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:
“Our own country furnishes antiquities as ancient and durable, and as useful, as any; rocks at least as well covered with lichens, and a soil which, if it is virgin, is but virgin mould, the very dust of nature. What if we cannot read Rome or Greece, Etruria or Carthage, or Egypt or Babylon, on these; are our cliffs bare?”
—Henry David Thoreau (1817–1862)
“There is ... an organic affinity between joyousness and tenderness, and their companionship in the saintly life need in no way occasion surprise.”
—William James (1842–1910)
“We are all murderers and prostitutes—no matter to what culture, society, class, nation one belongs, no matter how normal, moral, or mature, one takes oneself to be.”
—R.D. (Ronald David)