Dark, fertile, partially decomposed plant or animal matter – humus forms the organic portion of the soil.
In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Latin word for "earth" or "ground".
In agriculture, "humus" sometimes also is used to describe mature or natural compost extracted from a woodland or other spontaneous source for use as a soil conditioner. It is also used to describe a topsoil horizon that contains organic matter (humus type, humus form, or humus profile).
Humus has many nutrients that improve the health of soil, nitrogen being the most important. The ratio of carbon to nitrogen (C:N) of humus commonly ranges between 8:1 and 15:1 with the median being about 12:1. It also significantly improves (decreases) the bulk density of soil. Humus is amorphous and lacks the cellular structure characteristic of organisms.
The solid residue of sewage sludge treatment, which is a secondary phase in the wastewater treatment process, is also called humus. When not judged contaminated by pathogens, toxic heavy metals, or persistent organic pollutants according to standard tolerance levels, it is sometimes composted and used as a soil amendment.
English
Etymology 1
Borrowed from Latin humus.
Pronunciation
- enPR: hyo͞o'məs, IPA(key): /ˈhjuːməs/
- Rhymes: -uːməs
Noun
humus (usually uncountable, plural humuses)
- A large group of natural organic compounds, found in the soil, formed from the chemical and biological decomposition of plant and animal residues and from the synthetic activity of microorganisms.
Hypernyms
- organic matter
Meronyms
- humic acid
Derived terms
Translations
See also
- compost
