A soil separate consisting of particles of a certain equivalent diameter. The most commonly used size for silt is from 0.05 to 0.002 mm equivalent diameter. This is the size used by the Soil Science Society of America and the U.S. Department of Agriculture, but others recognize slightly different equivalent diameters. As compared to clay (less than 0.002 mm), the silt fraction is less reactive and has a low cation exchange capacity. Because of its size, which is intermediate between clay and sand, silt contributes to formation of desirable pore sizes, and the weathering of silt minerals provides available plant nutrients. Wind-blown silt deposits are referred to as "loess."

See Also

Soil Conservation; Soil Consistency; Soil Profile