Laboratory study of methane oxidation in paddy soils

Methane oxidation in paddy soils was investigated under laboratory conditions. Paddy soils collected before early rice transplanting could not oxidize atmospheric CH4 but could oxidize CH4 when the concentration exceeded 10 µl l-1. Initial CH4 oxidation rate increased with the increase of initial CH4 concentration. Soil with the maximum potential to produce CH4, also had the maximum CH4 oxidation activity and the maximum emission flux from paddy soil. High CH4 concentration stimulated the oxidation of CH4. After 10 days' incubation under atmosphere containing 1000 µl-1 or 104 µl l-1 CH4, the soil which could not oxidize atmospheric CH4 was able to oxidize it.