Soil Characteristics that Regulate Soil Reduction and Methane Production in Wetland Rice Soils

Methane production in soil is a microbiological process that occurs under strict anaerobic conditions. A laboratory incubation study was conducted using 10 wetland rice ( Oryza sativa L.) soils from the Philippines to establish soil characteristics that govern the redox characteristics and CH 4 production of soils upon wetting. Labile soil organic matter 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 fraction controlled the rate of reduction upon flooding, whereas the buffering capacity, measured as extractable Fe 3+ content, controlled the reduction capacity for the soils. Methane production was influenced both by the reduction characteristics of the soils and labile organic substrates.