METHANE EMISSION FROM FLOODED RICE FIELDS UNDER IRRIGATED CONDITIONS

In a study on CH4 emission from flooded rice fields under irrigated conditions, fields planted with rice emitted more methane than unplanted fields. The CH4 efflux in planted plots varied with the rice variety and growth stage and ranged from 4 to 26 mg h(-1) m(-2). During the reproductive stage of the rice plants, CH4 emission was high and the oxidation power of rice roots, in terms of alpha-naphthylamine oxidation, was very low. The CH4 emission reached a maximum at midday and declined to minimum levels at midnight, irrespective of the rice variety. The peak CH4 emission at midday was associated with higher solar radiation and higher soil/water temperature.