrogen

5.4.1 The importance of N managementNitrogenislargelyresponsibleforsettinguptheyieldpotentialofthecrop.Nitrogenisrequiredfortillerdevelopmentandrequiredbyplantstocreateprotein.TheNforplantgrowthissuppliedfromboththesoilandfromNfertiliserapplication.Nitrogenistakenupbytheoatplantwhenitisinaninorganicform(aseitherammoniumornitrate).Inthesoilover98%oftheNisinanorganicformwhichcannotbetakenupbytheoatplantuntilitismineralised.Alargeproportionoftheoatplant’srequirementforNissuppliedbythesoil.WheretheavailableNsupplyfromthesoilisinadequateforoptimumyieldandquality,Nfertiliserisrequired.SoiltestinghelpsestimatetheamountofNalreadyavailableinthesoil.Soiltype,croppinghistory,yieldpotentialandtheseasonareimportantfactorstoconsiderinNmanagementdecisions.

TheamountofNfertiliserrequiredtogrowagrainoroathaycanbeestimatedfromyourfertiliserdecisionsupportprograms.Asaruleofthumb,Nfertiliserat40to80kgperhectare(N/ha)hasbeenfoundidealformostgrowingconditionsinWesternAustralia.TheamountofNrequiredwillbemodifiedbyseasonalconditionsandtheoatvariety.DwarfvarietieshaveahigherNrequirement;itissuggestedthattheNapplicationrateusedbeincreasedbyabout20%abovethatrecommendedfornon-dwarfvarieties.

Oat hay and grain yield response to applied N depends on the soil moisture available during the season. In a dry season there is usually a poor crop response to applied N duetowaterbeingmorelimitingtoyieldthanNsupply.PoorfinishestotheseasonalsoreducecropyieldandgrainqualityirrespectiveofhowmuchNisapplied.

Nitrogencanleachinwetseasons,particularlyinsandysoils.Inleachingsituations,theNrequirementforoatscanbedelayedand/orsplittoreducetheNlostbyleaching.Inwaterloggedsoils,applyingUANcanachievebetterresponsesthanurea.Tomaximisehayquality,anylateNshouldbeappliedbetweentillering(Z25)andstemelongation(Z31). Applying N too late (later than Z33) causes nitrates to accumulate in the plant dry matter,reducinghayquality.Forgrainyield,profitableresponsestoNapplicationhavebeenfoundupto10weeksaftersowing.ThereisgenerallylittlechanceofaprofitableyieldincreasetoNfertiliseroccurringiftheNisappliedlaterthan10weeksafterseeding. 6

Increasing N supply:

• may increase hay yield

• increases hay greenness

• increasesstemfibrelevels(aciddetergentfibreandneutraldetergentfibre)

• decreases water-soluble carbohydrates (WSC)

• may increase in-vitro digestibility and metabolisable energy slightly

• may sometimes lead to high nitrate N levels – unacceptable in many hay markets

• interactswithvarietyforfibreandWSC

ThemethodofNapplicationneedstobeconsidered.SplitapplicationsofNappearimportant,particularlyforhay.

• Forhayproduction,donotapplyexcessivelevelsofNasitmaydecreasehayqualitybyincreasingstemfibrelevelsanddecreasingWSC.VarietiesmaydifferintheirresponsetotheamountandmethodofappliedN.

6 DAFWA(2015)Oats:Fertilisersandnutrition,https://www.agric.wa.gov.au/oats/oats-fertilisers-and-plant-nutrition

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Interaction with seeding rates

• IncreasingtheseedingratewillincreaseoatgrainandhayyieldsirrespectiveofNfertiliserlevels.Higherseedingratescanincreasegrainscreeningsandreduceleafgreennessinhay.However,higherNfertiliserrateswillincreaseyields.

ResearchhasshowntheresponseofoatgrainyieldstoseedingrateisindependentoftheNapplicationrates.HighseedingratesandhighNfertiliserratesincreasescreenings but no other quality parameters. Hay yield response to seeding rate was independentofthelevelofappliedN.

LeafgreennesswastheonlyaspectofhayqualitythatdecreasedasseedingrateandNlevelsincreased.AtlowlevelsofNtherewasalargerdropinuppercanopyleafgreennessasthenumberofplantssownincreased,comparedtogreateramountofNapplied.StemthicknessofoatsdecreasedasseedrateincreasedirrespectiveofNfertiliserwhichimproveshayquality.

