Predicting the spatial pattern of grain yield under water limiting conditions

197 Pages·2000·7.9 MB·English

by  Braga, Ricardo Nuno da Fonseca Garcia Pereira, 1970-

PREDICTINGTHESPATIALPATTERNOFGRAINYIELD
UNDERWATERLIMITINGCONDITIONS
By
RICARDONUNODAFONSECAGARCIAPEREIRABRAGA
ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL
OFTHEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT
OFTHEREQUIREMENTSFORTHEDEGREEOF
DOCTOROFPHILOSOPHY
UNIVERSITYOFFLORIDA
2000
Copyright2000
by
RicardoNunodaFonsecaGarciaPereiraBraga
ACKNOWLEDGMENTS
Manypeoplecontributedinavarietyofwaystothecompletionofthis
dissertationanddeservemydeepestgratitude. Dr.J.W.Jones,chairofthesupervisory
committee,playedakeyroleintheguidanceofthiseffort. Iwillcertainlybenefitfrom
manyofhisteachingsthroughoutmycareer. Theothersupervisorycommitteemembers
wereDr.J.TRitchie,Dr.K.J.Boote,Dr.W.D.GrahamandDr.P.A.Pinto.
Dr.J.T.Ritchie(MichiganStateUniversity)receivedmeinhisresearchgroupfor
twosummerstoconductfieldexperiments. HegavemeallthesupportIcouldhave
askedfor. Hewasextraordinaryinfindingabreakinhisscheduletocometo
Gainesville,Florida,forboththequalifyingexaminationanddissertationdefense. Dr.
K.J.Boote(UniversityofFlorida)taughtmeplantandcropphysiologywiththeright
balancebetweendescriptionandquantificationofthemainphysiologicalprocessesfrom
thecellularleveluptothecanopylevel. Dr.W.D.Graham(UniversityofFlorida)
introducedmetostochastichydrologyandkriging. Hercoursestochasticsub-surface
hydrologywasoneofthemostchallenginginmyprogrambutalsooneofthemost
rewarding. Dr.P.A.Pinto(TechnicalUniversityofLisbon,Portugal)triggeredmy
interestincropgrowthmodeling. Iamthankfulformanyofhisteachings,whichIused
throughoutmyPh.D.education,andforfindingabreakinhisscheduletocometo
Gainesville,Florida,forboththequalifyingexaminationanddissertationdefense.
TheAgriculturalandBiologicalEngineeringDepartmentatUniversityofFlorida
providedanexceptionalhomeduringthePh.D.program. Theenvironmentatthecrop-
modelinglabwasremarkable. IalsofeltathomeattheNowlinChairGroupatCropand
SoilScienceDepartment,MichiganStateUniversity. BrunoBassowasextraordinaryin
helpingtogetthefieldexperimentstarted. Ihadtheprivilegeofworkingwithvery
interestingandcompetentpeople. JohnAnibalsharedwithmehisexperiencewithfield
cropproductionintheMidwestandpracticalsolutionstovariousfieldproblemsasthey
occurred. BrianLongprovidedoutstandingtechnicalassistanceinthefieldwork.
APh.D.degreerequiresconsiderablefinancialsupport. Ibenefitedfromfundsof
TheCalousteGulbenkianFoundation(Portugal),theFulbrightFoundation
(USA/Portugal)andtheScienceandTechnologyFoundationofthePortugueseMinistry
ofScienceandTechnology(Portugal). Thecommitmentoftheseinstitutionstoimprove
thePortuguesehumanresourcesisoutstanding.
MyfamilyinPortugalgavemeextraordinarysupport. Eternalgratefulnessgoes
tomywife,Helga.
