Effectsofureaseandnitrificationinhibitorsaddedtoureaonnitrousoxideemissionsfromaloesssoil

摘要

Ureafertilizer-inducedN2Oemissionsfromsoilsmightbereducedbytheadditionofureaseandnitrificationinhibitors.Here,weinvestigatedtheeffectofureagranule(2–3mm)addedwithanewureaseinhibitor,anitrificationinhibitor,andwithacombinedureaseinhibitorandnitrificationinhibitoronN2Oemissions.Forcomparison,theureagranulessuppliedwithorwithoutinhibitorswerealsousedtopreparecorrespondingsupergranules.Thepotexperimentswithoutvegeta-tionwereconductedwithaloesssoilat(20±2)°Cand67%water-filledporespace.Ureawasaddedatadoseof86kgNha–1bysurfaceapplication,bysoilmixingofprills(<1mm)andgran-ules,andbypoint-placementofsupergranules(10mm)at5cmsoildepth.Asecondexperimentwasconductedwithspringwheatgrownfor70dinagreenhouse.Thesecondexperimentincludedtheapplicationofureaprillsandgranulesmixedwithsoil,thepoint-placementofsuper-granulesandtheadditionoftheureaseinhibitor,andthecombinedureaseplusnitrificationinhi-bitorsat88kgNha–1.Inbothexperiments,maximumemissionsofN2Oappearedwithin2weeksafterfertilization.Inthepotexperiments,N2Oemissionsaftersurfaceapplicationofureawereless(0.45%to0.48%oftotalfertilization)thanfromtheapplicationfollowedbymixingofthesoil(0.54%to1.14%).TheN2Oemissionsfromthepoint-placed-supergranuletreatmentamountedto0.64%oftotalfertilization.Inthepotexperiment,theadditionofthecombinedureaseplusnitrificationinhibitors,nitrificationinhibitor,andureaseinhibitorreducedN2Oemis-sionsby79%to87%,81%to83%,and15%to46%,respectively,atanysizeofureaapplica-tion.Also,theN2Oemissionsfromthesurfaceapplicationoftheurease-inhibitortreatmentexceededthoseofthegranulesmixedwithsoilandthepoint-placed-supergranuletreatmentsreceivingnoinhibitorsby32%to40%.Inthewheatgrowthexperiment,theN2Olossesweregenerallysmaller,rangingfrom0.16%to0.27%ofthetotalfertilization,thaninthepotexperi-ment,andtheapplicationoftheureaseinhibitorandthecombinedureaseplusnitrificationinhibi-torsdecreasedN2Oemissionsby23%to59%.Thepoint-placedureasupergranulewithoutinhi-bitorsdelayedN2Oemissionsupto7weeksbutresultedinslightlyhigheremissionsthanappli-cationoftheureaseinhibitorandtheureaseplusnitrificationinhibitorsundercroppedconditions.OurresultsimplythattheapplicationofureafertilizeraddedwiththecombinedureaseandnitrificationinhibitorscansubstantiallyreduceN2Oemissions.