World’s Soil Resources

ACRISOLS (Kan- great groups of Ultisols, e.g. with a kandic horizon)
Acrisols are characterized by movement and accumulation of low-activity clays (cation-exchange capacity
< 24 cmolc kg -1 clay) and a low base saturation (< 50 percent). The dominant soil processes involved in
Acrisol formation include argilluviation and base-cation leaching (Figure A 26).
Acrisols occur under equatorial or warm climates, fully humid or winter-dry with an annual precipitation
exceeding 1 200 mm. They typically carry a tropical deciduous or tropical evergreen forest or are under
savannah. They occur on old hilly land surfaces where the relief is variable but often steeply sloping. Their
parent material is saprolite or colluviums. These soils are commonly more than 200 000 years old.
Acrisols are used for forestry, recreation, agroforestry and shifting cultivation. They provide ecosystem
services such as water protection and biotechnology for human health.
Regional distribution is some 1 000 million ha worldwide, mainly in southeast Asia, the southern fringe
of the Amazon Basin, southeastern United States, and east and west Africa.
Status of the World’s Soil Resources | Main Report Annex | Soil groups, characteristics,
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distribution and ecosystem services