资源环境科技发展态势分析平台

Robust global simulation of soil background N₂O emissions (BNEs) is a challenge due to the lack of a comprehensive system for quantification of the variations in their magnitude and location. We mapped global BNEs based on 1353 field observations from globally distributed sites and high-resolution climate and soil data. We then calculated global and national total BNE budgets and compared them to the IPCC-estimated values. The average BNE was 1.10, 0.92, and 0.84 kg N ha⁻¹ year⁻¹ with variations from 0.18 to 3.47 (5th–95th percentile, hereafter), 0.20 to 3.44, and −1.16 to 3.70 kg N ha⁻¹ year⁻¹ for cropland, forestland, and grassland, respectively. Soil pH, soil N mineralization, atmospheric N deposition, soil volumetric water content, and soil temperature were the principle significant drivers of BNEs. The total BNEs of three land use types was lower than IPCC-estimated total BNEs by 0.83 Tg (10¹² g) N year⁻¹, ranging from −47% to 94% across countries. The estimated BNE with cropland values were slightly higher than the IPCC estimates by 0.11 Tg N year⁻¹, and forestland and grassland lower than the IPCC estimates by 0.4 and 0.54 Tg N year⁻¹, respectively. Our study underlined the necessity for detailed estimation of the spatial distribution of BNEs to improve the estimates of global N₂O emissions and enable the establishment of more realistic and effective mitigation measures.