The combination of nitrogen (N) fertilization and straw incorporation has complex influences on soil N transformations and derived nitrous oxide (N₂O) emissions. This study aimed to reveal the coupled effects of straw returning forms and N fertilizer management on soil N₂O emissions. Here, carbon (C) sources with varied availabilities were supplied by different straw returning forms, including straw, charred straw, and combined application of straw and charred straw. The time gaps between additions of exogenous N and C sources were carried out by managing the timing of N fertilization, including N application simultaneous with or delayed after straw return. Soil N₂O emissions under different straw returning forms and their response relationships to soil C, N, microbial biomass, as well as soil pH and oxygen (O₂) were explored. Co-application of straw and N fertilizer provided sufficient C and N sources, enhanced the microbial biomass, and consequently increased N₂O emissions. Delayed N fertilization could decouple the response of N₂O emissions to straw addition, because of constrained N availability and limited pH decline, which decreased the cumulative N₂O emissions significantly. Possibly due to straw induced N immobilization coupled with charred straw induced pH elevation, the combined application of straw and charred straw constrained soil N₂O emissions compared with straw only application, regardless of N fertilizer management. By shaping the microbial biomass and soil C, N, and O₂ dynamics, delayed application of N fertilizer could further enhance the inhibition effect of the charred straw and straw combination on soil N₂O emissions. Therefore, the varied straw returning forms and the timing of N fertilization could affect the supply of available C and N, influencing the hot moments of N₂O emissions, and the joint addition of straw and charred straw with a few weeks delayed N application could possibly reduce the risk of soil N₂O emissions from straw return systems. Such mitigation potential should be evaluated further under field conditions.

中文翻译：

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施秸秆和秸秆焦化后延迟施氮改变了土壤N2O排放的热时刻

氮 (N) 施肥和秸秆还田相结合对土壤氮转化和衍生的一氧化二氮 (N ₂ O) 排放具有复杂的影响。_{本研究旨在揭示秸秆还田方式和施氮肥管理对土壤N 2} O排放的耦合影响。在这里，不同可用性的碳（C）源由不同的秸秆还田形式提供，包括秸秆、秸秆炭化以及秸秆和秸秆炭化的联合应用。外源氮源和碳源添加之间的时间间隔是通过管理氮肥施肥的时间来实现的，包括在秸秆还田的同时或延迟施氮。土壤N ₂探讨了不同秸秆还田方式下的O排放及其对土壤C、N、微生物量、土壤pH值和氧气（O _{2 ）的响应关系。}秸秆与氮肥共施提供了充足的碳源和氮源，提高了微生物生物量，从而增加了N ₂ O的排放。_{延迟施氮可以解除 N 2} O 排放对秸秆添加的响应，因为受限的 N 可用性和有限的 pH 值下降显着降低了累积的 N ₂ O 排放。可能是由于秸秆诱导的 N 固定化加上烧焦的秸秆诱导的 pH 升高，秸秆和烧焦的秸秆的联合施用限制了土壤 N ₂O 排放量与仅施用秸秆相比，不考虑氮肥管理。通过塑造微生物生物量和土壤C、N和O _{2动态，延迟施用N肥可以进一步增强炭化秸秆和秸秆组合对土壤N 2} O排放的抑制作用。_{因此，不同的秸秆还田方式和施氮时机会影响速效C和N的供给，影响N 2} O排放的热点，秸秆与炭化秸秆联合施氮延迟数周可可能降低秸秆还田系统排放土壤 N ₂ O的风险。应在现场条件下进一步评估这种缓解潜力。