Complete decomposition of plant matter leaves a residue composed primarily of humus.
the verdict
REFUTED
the evidence says no
refutedsupported
the weight of evidence
1 source for · 1 against
Peer-reviewed literature demonstrates that complete decomposition of organic matter produces carbon dioxide, water, and inorganic compounds rather than humus.
nutrient-rich organic matter in soil formed by the decomposition of plants and animals; a topsoil horizon containing a large accumulation of organic carbon.
This glossary of agriculture is a list of definitions of terms and concepts used in agriculture, its sub-disciplines, and related fields, including horticulture, animal husbandry, agribusiness, and agricultural policy. For other glossaries relevant to agricultural science, see Glossary of biology, Glossary of ecology, Glossary of environmental science, and Glossary of botanical terms.
humus
1. A characteristically dark-colored, nutrient-rich organic matter in soil formed by the decomposition of plants and animals; a topsoil horizon containing a large accumulation of organic carbon.
2. In agriculture, any natural compost gathered from a woodland or some spontaneous source and used as a soil amendment to aid crop nutrition and improve moisture retention.
3. The solid residues that are a byproduct of the sewage sludge treatment of wastewater, which are also sometimes composted and added to agricultural soils.
Organic matter is a major component of soil. It has tremendous ecological significance; it determines soil health, influences ecosystem productivity, and affects climate quality. Soil organic matter (SOM) has three main fractions, fresh undecomposed residues, decomposing and partially decomposed materials, and a highly decomposed and stable product humus (it is not completely decomposed organic matter; complete decomposition of organic matter produces carbon dioxide, water, and other inorganics). Plant litters including dead leaves, stems, barks, flowers, fruits, and logs are the major sources of forest SOM. Soil animals, microorganisms, and roots also contribute to the SOM. The threshold value for organic matter in agricultural soil is 2 % by weight, beyond which soil quality does not remain sustainable, but no threshold level for forest soils has so far been established. Forest mineral soils have generally 1–5 % organic matter by weight. Forest soils usually have higher organic matter than agricultural soils. There are two types of organic matter in soil, active or labile and passive or stable. Humus is the stable fraction of SOM. Forest ecologists identify three types of humus: mull humus, mor humus, and moder humus depending on the degree of decomposition and integration with mineral matter, acidity, and base contents. This categorization is more pronounced in temperate and boreal forest soils. A deep O horizon also develops in these types of forests. SOM performs a varie