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180 kg·hm-2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0~60 cm土层硝态氮含量呈现"上升—下降—上升—下降—稳定"的变化趋势,而60~120 cm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240 kg·hm-2和300 kg·hm-2处理在60~100 cm土层硝态氮含量均显著高于其他处理。随着施氮量增加,0~120 cm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,179~209 kg N·hm-2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(Nmin). The results showed that the yield of spring maize increased significantly with N application rate increasing, but once the rate exceeded 180 kg·hm-2, 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 efficiency both first increased and then decreased. From seedling stage to maturity of spring maize, NO3--N content in 0~60 cm 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-2and 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-2, accumulated NO3--N in soil layer had high leaching risk. In view of grain yield, N utilization efficiency and environmental benefit, 179~209 kg N·hm-2was the reasonable N application rate for spring maize under the experimental conditions.