During grazing, some of the nutrients ingested by cattle are returned to grassland as urine and dung patches and can be lost as greenhouse gases. Sites where cattle congregate are more likely to have overlapping excreta patches favouring enhanced nitrous oxide (N₂O) emissions. However, there is no consensus about the magnitude of these or simultaneous methane (CH₄) emissions or potential mitigation options. This study investigated the effect of combined cattle dung and urine depositions on N₂O and CH₄ emissions, compared with emissions from separate depositions, under different weather conditions. Local emission factors (EFs) were then calculated for both gases. A quantitative assessment of published studies was also performed to search for N₂O emissions drivers. Two field experiments were performed during two 98-day trials under dry and wet conditions in Tandil, Argentina. Treatments included fresh excreta patches of urine (0.75 L), dung (2.50 kg), dung + urine (2.50 kg + 0.75 L) from Holstein dairy cows, and a control (without excreta). Soil and excreta properties were analysed, and N₂O and CH₄ fluxes from the patches were measured using the static chamber technique. Patches containing dung were shown to be localised CH₄ hotspots. Urine applied to soil, and the addition of urine to dung patches had a negligible effect on CH₄ fluxes. Urine, dung and combined patches were found to be localised N₂O sources. Adding urine to dung patches under wet weather had a significant synergetic effect (threefold increase) on cumulative N₂O emissions compared with the theoretical sum of separate excreta patches. Adding urine to dung patches under dry conditions gave an additive effect on N₂O. These findings suggest that preventing overlapping excreta patches under wet conditions can help mitigate N₂O emissions from temperate managed grazed pastures. The effect of combining excreta patches was also evident in the EF values obtained. That for CH₄ was consistent with the default IPCC value (0.75 g CH₄ kg⁻¹ VS), while N₂O (EF = 0.03–0.39%) was lower than the updated IPCC 2019 value of 0.6%.

在放牧期间，牛摄入的一些营养物质会以尿液和粪便的形式返回草原，并可能作为温室气体流失。牛聚集的地点更有可能有重叠的排泄物斑块，有利于增加一氧化二氮 (N ₂ O) 的排放。_{然而，对于这些或同时的甲烷 (CH 4} ) 排放量或潜在的缓解方案，尚无共识。本研究调查了牛粪和尿液联合沉积对 N ₂ O 和 CH _4的影响排放量，与不同天气条件下不同沉积物的排放量相比。然后计算两种气体的当地排放因子 (EF)。还对已发表的研究进行了定量评估，以寻找 N ₂ O 排放驱动因素。在阿根廷坦迪尔的干燥和潮湿条件下进行了两次为期 98 天的试验，进行了两次现场试验。处理包括来自荷斯坦奶牛的新鲜排泄物块（0.75 L）、粪便（2.50 kg）、粪便+尿液（2.50 kg + 0.75 L）和对照（无排泄物）。分析了土壤和排泄物特性，并使用静态室技术测量了来自贴片的N ₂ O 和 CH _4通量。显示含有粪便的斑块定位于 CH ₄热点。将尿液施用于土壤，将尿液添加到粪块中对 CH ₄通量的影响可以忽略不计。发现尿液、粪便和混合斑块是局部的 N ₂ O 源。与单独排泄块的理论总和相比，在潮湿天气下向粪块中添加尿液对累积 N ₂ O 排放具有显着的协同效应（增加三倍）。在干燥条件下将尿液添加到粪块中会对 N ₂ O 产生累加效应。这些发现表明，在潮湿条件下防止重叠的排泄物块有助于减轻 N ₂温带管理放牧牧场的 O 排放。在获得的 EF 值中，结合排泄物贴片的效果也很明显。CH ₄与 IPCC 的默认值（0.75 g CH ₄ kg ^-1 VS）一致，而 N ₂ O（EF = 0.03–0.39%）低于 IPCC 2019 年更新值 0.6%。