Methane production and its fate in paddy fields

Abstract

Extract

Leaching to the subsoil is one of the fates of methane produced in the plow layer of paddy fields (Kimura et al. 1992; Murase et al. 1993). Miura et al. (1992a, b) demonstrated in a column experiment that methane leached from the plow layer was anaerobically oxidized in the subsoil. They also showed that the rates of methane oxidation in the subsoil decreased at the end of the 30 d period of incubation at 25°C. In contrast, methane in the leachate was first detected more than 1 month after transplanting in a pot experiment, when easily decomposable organic materials such as rice straw were not incorporated into the soil (Murase et al. 1993). Based on these findings, it was important to determine the amount of methane oxidized in the subsoil during the cultivation period. In the present study, the amount of methane oxidized in the subsoil during the growth period of rice plants was estimated in a pot experiment.

Key Words:

• leaching
• paddy soil
• percolation