A model of biogeochemical processes for use in simulating greenhouse gas production and consumption is described. The model uses kinetic equations to describe a vertically distributed soil column that is characterized physically by soil properties. Transport processes move soluble and gaseous components in the soil column, including loss of gaseous components at the soil-atmosphere interface. Biogeochemical reactions are described beginning with hydrolysis of fresh, decomposable biopolymeric material to more resistant biopolymers and to monomers. Oxidative processes remove monomers and produce by-products including greenhouse gases. These processes include aerobic decomposition in aerobic zones and denitrification and germentation in anaerobic zones. Initial testing of the model for its general behavior indicates that this approach holds promise as a component of earth system models for simulating biogeochemical cycling.