Chinese milk vetch (Astragalus sinicus L) is a widely used leguminous green manure in paddy rice culture and has potential to replace or partly replace inorganic nitrogen (N) fertilizer. However, there is little quantitative information regarding replacing inorganic N with milk vetch on CH₄ and N₂O emissions. This study investigated the relationship between greenhouse gas production and carbon (C) and N release under 0%, 25%, 50%, 75% and 100% substitution of urea-N with milk vetch aboveground litter in a paddy soil. CH₄ and N₂O emission fluxes were measured using a static chamber method and milk vetch decomposition rates were tested by mesh bag method. After incorporation, C and N release from milk vetch followed a single exponential decay model, with 82.3–89.1% and 98.8–98.9% of the original C and N released during 125 days. CH₄ flux was positively correlated with milk vetch substitution ratio, while it was negative correlated with N₂O flux. Compared with 0% substitution, 25% substitution decreased global warming potential (GWP) and greenhouse gas intensity (GWP per unit of grain yield) by 12.1% and 10.3%, respectively, while 100% substitution increased GWP and greenhouse gas intensity by 38.4% and 65.2%, respectively. The results showed that soil pH, NH₄⁺-N and redox state were significantly correlated with CH₄ emission, while C and N remaining in the incorporated milk vetch residue and NH₄⁺-N were key factors regulating N₂O emission. It could be concluded that replacing 25% of urea-N with milk vetch was most effective in greenhouse gas mitigation while maintaining rice yield.

紫云英（Astragalus sinicus L）是水稻栽培中广泛使用的豆科绿肥，具有替代或部分替代无机氮（N）肥的潜力。_{然而，关于用紫云英代替无机氮对 CH 4}和 N ₂ O 排放的定量信息很少。本研究调查了稻田土壤中在 0%、25%、50%、75% 和 100% 尿素-N 与紫云英地上凋落物替代条件下温室气体产生与碳 (C) 和 N 释放之间的关系。CH ₄和 N ₂使用静态室法测量 O 排放通量，并通过网袋法测试紫云英分解率。掺入后，紫云英的 C 和 N 释放遵循单一指数衰减模型，在 125 天内释放了 82.3-89.1% 和 98.8-98.9% 的原始 C 和 N。CH ₄通量与紫云英替代率呈正相关，与N ₂ O通量呈负相关。与 0% 替代相比，25% 替代使全球变暖潜势（GWP）和温室气体强度（每单位粮食产量的 GWP）分别降低了 12.1% 和 10.3%，而 100% 替代使 GWP 和温室气体强度增加了 38.4%和 65.2%，分别。结果表明，土壤pH、NH ₄ ⁺_{-N和氧化还原状态与CH 4}排放呈显着相关，而紫云英残渣中残留的C和N以及NH ₄ ^{+ -N是调节N} ₂ O排放的关键因素。可以得出结论，用紫云英代替 25% 的尿素-N 在减少温室气体排放的同时保持水稻产量最有效。