Soil Classification

In Sweden, a system adapted to forest land emerged during the 1920s and 1930s. Cultivated soils are not formally included in this system, but may be classified under the category cultivated soils. This system, comprising, among other things, various forms of podzols as well as brown earths, swamp soils, and lithosols, was used in the national forest land inventory up to 2002.

In order, among other purposes, to enable comparison of soils between national systems, internationally applicable soil classification systems were developed in the late 1950s, including those by FAO/UNESCO. As new knowledge and experience emerge, the international classification systems continue to be developed and revised, including the FAO system. Since 1998, this soil classification system has been known as the World Reference Base for Soil Resources (the WRB system). The WRB system currently comprises 32 reference soil groups, such as Podzols, Cambisols, Histosols, Gleysols, Leptosols, Regosols, and Arenosols. The reference groups in this system can be further subdivided. See also a brief description of soils within the WRB system here.

Overall soil classes according to the Swedish soil classification system

The overall soil classes shown in the frequency maps on the Soils page have been created by combining the Site Type Mapping variables soil and humus form according to the scheme below (in Swedish):

Determination of soil class according to the WRB system, based on variables from the National Forest Soil Inventory for the 1983–1987 survey

Soil classes according to the WRB system (referred to as the FAO system prior to 1998) were created for the 1983–1987 inventory by retrospectively utilising a number of the inventoried site characteristics, in the manner illustrated by the flow chart below (in Swedish):