Nitrogen-rich organic soils under warm well-drained conditions are global nitrous oxide emission hotspots.

Nitrous oxide (N ₂ O) is a powerful greenhouse gas and the main driver of stratospheric ozone depletion. Since soils are the largest source of N ₂ O, predicting soil response to changes in climate or land use is central to understanding and managing N ₂ O. Here we find that N ₂ O flux can be predicted by models incorporating soil nitrate concentration (NO ₃ ^- ), water content and temperature using a global field survey of N ₂ O emissions and potential driving factors across a wide range of organic soils. N ₂ O emissions increase with NO ₃ ^- and follow a bell-shaped distribution with water content. Combining the two functions explains 72% of N ₂ O emission from all organic soils. Above 5 mg NO ₃ ^- -N kg ^-1 , either draining wet soils or irrigating well-drained soils increases N ₂ O emission by orders of magnitude. As soil temperature together with NO ₃ ^- explains 69% of N ₂ O emission, tropical wetlands should be a priority for N ₂ O management.