A large area, found outside the tropics, with grassland and occasional trees as natural vegetation, as in the prairies of North America, the South American pampas, the Russian steppes, and the South African veld. A prairie soil is a soil of the wetter prairies, resembling chernozem in its high humus content and its development under grassland. Prairie soils are leached of calcium, and are slightly acid. See Barrett and Randall (1998) Soil Sci. 163, 6.