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. ¹⁵N-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 ¹⁵N recovery rates, N₂O emissions and maize yield with three treatments: no straw returning with 225 kg N·ha^-1 under plastic film mulching (RP-N₂₂₅), straw returning with 225 kg N·ha^-1 under plastic film mulching (RPS-N₂₂₅), and straw returning with 20% nitrogen reduction (180 kg N·ha^-1) under plastic film mulching (RPS-N₁₈₀). After six years, both continue straw returning with plastic film mulching increased uptake of fertilizer nitrogen, had higher ¹⁵N recovery rates than RP-N₂₂₅, leading to increased ¹⁵N accumulation in grain and aboveground biomass, ultimately enhancing yield. The RPS-N₂₂₅ treatment exhibited the highest spring maize yield and nitrogen harvest index. The RPS-N₁₈₀ treatment significantly increased maize yield more than RP-N₂₂₅ 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-N₂₂₅ resulted in significantly higher cumulative N₂O emissions and yield-scaled N₂O emissions than the other treatments, whereas the RPS-N₁₈₀ treatment significantly decreased yield-scaled N₂O emissions compared to RP-N₂₂₅. Hence, combining continue straw returning with appropriate nitrogen reduction can effectively increase maize yield and yield-scaled N₂O 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.