Effect of Intermittent Drainage on Nitrous Oxide Emission and Global Warming Potential in Rice Paddy Soil

Water control is mainly one of the key factors that can affect nitrous oxide (N2O) emissions from soils. This study was undertaken to determine the effect of intermittent drainage compared to continuous flooding (conventional water regime) on N2O emission to global warming potential (GWP) with NPK (standard cultivation practice), NPK+Straw, and PK fertilizations. Nitrous oxide emission rates were collected twice a week using a closed chamber method. With continuous flooding, nitrogen (N) application increased N2O emission by 106.6% (0.64 kg ha in NPK) with respect to the PK treatment (0.31 kg ha), and straw addition to NPK enhanced 148.3% of seasonal N2O flux (0.77 kg ha in NPK+Straw). Although seasonal N2O emission slightly increased by 16.1-42.9% with intermittent irrigation, its seasonal CH4 emission drastically reduced at 43.5-52.8% resulting in a lower GWP at 48.9-58.5% with respect to that of continuously flooded treatments (4.51 Mg CO2 ha, PK; 7.60 Mg CO2 ha, NPK; 14.55 Mg CO2 ha, NPK+Straw). Rice yield, at similar fertilization with the continuously-flooded rice field, was not affected by intermittent irrigation. Conclusively, intermittent irrigation can be very effective and a rational soil management strategy to mitigate GWP with considering rice productivity in a temperate paddy rice field like Korea.