Mollisol is a soil type which has deep, high organic matter, nutrient-enriched surface soil (A horizon), typically between 60 and 80 cm in depth. This fertile surface horizon, called a mollic epipedon, is the defining diagnostic feature of Mollisols. Mollic epipedons are created by long-term addition of organic materials derived from plant roots and typically have soft, granular soil structure.
Mollisols typically occur in savannahs and mountain valleys (such as Central Asia, and the North American Great Plains). These environments have historically been strongly influenced by fire and abundant pedoturbation from organisms such as ants and earthworms. It was estimated that in 2003, only 14 to 26 percent of grassland ecosystems still remained in a relatively natural state (that is, they were not used for agriculture due to the fertility of the horizon). Globally, they represent ~7% of ice-free land area. As the world's agriculturally most productive soil order, the Mollisols represent one of the most economically important soil orders.
Though most other soil orders known today were formed at the beginning of the CarboniferousIce Age 280 million years ago, Mollisols are best known from the paleopedological record as early as the Eocene. Their development is very closely associated with cooling and drying of the global climate that occurred during the Oligocene, Miocene and Pliocene.
Soils which are mostly similar to Mollisols but contain either continuous or discontinuous permafrost, consequently affected by cryoturbation are common in high mountain plateaus of Tibet and the Andean altiplano. Such soils are called Molliturbels or Mollorthels and provide the best grazing land in such cold climates because they are not acidic like many other soils of very cold climates.
Other soils which have a mollic epipedon are classified as Vertisols because high shrink swell characteristics and relatively high clay contents dominate over the mollic epipedon. These soils are especially common in parts of South America in the Paraná River basin receiving abundant but erratic rainfall and extensive deposition of clay-rich minerals from the Andes. Mollic epipedons also occur in some Andisols but the andic properties take precedence.
^IUSS Working Group WRB (2015). "World Reference Base for Soil Resources 2014, Update 2015" (PDF). World Soil Resources Reports 106, FAO, Rome.
Brady, N.C. and Weil, R.R. (1996). ‘The Nature and Properties of Soils.’ 11th edition. (Prentice Hall, New Jersey).
Buol, S.W., Southard, R.J., Graham, R.C., and McDaniel, P.A. (2003). ‘Soil Genesis and Classification.’ 5th edition. (Iowa State University Press - Blackwell, Ames.)
External linksedit
. USDA-NRCS. Archived from the original on 2006-05-09. Retrieved 2006-05-14.
. University of Florida. Archived from the original on April 4, 2006. Retrieved 2006-05-14.
. University of Idaho. Archived from the original on 2006-05-15. Retrieved 2006-05-14.
November 27, 2023
mollisol, soil, type, which, deep, high, organic, matter, nutrient, enriched, surface, soil, horizon, typically, between, depth, this, fertile, surface, horizon, called, mollic, epipedon, defining, diagnostic, feature, mollic, epipedons, created, long, term, a. Mollisol is a soil type which has deep high organic matter nutrient enriched surface soil A horizon typically between 60 and 80 cm in depth This fertile surface horizon called a mollic epipedon is the defining diagnostic feature of Mollisols Mollic epipedons are created by long term addition of organic materials derived from plant roots and typically have soft granular soil structure MollisolA Mollisol profileUsed inUSDA soil taxonomyParent materialLoess LimestoneClimateHumid continental semi aridMollisols typically occur in savannahs and mountain valleys such as Central Asia and the North American Great Plains These environments have historically been strongly influenced by fire and abundant pedoturbation from organisms such as ants and earthworms It was estimated that in 2003 only 14 to 26 percent of grassland ecosystems still remained in a relatively natural state that is they were not used for agriculture due to the fertility of the horizon Globally they represent 7 of ice free land area As the world s agriculturally most productive soil order the Mollisols represent one of the most economically important soil orders Though most other soil orders known today were formed at the beginning of the Carboniferous Ice Age 280 million years ago Mollisols are best known from the paleopedological record as early as the Eocene Their development is very closely associated with cooling and drying of the global climate that occurred during the Oligocene Miocene and Pliocene Contents 1 Suborders 2 See also 3 References 4 External linksSuborders editAlbolls wet soils aquic soil moisture regime with an eluvial horizon Aquolls wet soils aquic soil moisture regime Cryolls cold climate frigid or cryic soil temperature regime Gelolls very cold climate mean annual soil temperature lt 0 C Rendolls lime parent material Udolls humid climate udic moisture regime Ustolls subhumid climate ustic moisture regime Xerolls Mediterranean climate xeric moisture regimeSoils which are mostly similar to Mollisols but contain either continuous or discontinuous permafrost consequently affected by cryoturbation are common in high mountain plateaus of Tibet and the Andean altiplano Such soils are called Molliturbels or Mollorthels and provide the best grazing land in such cold climates because they are not acidic like many other soils of very cold climates Other soils which have a mollic epipedon are classified as Vertisols because high shrink swell characteristics and relatively high clay contents dominate over the mollic epipedon These soils are especially common in parts of South America in the Parana River basin receiving abundant but erratic rainfall and extensive deposition of clay rich minerals from the Andes Mollic epipedons also occur in some Andisols but the andic properties take precedence In the World Reference Base for Soil Resources WRB Mollisols are split up into Chernozems Kastanozems and Phaeozems Shallow or gravelly Mollisols may belong to the Leptosols Many Aquolls are Gleysols Stagnosols or Planosols Mollisols with a natric horizon belong to the Solonetz 1 See also editPedogenesis Pedology soil study Soil classification Soil science Soil typeReferences edit IUSS Working Group WRB 2015 World Reference Base for Soil Resources 2014 Update 2015 PDF World Soil Resources Reports 106 FAO Rome Brady N C and Weil R R 1996 The Nature and Properties of Soils 11th edition Prentice Hall New Jersey Buol S W Southard R J Graham R C and McDaniel P A 2003 Soil Genesis and Classification 5th edition Iowa State University Press Blackwell Ames External links edit Mollisols USDA NRCS Archived from the original on 2006 05 09 Retrieved 2006 05 14 Mollisols University of Florida Archived from the original on April 4 2006 Retrieved 2006 05 14 Mollisols University of Idaho Archived from the original on 2006 05 15 Retrieved 2006 05 14 Retrieved from https en wikipedia org w index php title Mollisol amp oldid 1133599751, wikipedia, wiki, book, books, library,
