Carbon controls on spodosol nitrogen, sulfur, and phosphorus cycling

The movement, accumulation, and transformations of organic carbon (C), nitrogen (N), sulfur (S), and phosphorus (P) are poorly understood in Spodosols and soils developed by similar formation processes. This chapter discusses the solid and solution chemistry of organic matter found in the forest floor and spodic horizons. It describes a conceptual biogeochemical model that considers the processes and mechanisms of soluble organic matter involved in C, N, S, and P nutrient cycling. In most studies involving Spodosols, organic S dominates the soil S pool, with smaller amounts of the S pool comprised of sulfate or other inorganic S forms. The podzolization process redistributes organic matter in soil profiles from the forest floor to the mineral soil. Dissolved organic C concentrations are greatest in forest floor leachates as chemical and microbial decomposition and solubilization of surface litter and organic matter is a dominant process that controls dissolved organic carbon levels.