IV
11
TABLEOFCONTENTS
page
ACKNOWLEDGMENTS
iii
LISTOFTABLES viii
LISTOFFIGURES x
ABSTRACT xviii
CHAPTERS
INTRODUCTION
1 1
WhatIsSite-SpecificManagement? 1
TechnologyinSite-SpecificManagement 2
TheChallengeofSite-SpecificManagement 3
ObjectiveoftheDissertation 4
OutlineoftheDissertation 4
2 SPATIALVARIABILITYOFCORNGROWTHANDYIELDDETERMINEDBY
SOIL-WATERANDPLANTPOPULATION 7
Introduction 7
Soil-waterAvailabilitytoPlants 8
PlantPopulation 10
Objective 10
MaterialsandMethods 1
FieldExperiment 1
StatisticalAnalysis 14
ResultsandDiscussion 16
IndependentVariables 16
DependentVariables 21
IndependentVariablesEffect:RegressionAnalysis 30
Conclusions 32
3 WITHINFIELDSPATIALVARIABILITYOFCORNYIELDANDSOIL
PROPERTIESINRELATIONTOTOPOGRAPHICTERRAINATTRIBUTES...34
Introduction 34
TopographicTerrainAttributes 34
Objective 36
MaterialsandMethods 37
v
FieldExperiment 37
TopographicAttributes 38
StatisticalAnalysis 40
ResultsandDiscussion 41
Weather 41
IndependentVariables:TopographicAttributes 41
DependentVariables:SoilVariables 48
DependentVariables:CropVariables 50
Conclusions 54
4 PREDICTINGTHESPATIALPATTERNOFCORNYIELDUSINGANEURAL
NETWORKMODEL 55
Introduction 55
NeuralNetworkModels 56
Objective 58
MaterialsandMethods 59
NeuralNetworkDesign,TrainingandTesting 59
AgronomicVariables 60
SeasonRainfall 60
TopographicAttributes 61
ResultsandDiscussion 62
Conclusions 74
5 PREDICTINGWITHINFIELDSPATIALVARIABILITYOFCORNGROWTH
ANDYIELDWITHACROPSIMULATIONMODEL 75
Introduction 75
CropSimulationModels 75
Objective 78
MaterialandMethods 78
FieldExperiment 78
CropSimulationModel 80
ModelInputs 82
SimulationAnalysis 83
ResultsandDiscussion 83
ModelPredictabilityofGrowthandYield 83
FactorContributiontoPredictabilityoftheModel 91
Conclusions 93
6 USINGOPTIMIZATIONTOESTIMATESOILINPUTSOFCROPMODELSFOR
USEINSITE-SPECIFICMANAGEMENT 96
Introduction 96
Site-SpecificParametersEstimationUsingOptimization 97
Objective 100
MaterialandMethods 100
FieldExperiment 100
CropSimulationModelandInputs 102
InputSearchTechniqueandObjectiveFunctionVariables 103
vi
ResultsandDiscussion 105
GrainYieldasObjectiveFunctionVariable 105
Soil-waterContentasObjectiveFunctionVariable 118
Conclusions 127
7 SUMMARYANDCONCLUSIONS 129
FieldExperiment 130
Study1-RelatingCornGrowthandYieldtoSoil-WaterandPlantPopulation 131
Study2-RelatingCornYieldandSoilPropertiestoTopography 134
Study3-PredictionofSpatialYieldVariabilityWithNeuralNetworkModels 137
Study4-PredictionofSpatialYieldVariabilityWithCropSimulationModels 139
Study5-EstimationofSite-SpecificCropModelSoilInputs 141
GeneralConclusions,RecommendationsandFutureResearch 147
APPENDICES
A CROPANDSOILDATA 148
B ADDITIONALGRAPHSFORCHAPTERS5AND6 152
LISTOFREFERENCES 169
BIOGRAPHICALSKETCH 176
Vll
LISTOFTABLES
Table Page
Table1. Classificationofsoilseriespresentattheexperimentalfield 14
Table2-Meanvaluesandrangeofvariationforindependentanddependentvariablesin
thestudy 19
Table3. Coefficientsofdeterminationbetweenindependentanddependentvariablesfor
1997.Nonsignificantrelationshipsaremarkedwithn.s.Thesignificant
correlationareclassifiedaccordingtothelevelofsignificance(*p<0.05,**
p<0.01,***p<0.001) 23
Table4. Coefficientsofdeterminationbetweenindependentanddependentvariablesfor
1998.Nonsignificantrelationshipsaremarkedwithn.s.Thesignificant
correlationsareclassifiedaccordingtothelevelofsignificance(*p<0.05,**
p<0.01,***p<0.001) 24
Table5. Definitionsofthetopographicterrainattributesusedinthestudytocharacterize
thefieldtopography 39
Table6. Correlationcoefficientsbetweentopographicattributes.Topographicattribute
acronymsaredefinedinTable5.Nonsignificantrelationshipsaremarked
withn.s.Thesignificantcorrelationsareclassifiedaccordingtothelevelof
significance(*p<0.05,**p<0.01,***p<0.001) 49
Table7. Coefficientsofdeterminationbetweenindependentanddependentvariables.