Interaction with potassium

• MaintainingadequateamountsofNandKnutritionarenecessaryforoptimumgrainandhayyields.SupplyingadequateratesofKresultedinbettergrainandhayquality

TrialshaveshownthatbothNandKareimportanttooptimiseyieldandqualityofoathayandgrain.WhensoiltestKlevelsarelow(ColwellKsoiltestoflessthan80mg/kg)theresponseofoatplantstofertiliserNcanbeaffectedbyKdeficiency.TooptimisetheresponsetofertiliserN,adequateKfertiliserhastobeapplied.

Results suggested that both oat hay and grain yields were governed mainly by applied N but required at least 70 kg K/ha to achieve their optimum levels.

WhilstNandKinteracttoinfluencehayyield,theydonotinteracttoinfluencehayquality.OnK-deficientsoils,increasingK(regardlessofNsupply)reducesNDFandcrudeproteinandincreasesWSCofthehay.

GrainyieldincreasesascombinedNandKfertiliserratesincrease.TherelationshipsuggeststhatitwouldnotbeeconomicaltoaddKwithoutanadequateamountofNfertiliser.

Aswithgrainyield,NandKcanalsointeracttoinfluencegrainquality.GrainqualityisalsoaffectedbycombinedNandKfertilisers.UnderlowNsupply,Kprovideslittlebenefit,butifNsupplyishigh,alackofKcanaffectquality.7

N-deficiency symptomsNitrogen-deficiencysymptomsofoatsappearintheearlygrowthstagesandbecomemoresevereastheplantgrows.Whenthecropisyoung,stemsareshortandthin;leavesandstemsarepalegreen.Atflowering,N-deficientplantsarestunted,havefewertillersandsmallerheadsthanN-adequateplants.Atmaturity,thecropismulticoloured with upper leaves pale green and middle leaves yellow to pale green with redtips.Theoldestleavesmayhavedied,turnedbrownandfallenontothesoil.Grainyieldisreducedprimarilyduetotherebeingfewerkernelsperheadandlowerheaddensity. 8

5.5 PhosphorusPhosphorousisimportantforoatproduction.AddingPfertilisercanincreasebothhayandgrainyield,dependingonthesoiltestP.TheoptimumPrequirementsforhayandgrainappeartobedifferent.OatvarietiesmaydifferintheirPrequirements.

7 DAFWA(2015)Oats:Fertilisersandnutrition,https://www.agric.wa.gov.au/oats/oats-fertilisers-and-plant-nutrition

8 DAFWA(2015)Oats:Fertilisersandnutrition,https://www.agric.wa.gov.au/oats/oats-fertilisers-and-plant-nutrition

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Phosphorusisamajornutrientforimprovingoatenhayandgrainproduction.Phosphorusisavitalcomponentofadenosinetriphosphate(ATP),the‘energyunit’ofplants.ATPformsduringphotosynthesisandisusedfromthebeginningofseedlinggrowththroughtotheformationofgrainandmaturity.Deficienciesresultinslowgrowth,decreasedhayandgrainyields,inferiorqualityandsubsequentlylostincome.

It is suggested that P can be applied at crop establishment as an adequate supply is criticalforrapiddevelopment.Phosphorusisneededduringearlygrowthforplantrootdevelopmentandelongation,soPfertilisersaredrilledwiththeseedduringsowing.Aneconomicresponseisunlikelyiftheapplicationisdelayedformorethan10daysaftersowing.

TheoatcropresponsetoPwillbeinfluencedbythelevelofColwellPandtheabilityofthesoiltoretainP(PhosphorousRetentionIndex–PRI).OnlowP-fixingsoils(PRI<2mL/g,reactiveFe<280mg/kgandPhosphorousBufferingIndex<15),Pisheldveryloosely,makingitmoreavailabletoplantrootsandpotentiallyreducingtheamountofPrequiredformaximumeconomicyield.OnmediumandhighP-fixingsoils(PRI2–15mL/gand>15mL/g,reactiveFe280–1000mg/kgand>1000mg/kg,respectively),Pis held more tightly with less available to plant roots. A better response to applied P isexpectedwheresoilColwelltestsarelow.SoiltestingisthereforerequiredbeforedecidingwhatrateofPtoapply.9

