Methane and nitrous oxide emissions and their GWPs: research on different irrigation modes in a rice paddy field

CH4 and N2O emission fluxes from a rice paddy field were measured in the cold region of Heilongjiang under four irrigation modes (control irrigation, wet irrigation, intermittent irrigation, and flood irrigation) by the static chamber-gas chromatograph technique. The emission rates of CH4 and N2O were simultaneously monitored once a week. The net global warming potential (GWP) was calculated as CO2 equivalents. The CH4 and N2O emission peak appeared in the rice active growth period, while the emissions were reduced in the remaining period regardless of the irrigation method utilised. The CH4 emission under flood irrigation was the highest, whereas that of the wet irrigation was 27.2% lower; the control and the intermittent irrigation manifested a decrease by 34% and 48.2%, respectively. N2O emission under flood irrigation was 0.41 kg•hm−2 smaller than that in the intermittent irrigation, but it was higher than those in the control and wet irrigation, respectively. By applying water-saving irrigation techniques, the greenhouse gas emissions from paddy fields can be effectively decreased.