Influence mechanism of controlled irrigation on N<sub>2</sub>O emissions from paddy fields

Abstract

In order to study the effects of controlled irrigation (CI) on seasonal variations of N2O emissions from paddy fields, N2O emissions from CI paddy fields were investigated by the method of static chamber/gas chromatography. Soil moisture, soil temperature and soil redox potential (Eh) were also measured. The quantitative relationships between N2O emissions and affecting factors were analysed. Soil drying incurred substantial N2O emissions, while no substantial N2O emission was observed after the soil was re-wetted following the drying phase. The peaks of N2O emissions from the CI paddy fields were all observed 8-10 days after soil drying with the WFPS ranging from 78.1% to 85.3%. However, no significant correlation was found between soil temperature and N2O emissions (p > 0.05), indicating that soil temperature is not a critical factor in N2O emission. N2O peaks were observed at soil Eh values ranging from +207.5 to +275.2 mV in CI paddy fields. No significant N2O emission occurred at Eh values higher than +300 mV or lower than +120 mV. These results suggest that N2O emissions may be reduced obviously by keeping the WFPS higher than 83.5% after each fertilizer application.