Living cells are made up of carbon based molecules and therefore organic matter is carbon based components found in the environment. Organic matter comprises of dead remain of the living organisms. The primary source of organic matter in soil are plant residues such as grass clippings, leaves, stem, straw, wood, green manure, peels of fruits and vegetables, remains of food material, waste products of animals etc.. In agricultural field, forest or grassland, dead plants, shed leaves can be transformed by the soil microorganisms. The various group of microorganisms can breakdown the organic matter releasing the nutrient in to the soil. This process of disintegration of organic matter by soil microorganisms is known as decomposition. Carbon moves between living and non-living components of the ecosystem and travels through air, soil and water via processes such as photosynthesis, respiration, decomposition and burning of fossil fuel.
Carbon being the main component of all life forms is bounded with other elements such as hydrogen, oxygen, nitrogen, phosphorous and sulfur. The covalent bonding between these elements make up most of the biological molecules.
Cells of the life forms are made up of biomolecule such as carbohydrates, lipids, protein, nucleotides and the fundamental component of these complex molecules is carbon. Carbon because of the four valence form a covalent bond to as many as four different atoms configuring the basic structure. A molecule (cluster of atoms) present in organic matter is held together by a covalent bond and the property of any bond is its strength. The bond strength is the energy required to break the bond. So making or breaking of covalent bond in a living cell can be worked upon by specific enzymes.
- Sugars are the primary source of the chemical energy for the cells
- Lipids/Fatty acid serve as energy reserve and are also the main component of the cell membranes
- Amino-acid chain make up the protein and protein perform specific function in a cell
- Nucleotides are organic molecule forming the nucleic acid such as RNA (ribonucleic acid) and DNA (deoxyribonucleic acid) and plays a critical role in energy transfer
These biomolecule or the organic compound found in plant residues are initially fragmented by small animals or organisms and later the fragmented substrate is worked upon by various group of microorganisms in soil depending on the nature of substrate and the enzymes produced by the soil microbes. Decomposed and mineralized organic matter liberates nutrient in the soil which can be utilized by the plant for its growth and development. The semi-stabilized product after decomposition of organic matter is compost. Many microorganisms working on compost maximizes the rate of decomposition. A good mature compost when incorporated in to the soil provides soil a better structure.
Organic matter when completely decomposed into a stable substance which resist further degradation is known as humus. Humus integrates into the soil improving the physical and chemical structure of the soil providing functionality to the soil that is nutrient cycling, storage, maintaining biodiversity, improves biomass production, water retention etc. An eroded or degraded soil can be made functional by incorporating the final product of the organic matter.