World’s Soil Resources

7 | Soils with a clay-enriched subsoil
RETISOLS (Glossic great groups of Alfisols and Ultisols)
The clay illuviation within Retisols is typically manifested by an interfingering of bleached coarser-textured
soil material into the illuvial horizon, forming a net-like pattern (e.g. a glossic horizon). The dominant soil
processes involved in Retisol formation are argilluviation and biological enrichment of base cations. They are
often characterized by ‘waxy’ argillans; a subangular blocky structure; silty or loamy textural classes; active
and superactive CEC (cation-exchange capacity) classes; and the occurrence of lithologic discontinuities
(Figure A 25).
Retisols occur in climates where winters are cold and summers are short and cool with an annual
precipitation between 500 and 1000 mm. They typically carry a temperate needle-leaf evergreen forest/
woodland on often steeply sloping land. Their parent material is variable and includes loess, till, lacustrine
and alluvium. Retisols are dated from the mid-Holocene or older e.g. > 5 000 years old. These soils generally
exist in ‘tension zones’ (ecotones), reflecting a change in climate and/or vegetation.
Regional distribution of the 320 million ha of Retisols is mainly in Europe and northern and central
Asia. There are about 85 000 ha in the United States. Retisols are important for forestry, recreation, and
limited livestock farming and they provide ecological services such as watershed protection and ecological
sustainability
Status of the World’s Soil Resources | Main Report Annex | Soil groups, characteristics,
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distribution and ecosystem services