Nitric oxide (NO), as a short-lived climate forcer, has direct and indirect detrimental impacts on environmental quality and human health. The amount of nitrogen (N) fertilizer application to agricultural soils is considered a robust predictor of total NO emissions, but the estimates of cropland NO emissions have large uncertainties due to the widely used constant emission factors (EF) as e.g., default values recommended by Intergovernmental Panel on Climate Change (IPCC) methodologies. By compiling 223 field experiments with at least three N-input levels across various croplands, we performed a meta-analysis to determine how soil NO emissions respond to N inputs. Our results showed for the first time that the mean change in EF per unit of additional N input (∆EF) across all available data was significantly higher as compared to zero, indicating that the NO response to N additions increased significantly faster than the assumed linear. On average, upland grain crops showed significantly higher ∆EF than that of horticultural crops or lowland rice. A higher ∆EF was also appeared in sites with mean annual precipitation < 600 mm, mean annual temperature ≥ 15 °C, soil organic carbon ≥ 14 g C kg^− 1 or total N ≥ 1.4 g N kg^− 1, and where synthetic N fertilizers were usually applied. By assuming various N application rates, the IPCC default (0.7% or 1.1%) EF model would have overestimated or underestimated NO emissions compared to our ∆EF model. Overall, our meta-analysis results exert high potential to improve estimates of cropland NO inventories, and help address disparities in global NO budgets and develop more targeted mitigation efforts.

一氧化氮（NO）作为一种短暂的气候驱动因素，对环境质量和人类健康具有直接和间接的有害影响。农业土壤的氮肥施用量被认为是 N2O 总排放量的有力预测指标，但由于广泛使用的恒定排放因子 (EF)，农田 N2O 排放量的估算具有很大的不确定性，例如，政府间气候变化专门委员会 (IPCC) 方法。通过对不同农田至少三种氮输入水平进行 223 项田间实验，我们进行了荟萃分析，以确定土壤 NO 排放对氮输入的反应。我们的结果首次表明，所有可用数据中每单位额外 N 输入 (ΔEF) 的 EF 平均变化显着高于零，这表明 NO 对 N 添加的响应增加明显快于假设的线性。平均而言，旱地粮食作物的 ΔEF 显着高于园艺作物或低地水稻。年平均降水量 < 600 mm、年平均气温 ≥ 15 °C、土壤有机碳 ≥ 14 g C kg ^{− 1}或全氮≥  1.4 g N kg ^{− 1}以及合成氮的地点也出现较高的 ΔEF通常施用肥料。通过假设不同的施氮量，与我们的 ΔEF 模型相比，IPCC 默认（0.7% 或 1.1%）EF 模型会高估或低估 NO 排放量。总体而言，我们的荟萃分析结果在改进农田二氧化氮库存估算方面具有很大潜力，有助于解决全球二氧化氮预算的差异，并制定更有针对性的减排工作。