Grazing-based production systems are a source of soil greenhouse gas (GHG) emissions triggered by excreta depositions. The adoption of Urochloa forages (formerly known as Brachiaria) with biological nitrification inhibition (BNI) capacity is a promising alternative to reduce nitrous oxide (N₂O) emissions from excreta patches. However, how this forage affects methane (CH₄) or carbon dioxide (CO₂) emissions from excreta patches remains unclear. This study investigated the potential effect of soils under two Urochloa forages with contrasting BNI capacity on GHG emissions from cattle dung deposits. Additionally, the N₂O and CH₄ emission factors (EF) for cattle dung under tropical conditions were determined. Dung from cattle grazing star grass (without BNI) was deposited on both forage plots: Urochloa hybrid cv. Mulato and Urochloa humidicola cv. Tully, with a respectively low and high BNI capacity. Two trials were conducted for GHG monitoring using the static chamber technique. Soil and dung properties and GHG emissions were monitored in trial 1. In trial 2, water was added to simulate rainfall and evaluate GHG emissions under wetter conditions. Our results showed that beneath dung patches, the forage genotype influenced daily CO₂ and cumulative CH₄ emissions during the driest conditions. However, no significant effect of the forage genotype was found on mitigating N₂O emissions from dung. We attribute the absence of a significant BNI effect on N₂O emissions to the limited incorporation of dung-N into the soil and rhizosphere where the BNI effect occurs. The average N₂O EFs was 0.14%, close to the IPCC 2019 uncertainty range (0.01–0.13% at 95% confidence level). Moreover, CH₄ EFs per unit of volatile solid (VS) averaged 0.31 g CH₄ kgVS⁻¹, slightly lower than the 0.6 g CH₄ kgVS⁻¹ developed by the IPCC. This implies the need to invest in studies to develop more region-specific Tier 2 EFs, including farm-level studies with animals consuming Urochloa forages to consider the complete implications of forage selection on animal excreta based GHG emissions.

以放牧为基础的生产系统是由排泄物沉积引发的土壤温室气体 (GHG) 排放源。采用具有生物硝化抑制 (BNI) 能力的Urochloa牧草（以前称为Brachiaria）是减少排泄物斑块中的一氧化二氮 (N ₂ O) 排放的有前景的替代方案。然而，这种草料如何影响排泄物斑块的甲烷 (CH ₄ ) 或二氧化碳 (CO ₂ ) 排放仍不清楚。本研究调查了两种具有不同 BNI 能力的Urochloa牧草下土壤对牛粪沉积物温室气体排放的潜在影响。此外，N ₂ O 和 CH ₄确定了热带条件下牛粪的排放因子 (EF)。牛放牧星草（不含 BNI）的粪便沉积在两个草料地块上：Urochloa hybrid cv. Mulato 和Urochloa humidicola cv. Tully，分别具有低和高 BNI 容量。使用静态室技术进行了两项温室气体监测试验。在试验 1 中监测土壤和粪便特性以及温室气体排放。在试验 2 中，添加水以模拟降雨并评估潮湿条件下的温室气体排放。我们的研究结果表明，在粪块下，牧草基因型影响每日 CO ₂和累积 CH ₄在最干燥的条件下排放。然而，没有发现牧草基因型对减轻粪便中的 N ₂ O 排放有显着影响。_{我们将 BNI 对 N 2} O 排放没有显着影响归因于粪氮有限地掺入到发生 BNI 效应的土壤和根际。平均 N ₂ O EF 为 0.14%，接近 IPCC 2019 的不确定性范围（在 95% 的置信水平下为 0.01-0.13%）。此外，每单位挥发性固体 (VS) 的 CH ₄ EF 平均为 0.31 g CH ₄  kgVS ^-1，略低于 0.6 g CH ₄  kgVS ^-1由 IPCC 开发。这意味着需要对研究进行投资，以开发更多针对特定区域的二级 EF，包括对食用Urochloa牧草的动物进行农场层面的研究，以考虑牧草选择对基于动物排泄物的温室气体排放的完整影响。