Effects of water-saving irrigation on seasonal characteristics of N₂O emission from paddy fields

In order to study the effects of water-saving irrigation on seasonal characteristics of N2O emission from paddy fields, N2O emissions from water-saving irrigation paddy fields (WIPF) were investigated by the method of static chamber/gas chromatography. The results showed that the average flux of N2O emissions from WIPF was 41.84 μg/(m2 ?h), increased by 33.3% compared with that from flooded paddy fields (FPF). The cumulative N2O emission from WIPF was 119.86 mg/m2, increased significantly by 17.8% compared with that from FPF (p<0.05). Seasonal variations of N2O emission from WIPF were obvious. There were two peaks during the rice growing season. These peaks of N2O emissions mainly appeared about 7 days just after fertilizer applications. Soil drying in WIPF incurred N2O emission. Moreover, variations of N2O flux caused by re-flooding were different and the extent of these variations was not large. Soil drying in FPF during the yellow ripeness stage led to the compensation effect of N2O emission. Seasonal variations of N2O emissions from paddy fields under different water managements were depended on soil moisture. Compared with flooded irrigation, the controlled irrigation significantly increased cumulative N2O emission.