The Effect of Redox Potential and Rice Plants On Greenhouse Gas Emissions From Paddy Soil.

Because rice paddy fields could be under either an aerobic or an anaerobic condition, they are one of the major sources of methane and nitrous oxide. The aim of this study was to investigate the effect of redox potential and rice plants on the emission of greenhouse gases ( CH4, N2O and CO2 ) from a paddy soil. Greenhouse gas emissions and redox potential were measured in a rice paddy field with rice plants and in soil columns with no rice plant. The measurements of gas emissions were made using a closed chamber method. Results showed that CH4 flux was larger when redox potential was lower, an anaerbic condition, in the columns. In contrast, N2O flux was larger when redox potential was higher, an aerobic condition, in the columns. Methane flux in the rice paddy field was larger than one in the columns. Nitrous oxide flux in the rice paddy field was similar than one in the columns. Carbon dioxide flux in the rice paddy field was negative, but was positive in the columns. Therefore, CH4 and CO2 fluxes were affected by the existence of rice plants, but little was N2O flux.