Abstract: In order to investigate the optimum reduction of nitrogen fertilizer rate of the wheat⁃maize rotation system，from 2018 to 2020，different fertilization measures were considered in the yellow⁃cinnamon soil area，and a total of 7 treatments were set up，including no nitrogen fertilizer（CK），conventional fertilization（FP，N 225 kg/ha），optimized fertilization（CF，N 180 kg/ha），conventional nitrogen reduction by 10%（90%FP，N 202.5 kg/ha），conventional nitrogen reduction by 20%（80%FP，N 180 kg/ha），conventional nitrogen reduction by 30%（70%FP，N 157.5 kg/ha），combined application of controlled loss urea and common urea with 7∶3（CRU，N 180 kg/ha），and the effect of reduction of nitrogen fertilizer rate on grain yield and nitrogen utilization under wheat⁃maize rotation system was explored. The results showed that in the two crop rotation cycles，the yields of wheat and maize of CF treatment were the highest，followed by CRU treatment，there was no significant difference between CRU treatment and CF treatment. Compared with FP treatment，the yields of wheat under CF treatment and CRU treatment increased by 3.62% and 2.57%，and yields of maize increased by 3.53% and 1.85% in the two crop rotation cycles，respectively；the yields of wheat and maize of 80%FP treatment decreased，but there was no significant difference.The yields of wheat and maize of the treatment with conventional nitrogen reduction by 30% decreased compared with FP treatment in the two crop rotation cycles.In the two crop rotation cycles，the contents of organic matter，total nitrogen and hydrolyzed nitrogen of CF and CRU treatments were higher than the other treatments in soil，there was no difference between the two treatments，and the content of hydrolyzed nitrogen of 70%FP treatment generally significantly decreased compared with FP treatment.The nitrogen recovery rate，agronomic efficiency of nitrogen and partial productivity of nitrogen of wheat and maize of CF and CRU treatments were higher，there was no difference between the two treatments，but were all significantly higher than FP treatment in the two crop rotation cycles. Among them，the nitrogen recovery rates of wheat and maize of CRU treatment increased by 32.1%—50.8% and 41.7%—44.2%，respectively；the agronomic efficiency of nitrogen increased by 31.7%—35.6% and 29.5%—31.9%，respectively；the partial productivity of nitrogen increased by 27.4%—28.9% and 26.9%—27.7%，respectively.Overall，for the wheat⁃maize rotation system in yellow⁃cinnamon soil area，optimized fertilization（CF treatment）and combined application of controlled loss urea and common urea with 7∶3（CRU treatment）under conventional nitrogen reduction by 20% could improve crop yield and nitrogen use efficiency，while conventional nitrogen reduction by 30% risked reduction of yield.Comprehensively considered，combined application of controlled loss urea and common urea with 7∶3 with one⁃time fertilization is the best fertilization measure in the wheat⁃maize rotation system in the yellow⁃cinnamon soil area.

Key words: Wheat, Maize, Rotation, Reduction of nitrogen fertilizer rate, Grain yield, Nitrogen use efficiency, Yellow?cinnamon soil

摘要： 为了明确黄褐土区小麦—玉米轮作体系最佳的氮肥减施量，2018—2020年在黄褐土区设置不施氮肥（CK）、常规施肥（FP，施氮225 kg/hm²）、优化施肥（CF，施氮180 kg/hm³）、常规施肥基础上减氮10%（90%FP，施氮202.5 kg/hm²）、常规施肥基础上减氮20%（80%FP，施氮180 kg/hm²）、常规施肥基础上减氮30%（70%FP，施氮157.5 kg/hm²）、控失尿素和普通尿素7∶3配施（CRU，施氮180 kg/hm²）共7个处理，探讨氮肥减施对小麦—玉米轮作体系产量和氮肥吸收利用的影响。结果表明，所有施氮处理中，2个轮作周年，CF处理小麦、玉米产量均最高，CRU处理次之，两者无显著差异。与FP处理相比，在减氮20%条件下，2个轮作周年，CF处理和CRU处理小麦产量分别提高3.62%和2.57%，玉米产量分别提高3.53%和1.85%；80%FP处理小麦、玉米产量均降低，但不显著。减氮30%处理小麦、玉米产量均较FP处理明显减产。2个轮作周年，CF处理和CRU处理土壤中有机质、全氮和水解氮含量较高，高于其他处理，但两者差异不显著，70%FP处理总体上较FP处理显著降低土壤水解氮含量。2个轮作周年，CF处理和CRU处理小麦、玉米的氮肥回收率、氮肥农学效率和氮肥偏生产力均较高，两者差异不显著，但均显著高于FP处理。其中，CRU处理小麦和玉米的氮肥回收率分别提高32.1%~50.8%和41.7%~44.2%，氮肥农学效率分别提高31.7%~35.6% 和29.5%~31.9%，氮肥偏生产力分别提高27.4%~28.9% 和26.9%~27.7%。综上，黄褐土区小麦—玉米轮作体系中，减氮20%条件下优化施肥、控失尿素和普通尿素7∶3配施均能提高作物产量和氮素利用效率，而减氮30%则存在减产风险。综合考虑，控失尿素和普通尿素7∶3配施并一次性施肥为黄褐土区小麦—玉米轮作区的最佳施肥措施。

关键词: 小麦, 玉米, 轮作, 氮肥减施, 产量, 氮肥利用率, 黄褐土