N₂O is a highly potent greenhouse gas and arable soils represent its major anthropogenic source. Field-scale assessments and predictions of soil N₂O emission remain uncertain and imprecise due to the episodic and microscale nature of microbial N₂O production, most of which occurs within very small discrete soil volumes. Such hotspots of N₂O production are often associated with decomposing plant residue. Here we quantify physical and hydrological soil characteristics that lead to strikingly accelerated N₂O emissions in plant residue-induced hotspots. Results reveal a mechanism for microscale N₂O emissions: water absorption by plant residue that creates unique micro-environmental conditions, markedly different from those of the bulk soil. Moisture levels within plant residue exceeded those of bulk soil by 4–10-fold and led to accelerated N₂O production via microbial denitrification. The presence of large (∅ >35 μm) pores was a prerequisite for maximized hotspot N₂O production and for subsequent diffusion to the atmosphere. Understanding and modelling hotspot microscale physical and hydrologic characteristics is a promising route to predict N₂O emissions and thus to develop effective mitigation strategies and estimate global fluxes in a changing environment.

中文翻译：

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植物残渣吸收水分增强了土壤N2O排放的热点

N ₂ O是一种强力温室气体，可耕土壤是其主要的人为来源。由于微生物N ₂ O产生的情景和微观性质，田间规模的土壤N ₂ O排放评估和预测仍然不确定且不精确，其中大多数发生在非常小的离散土壤体积内。N ₂ O产生的这种热点通常与分解植物残渣有关。在这里，我们对导致植物残渣引起的热点中N ₂ O排放急剧加速的物理和水文土壤特征进行了量化。结果揭示了微尺度N ₂的机制O排放：植物残渣吸收的水会产生独特的微环境条件，与散装土壤的环境明显不同。植物残渣中的水分含量比散装土壤中的水分含量高4-10倍，并通过微生物反硝化作用加速了N ₂ O的产生。大孔隙（∅ >  35μm）的存在是最大化产生热点N ₂ O以及随后扩散到大气中的先决条件。了解和建模热点的微观尺度的物理和水文特征是预测N ₂ O排放并因此开发有效的缓解策略并估计变化的环境中的总体通量的有前途的途径。