Soil Organic Matter

{
  "id": "MLC-T-ENV-026001",
  "term": "Soil Organic Matter",
  "field": "Environment",
  "definition": "1. The organic component of the soil consisting in living organisms, dry plants and residues of animal origin. In a mass unit, this organic component is the most chemically active of the soil. Such a component stores several essential elements, stimulates the proper structure of the soil, is a source with capacity for the exchange of cations and regulates the pH changes, supports the relationship between air and water in the soil, and is a huge geochemical storage of carbon.\n\n2. Carbon-containing material composed of both living organisms and formerly living decomposing plant and animal matter. Soil organic matter (SOM) content can be supplemented with compost or other partially decomposed plant and animal material. Soil organic matter content is commonly measured using “loss on ignition” tests that measure the amount of the element carbon, a key constituent of all organic matter.\n\n3. The total organic matter in the soil. It can be divided into three general pools: living biomass of microorganisms, fresh and partially decomposed residues (the active fraction), and the well-decomposed and highly stable organic material. Surface litter is generally not included as part of soil organic matter.",
  "abbreviation": "SOM",
  "references": [
    "Chesapeake Bay Glossary",
    "Adapted from Office of the President Council on Environmental Quality Guidance for Federal Agencies on Sustainable Practices for Designed Landscapes at https://www.whitehouse.gov/sites/default/files/microsites/ceq/recommendations_on_sustainable_landscaping_practices.pdf",
    "USDA Natural Resources Conservation Services Soil Health Glossary"
  ],
  "url": "https://mlchart.com/terminology/environment/soil-organic-matter/"
}