Abstract: The aim of this study was to investigate effect of straw returning on crop yield and nitrogen uptake and utilization efficiency of wheat rice rotation system. There are low nitrogen use efficiency and the high production of crop residues and improper handling of straw caused a series of environmental pollution in wheat-rice rotation system of Chengdu Plain. A field experiment was conducted to study the effect of different amount of straw incorporation on grain yield, dry matter accumulation and nitrogen use efficiency in wheat wheat-rice rotation system. No fertilizer, chemical fertilizer and no straw incorporation (control), chemical fertilizer and total straw incorporation, chemical fertilizer and half of straw incorporation, and chemical fertilizer and 1.5 times straw incorporation were investigated. Results showed that compared with no straw mulching treatment, straw incorporation could increase the grain yields of wheat and rice, wheat yield increased by 8.4% to 19.6%, and wheat yield-raising range improved with the amount of straw increasing; rice yield increased by 4.3% to 17.1%, and rice yield-raising range reduced with the amount of straw increasing. Comparing with no straw incorporation treatment, the results also indicated that straw incorporation promoted the growth of wheat and rice, and increased nitrogen uptake and grain nitrogen accumulation. The N uptake and grain nitrogen accumulation of wheat improved with the amount of straw increasing; straw incorporation inhibited rice growth and nitrogen uptake before the jointing stage, but acted reversely after the stage. The N uptake and grain nitrogen accumulation of rice reduced with the amount of straw increasing. Straw incorporation increased grain yield, N fertilizer use efficiency, and agronomic N use efficiency in straw incorporation treatments were higher than control by 10% to 13.8%, 19.5% to 26.7%, and 6.71 to 8.21 kg·kg^-1 in the wheat rice rotation system respectively; Half straw incorporation (CT+0.5S) was the most advantageously treatment to improve the yield and nitrogen use efficiency under the experimental conditions, and compared half amount of straw (CT+0.5S) with full amount of straw (CT+1S), both of yield and nitrogen use efficiency both showed no significant difference. Considering the stock of straw resources, the crop yield and nitrogen use efficiency, we suggest that the full amount of straw incorporation (CT+1S) is suitable for rice wheat rotation system in Chengdu plain. The research findings will provide references for avoiding the pollution of environmental pollution caused by large amount of crop straw.

Key words: straw incorporation, wheat-rice rotation, grain yield, N uptake and utilization

摘要： 为探讨秸秆还田量对麦-稻轮作体系作物产量、氮素吸收利用效率的影响,以小麦(内麦863)和水稻(F优498)为试验材料,在麦-稻轮作体系作物氮肥利用效率低的成都平原,采用田间小区试验,研究秸秆不还田、半量还田、全量还田和1.5倍量还田等处理模式对麦-稻轮作体系作物产量、氮素吸收以及利用效率的影响.结果表明,与对照(无秸秆还田处理)相比,秸秆还田提高了小麦和水稻产量,小麦增产8.4%~19.6%,增产幅度随秸秆还田量的增加而增加;水稻增产4.3%~17.1%,增产幅度随秸秆还田量的增加而减少.秸秆还田促进小麦和水稻的生长,增加小麦和水稻氮素吸收和籽粒氮素累积;小麦氮素吸收量和籽粒的氮素累积量均随秸秆还田量增加而增加;秸秆还田抑制了水稻前期(拔节期)生长和氮素累积,促进后期生长和氮素累积,水稻氮素吸收量和籽粒的氮素累积量均随秸秆还田量增加而减少.相较对照,麦-稻轮作体系的产量、氮素表观利率和氮素农学利用效率分别增加10%~13.8%、19.5%~26.7%、6.71~8.21 kg·kg^-1,其中半量还田最有利于提高稻麦轮作体系的产量和氮素利用效率,但半量秸秆和全量秸秆还田相比,产量以及氮素利用效率差异均不显著.综合考虑秸秆资源存量情况、作物产量和氮素利用效率,秸秆全量还田较适宜成都平原麦-稻轮作区,有利于实现作物高产,氮素高效利用.该研究将为避免作物秸秆产生量大而处理不当引起的环境污染提供参考.

关键词: 秸秆还田, 麦-稻轮作, 产量, 氮素吸收利用