TopographicattributeacronymsaredefinedinTable5.Nonsignificant
relationshipsaremarkedwithn.s.Thesignificantcorrelationsareclassified
accordingtothelevelofsignificance(*p<0.05,**p<0.01,***p<0.001) 50
Table8. Coefficientsofdeterminationbetweenindependentanddependentvariablesfor
1997corngrowingseason.Topographicattributeacronymsaredefinedin
Table5.Nonsignificantrelationshipsaremarkedwithn.s.Thesignificant
correlationsareclassifiedaccordingtothelevelofsignificance(*p<0.05,**
p<0.01,***p<0.001) 51
Table9. Coefficientsofdeterminationbetweenindependentanddependentvariablesfor
1998corngrowingseason.Topographicattributeacronymsaredefinedin
viii
Table5.Nonsignificantrelationshipsaremarkedwithn.s.Thesignificant
correlationsareclassifiedaccordingtothelevelofsignificance(*p<0.05,**
p<0.01,***p<0.001) 52
Table10.Rootmeansquareerror(kg/ha)forthedifferentneuralnetworkmodels.The
averagerelativeerror(%)ispresentedbetweenparentheses 62
Table11. Pcamra3/mectme3r)aenstdimsaattuersatfioronl(owSeArT,licmimt3(/LcLm,3)cfmor3/scimte3)2,drersauilnteadntupfpreormltihmeitD(SDSUALT,
andSaxtonpedotransferfunctionsandfromtheoptimizationbasedprocedure
usingyield(yield-based)andsoilwatercontent(SWC-based)asobjective
functions 106
Table12. Pcamra3/mectme3r)aenstdismaattuersatfoironl(owSeArT,licmimt3(/LcLm,3)cfmor3/scimte3)4,2drraeisunletdanutppferromlitmhietD(DSUSLA,T
andSaxtonpedotransferfunctionsandfromtheoptimizationbasedprocedure
usingyield(yield-based)andsoilwatercontent(SWC-based)asobjective
functions 107
Table13. Rootmeansquareerrorofgrainyield(kg/ha)forthesoilparameterestimation
strategies.Theaveragerelativeerror(%)ispresentedbetweenparentheses 108
Table14. Observedandsimulatedgrainyield(kg/ha)foreachoftheestimation
proceduresfor1997 109
Table15. Observedandsimulatedgrainyield(kg/ha)foreachoftheestimation
proceduresfor1998 110
Table16. Rootmeansquareerrorofsoil-watercontent(cm cm')andrelativeerrorby
soillayerdepthfortheyieldbasedandsoil-waterbasedestimation
procedures 117
Table17. Observedsitevaluesofcropvariablesin1997 149
Table18. Observedsitevaluesofcropvariablesin1998 150
Table19. Observedsitevaluesofsoilvariables 151
IX
LISTOFFIGURES
Figure Page
Figure1. Mapshowingthelocationofthe43samplingpointsusedinthestudyandthe
soilseriesdesignatedby2or3-lettercodesaccordingtotheordertwosoil
surveyat1:20000scale(ThrelkeldandFeenstra,1974).(Bt=Breckenridge;
MaA=Macomb;MsA=Metamora;WeA=Wasepi;andCtA=Conover) 13
Figure2. Cumulativerainfallfor1997and1998yearsandforthecomgrowingseasons
inthesetwoyearsmeasured200mawayfromthefieldborder 15
Figure3. Dailymeanairtemperature(above)andsolarradiationduring1997and1998
corngrowingseasons 17
Figure4. Mapsoftheaveragesand(above)andclay(below)content(%)forthetop105
cmofsoil 20
Figure5. Mapoftheeffectivesoildepth(cm) 20
Figure6. Mapofplantpopulation(#/m2)for1997(above)and1998(below)corngrowth
seasons 22
Figure7. Mapofcorngrainyield(kg/ha)for1997(above)and1998(below)growing
seasons 22
Figure8. Area-basedcumulativefrequencyofcorngrainyieldfor1997and1998
growingseason 23
Figure9. Mapofgrainnumberperearfor1997(above)and1998(below)corngrowing
seasons 25
Figure10. Mapofunitgrainweightfor1997(above)and1998(below)corngrowing
seasons 26
Figure11. Mapofgrainnumberperunitarea(#/m2)for1997(above)and1998(below)
corngrowingseasons 27
Figure12. Mapofleafareaindexatanthesisfor1997(above)and1998(below)com
growingseasons 28
x