Soil organic matter (SOM) is the organic matter component of soil. It can be divided into three general pools: living biomass of microorganisms, fresh and partially decomposed residues, and humus: the well-decomposed organic matter and highly stable organic material. Surface litter is generally not included as part of soil organic matter.
According to Troeh and Thompson's Soils and Soil Fertility, "Organic matter constitutes from 1 to 6% of the topsoil weight of most upland soils. Topsoils with less than 1% organic matter are mostly limited to desert areas. At the other extreme, the organic matter content of soils in low wet areas may be as high as 90% of more. Soils with more than 12-18% organic carbon (approximately 20-30% organic matter) are called organic soils."
Famous quotes containing the words soil, organic and/or matter:
“Let none admire
That riches grow in hell; that soil may best
Deserve the precious bane.”
—John Milton (1608–1674)
“Technology represents intelligence systematically applied to the problem of the body. It functions to amplify and surpass the organic limits of the body; it compensates for the body’s fragility and vulnerability ...”
—Shoshana Zuboff (b. 1951)
“Cities need old buildings so badly it is probably impossible for vigorous streets and districts to grow without them.... for really new ideas of any kind—no matter how ultimately profitable or otherwise successful some of them might prove to be—there is no leeway for such chancy trial, error and experimentation in the high-overhead economy of new construction. Old ideas can sometimes use new buildings. New ideas must use old buildings.”
—Jane Jacobs (b. 1916)