Methanogenesis during rice growth as related to the water regime between crop seasons

In a long-term pot experiment with paddy rice, the effect of a wet or dry fallow on methanogenesis was studied during the ninth season. At times of CH₄ measurement, the oxidation of CH₄ was suppressed by C₂H₂. Methanogenesis started earlier in continuously flooded soil and was higher during the entire rice-growing period than in soil kept dry during the fallow and rewetted again before transplanting the rice seedlings. Increased CH₄ emission from the wet fallow treatment was, in contrast to the dry fallow treatment, associated with constantly low redox potentials. The experiment shows that the water regime during the fallow period is important to methanogenesis during the growth of rice plants.