Rainfall and irrigation trigger large pulses of the powerful greenhouse gas N₂O from intensively managed pastures, produced via multiple, simultaneously occurring pathways. These N₂O pulses can account for a large fraction of total N₂O losses, demonstrating the importance to determine magnitude and source partitioning of N₂O under these conditions. This study investigated the response of different pathways of N₂O production to wetting across three different textured pasture soils. Soil microcosms were fertilised with an ammonium nitrate (NH₄NO₃) solution which was either single or double ¹⁵N labelled, wetted to four different water-filled pore space (WFPS) levels, and incubated over two days. The use of a ¹⁵N pool mixing model together with soil N gross transformations enabled the attribution of N₂O to specific pathways, and to express N₂O emissions as a fraction of the underlying N transformation. Denitrification and nitrification mediated pathways contributed to the production of N₂O in all soils, regardless of WFPS. Denitrification was the main pathway of N₂O production accounting for >50% of cumulative N₂O emissions even at low WFPS. The contribution of autotrophic nitrification to N₂O emissions decreased with the amount of wetting, while the contribution of heterotrophic nitrification remained stable or increased. Following the hole-in-the-pipe model, 0.1%–4% of nitrified N was lost as N₂O, increasing exponentially with WFPS, while the percentage of denitrified N emitted as N₂O decreased, providing critical information for the representation of N₂O/WFPS relationships in simulation models. Our findings demonstrate that the wetting of pasture soils promotes N₂O production via denitrification and via the oxidation of organic N substrates driven by high carbon and N availability upon wetting. The large contribution of heterotrophic nitrification to N₂O emissions should be considered when developing N₂O abatement strategies, seeking to reduce N₂O emissions in response to rainfall and irrigation from intensively managed pastures.

降雨和灌溉会触发来自集约化管理的牧场的强温室气体 N ₂ O 的大量脉冲，通过多个同时发生的途径产生。这些 N ₂ O 脉冲可以占 N ₂ O总损失的很大一部分，表明在这些条件下确定 N ₂ O 的幅度和源分配的重要性。本研究调查了 N ₂ O 生产的不同途径对三种不同质地牧场土壤润湿的响应。土壤微观世界用硝酸铵 (NH ₄ NO ₃ ) 溶液施肥，该溶液为单¹⁵或双¹⁵N 标记，润湿到四种不同的充满水的孔隙空间 (WFPS) 水平，并孵育两天。使用¹⁵ N 池混合模型以及土壤 N 总转化能够将 N ₂ O归因于特定途径，并将 N ₂ O 排放表示为基础 N 转化的一部分。反硝化和硝化介导的途径有助于所有土壤中 N ₂ O的产生，无论 WFPS 是什么。反硝化是 N ₂ O 生产的主要途径，即使在低 WFPS 下，N ₂ O的累积排放量也超过 50% 。自养硝化作用对N ₂的贡献O 排放量随着润湿量的增加而减少，而异养硝化作用的贡献保持稳定或增加。遵循管中洞模型，0.1%–4% 的硝化 N 以 N ₂ O 的形式损失，随 WFPS 呈指数增加，而随着 N ₂ O排放的反硝化 N 的百分比减少，为表示提供了关键信息模拟模型中的 N ₂ O/WFPS 关系。我们的研究结果表明，牧场土壤的润湿通过反硝化作用和通过润湿时高碳和氮的可用性驱动的有机氮底物的氧化促进了 N ₂ O 的产生。异养硝化对 N ₂的巨大贡献在制定 N ₂ O 减排策略时应考虑 O 排放，寻求减少 N ₂ O 排放以应对集约化管理牧场的降雨和灌溉。