通过八年的田间定位试验,研究玉米秸秆还田配施氮肥对春玉米产量、剖面土壤无机氮积累、氮素平衡和氮肥利用效率的影响。结果表明,通过线性加平台回归方程,求得2012～2019年最高玉米产量所需要的适宜施氮量依次为202.7、193.7、182.2、171.2、163.6、156.1、150.7和150.5 kg/hm_²。氮素表观损失量和土壤残留矿质氮量均随着施氮量增加而显著增加,并且两者与施氮量之间均呈显著的正相关关系。每增加10 kg/hm_²施氮量,土壤残留矿质氮量、氮素表观损失量分别增加9.09～10.34、5.89～7.34 kg/hm2。当施氮量超过150 kg/hm_²时,各处理间玉米吸氮量差异不显著,而土壤残留矿质氮、氮素表观损失量之间差异均达显著水平(P<0.05)。另外,随着施氮量增加,氮肥利用率呈现先增加后减小趋势,当施氮量为150 kg/hm_²时,两年氮肥利用率分别达到最高(75.2%和92.3%)。当施氮量为210～330 kg/hm_²,剖面土壤无机氮残留量显著增加,造成土壤无机氮在土壤深层(60～100 cm)的大量累积。

The effects of combined straw returning and applying nitrogen fertilizer on yield of spring maize, accumulation of inorganic nitrogen in soil profile, nitrogen balance and nitrogen use efficiency were studied in a field experiment for eight years. The results showed that t the optimum nitrogen application rates for 2012-2019 were 202.7, 193.7, 182.2, 171.2, 163.6, 156.1, 150.7 and 150.5 kg/hm_² respectively, according to the linear regression equation. Both apparent nitrogen loss and residual mineral nitrogen increased significantly with the increase of nitrogen application rate, and there was a significant positive correlation between them and nitrogen application rate. For applying nitrogen amounts of 100kg/hm_² , the residual mineral N and the apparent loss of N increased by 9.09-10.34 and 5.89-7.34 kg/hm_² respectively. When the nitrogen application rate exceeded 150 kg/hm_², there was no significant difference in nitrogen uptake, but the apparent loss of N and residual mineral N in soil was significant among different treatments. With the increase of N application rate, N use efficiency increased at first and then decreased. When N application rate reached 150 kg/hm2, N use efficiency reached the highest (75.2% and 92.3%). In the range of 210-330 kg/hm2 nitrogen application, the residual inorganic nitrogen increased significantly, which resulted in the accumulation of inorganic nitrogen in deep soil (60-100cm).

吉林省农业科技创新工程杰出青年项目（CXGC2017JQ008）项目资助、吉林省科技发展计划项目(20200402103N C)、国家重点研发计划项目（2016YFD0200304)