Abstract:

With the intensification of global climate change, extreme precipitation events are becoming more frequent and intense, which alters regional soil water dynamics and subsequently affects soil nitrous oxide (N₂O) emissions and microbial mechanisms. However, the underlying mechanism of N₂O emission in response to extreme precipitation events remains unclear. This review summarized the effects of extreme precipitation on soil N₂O emissions across different land-use types (e.g., cropland, grassland, forest and wetland), based on differences in N₂O fluxes among these systems, and explored the associated microbial mechanisms, aiming to address the challenges of achieving carbon neutrality in agricultural systems. The results showed that extreme precipitation generally increased soil N₂O emissions by modifying soil moisture dynamics, carbon and nitrogen availability and microbial functional genes expression. Nevertheless, the specific effects were jointly influenced by multiple factors, including soil type, land use practices and precipitation characteristics. At the microbial level, extreme precipitation rapidly stimulated microbial activity, alters the abundance and activity of functional genes related to nitrification and denitrification (such as amoA, nirS, nosZ), and consequently regulated the pathways of N₂O emissions. Future research should expand the range of land-use types, enhance the understanding of microbial community structure and functional gene expression, and comprehensively consider the interactive effects of multiple environmental factors on soil N₂O emissions. This would provide a theoretical basis for mitigating soil N₂O emissions and support the achievement of carbon peaking and carbon neutrality goals.

Key words: Nitrous oxide, Extreme precipitation events, Land?use type, Soil microorganism