Simulation of Methane Production in Anaerobic Rice Soils by a Simple Two-Pool Model

Methane (CH4) is produced in flooded rice fields by anaerobic decomposition of applied organic residues, root-derived materials and native soil organic matter (SOM). Since CH4 is an important greenhouse gas it is important to understand, and to be able to model, the processes which produce it. Anoxic incubation of soils employed in the cultivation of irrigated rice, with and without the addition of various potentially-available organic substrates, provides information on potential CH4 emissions which can be incorporated into process-based models. In this study, a simple two-pool model is employed to simulate the CH4 production of a number of anaerobically-incubated rice soils, and their responses to amendment with a variety of organic substrates. The model differs from most accounts of SOM transformation in that kinetics are microbially-mediated rather than first-order. Simulation yields a reproduction of the general trends of CH4 production in response to amendments of acetate, glucose and rice straw.