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IOWASOYBEANASSOCIATIONRESEARCHUPDATEPeterKyveryga,Ph.D.,DirectorofAnalytics,IowaSoybeanAssociationSuzanne Fey, Data Analyst, Iowa Soybean Association

Rainfall,FieldManagementandSoilsImpactonWithin-FieldProfitability

Profitabilityincropproductionislargelydrivenbycropyield,productioncostsandcommodityprices.Anyoneintheindustryisawarethatmuchoftheartofsuccessfulfarminginvolvesriskmanagementandmitigation.Farmershavelimitedcontroloverkeyfactorsthatsignificantlydriveprofitabilitysuchasinputcosts,marketpricesandtheweather.Thesearethebestunderstoodandmostreadilyacceptedaspectsofriskmanagement.

Marketshavenotbeenfavorableforcommoditiesinthelastfourtofiveyears.AccordingtoIowaStateUniversityExtensionandOutreach(ISUEO,2007-2017)andtheUnitedStatesDepartmentofAgriculture(USDA)NationalAgriculturalStatisticsSurvey(NASS,2018),theaveragecornandsoybeanpricesin2010-2012generatedaprofit,whereastheaveragecornandsoybeanpricesin2014-2017generatedaneconomicloss(Figure.1).

Figure1:AverageIowacommoditypricesandinputcostsincornandsoybeanproduction,2007-2017.

Quantifyingtheinteractionbetweenweather,cropproductivityandfieldvariabilityiscomplex(Muth,2014;Kyverygaetal.,2012).Modernprecisionagriculturaltechnologiesandpubliclyavailablespatialdataaboutweatherandsoilsnowprovideinformationthatenablesfocusatsubfieldlevels(Bonneretal.,2014;Brandesetal.,2016).Theimpactoffieldmanagement,weatherandfieldspatialvariabilityisoftendifficulttoassessforindividualfieldsorforagroupoffieldswithinagivengeographicarea.

Inthispublication,profitandreturnoninvestment(ROI)mapsofmanyfarmers’fieldsareusedtoquantifytheimpactofin-seasonrainfallandsoilcharacteristicsonwithin-fieldprofitabilityintwoIowalandformregions.

Analyzingdatacollectively

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FarmersfromCentralandNortheastIowasharedcornandsoybeanyielddatacollectedbetween2007and2014.Thedatasetcomprised380site-years-worthofyieldmapsfrom77individualfields(Figure2).Eachfieldhadatleastthreeyearsofspatialyielddata.Onaverage,fieldshadfouryearsofyielddataandsomefieldshadeightconsecutiveyearsofdata.

Figure2.Locationsof77cornandsoybeanfieldsinCentral(DesMoinesLobe)andEastern(IowanSurface)Iowausedinprofitabilityanalyses.

SpatialyielddatacollectedbyGPS-enabledyieldmonitorswereprovidedbyfarmers.Additionalinformationaboutfieldmanagement,fieldhistoryandthecroppingsystemwerecollectedaswell.Whilesomefarmersalsoprovidedfield-specificcropbudgetinformation,analysesreliedoncurrentandhistoricalcostofproductionestimates(EstimatedCostsinCropProductioninIowa,IowaStateUniversity).Theproductioncostinformationincludes,amongotheritems,thestateaveragecostforfertilizerandchemicals,planting,applicationandharvestmachinery,landrentandlabor,insuranceandloaninterest.Sincerelativewithin-fieldspatialprofitabilityremainedconstantregardlessofbudgettemplate,standardproductioncostswereemployedtoeliminatethisvariable,therebymakingdifferencesrelatedtothefactorswewerestudyingmoreapparent.

Acommercialsoftware,ProfitZoneManager(AgSolver,2015),wasusedtoproduceprofitabilityandROImaps.Standarddeviationinprofitacrossallavailableyearswascalculatedfromprofit,creatingthethreemapsinFigure3.

Inaddition,ISAdividedtheprofitabilityandROImapsinto30x30-footgridcellsandaddedfieldmanagement,landformregion,soilcharacteristicsandrainfallinformation.

SpatialdatalayersusedintheanalysesincludeSoilConditioningIndex,erosionestimates,SSURGOsoils(NRCS),elevationandslope(NationalElevationDataset)andLiDARPotholeandWetlandsimages(IowaDNR).ProfitabilityandROIrasterimageswereconvertedtovectorpointfiles.Spatialdatawereanalyzedat30x30-footresolution.Datawereresampledtomaintainconstantresolution.Monthlyrainfallvaluesfromthe4kmrainfallestimatesintheIowaEnvironmentalMesonetdatabasewereaddedtoeachfield.

