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:
“Ah! never shall the land forget
How gushed the life-blood of her brave—
Gushed, warm with hope and courage yet,
Upon the soil they fought to save.”
—William Cullen Bryant (1794–1878)
“When life has been well spent, age is a loss of what it can well spare,—muscular strength, organic instincts, gross bulk, and works that belong to these. But the central wisdom, which was old in infancy, is young in fourscore years, and dropping off obstructions, leaves in happy subjects the mind purified and wise.”
—Ralph Waldo Emerson (1803–1882)
“It does not matter much in what wars we serve, whether in the Highlands or the Lowlands. Everywhere we get soldiers’ pay still.”
—Henry David Thoreau (1817–1862)