Topsoil

Definition

Topsoil is the uppermost layer of the soil profile, richer in organic matter, roots and living organisms than the layers below. It is the most productive layer because most roots feed there and most rainfall is absorbed there, and it is also the first layer to be lost to erosion. Its thickness varies widely: a deep dark layer can be a sign of good management or natural richness, while pale patches on slopes often mean it has gone. Once lost, it cannot be replaced within a lifetime. See also: Subsoil, Soil horizon, Erosion, and the guide "Soil Erosion by Water and Wind: Mechanisms and Warning Signs".