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Figure3.MapsofMeanProfit,ROIandStandardDeviationofprofitacrossfouryearsforafieldincorn-soybeanrotation.

CentralIowaresults

Distributionsofwithin-fieldprofitvaluesforfieldsplantedtosoybean,cornaftersoybeanandcornaftercornfrom2008-2013indicatethatareaswitheconomiclossrangedfrom5to45percent(Figure4).Theeffectoflowgrainpricesandincreasedlandrentpricesweremorepronouncedin2013.Thehistogramsfor2009and2011showbimodaldistributionsofprofitvalues,indicatingsomeotherfactorsaffectedprofitabilityinadditiontomarketpriceandproductioncost.

Figure4.Histogramsof30x30-footprofitcellsacross52fieldsinCentralIowafrom2008-2013.Theredverticallineseparatesgridcellswithpositiveandnegativeprofit.

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ThecumulativedistributionsinFigure5indicatethatacorncropwasmorelikelytobeprofitablethansoybean,andthatthefield-levelprofitwassubstantiallyreducedinpotholeareascomparedwithuplandareas–especiallywhenspringrainfallwasexcessive.Althoughsoybeanfieldstendedtohavealowerprofit,theyalsowerelessaffectedbytheexcessiverainfallandpoorlydrainedpotholeareas.

Figure5.DistributionofprofitvaluesinpotholeanduplandareaswithincornandsoybeanfieldsofCentralIowafrom2007through2014.Theprofitgridcellswereclassifiedbasedonthespringrainfall:wet(>12inches)andnormal.Thecumulativedistributioncurvesindicatetheprobabilityofaprofitvalueatspecificvalueandbelow.Thedifferencebetweentwocategoriesissignificantiftwocumulativedistributioncurvesdonotcrosseachother.

Multivariateanalysesoffield-levelmedianprofitvaluessuggestedthatearlyseasonrainfallwasoneofthedrivingfactorsinreducingprofitabilitywithintheDesMoinesLobe(datanotshown).WitheachadditionalcmofrainfallinMayorJune,medianfieldlevelprofitwasreducedby$22to$55anacreforfieldsplantedtocorn(Figure5).AsshowninFigure6,comparedwithcorn,soybeanfieldswereunaffectedbyMayrainfallandlessaffectedbyJunerainfall.

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Figure6.EffectofMayandJunerainfallonfield-levelmedianprofitsforfieldsplantedtosoybean,cornaftersoybeanandcornaftercornwithintheDesMoinesLobelandformregion.

EasternIowaresults

SimilartoCentralIowa,analysesof25fieldswith111siteyearsofdatainEasternIowa(IowanSurface)showedthatsubstantialportions,upto50percent,hadeconomicloss,especiallyduring2013and2014(datanotshown).TheeffectofearlyseasonrainfallwasdifferentinEasternIowathaninCentralIowa.Excessivespringrainfallhadnosignificanteffectonfieldlevelprofitability(Figure7).However,fieldmedianprofitvaluestendedtoincreasewithabove-normalJulyrainfall.Thisindicatesthatsomeoftheareas(likelythosewithsandysoils)ranoutofwaterduringmidsummerandbenefitedfromadditionalrainfallinJuly.

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Figure7.Effectofspring(MarchthroughMay)andJulyrainfallonfield-levelmedianprofitsforfieldsplantedtosoybean,cornaftersoybeanandcornaftercornwithinEasternIowa.ThecumulativedistributionfunctionsofprofitvaluesinFigure8suggestthatexcessivelydrainedwithin-fieldareasinEasternIowahadlowerprofitcomparedwiththepoorlyorwelldrainedareas,exceptincornoncornfields.Somesoybeanfields,however,tendedtobemoreaffectedbysoildrainagethancornfields.

TheeffectofrainfallinEasternIowawasdifferentthaninCentralIowa.Specifically,theprofitabilityincreasedbyabout$20anacrewitheachadditionalinchofJulyrainfall.

