Secondary carbonates (WRB)

Secondary carbonates is one of the diagnostic properties used, in the WRB system, to discriminate some soils from others.

Description

The term "Secondary carbonates" (from Latin carbo, coal) refers to lime, precipitated in place from the soil solution rather than inherited from a soil parent material. As a diagnostic property, it should be present in significant quantities.

Criteria

Secondary carbonates either may disrupt the soil structure or fabric, forming masses, nodules, concretions or spheroidal aggregates (white eyes) that are soft and powdery when dry, or may be present as soft coatings in pores, on structural faces or on the undersides of rock or cemented fragments. If present as coatings, secondary carbonates cover 50 percent or more of the structural faces and are thick enough to be visible when moist. If present as soft nodules, they occupy 5 percent or more of the soil volume. Filaments (pseudomycelia) are only included in the definition of secondary carbonates if they are permanent and do not come and go with changing moisture conditions. This can be checked by spraying some water.

RSG in which secondary carbonates can be observed

• Chernozem
• Kastanozem

See also

• The FAO reference text, (2007 version)