Pulsed N2O emissions resulting from field management practices (N fertilization addition and straw return) or rainfall events make for a significant proportion of the total annual N2O budget from croplands. However, it remains unclear whether altered rainfall patterns induced by climate change will stimulate the responses of pulsed N2O emissions to various field practices. In this study, we aimed to elucidate the underlying mechanisms driving pulsed N2O emissions in response to extreme rainfall events and examine their interaction with carbon and nitrogen availability. We hypothesized that highly available substrates rapidly induce an anaerobic environment and N2O pulses during extreme rainfall events. A soil column experiment under simulating extreme rainfall events was conducted to investigate the responses of pulsed N2O emissions to three common farming practices: nitrogen fertilization (N), nitrogen fertilization coupled with low straw return (N+LS), and nitrogen fertilization coupled with high straw return (N+HS). We frequently monitored surface emissions and soil concentrations of N2O and CO2, and measured O2, NH4+, NO3- and DOC concentrations. N and straw amendments together under simulated rainfall events significantly depleted O2, and simultaneously increased pulsed N2O emissions. The N+HS treatment exhibited the highest soil N2O concentration (51.9 µL L−1) and lowest O2 concentration (4.3 %), along with high soil moisture levels (24.8 %–32.2 %). Correspondingly, the highest cumulative N2O emissions were observed in the N+HS treatment (117.8 mg m−2), followed by 52.2, 31.9, and 11.0 mg m−2 for the N+LS, N, and CK treatments, respectively. The promotion of N2O production by highly available substrates confirms our hypothesis. Our work contributes to the refinement of global climate models and field mitigation practices, as pulsed N2O emissions from croplands will increase under future extreme rainfall events owing to climate change.

中文翻译：

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在模拟极端降雨事件和农业土壤秸秆改良剂下，一氧化二氮排放量显著增加


田间管理实践（施氮和秸秆还田）或降雨事件产生的脉冲 N2O 排放占农田年度 N2O 总预算的很大一部分。然而，目前尚不清楚气候变化引起的降雨模式改变是否会刺激脉冲 N2O 排放对各种田间实践的响应。在这项研究中，我们旨在阐明响应极端降雨事件驱动脉冲 N2O 排放的潜在机制，并检查它们与碳和氮可用性的相互作用。我们假设在极端降雨事件期间，高可用性底物会迅速诱导厌氧环境和 N2O 脉冲。在模拟极端降雨事件下进行了土壤柱实验，以研究脉冲 N2O 排放对三种常见耕作方式的响应：氮肥施用 （N）、氮肥配低秸秆还田 （N+LS） 和氮肥配肥配高秸秆还田 （N+HS）。我们经常监测地表排放物以及土壤中 N2O 和 CO2 的浓度，并测量 O2、NH4+、NO3- 和 DOC 浓度。在模拟降雨事件下，氮和秸秆改良剂一起显着消耗了 O2，同时增加了脉冲 N2O 排放。N+HS 处理表现出最高的土壤 N2O 浓度 （51.9 μL L-1） 和最低的 O2 浓度 （4.3 %），以及高土壤水分水平 （24.8 %–32.2 %）。相应地，在 N+HS 处理中观察到最高的累积 N2O 排放量 （117.8 mg m-2），其次是 N+LS、N 和 CK 处理的 52.2、31.9 和 11.0 mg m-2。高可用性底物对 N2O 产生的促进证实了我们的假设。 我们的工作有助于完善全球气候模型和现场缓解实践，因为在气候变化导致的未来极端降雨事件中，农田的脉冲 N2O 排放将增加。