Straw returning and nitrogen reduction: Strategies for sustainable maize production in the dryland.

Implementing continue straw returning practices and optimizing nitrogen application can mitigate nitrogen losses and enhance nitrogen use efficiency (NUE) in dryland. N-labeled technique offers a robust approach for tracking fertilizer nitrogen fate and assessing nitrogen use efficiency. Based on the continue (>6 yr) experiment, we conducted a two-year experiment (2020 and 2021) to evaluate the effects of straw returning and nitrogen management under plastic film mulching on N recovery rates, NO emissions and maize yield with three treatments: no straw returning with 225 kg N·ha under plastic film mulching (RP-N), straw returning with 225 kg N·ha under plastic film mulching (RPS-N), and straw returning with 20% nitrogen reduction (180 kg N·ha) under plastic film mulching (RPS-N). After six years, both continue straw returning with plastic film mulching increased uptake of fertilizer nitrogen, had higher N recovery rates than RP-N, leading to increased N accumulation in grain and aboveground biomass, ultimately enhancing yield. The RPS-N treatment exhibited the highest spring maize yield and nitrogen harvest index. The RPS-N treatment significantly increased maize yield more than RP-N and had the highest NUE, partial factor productivity of nitrogen fertilizer, and nitrogen uptake efficiency, with improvements ranging from 1.7 to 2.4%, 19.3-29.6%, and 17.3-27.5%, respectively, compared to the other treatments. Moreover, RPS-N resulted in significantly higher cumulative NO emissions and yield-scaled NO emissions than the other treatments, whereas the RPS-N treatment significantly decreased yield-scaled NO emissions compared to RP-N. Hence, combining continue straw returning with appropriate nitrogen reduction can effectively increase maize yield and yield-scaled NO emissions. By offering insights into optimizing nitrogen fertilizer management after continue maize straw return, this study is contributed to widespread adoption of straw return practices and sustainable agricultural development in semi-arid areas.