关键词: 小麦, 玉米, 轮作, 氮肥减施, 产量, 氮肥利用率, 黄褐土

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