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Figure8.Cumulativedistributionfunctionsoffield-levelprofitvaluesforexcessively,poorly,andwell-drainedareaswithinfieldsplantedtosoybean,cornaftersoybeanandcornaftercornwithinEasternIowabetween2007and2014.Analysisofspatialvariabilityinprofit,ROIorstandarddeviationvaluesacrossseveralyearssuggestthatonlyasmallpercentageofwithin-fieldvariabilitycouldbeexplainedbyspatialvariables.Forexample,inseveralfields,cornsuitabilityrating(CSR)indexexplainedabout16percentofspatialvariability,drainageexplained22percentandsoilorganicmatterexplainedabout15percentofthespatialvariabilityinEasternIowa.Soilswithhigherproductivity,higherCSRandlessexcessivedrainagetendedtohavehigherprofitabilityandROIalongwithlowerstandarddeviationvaluesthanthosefieldswithlowersoilorganicmatterandlowerproductivity.Logically,thefactthatspatialvariablescouldonlyexplainasmallpercentagewithin-fieldvariabilityinprofitcouldbetheresultoflargelyuniformtractsoflandwithinthefieldsevaluated.Fieldsselectedforin-depthspatialevaluationswerelimitedtothosewithfiveormoreyearsofspatialdata.Morestudyisrequiredtosupportthishypothesis.ConclusionIncentralIowa,potholeshadconsistentlylargereconomiclosses(15to75percent),withgreaterlossesoccurringduringawetspringwithmorethan12inchesofrainfallbetweenMarchandMay.Whilefieldsplantedtocorntendedtohavehigherprofitabilitythanthoseplantedtosoybean,thecornprofitabilitywasreducedmorebypoorsoildrainage,especiallyduringwetsprings.

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DuringanormalspringinCentralIowa,cornfieldsweremorelikelytohavealargerprofitthansoybeanfields.Forthepotholeareas,soybeanfieldswerelessnegativelyaffectedbyspringrainfallandhadlowereconomiclossesthancornfields.Therefore,soybeanislessaffectedbyexcessivemoistureandpoorlydrainedsoilswithinpotholeareas.

WithintheIowanSurface,halfofthewithin-fieldareashadeconomicloss,especiallyin2013and2014.Comparedtocorn,excessivedrainagehadapronouncednegativeeffectonwithin-fieldprofitabilityinsoybean.TheeffectofrainfallintheIowanSurfaceregionwasdifferentthanthatwithintheDesMoinesLobe.Above-normalJulyrainfalltendedtoincreaseprofitabilityincornfieldsbyabout$20anacrewitheachadditionalinchofrainfall,indicatingthatsomeoftheareas(likelysandyorexcessivelydrained)mayhaverunoutofmoistureduringmidsummer.

Thisstudyusedspatialcornandsoybeanyielddataandcropbudgetsinconjunctionwithsite-specificrainfallandsoilcharacteristicstoidentifythedegreetowhichacombinationofseveralfactorscanbeusedtohelpfarmersmakethebestland-usedecisions.Thepresentedanalysesarecriticalforguidingthedesignanddevelopmentoffurtherstudiesthatcanleadtothecreationofriskmitigationtoolsforfarmers.

WewouldliketothanktheIowafarmerswhogenerouslysharedtheirdatawithusandOn-FarmNetwork®staffwhohelpedtocollectandprocessthedata.WewouldalsoliketothankAgSolver,Inc.,Ames,Iowaforrecruitingparticipants,themassgenerationofcustomdatasets,forresponsivecustomerserviceanddeliveryonspecialrequests.

References

Brandes,E.,G.S.McNunn,L.A.Schulte,I.J.Bonner,D.J.Muth,B.A.Babcock,B.Sharma,E.A.Heaton.2016.Subfieldprofitabilityanalysisrevealsaneconomiccaseforcroplanddiversification.EnvironmentalResearchLetters,doi:10.1088/1748-9326/11/1/014009.

Bonner,I.J.,K.G,Cafferty,D.J.Muth,M.D.Tomer,E.J.James,S.A.Porter,D.Karlen.2014.Opportunitiesforenergycropproductionsbasedonsubfieldscaledistributionofprofitability.Energies,7:6509-6526.

Kyveryga,P.M.,T.M.Blackmer,P.C.Caragea.Categoricalanalysisofspatialvariabilityineconomicyieldresponseofcorntonitrogenfertilization.AgronomyJ.2011,103,796–804.

Muth,D.2014Profitabilityversusenvironmentalperformance:aretheycompeting?J.SoilWaterCons.69203a–06aa.ProfitZoneManager.2015.AgSolverInc,Ames,IA.

Thanks to Dr. Larry Hendrickson, Iowa State University, for review of this article.