What is soil carbon?
Soil carbon is both organic and inorganic carbon contained in soil. Carbon dioxide is converted into organic carbon by plants during photosynthesis, and is then deposited in the soil through their roots and in plant residue. Organic carbon is found in the top layer of soil, the A horizon. Inorganic soil carbon are carbonates that form through non-biological interactions. They are a minor amount compared to organic carbon, but are considered more permanent.
Soil carbon is both organic and inorganic carbon contained in soil. During photosynthesis, plants convert CO2 into organic carbon, which then is deposited in the soil through their roots and as plant residue. Organic carbon is found in the top layer of soil, the A horizon. Inorganic soil carbon comprises carbonates that form through non-biological interactions. They are a minor amount compared with organic carbon, but are considered more permanent. Large plant roots, such as those of trees, are considered biomass and not part of the soil, but the organic matter, if you look closely, includes many fine root hairs, where much of the CO2 “exchange” from the plant to the soil occurs.
Soil carbon, or soil organic carbon (SOC) as it is more accurately known, is the carbon stored within soil. It is part of the soil organic matter (SOM), which includes other important elements such as calcium, hydrogen, oxygen, and nitrogen. Soil organic matter is made up of plant and animal materials in various stages of decay. Un-decomposed materials on the surface of the soil, such as leaf litter, are not part of the organic matter until they start to decompose.
