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.
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