春玉米产量、氮肥效率及土壤矿质氮对施氮的响应

为了提高氮肥增产效益，减少对环境的污染，通过田间试验研究了施氮量对春玉米产量、氮肥效率及土壤矿质氮的影响。结果表明，施氮量较低时，春玉米籽粒产量随施氮量增加显著增加，当施氮量高于180kg·hm2时，产量保持不变或有减少趋势。氮肥农学利用率、氮素吸收效率、氮素偏生产力和氮收获指数均随着施氮量增加显著降低，氮肥表观利用率和氮肥生理利用率均先增加后降低。从苗期到收获期，施氮处理0～60cm土层硝态氮含量呈现“上升一下降一上升一下降一稳定”的变化趋势，而60～120cm土层硝态氮在春玉米生长后期有增加的趋势。随着土层加深，土壤硝态氮含量呈波浪式下降，施氮量240kg·hm-2和300kg·hm-2处理在60～100cm土层硝态氮含量均显著高于其他处理。随着施氮量增加，0～120cm土层硝态氮累积量显著增加，当施氮量超过240kg·hm-2时，土层中累积的硝态氮存在着较大的淋溶风险。综合考虑产量、氮肥效率和环境效应，179—209kgN·hm。是本试验条件下春玉米的合理施氮量。

Response of Spring Maize Grain Yield,Nitrogen Efficiency and Soil Mineral Nitrogen to Nitrogen Application

In order to increase crop production and reduce environmental pollution by nitrogen（N ） fertilizer, a field experiment was carried out to study the effects of N application rate on spring maize grain yield, N use efficiency and temporal and spatial dynamics of soil mineral N （N）. The results showed that the yield of spring maize increased significantly with N application rate increasing, hut once the rate exceeded 180 kg. hmq, the yield began to keep stable or trend to decline. With increasing of N application rate, N agronomic use efficiency, N uptake efficiency, N partial productivity and N harvest index all decreased significantly, however, N apparent use efficiency and N physiological use et~iciency both first increased and then decreased. From seedling stage to maturity of spring maize, NO3--N content in 0-60 era soil layer showed a trend of increase-decrease-increase-decrease and keeping stable at the end, but in 60-120 cm soil layer showed a trend of in- crease at the late growing stage under N treatment. With increasing of soil depth, soil NO3--N content decreased in a wave manner, when N application rates were 240 kg-hm-2 and 300 kg-hm-2, NO3--N content in 60--100 cm soil layer was significantly higher than that under other N treatments. With the increase of N application rate, NO3--N accumulation in 0--120 cm soil layer increased significantly, but once the rate exceeded 240 kg＂ hm-g, accumulated NOf-N in soil layer had high leaching risk. In view of grain yield, N utilization efficiency and environ- mental benefit, 179--209 kg N·hm-2 was the reasonab]e N application rate for spring maize under the experimental conditions.