Dinitrogen (N₂) and nitrous oxide (N₂O) produced via denitrification may represent major nitrogen (N) loss in terrestrial ecosystems. A global assessment of soil denitrification rate, N₂O/(N₂O+N₂) ratio, and their driving factors and mitigation strategies is lacking. We conducted a global synthesis using 225 studies (3367 observations) to fill this knowledge gap. We found that daily N loss through soil denitrification varied with ecosystems and averaged 0.25 kg N ha⁻¹. The average emission factor of denitrification (EF_D) was 4.8%. The average N₂O/(N₂O+N₂) ratio from soil denitrification was 0.33. Soil denitrification rate was positively related to soil water-filled pore space (WFPS) (p < 0.01), nitrate (NO₃^-) content (p < 0.05) and soil temperature (p < 0.01), and decreased with higher soil oxygen content (p < 0.01). N₂ emissions increased with latitude (p < 0.05), WFPS (p < 0.01) and soil mineral N (p < 0.05) but decreased with soil oxygen content (p < 0.05). The N₂O/(N₂O+N₂) ratio increased with soil oxygen content (p < 0.01) but decreased with organic carbon (C) (p < 0.05), C/N ratio (p < 0.01), soil pH (p < 0.05) and WFPS (p < 0.01). We also found that optimizing N application rates, using ammonium-based fertilizers compared to nitrate-based fertilizers, biochar amendment, and application of nitrification inhibitors could effectively reduce soil denitrification rate and associated N₂ emissions. These findings highlight that N loss via soil denitrification and N₂ emissions cannot be neglected, and that mitigation strategies should be adopted to reduce N loss and improve N use efficiency. Our study presents a comprehensive data synthesis for large-scale estimations of denitrification and the refinement of relevant parameters used in the submodels of denitrification in process-based models.

通过反硝化作用产生的二氮(N ₂ ) 和一氧化二氮 (N ₂ O) 可能代表陆地生态系统中主要的氮 (N) 损失。缺乏对土壤反硝化率、N ₂ O/(N ₂ O+N ₂ ) 比率及其驱动因素和缓解策略的全球评估。我们使用 225 项研究（3367 项观察）进行了全球综合，以填补这一知识空白。我们发现，土壤反硝化导致的每日氮损失因生态系统而异，平均为 0.25 kg N ha ^-1。反硝化的平均排放因子（EF _D）为4.8%。平均 N ₂ O/(N ₂ O+N ₂) 来自土壤反硝化的比率为 0.33。土壤反硝化率与土壤充水孔隙空间（WFPS）（p < 0.01）、硝酸盐（NO ₃ ^-）含量（p < 0.05）和土壤温度（p < 0.01）呈正相关，并随着土壤氧含量的升高而降低(p < 0.01)。 N ₂排放量随纬度(p < 0.05)、WFPS (p < 0.01) 和土壤矿物质N (p < 0.05) 而增加，但随土壤含氧量(p < 0.05) 而减少。 N ₂ O/(N ₂ O+N ₂) 比率随土壤含氧量 (p < 0.01) 增加，但随有机碳 (C) (p < 0.05)、C/N 比 (p < 0.01)、土壤 pH (p < 0.05) 和 WFPS (p < 0.01) 而降低. 我们还发现，优化施氮量、使用铵基肥料与硝酸基肥料相比、生物炭改良剂和应用硝化抑制剂可以有效降低土壤反硝化率和相关的 N ₂排放。这些发现强调了通过土壤反硝化作用和 N ₂排放不可忽视，应采取减缓战略，减少氮损失，提高氮利用效率。我们的研究提供了一个全面的数据综合，用于大规模估计反硝化作用和改进在基于过程的模型中反硝化作用子模型中使用的相关参数。