SOIL CHARACTERISTICS THAT REGULATE SOIL REDUCTION AND METHANE PRODUCTION IN WETLAND RICE SOILS

Methane production in soil is a microbiological process that occurs un der strict anaerobic conditions. A laboratory incubation study was con ducted using 10 wetland rice (Oryza sativa L.) soils from the Philippi nes to establish soil characteristics that govern the redox characteri stics and CH4 production of soils upon wetting. Labile soil organic ma tter in the Ap horizon was quantified as enrichment of C and N and non -clay protected C and N fractions. The C/N ratio of the enriched fract ion controlled the rate of reduction upon flooding, whereas the buffer ing capacity, measured as extractable Fe3+ content, controlled the red uction capacity for the soils, Methane production was influenced both by the reduction characteristics of the soils and labile organic subst rates.