英语1126.docx

英语1126.docx

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英语1126

EffectsofDifferentTillageSystemonSoilAggregatesofDryLand

Abstract：

manyrecentstudiesshowthatthetraditionaltillagesystembringsalotofsoildisturbance,damagingsoilstructureanddestroyingtheformationandstructureofsoilaggregates.Therefore,basedonthelong-termexperimentonthepea-wheatdouble-sequencerotationcroponrain-fedfarmlandinLongdong,LoessPlateau,undervariedtillagesystem,4tillagesystemsweresetup.Traditionaltillage（T）NotillageNocovering（NT）Traditionaltillage+Strawreturning（TS）No-tillage+strawmulching（NTS）.Theresultsshowthat,comparedwithtraditionaltillage,no-tillage,bothtraditionaltillage+strawreturningandno-tillage+strawmulchingcouldenhancethemechanicalstabilityandtheamountofwater-stablelargeaggregatesanditsstability,improvetheMWDofsoilaggregatesanddecreasethebrokerateoftheaggregates,outofwhich,no-tillage+strawcovershowspreferredresults.Simultaneously,comparedwiththeoneexperimentedin2006/2007,thewaterstabilityofthetreatedaggregatesin2013/2014wassignificantlyimproved.

Keywords：

Tillagesystem,Aggregates,MWD,PAD

Introduction

Asanutrientstorageforcropgrowthandatransformerforenergy

flow,soilisplayinganimmeasurableroleincropgrowingandecologicalenvironmentconservation.Thesoilaggregate,byconferringaharmonizedrelationshipbetweentheconsumptionandaccumulationofthesoilorganicmatter,donotonlystabilizethesoiltemperatureinthefirstplace,butalsoimprovesoiltilth,facilitatingtherootgrowth.Asaresult,soilwithbettercrumblestructurecanresultinhighyieldcropthroughimprovedaeration,thermalinsulation,moisturepreservationandfertilitypreservation.

Beingthebasicunitofsoilstructure,theamountofsoilaggregate,toacertainextent,reflectssoilcapacityintermsofnutrientsupplyandstorage,waterretentionandpermeability[1].Aggregatesofdifferentgrainsizesvaryincapacityonnutrientsretention,supplyandtransformation.Soilwithgoodstructureischaracterizedbyalargeamountofsoilaggregateswithappropriatedistributionofvariousgrainsizesandstablesoilproperty,especiallystablewaterretention.Therefore,themulti-levelsoilporositycanbemaintainedinthatwaysothatthesoilstructurewillnotdeteriorateundertheimpactsbroughtbytillage,fertilization,irrigationandraindrop[2].Soilaggregateisanindicatornotonlyforsoilstructure,butalsoforthesoilfertility.Nevertheless,soilaggregate≥0.25mmholdshighsusceptibilitytotillagesystem.Alargenumberofdomesticandforeignstudiesshowin[3-5]that,reasonablecroppingsystemcanperfectsoilstructureandreducesoilerosion,whiletheirrationalfarmingpracticescanleadtosoilfertilitydeclineandsoilerosion.Thesemi-aridareaof​​theLongzhongLoessPlateauinGansuProvince,affectedbyitstypicalclimate,geographicalposition,topography,soilstructureandetc,hasbecomeoneoftheregionswiththemostaggressivesoilerosionandfragileecologicalenvironmentbothathomeandabroad[6].Excessivesoiloverturningunderconventionaltillagetypicalinthisarearesultsinthedestructionofsoilaggregates,whiletheexposedtopsoilduringthefallowperiodcausesstrongwaterevaporationandlowutilization.Meanwhile,theremovalofcropstrawsreducesthecontentofsoilorganicmatter,whichaggravatesthedeteriorationofcultivatedlandquality[6-8].Therefore,inordertoalleviateorimprovethesoilquality,toseekappropriatecultivationmeasuresisratherpressing.Atpresent,alotofresearchesfocusesontheinfluenceoflanduseonsoilcarbonandnitrogenpool,however,fewstudiesontheeffectsofdifferentfarmingpracticesonthesame,especiallyonetargetingtheLongzhongLoessPlateauinthisparticularisrarelyreported.Forinvestigatinginfluencesonthesoilphysicalpropertyunder13aconservationtillage,inthisstudy,reliedonthelong-termconservationtillageexperimentconductedbyGansuAgriculturalUniversityin2001,inthetownofMaZichuanVillage,LiJiabuTown,AndingDistrict,DingxiCity,analysisonthecharacteristicsofsoilaggregatesin2006,2013and2014werecarriedout,withanultimategoaltoexploretheimpactsontheconstitutionanddistributionofsoilaggregatesandthebestfarmingpracticesforsustainabledevelopmentoftheLoessPlateauunderdifferenttillagepractices,providingreliabledataforfurtherresearch.

MATERIALANDMETHODS

Sitedescription.

∙TheexperimentwasperformedattheDingxiExperimentalStation（35°28'N,104°44'E）,Gansuprovince,northwestChina,atypicalsemi-aridtemperatefeaturingbydroughtandfrequentnaturaldisasters.Thesoilissandy-loamwithpHof8.3andlowfertilitysoilorganiccarbonbelow7.63g/kg.thisareaenjoyAverageelevationof2,000meters,140frost-freedays,AverageannualHoursofSunshineof2476.6h,annualsolarradiationof594.7kJ·cm-2,averageannualtemperatureof6.4°C,≥0,Caccumulatedtemperature2933.5°C,≥10°,drynessdegreeof2.53.Long-termannualrainfallatDingxiaverages391mm,withannualevaporationof1531mm,80%assuringrainfallof365mm,coefficientofdifferentiationof24.3%.Itisevidentthatthisareaisatypicalrain-fedone.