P-deficiency symptomsPhosphorusdeficiencyresultsinpoorseedlingestablishmentandrootdevelopment.ThedeficiencysymptomsusuallyonlyoccurifthedeficiencyissevereandaremorenoticeableinyoungplantsastheyhaveagreaterrelativedemandforPthanmorematureplants.Thetipsoftheoldleavesbecomedarkorange-yellowandthiscolourmovestowardsthebase,usuallyalongtheleafedges.Theaffectedleavesoftenhavegreenbases,orange-yellowmid-sectionsandbrightredorpurpletipsandtheedgesoftheleavesarerolledinwards.Inseveredeficiency,affectedareasdieandturnredandpurple. 10

5.6 PotassiumPotassiumisanimportantnutrientforoatproduction.HaycropsremovelargeamountsofK.Potassiumisrequiredforphotosynthesis,transportofsugars,enzymeactivationandcontrollingwaterbalancewithinplantcells.AdeficiencyofKresultsinpoorrootgrowth,restrictedleafdevelopment,fewgrainsperheadandsmallergrainsizewhichaffectsyieldandquality.

PotassiumdeficiencyismorecommononlightertexturedsoilswherethereislessclayandorganicmattertoretaintheKintherootzone.Thedeepersandsoncoastalplains,whicharepeatyandoccuronthesouthcoast,arethemostprevalentK-deficientsoilsofthehighrainfallzoneofWesternAustralia.Potassiumdeficiencyislikelytooccurifthesoilhaslessthan60mg/kgofKinthetopsoil.

Potassiumdeficiencycanreducethetoleranceofplantstoenvironmentalstressessuchasdrought,frostandwaterlogging,aswellaspestsanddiseases.Potassiumdeficiencycan reduce straw or stalk length leading to lodging problems.

CroprequirementsforKchangeduringthegrowingseason.Potassiumuptakeislowwhenplantsaresmallandincreasesduringlatevegetativeandfloweringstages.Research in Western Australia has shown that oat yield response to added K depends on the soil extractable K (Colwell K) and environmental conditions. Adding K has a positiveeffectonqualityforhayandgrainwheresoilKlevelsarelowtodeficient.

9 DAFWA(2015)Oats:Fertilisersandnutrition,https://www.agric.wa.gov.au/oats/oats-fertilisers-and-plant-nutrition

10 DAFWA(2015)Oats:Fertilisersandnutrition,https://www.agric.wa.gov.au/oats/oats-fertilisers-and-plant-nutrition

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SECTION 5 OATS - Nutrition and fertiliser

6Know more. Grow more.

February 2016

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SymptomsofKdeficiencyprogressslowlyandcanbecostlyifnotdetectedintime.RegularsoilandplantanalysisandnutrientbudgetingcanensurethatKdeficiencydoesnotoccur.Muriateofpotash(KCl)isthecheapestformofK.Itisappliedbytopdressingeitherbeforeseedingorupto5weeksafterseeding.IfKdeficiencyisdiagnosedinthesoilbyColwell-extractablesoiltests,applying20–40kgK/haasmuriateofpotash(40–80kg/ha)maygiveaneconomicyieldincrease.Potassiumatlowratescanbebandedbeloworwiththeseedatsowing,withsulfateofpotashsaferthanmuriateofpotash.HigheramountsofKdrilledwithseedcandecreaseseedlinggermination,mainlyduetosalteffect.WesternAustralianresearchhasshownthatbandedKistwiceasefficientastop-dressedK.Inotherwords,applying10kgofKinthefurrowachievesanequivalentplantresponseoftop-dressing20kg/haofK.

HaycropsremovegreateramountsofK(about10kgK/t)comparedtoKlossesingrain.Theremovalofnutrientsinhayhastobeconsideredwhenplanningfertiliserrequirementsforfollowingcrops.PracticessuchasswathingofcanolaandconcentratingandburningofwindrowscanhavesignificanteffectsonthespatialdistributionofKacrossthepaddock.Forthesereasonsgrowersshouldusesoiltestresults in conjunction with plant tissue testing and visual symptoms to determine applicationratesforpaddocks.DecisionsupporttoolsrelatesoiltestvaluesandothersoilcharacteristicstoyieldpotentialtofiverecommendedKapplicationrates.11

K-deficiency symptomsPotassiumisverymobileinplants.Indeficientplants,Kisredistributedtothenewgrowthandthedeficiencysymptomsfirstappearintheolderleaves,whichturnpalegreenandbronzewithyellowareasdevelopinginthemid-sectionoftheleafbetweentheedgeandmid-vein.Theseareasquicklyextendtowardstheleaftipuntilthetoptwo-thirdsoftheleafisbronze-yellow.Grey-brownspotsdevelopwithinthebronze-yellowareas.Typically,thedeficientplantdevelopsathree-toneappearancewithgreenyoungerleaves,greenwithyellowtobronzecoloursonthemiddleleavesandbrownolder leaves. 12

5.7 SulfurSulfurhasanimportantroleinformingproteinsandisessentialforproducingchlorophyll. Crops that have a high N requirement must have adequate S to optimise N utilisation and protein synthesis.

