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:
“An underground grower, blind and a common brown;
Got a misshapen look, it’s nudged where it could;
Simple as soil yet crowded as earth with all.”
—Richard Wilbur (b. 1921)
“A special feature of the structure of our book is the monstrous but perfectly organic part that eavesdropping plays in it.”
—Vladimir Nabokov (1899–1977)
“This great kindness pervades Chekhov’s literary work, but it is not a matter of program or of literary message with him, but simply the natural coloration of his talent.”
—Vladimir Nabokov (1899–1977)