Nitrous oxide emissions in response to straw incorporation is regulated by historical fertilization.

The incorporation of crop straw with fertilization is beneficial for soil carbon sequestration and cropland fertility improvement. Yet, relatively little is known about how fertilization regulates the emissions of the greenhouse gas nitrous oxide (NO) in response to straw incorporation, particularly in soils subjected to long-term fertilization regimes. Herein, the arable soil subjected to a 31-year history of five inorganic or organic fertilizer regimes (unfertilized; chemical fertilizer application, NPK; 200% NPK application, 2 × NPK; manure application, M; NPK plus manure application, NPKM) was incubated with and without rice straw to evaluate how historical fertilization influences the impact of straw addition on NO emissions. The results showed that compared to the unfertilized treatment, historical fertilization strongly increased NO emissions by 0.48- to 34-fold, resulting from increased contents of hot water-extracted organic carbon (HWEOC), NO, and available phosphorus (Olsen-P). Straw addition had little impact on NO emission from the unfertilized and NPK treatments, primarily due to Olsen-P limitation. In contrast, straw addition increased NO emissions by 102-316% from the 2 × NPK, M, and NPKM treatments as compared to the corresponding straw-unamended treatments. These results indicated that NO emissions in response to straw addition were largely regulated by historical fertilization. The NO emissions were closely associated with the depletion of NO and decoupled from change in NH content, suggesting that NO was the main substrate for NO production upon straw addition. The stoichiometric ratios of HWEOC to mineral N and mineral N to Olsen-P were key factors affecting NO emissions, underscoring the importance of resource stoichiometry in regulating NO emissions. In conclusion, historical fertilization largely regulated the impacts of crop straw incorporation on NO emissions via shifts in NO depletion and the stoichiometry of HWEOC, mineral N, and Olsen-P.