SulfurdeficiencyinoatcropsisrareinWesternAustralia,mainlybecauseofthewidespreaduseofsuperphosphate(11%S).AswithNandP,mostoftheSinthesoilisinorganicform.SoilswithlowamountsoforganicmatterarepronetoSdeficiency.Sulfurinorganicmattermustbemineralisedtosulfatebeforebeingtakenupbyroots.Sulfateismobileinsoilsandcanbeleachedoutoftherootingzoneduringwinter.Deficienciesthereforemostoftenoccurinwetteryears.Onduplexsoils,deficiencysymptoms may be only temporary as roots grow into the deeper soil layers where more S is available.

SulfurdeficiencyisexpectedtoincreaseinoatcropsinthefutureasmorecompoundfertiliserscontaininglowerSareusedinoatproduction.Hayproduction,particularlyonsandysoilsisexpectedtoincreasetheriskofSdeficiencyashaycropsremoveabout1.5kgS/hapertonneofhay.

Asoiltestvalueoflessthan10mg/kginthesoilsurface(0–10cm)indicateslikelySdeficiency.However,Sinthesoilfrequentlyincreasesdownthesoilprofile,soknowledgeofthedistributionofSinthesoilprofileisrequired.Thismayinvolvedeepersoil sampling to know the S supply in the soil. Applying P as superphosphate and

11 DAFWA(2015)Oats:Fertilisersandnutrition,https://www.agric.wa.gov.au/oats/oats-fertilisers-and-plant-nutrition

12 DAFWA(2015)Oats:Fertilisersandnutrition,https://www.agric.wa.gov.au/oats/oats-fertilisers-and-plant-nutrition

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compoundfertilisersthatapplySat5to10kg/hacanavoidSdeficiency.Similarlysulfateofammoniacanbeacost-effectivesourceofNandS.

S-deficiency symptomsTheyoungestleavesofS-deficientplantsarepalegreenandthenpaleyellowacrossthewholeleaf(nostriping).Underseveredeficiencytheentireplantbecomesalemon-yellow colour with red stems.13

5.8 ZincZincisacomponentofmanyplantenzymesandessentialforhealthyplantgrowthandleafformation.OatsarehighlysusceptibletodeficientlevelsofZninthesoil.Aftertheinitialrecommendedapplication,mostmicronutrientshavealongresidualvalueinthesoil.Tissuetestingistheonlyeffectivewaytodetermineifthereisadequateplant-available Zn in the soil.

AlthoughplantsymptomsmaybesufficienttodiagnoseZndeficiency,atissuetestmayalsoberequired.Zincconcentrationsintheyoungleavesoflessthan14mg/kgindicatethattheplantisZndeficient.

Aninitialapplicationof1to2kg/hazincoxide(75%Zn)willcorrectadeficiencyformanyyears.Afoliarsprayof1kg/hazincsulfate(23%Zn)in50–100LofwatershouldbeappliedassoonasZndeficiencyisdetectedtopreventgrainandhayyieldlosses.

Zn-deficiency symptomsZincdeficiencycausespatchygrowth,withplantsinpoorareasstuntedwithpalegreenleavesandyellowororange-redtips.Youngestleavesusuallyremaingreen,middleandolderleavesturnpalegreenandpaleyellowareasdevelopbetweentheleafedgeandmid-veinatthetip.Brownspotsoccurintheaffectedareas,increasinginsizeuntiltheleaftipdies,oftenturningred-browntoblack.

Withseveredeficiencythestemremainsveryshortandyoungestleaveshavedifficultyemergingfully.ThesymptomscanbemistakenwiththatofBarley yellow dwarf virus andseverePdeficiency.14

5.9 ManganeseOatscanbefoundtobehighlysusceptibletoMndeficiencywhichcancausesignificantyieldlosses.Inseverecases,thecropmaydie.

TissuetestsandvisualsymptomscanbeusedtohelpdiagnoseMndeficiency.Mnconcentrationslessthan20ppm(mg/kg)inwholeshootsindicateMndeficiency.TheconcentrationsofMnintissuesvaryacrossoatvarieties.

