Organic matter
Organic matter is carbon-containing material derived from living organisms or their remains, ranging from individual molecules to biological debris.
Carbon: A chemical element that forms the backbone of most molecules in living organisms. Carbon’s ability to form stable bonds underlies the diverse compounds classified as organic matter.
Decomposition: The breakdown of dead organisms and organic substances by physical, chemical, and biological processes. Decomposition transforms organic matter and releases its constituents into ecosystems.
Soil organic carbon: The carbon contained in organic compounds in soil, excluding inorganic carbonates. It is a widely measured component used to track soil organic matter and carbon storage.
Carbon cycle: The movement of carbon among organisms, the atmosphere, oceans, soils, and rocks. Organic matter is a major pathway and store in exchanges among organisms, soils, and waters.
Biomolecule: A molecule produced by living organisms, including proteins, nucleic acids, carbohydrates, and lipids. Biomolecules are the molecular components of organic matter.
Soil respiration: The release of carbon dioxide from soil through root and microbial metabolism. Respiration returns carbon from decomposing soil organic matter to the atmosphere.
Soil fertility: The capacity of soil to support plant growth by supplying suitable nutrients and conditions. Organic matter supports nutrient cycling and improves several soil properties related to fertility.
Blue carbon: Carbon captured and stored by coastal and marine ecosystems, especially in their vegetation and sediments. Organic matter buried in coastal sediments contributes to long-lived ecosystem carbon stores.
Humus: A persistent, dark mixture of decomposed organic substances in soil. Humus is a transformed, relatively stable fraction of organic matter.
Microbial biomass: The living mass of microorganisms in a defined environment, such as soil or sediment. Microbes consume organic matter and convert some of it into living biomass.