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 ($N_2O$) emissions from soils. This study was undertaken to determine the effect of intermittent drainage compared to continuous flooding (conventional water regime) on $N_2O$ 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 $N_2O$ emission by 106.6% ($0.64kg\;ha^{-1}$ in NPK) with respect to the PK treatment ($0.31kg\;ha^{-1}$), and straw addition to NPK enhanced 148.3% of seasonal $N_2O$ flux ($0.77kg\;ha^{-1}$ in NPK+Straw). Although seasonal $N_2O$ emission slightly increased by 16.1-42.9% with intermittent irrigation, its seasonal $CH_4$ 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 ($4.51Mg\;CO_2\;ha^{-1}$, PK; $7.60Mg\;CO_2\;ha^{-1}$, NPK; $14.55Mg\;CO_2\;ha^{-1}$, 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.