Reference soil groups (WRB)

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World Reference Base for soil resources

The Reference soil groups

The 32 reference soil groups can be sorted in 10 categories :

Soils with thick organic layers

Soils with strong human influence

  • Anthrosols, soils with long and intensive agricultural use
  • Technosols, soils containing many artefacts

Soils with limited rooting due to shallow permafrost or stoniness

Soils influenced by water

  • Vertisols, with alternating wet-dry conditions, rich in swelling clayss
  • Fluvisols, floodplains, tidal marshes
  • Solonetz, alkaline soils
  • Solonchaks, with salt enrichment upon evaporation
  • Gleysols, groundwater affected soils

Soils set by Fe/Al chemistry

  • Andosols : with allophanes or Al-humus complexes
  • Podzols : with cheluviation and chilluviation
  • Plinthosols : with an accumulation of Fe under hydromorphic conditions
  • Nitisols : with low-activity clay, P fixation, strongly structured
  • Ferralsols : dominance of kaolinite and sesquioxides

Soils with stagnating water

  • Planosols, with abrupt textural discontinuity
  • Stagnosols, with structural or moderate textural discontinuity

Accumulation of organic matter, high base status

Accumulation of less soluble salts or non-saline substances

Soils with a clay-enriched subsoil

  • Albeluvisols, with albeluvic tonguing
  • Alisols : with a low base status, high-activity clay
  • Acrisols : with a low base status, low-activity clay
  • Luvisols : with a high base status, high-activity clay
  • Lixisols : with a high base status, low-activity clay

Relatively young soils or soils with little or no profile development

See also