氮肥减量后移对土壤氮素供应和夏玉米氮素吸收利用的影响

采用田间试验研究了氮肥减量后移对土壤氮素供应和夏玉米氮素吸收利用的影响。结果表明，与农民习惯施肥（N 240 kg/hm2，基肥和大喇叭口追肥为1∶2）相比，氮肥减量后移（N 168 kg/hm2，基肥、大喇叭口肥和吐丝肥为1∶3∶1）处理的产量、植株干物质积累量、植株氮积累量和积累速率均没有降低，而氮肥利用率显著增加。氮肥减量后移可使耕层无机氮供应较好地与作物吸收同步，降低收获期0—100 cm土层硝态氮积累，减少氮素的田间表观损失。基于夏玉米不同生育阶段的氮素吸收特征进行氮肥减量后移可节省氮肥30%，是较为理想的氮素施用方式。

Effects of reducing and postponing nitrogen application on soil N supply,plant N uptake and utilization of summer maize

Field experiment was conducted to investigate effects of reducing and postponing N application on soil N supply,plant N uptake and utilization of summer maize.The results show that N accumulation rate is increased under the reducing and postponing N application(N 168 kg/ha,1/5 basal,3/5 topdressing at stalk enlongation stage and 1/5 topdressing at silking stage,respectively) compared with farmers' practice(N 240 kg/ha,1/3 basal and 2/3 topdressing at booting stage,respectively),while N use efficiency,dry bi...