Assessing the relationship between soil reduction and methane emission in Texas rice fields

Reduction processes and methane emissions have been observed in six rice fields along a sand-clay-silt gradient for one growing season. Variations in reduction processes occurred by depth and upon field draining, as well as among fields of differing soil sand content. Analysis at four 2.5 cm-intervals revealed that greater microbial activity appears to be occurring close to the surface of the soil, and decreases with depth. This may be due to greater substrate availability through decomposition of organic matter from roots and dead plant material at that location. Also, it was observed that the re-entry of oxygen upon field draining decreases the amount of reduction occurring, as well as the levels of methane emitted. In this study, greater amounts of emitted methane were measured from the sandy soil extreme. Reduction processes, however, were found to be similar in both clayey and sandy soils