Knowra Soil organic matter Soil organic matter Soil organic matter is carbon-based material in soil derived from organisms at different stages of decomposition. It includes fresh residues, living microbial biomass, and transformed organic compounds.
Decomposition : The breakdown of organic material into simpler substances by physical, chemical, and biological processes. It turns plant and animal residues into progressively altered soil organic matter.
Soil organic carbon : The carbon contained in organic compounds in soil. It is the measurable carbon component used to estimate the size of the organic matter pool.
Soil fertility : The capacity of soil to support plant growth by supplying nutrients and suitable physical and chemical conditions. Organic matter contributes nutrients and improves conditions that support crop growth.
Soil carbon cycle : The movement of carbon among soil, organisms, the atmosphere, water, and other reservoirs. Soil organic matter is a major pool within this larger cycle.
Soil food web : The interacting community of organisms that live in soil and transfer energy through feeding relationships. Its organisms consume residues and reshape organic matter through feeding and waste production.
Soil organic matter fractions : Operationally separated groups of soil organic matter defined by properties such as size, density, or chemical extractability. Fractionation distinguishes rapidly cycling material from more persistent forms.
Soil structure : The arrangement of soil particles into aggregates and the resulting pore spaces. Organic matter helps stabilize aggregates, influencing aeration, water movement, and resistance to erosion.
Soil respiration : The release of carbon dioxide from soil through root and microbial activity. Decomposition of organic matter contributes to carbon dioxide released by soils.
Humification : The formation of transformed organic compounds during the decomposition of biological residues. It describes one pathway by which decomposing inputs become persistent soil organic matter.
Particulate organic matter : Relatively large, lightly decomposed organic fragments in soil, often separated by size or density. It represents a recognizable, often fast-cycling fraction of soil organic matter.
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