How do soils store carbon?
Soils store carbon in two ways. According to the Soil Science Society of America, direct and indirect fixation of atmospheric carbon dioxide is stored in soils. Direct fixation occurs through inorganic chemical reactions that convert carbon dioxide into soil inorganic carbon compounds such as calcium and magnesium carbonates. Direct plant carbon sequestration occurs as plants photosynthesize atmospheric carbon dioxide into plant biomass. Some of this plant biomass is indirectly sequestered as soil organic carbon (SOC) during the decomposition processes of organic matter. Increases in SOC generally improve soil structure, increase porosity and water holding capacity, and generally improve the biological health of soils. This SOC occurs largely in the upper levels, or topsoil.