ExperimentalDesign.

Intheexperimentalfield,springwheat（cv.DingxiNo.35）andfieldpea（cv.LvnongNo.40）arecroppedunderdoublerotationsystemasspringwheat→fieldpea→springwheat（referredasW→P→Wrotation）,withspringwheatasthecropoftheseason,andfieldpea→springwheat→fieldpea（referredasP→W→Protation）,withfieldpeaasthecropoftheseason.Thetwo-rotationcropwereconductedunderfourtillagesystemasconventionaltillagewithstubbleremoved（T）,no-tillwithstubbleremoved（NT）,no-tillwithstubbleretained（NTS）andconventionaltillagewithstubbleincorporated（TS）triplereplicatedwithrandomblockdesign.Thedesignedexperimentalblockconsistsof24plotswithanareaof20m×4m=80m2.Theseedbedsforconventionaltillagewerepreparedbyploughingtoadepthof10–20cm.Ploughingwascarriedoutimmediatelyafterharvestofthepreviouscrop.Harrowingwasconductedpriortosowinginspring.InTplots,allstubbleswereremovedbeforeploughing,whereasinTSplots,allstubblesfromthepreviouscropwerereturnedtotheoriginalplotsimmediatelyafterthreshingandthenincorporatedintothesoilbyploughing.Noploughingwasperformedthroughouttheseasonintheno-tillsystem.Thecropsweresownwithno-tillseeder.InNTplots,allthestubbleswereremovedatcropharvest,whereasinNTSplots,allthestubblesfromthepreviouscropwerereturnedtotheoriginalplotsonthesoilsurfacewithoutincorporation.Plotswere4mwide×17mlonginblock1,21mlonginblocks2and3and20mlonginblock4.Thisstudywasconductedonblocks1,2and4.Springwheatwassowninmid-March,2013,atarateof187.5kg/ha,withalinespacingof20cm,andharvestedinlateJulytoearly-August.Inaddition,undereachmentionedtillagesystem,thecroppingpracticewasaccompaniedwithfertilizerapplicationofN105kg·hm-2,P2O5105kg·hm-2.FieldpeawassowninearlyApril,2013,atarateof187.5kg/hawithalinespacingof24cmandharvestedinearlyJulyeachyear,andthecroppingactivityundereachtillingsystemwasaccompaniedbyapplyingN20kg·hm-2,P2O5105kg·hm-2.Nitrogenandphosphoruswereappliedatseedingat105kg/haasurea（46%N）andat45.9kgP/haascalciumsuperphosphate（6.1%P）forspringwheatand20kgN/haand45.9kgP/haforfieldpea.Thefertilizerwasappliedsimultaneouslyatsowingbytheno-tillseeder.Theresiduesofthepreviouscrop,appliedformulching,wasgrind,cutandspreadintheplotsinanevenway.

MeasurementsandData

1500gsoilsampleswerecollectedfromthreedepthsof0–5,5–10and10–30cmoneachplotat5-spot,beforefrostedinOctober,2015andbroughtbacktolaboratoryinrigidplasticpreservationboxfordesignedexperiment（1000gsoilsampleforanalysisonsoilaggregateandrestonphysicalandchemicalproperties）.Soilorganiccarbonwasdeterminedbyamodifiedalkley-Blackwetoxidationmethod（NelsonandSommers1982）.Themethodofchloroformfumigationandextraction（FE）asdescribedbyLaddandAmato（1989）wasemployedtodeterminethemicrobialbiomasscarbon.Plantstemsandleavesweresampledfromeachplotatharvestin2014and2015croppingseasonforcarbonandnitrogenanalysis.Thecarbonandnitrogencontent（%）weredeterminedinthestemandleafwithCandNanalyzer（ElementarVarioMacroCube,Hanau,Germany）.TherootbiomassofspringwheatandfieldpeaweresampledfromeachplotatfloweringusingthemethodasdescribedbyHuangetal.（2012）.（该部分汉语中没有对应内容，请确认是否需要？

）Intheexperiment,rotatingvibratingscreen,whichcanreducethebreakrateofsoilaggregatecausedbyscreening，wasappliedtodeterminethecontentofsoilaggregatewithmechanicalstability（≥5mm、2~5mm、0.25~2mm、<0.25mm）.Eachof72soilsamplesintotalwasscreenedby5times,200gforeachtimein5minsandthecropresidueswereremovedthroughelectrostaticadsorptionafterscreeningfinished.MWD（mm）wasappliedtorepresentthestabilityofsoilaggregate.

Intheformula:

RirepresentstheMWDofsoilaggregate,wirepresentsthedryweightofthesoilaggregate.

∙Inthisstudy,thedataanddiagramwereprocessedbyExcel2003andanalyzedbySPSS19.0,thedistinctivedifferentialanalysiswasperformedbynewmultiplerangemethod.

Dataanalysis.

Statisticalanalyseswereperformedwithone-wayanalysisofvariance（ANOVA）atP<0.05throughSPSS22.0（IBMCorporation,Chicago,