Effect of Intermittent Drainage on Methane and Nitrous Oxide Emissions under Different Fertilization in a Temperate Paddy Soil During Rice Cultivation

Although intermittent drainage is regarded as a key factor to reduce methane (CH4) emission from paddy soil during rice cultivation, it also could increase nitrous oxide (N2O) emission. However, the effects of intermittent drainage on CH4 and N2O emissions with different global warming potential (GWP) values have not been well examined. In the present study, the effect of a 26-day intermittent drainage from the 34th day after transplanting (DAT) to the 60th DAT on two greenhouse gas (GHG) fluxes and yield properties were compared with those of a continuous flooding system under different fertilization (NPK as control, PK, and NPK+straw) during rice cultivation. The effect of intermittent drainage on changing two GHG emissions was compared using the GWP value, calculated as CO2, equivalents by multiplying 25 and 298 to the seasonal CH4 and N2O fluxes, respectively. Under the same irrigation condition, addition of nitrogen to PK significantly increased seasonal CH4 and N2O fluxes, and addition of straw to NPK increased CH4 and N2O. Irrespective with fertilization background, the intermittent drainage significantly reduced the total GWP by ca. 41-70% as affected by the big reduction of seasonal CH4 fluxes by ca. 43-53% to that of the continuous flooding even with an increase of seasonal N2O emissions by ca. 16-43%. Rice productivity was not significantly different between the two different irrigation systems under same fertilization background. As a result, total GWP per grain yield was significantly lower in all fertilization treatments with intermittent drainage compared with continuous flooding.