5.7 - Alfisols

Alfisols are found in cool to hot humid areas, and in the semiarid tropics; they are formed mostly under forest vegetation, but also under grass savanna.  Extensive areas of Alfisols are found in the Mississippi and Ohio River valleys in the USA, through Central and Northern Europe into Russia, and in the South-central region of South America.

Alfisols generally show extensive profile development, with distinct argillic (clay) accumulations in the subsoil. Extensive leaching often produces a light-colored E horizon below the topsoil.

Generally fertile and productive, these soils typically have a high concentration of nutrient cations (Ca, Mg, K, and Na) and form in regions with sufficient moisture for plants for at least part of the year. Natural fertility and productive capacity of Alfisols is considered to be greater than that of Ultisols, but less than that of Mollisols.

Soil order - Alfisols. Image courtesy of USDA-NRCS

Profile example - Menfro Series. Image courtesy of USDA-NRCS

Missouri State Soil

USDA details

More information by the University of Idaho

Key Characteristics:  Alfisols

  • Found under forest and savanna vegetation
  • Clay accumulations in subsoil horizons
  • Often are leached below topsoil (E horizon)
  • Generally fertile, with high base saturation%.
  • Comparable in productivity to Mollisols and Ultisols.
  • Extensive in humid mid-latitudes
  • Extent of world ice-free land area: 10%

U.S. Order Distribution Map for Alfisols. Image courtesy of USDA-NRCS

Further Detail by the NRCS



What type of Native Vegetation is most commonly associated with formation of soils of the Alfisol Order?‏

Looks Good! Correct: Alfisols are formed mostly under native deciduous vegetation, but also under grass savanna.

What sequence of horizons could be expected to be found in a well-developed (mature), unplowed Alfisol soil profile?‏  

Looks Good! Correct: Accumulation of surface litter forms an organic and potentially acidic 'O' horizon that promotes leaching of organic matter, clay, and nutrients in the topsoil layers below it.