Abstract:

The efficacy of integrating green manure in arid irrigation regions to enhance maize yield and nitrogen (N) uptake efficiency has been extensively explored. However, limited research has delineated the contribution of green manure N vs. soil N on crop N utilization efficiency. This study integrated field experiments with micro-plot experiments to examine green manure (common vetch) management practices for achieving high maize yield and N uptake. In a micro-plot experiment, ¹⁵N technology was utilized to label green manure crops. Five treatments were applied in the research methodology: conventional tillage without green manure as the control (CT), tillage with total green manure incorporation (TG), no-tillage with total green manure mulching (NTG), tillage with only root incorporation (T), and no-tillage with removal of aboveground green manure (NT). The results of the micro-plot experiment were consistent with those observed in the field, demonstrating that the utilization of green manure substantially increased maize yield and nitrogen uptake efficiency (NU_PE) compared to CT. In particular, under NTG, N uptake by maize from green manure was higher than NT and T, accounting for 59.1% of maize N uptake. Furthermore, applying NTG boosted the NU_PE of soil N in maize to 50.7%, higher than TG by 5.5%. Meanwhile, it decreased the proportion of soil N in the maize. The difference between NTG and TG was primarily shown in the maize grains. For N transport in the soil, NTG decreased N loss while increasing soil N retention. Also, it facilitated the mineralization of soil organic N before the flowering stage. In conclusion, adopting no-tillage with total green manure mulching increased N uptake from green manure and the soil and decreased the proportion of soil-derived N in maize.