Organic matter
Carbon-based compounds from organisms, vital for nutrient cycling and soil health.
Organic matter, also known as natural organic matter (NOM), is the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is composed of organic compounds that have come from the feces and remains of organisms such as plants and animals, though organic molecules can also be made by chemical reactions that do not involve life. Organic matter is very important in the movement of nutrients in the environment and plays a role in water retention on the surface of the planet.
- field
- Environmental science, soil science, ecology
- known_for
- Source of carbon-based compounds; crucial for nutrient cycling, water retention, and soil fertility
- composition
- Cellulose, tannin, cutin, lignin, proteins, lipids, carbohydrates
- key_process
- Decomposition by microbial and fungal activity; oxidative polymerization
- ecosystem_role
- Nutrient availability, pH buffering, water and nutrient retention in soil
Lore & Background
Organic matter forms from the decomposition of living organisms. During life, organisms secrete or excrete organic compounds; after death, materials such as roots and leaves are decomposed by microbial and fungal activity. Through oxidative polymerization, smaller degradation products recombine into complex, larger-scale organic molecules. The composition of natural organic matter depends on its origin, transformation mode, age, and existing environment, so its bio-physicochemical functions vary with different environments.
Reader's Guide
Organic matter is fundamental to ecosystem function and agriculture. It cycles through decomposition processes by soil microbial communities, which are crucial for nutrient availability. After degrading, it can move into soil and mainstream water via waterflow, providing nutrition to living organisms. Organic matter acts as a buffer in aqueous solutions to maintain a neutral pH, a property proposed to be relevant for neutralizing acid rain. In soil, organic matter improves the capacity to hold water and nutrients, allowing their slow release and improving conditions for plant growth. Humus, a stable form of organic matter, helps soil stick together, aiding nematodes and bacteria in decaying nutrients. Soil organic matter is crucial to all ecology and agriculture, especially emphasized in organic farming. This effect can accelerate or immobilize mineralization and remains generally misunderstood, though it is regarded as common in most plant soil systems.
Did You Know?
- Organic molecules can be made by chemical reactions that do not involve life.
- Real priming effects have not been observed in sterile environments.
- Soil organic matter improves the capacity of soil to hold water and nutrients, allowing their slow release.
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