Enhanced N2O Emissions from Winter Wheat Field Induced by Winter Irrigation in the North China Plain

Winter irrigation is important for wheat in meeting crop water requirements in spring, but it alters soil moisture dynamics and affects soil N2O production and emission. To assess the effects of winter irrigation on soil N2O emissions in a winter wheat field, an in situ experiment was conducted from 1 October 2019 to 1 March 2020 with one control treatment (CK) and five levels of winter irrigation quantities (irrigated to 60%, 70%, 80%, 90%, 100% of the soil water holding capacity, namely WHC60-WHC100, respectively). The results showed that winter irrigation had an impact on soil N 2 0 emission. The emission peaks were not investigated immediately after winter irrigation, but at two days after, which were increased by 4.3-17.0 mu g.m(-2).h(-1) under WHC60-100 treatments compared to the CK. The cumulative N2O emissions after winter irrigation from WHC60-100 were 1.1-3.9 times higher than that of CK, indicating that the cumulative N2O emission has an increase trend with the increase of soil water content regulated by irrigations. Pearson correlation analysis showed that the correlation between soil N2O flux and soil temperature were moderate with correlation coefficients of about 0.65. While the correlation between soil N2O flux and soil water content was poor during the investigate winter season with correlation coefficients ranging between 0.08 and 0.25. Future studies should focus on the general N2O emission responses to winter irrigation and environmental factors with the support of experiment data from several winter seasons.