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

Abstract

Nitrous oxide (N₂O) is a powerful greenhouse gas and the main driver of stratospheric ozone depletion. Since soils are the largest source of N₂O, predicting soil response to changes in climate or land use is central to understanding and managing N₂O. Here we find that N₂O flux can be predicted by models incorporating soil nitrate concentration (NO₃^-), water content and temperature using a global field survey of N₂O emissions and potential driving factors across a wide range of organic soils. N₂O emissions increase with NO₃^- and follow a bell-shaped distribution with water content. Combining the two functions explains 72% of N₂O emission from all organic soils. Above 5 mg NO₃^--N kg^-1, either draining wet soils or irrigating well-drained soils increases N₂O emission by orders of magnitude. As soil temperature together with NO₃^- explains 69% of N₂O emission, tropical wetlands should be a priority for N₂O management.