Ifmanganesesulfate(25%Mn)isappliedasafoliarsprayatarateof4kg/ha(1kgMn/hain50to100Lofwater)whensymptomsfirstappearitisusuallyeffectiveincorrectingMndeficiency;however,arepeatsprayafewweekslatermaybenecessary.

ApplyingammoniumsulfateandammoniumnitratecanmarkedlyreduceMn-deficiencysymptoms.DrillingfertilisersenrichedwithMncanreducetheriskofcropdamagefromMndeficiency.However,evenwhereanammonium-enrichedfertiliserhasbeenused,severelydeficientpatchesmaystillrequireafoliarMnspray.

OneofthesideeffectsofcorrectinganacidicsoilwithlimeisthathighersoilpHlevelsreducetheavailabilityofmanganese.Thisismostcommonongravelysoils.

13 DAFWA(2015)Oats:Fertilisersandnutrition,https://www.agric.wa.gov.au/oats/oats-fertilisers-and-plant-nutrition

14 DAFWA(2015)Oats:Fertilisersandnutrition,https://www.agric.wa.gov.au/oats/oats-fertilisers-and-plant-nutrition

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Mn-deficiency symptomsInoats,Mndeficiencyproducesaconditioncalled‘greyspeck’whichoccursinpatches.Oatsbecomepalegreenandyoungleaveshavespotsorlesionsofgrey/brown necrotic tissue with orange margins. These lesions will coalesce under severe Mn-deficientconditions.Plantsareweak,stunted,floppyandpalegreen-yellowandappear water-stressed even when adequate soil moisture is available.

Closeexaminationoftheleafmayshowslightinterveinalchlorosis.Thedistinctionbetweengreenveinsandyellowinterveinalareasispoor.Symptomscanbeconfusedwithredleatherleaf,whichisfavouredbyprevailinghighhumidityinhighrainfallareas.Symptomscanalsobemistakenfortake-all.15

5.10 CopperOatsarelesssusceptibletocopperdeficiencywhencomparedtowheatandbarley;however,Cuisessentialforgrowthanddevelopment.PlantsneedCutoproducenewcellsandforpollendevelopment(sterilepollen),andhenceCudeficiencyseverelyaffectsgrainyield.Deficientplantsthatapparentlylookhealthycanproduceshrivelledgrain,reducingbothgrainyieldandquality.

TissuetestsusingtheyoungestemergedleafcanhelpdiagnoseCudeficiency.TissuetestswithCuconcentrations<1.3mg/kgindicatetheplantisseverelyCudeficient.Applying3to9kg/haofcoppersulfate(25%Cu)withfertiliseratseedinginareassuspectedtobedeficientinCucorrectthedeficiency.Copperfertiliserhasalongresidualinthesoil,andasingleCuapplicationatrecommendedratescanlast20–30years.

Intermittenttissuetestingoftheyoungestleavescanhelpmonitortheplant-availableCu in the soil.

Ifadeficiencyisdetectedinatissuetest,itcanbecorrectedwithafoliarapplicationofCusprayedonthecropuptobootingstage.Thisisrelativelyinexpensiveandveryeffectiveatcorrectingadeficiencyandoptimisingyield.

Cu-deficiency symptomsCopper-deficientcropshaveapatchyappearance.Plantsinpoorareasarestunted,pale green and look limp and wilted even with ample soil water. Late tillers may develop at nodes or joints above ground. Young leaves turn pale green whereas old leaves remaingreen.Underconditionsofseveredeficiency,plantsmayhaveleaveswhichdiebackfromthetipandtwistintocurls.

TheearsofCu-deficientplantsareshrunkenwithgapssuchas‘frostedheads’.TheheadsofCu-deficientplantshavepoorseedsetfromsterilepollenwhichresultsin‘whiteheads’,similartotheearheadsaffectedbydrought,heatstressandfrost.16

CerealgrainyieldcanoftenbeseverelylimitedbyCudeficiencywithoutshowinganypreviousvisualsymptomsuntilthereisafailuretoformgrain.ThatiswhytissuetestingearlierintheseasonissovaluableinareaswhereCudeficiencymayoccur.

15 DAFWA(2015)Oats:Fertilisersandnutrition,https://www.agric.wa.gov.au/oats/oats-fertilisers-and-plant-nutrition

16 DAFWA(2015)Oats:Fertilisersandnutrition,https://www.agric.wa.gov.au/oats/oats-fertilisers-and-plant-nutrition