Effect of N Fertilization on Grain Yield of Winter Wheat and Apparent N Losses

(整期优先)网络出版时间:2006-06-16
/ 1
Excessivenitrogen(N)fertilizerapplicationtowinterwheatisacommonproblemontheNorthChinaPlain.TodeterminetheoptimumfertilizerNrateforwinterwheatproductionwhileminimizingNlosses,fieldexperimentswereconductedfortwogrowingseasonsateightsites,inHuiminCounty,ShandongProvince,from2001to2003.TheoptimumNrateformaximumgrainyieldwasinverselyrelatedtotheinitialsoilmineralNcontent(Nmin)inthetop90cmofthesoilprofilebeforesowing.TherewasnoyieldresponsetotheappliedNatthethreesiteswithhighinitialsoilmineralNlevels(average212kgNha-1).TheaverageoptimumNratewas96kgNha-1forthefivesiteswithlowinitialsoilNmin(average155kgNha-1)beforesowing.ResidualnitrateNinthetop90cmofthesoilprofileafterharvestincreasedwithincreasingfertilizerNapplicationrate.TheapparentNlossesduringthewheat-growingseasonalsoincreasedwithincreasingNapplicationrate.TheaverageapparentNlosseswiththeoptimumNrateswerelessthan15kgNha-1,whereasthefarmers'conventionalNapplicationrateresultedinlossesofmorethan100kgNha-1.Therefore,optimizingNuseforwinterwheatconsiderablyreducedNlossestotheenvironmentwithoutcompromisingcropyields.