Mitigating N2O Peaks in Rice–Wheat Rotations: Targeting Wheat-Season Windows with Straw Return

Summary

Nitrous oxide (N2O) emissions in cereal-based rotations often show short-lived peaks after fertilization, but their contribution to annual budgets and their responsiveness to straw management remain poorly quantified. We combined a 13-year legacy fertilization experiment with two years of high-frequency N2O monitoring in a rice–wheat rotation in central China to quantify post-fertilization peak windows and test how straw-return rate modulates these windows and annual emissions. Five long-term treatments were compared: an unfertilized control (CK), straw only (2M, 12 t ha−1 yr−1), mineral fertilizer (NPK), and NPK with 6 or 12 t ha−1 yr−1 straw (MNPK and 2MNPK). Under N input, wheat-season emissions dominated annual totals, with the ratio of wheat-season to annual N2O emissions (WN/TN, wher