摘要：

针对华北地区冬小麦-夏玉米轮作区氮肥用量大、损失严重而控释尿素成本高、推广难的问题,基于3 a 6季冬小麦-夏玉米轮作田间定位试验,探究不同减氮条件下普通尿素配施控释尿素对氮素利用的影响,以期在前期明确控释尿素与普通尿素适宜配比的基础上进一步优化施氮量,进而为华北冬小麦-夏玉米轮作区化学氮肥减量增效和控释尿素的推广应用提供技术参考。试验设置6个处理:不施氮(CK)、农民习惯施氮(FH,冬小麦季施氮270 kg/hm²,夏玉米季施氮240 kg/hm²,基追比为1∶1)和不同减氮条件下配施控释尿素的处理(N1、N2、N3和N4:冬小麦季分别施氮243,216,189,162 kg/hm²,其中控释氮占40%;夏玉米季分别施氮216,192,168,144 kg/hm²,其中控释氮占30%;均一次性基施)。结果表明:与FH处理相比,仅N1处理可实现冬小麦和夏玉米的连年增产增收,可使冬小麦在2017-2018年,2019-2020年分别显著增产4.0%,5.4%,即使在2018-2019年其他减氮处理均减产的情况下仍可增产1.6%;可使各年夏玉米青贮产量显著增加,平均增产10.9%;各季作物收获后0~100 cm,60~100 cm土层土壤无机氮积累量较FH显著降低,6季作物累计氮素利用率较FH提高11.3百分点。在减氮10%条件下按适宜比例配施控释尿素(即:冬小麦季施氮243 kg/hm²,配施40%控释氮;夏玉米季施氮216 kg/hm²,配施30%控释氮)可提高小麦-玉米轮作中的作物产量和累计氮肥利用率,并减少土壤无机氮素的累积和淋失。

关键词: 小麦-玉米轮作, 氮, 控释尿素, 产量, 氮肥利用率

Abstract:

In view of the problems of excessive input of nitrogen(N)fertilizer,serious nitrogen loss and soil N accumulation,and hard to popularize controlled-release urea(CRU)because of its high cost,this research,based on the field experiment including six crop growing seasons over three years,explored the application effect of combined CRU with urea under the condition of reduced N rate in winter wheat-summer maize rotation and aimed for optimizing the N application rate under applying the optimized blending application ratio of CRU and urea,so as to provide the technical references for reducing chemical N fertilizer input,increasing its use efficiency and generalizing CRU.The experimental design consisted of six treatments:CK(No N application),FH(urea with 270-240 kg/ha N application on winter wheat and summer maize respectively;50% of the total N applied once and 50% dressing).For N1,N2,N3 and N4 treatments, mixture of CRU and urea(controlled release nitrogen accounting for 40% of the total nitrogen content) was applied once before planting at 243,216,189 and 162 kg/ha respectively for winter wheat,and was applied at 216, 192, 168, and 144 kg/ha with controlled release nitrogen accounting for 30% respectively for summer maize.The results showed that:compared with FH,only N1 increased the yield and net profit of winter wheat and summer maize for three consecutive years.For winter wheat,N1 increased significantly the yield by 4.0%,5.4% in 2017-2018 and 2019-2020,respectively,and still increased the yield by 1.6% even in 2018-2019 that the yields of other treatments were decreased.N1 also increased significantly summer maize's yield by 10.9%.In addition,after harvesting winter wheat and summer maize per year,amount of accumulation of inorganic N in 0-100 cm and 60-100 cm soil layer of N1 was significantly lower than that of FH, while the cumulative N use efficiency of N1 after 6 growing seasons of crop was increased by 11.3 percentage point.These results demonstrated that a mixture of CRU and urea (at a ratio of controlled release nitrogen accounting for 40% and 30% of the total nitrogen content for wheat and maize respectively)with a 10% reduction in N application rate compared to FH could be more beneficial to increase crop yield and nitrogen use efficiency, and reduce leaching of soil inorganic nitrogen in wheat-maize rotation system.

Key words: Wheat maize rotation, Nitrogen reduction, Controlled-released urea, Yield, Nitrogen use efficiency