Effect of postponing N application on soil N supply,plant N uptake and utilization in winter wheat

摘要: Field experiment was carried out to investigate postponing N application on soil supply,plant uptake and utilization in winter wheat.Results obtained showed that,compared with farmers' practice(N 300 kg/ha,1/2 basal 1/2 topdressing at jointing stage,respectively),postponing treatment(N 210 kg/ha,1/3 basal,1/3 top- dressing stage 1/3 booting stage,respectively)improved use efficiency greatly,and mini- mized apparent losses without grain yield losses.Excessive application(N kg/ha)increased NO_3~--N content be- low 60 cm profile different growth stage,which would result high risk of NO3--N leaching into underground wa- ter.Postponing increased nitrate accumulation the 0-20 reduced 20-100 profile.Therefore it concluded that based plant is a feasible management practice,and nitrogen fertilizer could be saved by 30 % as compared farm- ers' practice.