A meta-analysis of 78 studies (233 site-years) reveals that nitrous oxide (N₂O) emissions from agricultural soils increase exponentially with nitrogen (N) fertilizer inputs, contradicting the linear assumptions used in IPCC greenhouse gas inventories. The study found that N₂O emissions grow significantly faster than linear for synthetic fertilizers and most crop types, with N-fixing crops showing the highest rate of change in emission factors (ΔEF). Soils with carbon >1.5% and pH <7, and those with annual fertilizer applications, also showed higher ΔEF. The results suggest that N₂O emissions increase exponentially as N inputs exceed crop needs. This finding implies that current IPCC default emission factors (1%) may be too conservative for high N-input rates. The study highlights the importance of using a nonlinear emission factor to improve the accuracy of N₂O emission assessments, address global budget disparities, and refine mitigation strategies. In low-input systems like those in sub-Saharan Africa, modest N additions have little impact on emissions, while excessive fertilization leads to disproportionate increases. The study also shows that the current IPCC default EF may underestimate emissions in high-input regions, such as China's North China Plain. The ΔEF model developed in this study provides a more accurate representation of N₂O emissions than the IPCC default, particularly for N inputs above 90 kg·ha⁻¹. The findings suggest that the largest mitigation gains can be achieved in areas with excessive fertilizer use, while little mitigation is possible in regions where N is most needed. The study underscores the need for more research on N₂O emissions from agricultural soils, particularly in different climates and with varying fertilizer formulations. The results have important implications for improving the accuracy of national and regional inventories of N₂O emissions from fertilized agricultural land.A meta-analysis of 78 studies (233 site-years) reveals that nitrous oxide (N₂O) emissions from agricultural soils increase exponentially with nitrogen (N) fertilizer inputs, contradicting the linear assumptions used in IPCC greenhouse gas inventories. The study found that N₂O emissions grow significantly faster than linear for synthetic fertilizers and most crop types, with N-fixing crops showing the highest rate of change in emission factors (ΔEF). Soils with carbon >1.5% and pH <7, and those with annual fertilizer applications, also showed higher ΔEF. The results suggest that N₂O emissions increase exponentially as N inputs exceed crop needs. This finding implies that current IPCC default emission factors (1%) may be too conservative for high N-input rates. The study highlights the importance of using a nonlinear emission factor to improve the accuracy of N₂O emission assessments, address global budget disparities, and refine mitigation strategies. In low-input systems like those in sub-Saharan Africa, modest N additions have little impact on emissions, while excessive fertilization leads to disproportionate increases. The study also shows that the current IPCC default EF may underestimate emissions in high-input regions, such as China's North China Plain. The ΔEF model developed in this study provides a more accurate representation of N₂O emissions than the IPCC default, particularly for N inputs above 90 kg·ha⁻¹. The findings suggest that the largest mitigation gains can be achieved in areas with excessive fertilizer use, while little mitigation is possible in regions where N is most needed. The study underscores the need for more research on N₂O emissions from agricultural soils, particularly in different climates and with varying fertilizer formulations. The results have important implications for improving the accuracy of national and regional inventories of N₂O emissions from fertilized agricultural land.