水稻-油菜轮作条件下氮肥效应及其后效

【目的】从周年轮作的角度分析了氮肥施用对水稻-油菜轮作体系中作物产量、氮素吸收量、肥料利用率的影响以及水稻季施用氮肥在油菜季的后效特点，比较和明确不同施肥处理下水稻-油菜轮作体系经济效益的差异。【方法】2010-2011年在湖北省洪湖市布置前茬水稻不同氮肥用量以及后茬油菜裂区施氮和不施氮两个副区的田间试验，研究了不同施氮条件下水稻和油菜的产量、氮素吸收量和氮肥利用率。根据试验结果分析稻油轮作系统氮肥后效及经济效应。【结果】由于氮肥用量和分配的不同，作物产量、氮肥利用率和经济效应表现出明显地差异，水稻季施氮165 kgN?hm-2产量最高，氮肥利用率最大；水稻季施用的氮肥具有明显的后效，显著增加油菜产量107-644 kg?hm-2，氮素吸收量增加3.9-35.2 kg?hm-2，相当于油菜季施氮5-33 kgN?hm-2的增产效果。氮肥的后效与施氮量成正比，虽然水稻季高氮处理增加氮肥后效，但是降低了水稻产量、当季氮肥利用率以及经济效益。本试验条件下，水稻季和油菜季施氮量均为165 kgN?hm-2时，经济效益最高。【结论】合理的氮肥施用能明显提高水稻和油菜的产量，在整个周年水旱轮作中水稻季氮肥具有一定的后效，油菜生长季应该在充分考虑前茬水稻氮肥后效的基础上进行优化推荐施用。

Study on N Fertilizer Efficiency and the Residual Effect Under Rice-Oilseed Rape Rotation System

【Objective】 To optimize fertilization strategy further in the rice-oilseed rape rotation system, the effects of N fertilizer application on crop yield, N uptake, N use efficiency and the residual effects of N fertilizer applied in rice season were studied in the annual rotation system. Meanwhile, the economical benefit with different N fertilizer treatments in the rice-oilseed rape rotation system were estimated. 【Method】A field experiment, to study crop yield, N uptake, N use efficiency, the residual effects of N fertilizer and economical benefit in the rice-oilseed rape rotation system were conducted in Honghu county, Hubei province from May 2010 to May 2011. Different N application rate treatments was included in the rice season. While in the oilseed rape season the original treatment in the rice season was split into with and without N application sub-treatments. 【Result】 Due to the different application rate and allocations of N fertilizer, the differences among the yield, N use efficiency and economical benefit were significant. In rice season, the yield and N use efficiency were the highest when N application rate was 165 kg N•hm-2. The residual effects of N fertilizer applied in rice season were significant, which could improve the yield of oilseed rape, ranging from 107 to 644 kg•hm-2. The N uptake of oilseed rape also increased significantly, from 3.9 to 35.2 kg N•hm-2. The residual effects of N fertilizer were equivalent to 5-33 kg N•hm-2 N fertilizer applied in the oilseed rape season. The residual effects were positively correlated with N application rate. Nevertheless, in the rice season excessive N fertilizer application rate would decrease the rice yield, N use efficiency and economical benefit. Overall the economical benefit was the largest when both N application rate in rice and oilseed rape season were 165 kg•hm-2. 【Conclusion】Reasonable N fertilization could significantly increase yield of rice and oilseed rape. N application in rice season had a significant residual effect. Therefore, optimum N fertilization management in oilseed rape season should consider the residual effect of N application in rice season.