土壤高残留氮条件下施氮对夏玉米氮素平衡、利用及产量的影响

土壤残留氮是不容忽视的土壤氮素资源.通过田间小区试验研究了土壤高残留氮下不同施氮量(0、80、160、240和320 kg/hm2)对夏玉米土壤硝态氮积累、氮素平衡、氮素利用及产量的影响,分析了夏玉米的经济效益.结果表明,土壤剖面硝态氮积累量随施氮量的增加而增加,且施氮处理硝态氮积累量显著高于不施氮处理；各施氮处理土壤硝态氮在0-60 cm土层含量最高,在0--180 cm剖面呈先减少后增加的变化趋势.不施氮处理夏玉米收获后土壤无机氮残留量高达378 kg/hm2,随施氮量的增加,无机氮残留和氮表观损失显著增加.作物吸氮量、氮表观损失量与总氮输入量呈显著正相关,总氮输入量每增加l kg作物吸氮量增加0.156 kg,而表观损失量增加0.369 kg,是作物吸氮量的2.4倍.高残留氮土壤应严格控制氮肥用量,以免造成氮素资源的大量浪费.夏玉米籽粒吸氮量随施氮量的增加呈增加的趋势,氮收获指数呈降低的趋势.氮肥农学效率、氮肥生理利用率、氮肥利用率和氮素利用率在施氮量80 kg/hm2时最高,随施氮量的增加降低；增施氮肥能降低高残留氮土壤中氮肥的增产效果和利用率.综合考虑产量、氮素利用和环境效应,N 80 kg/hm2是氮素高残留土壤上玉米的合理施氮量.

Effects of nitrogen application on nitrogen balance and use efficiency and yield of summer maize in soil with high residual nitrogen

 Residual mineral nitrogen (Nmin) is an important nitrogen resource in soils. A field experiment was carried out to study the effects of different nitrogen application rates (0, 80, 160, 240 and 320 kg/ha) on soil NO₃^--N accumulation, nitrogen balance and use efficiency and yield of summer maize in soil with high residual nitrogen. The results indicate that soil NO₃^--N accumulation are increased with the increase of nitrogen application rates.NO₃^--Naccumulations of the nitrogen treatments are significantly higher than that of the non nitrogen treatment. The highest NO₃^--N accumulation appears at 0-60 cm soil layers. The NO₃^--Naccumulations are decreased at first, and then increased with the depth of soil profile. The residual Nmin of the non nitrogen treatment is high as 378 kg/ha after summer maize harvest. With the increase of nitrogen application rates, the residual Nmin and nitrogen apparent loss are increased significantly. There are positively correlation between crop nitrogen uptake, nitrogen apparent loss and total nitrogen input. As total nitrogen input is increased by 1 kg, crop nitrogen uptake and nitrogen apparent loss are increased by 0.156 and 0.369 kg, respectively. Nitrogen fertilizer application rates must be controlled strictly in high residual nitrogen soils to avoid the waste of nitrogen resources. With the increase of nitrogen application rates, grain nitrogen uptake of summer maize increases, while the nitrogen harvest index decreases. Nitrogen fertilizer agronomic efficiency, physiological use efficiency, and nitrogen use efficiency are the highest in the treatment of N 80 kg/ha, and they decrease with the increase of nitrogen application rates. The nitrogen application reduces the yield increasing effect and nitrogen utilization in high residual nitrogen soils. In view of the yield, nitrogen utilization and environmental benefit, N 80 kg/ha is the reasonable nitrogen application rate in soils with high residual nitrogen.