绿洲灌区小麦复种绿肥并翻压还田对翌年玉米产量形成及氮素吸收利用的影响

  【目的】  针对农田化学氮肥施用量高、利用率低等问题，探究绿肥替代部分化肥氮对玉米产量形成及氮素吸收利用的影响，为优化绿洲灌区玉米的施氮制度提供理论参考。  【方法】  于2019—2021年，在甘肃河西绿洲灌区开展小麦复种绿肥并翻压还田后翌年轮作玉米减施氮肥田间试验。玉米季设传统施氮量(Nck)和绿肥替代10%、20%、30%、40%的化肥氮处理（即N10、N20、N30、N40处理）。分析了各处理玉米产量及其构成和氮素积累量、转运量及利用效率。  【结果】  与Nck相比，N10、N20处理籽粒产量、产量构成因素及叶面积指数无显著差异，玉米植株氮素总积累量、籽粒氮素积累量及转运氮对籽粒氮素的贡献率也无显著差异；2020年N10、N20处理对玉米茎叶的氮素积累量、转运量及转运率无显著影响，2021年N20处理玉米叶片和茎的氮素积累量分别降低5.0%和17.8%，叶片和茎的氮素转运量分别提高5.5%和9.1%，氮素转运率分别提高5.0%和14.1%。相比Nck，N30、N40处理提高了茎叶的氮素积累量，但降低了氮素转运量和转运率，降低了转运氮对籽粒氮素的贡献率以及籽粒和植株的氮素积累量，N30、N40处理籽粒产量分别降低了16.8%～19.0%、27.9%～28.9%。与Nck相比，N10和N20处理氮素利用效率无显著变化，2021年N20处理氮素收获指数显著提高了3.5%，N30和N40处理降低了氮素利用效率与氮素收获指数。绿肥替代化肥氮各处理均显著提高氮肥偏生产力，以N20处理提高幅度最大。  【结论】  小麦–绿肥–春玉米体系下，绿肥翻压替代翌年玉米20%的化肥氮投入能有效协调玉米产量形成和氮素的积累转运，维持玉米籽粒产量及氮素利用效率，提高氮素收获指数与氮肥偏生产力，实现绿洲灌区玉米稳产和减氮的生产目标。

Effects of wheat multiple cropping with green manure on grain yield formation and nitrogen absorption and utilization of maize in oasis irrigation area in Northwest China

  【Objectives】  In order to avoid the low fertilizer efficiency caused by excessive chemical nitrogen (N) fertilizer input, we explored the effect of partial replacement of chemical fertilizer with green manure in oasis irrigation areas.  【Methods】  A field experiment was conducted in the Hexi Oasis Irrigation Area of Gansu in 2019–2021. Conventional chemical N rate (Nck) and different rates of substituting chemical N with 10%, 20%, 30%, 40% of green manure N, coded as N10, N20, N30, N40 respectively, were the treatments in the experiment. The maize grain yield, yield components, and the accumulation, transportation and utilization efficiencies of N were investigated.   【Results】  Compared with Nck, N10 and N20 treatments did not significantly change maize yield, yield components, maize leaf area index, total plant N accumulation, grain N accumulation at the maturity stage, and contribution of N from leaves and stems to grain. Compared with Nck, the N accumulation in the stems and leaves of maize, N translocation amount and rate were not significantly affected by N10 and N20 treatments in 2020. However, N20 significantly reduced N accumulation in leaf and stem by 5.0% and 17.8%, respectively, but significantly increased N translocation amount in leaf and stem by 5.5% and 9.1% respectively, and N translocation rate in leaf and stem by 5.0% and 14.1% in 2021, respectively. N10 and N20 treatments had no impact on the N utilization efficiency in 2020, while N20 treatment increased the N harvest index by 3.5% in 2021. Compared with Nck, N30 and N40 treatments decreased maize yields by 16.8%–19.0% and 27.9%–28.9%, respectively, reduced N translocation amount and translocation rate, contribution of N from leaves and stems to grain, but increased the N accumulation in maize leaves and stems. Compared with Nck, N30 and N40 treatments significantly reduced N use efficiency and N harvest index. Green manure substitution treatments significantly increased the partial productivity of fertilizer N. Among them, N20 treatment had the highest partial productivity of nitrogen fertilizer.  【Conclusions】  Under the spring wheat-green manure-maize system, the substitution of 20% chemical N fertilizer by green manure could effectively improve maize yield formation, and nitrogen accumulation and transportation, maintain maize yield and nitrogen utilization efficiency, and increase nitrogen harvest index and partial nitrogen fertilizer productivity. This could ultimately enhance yield stability and decrease chemical N input for maize in the Hexi oasis irrigation area.