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Pedogenesis
 
 
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Pedogenesis or soil evolution (formation) is the process by which soil
Soil

Soil is the naturally occurring, unconsolidated or loose covering on the Earth's surface. Soil is composed of particles of broken rock that have been altered by chemical and environmental processes including weathering and erosion....
 is created. It is the major topic of the science of pedology
Pedology (soil study)

Pedology is the study of soils in their natural environment. It is one of two main branches of soil science, the other being edaphology. Pedology deals with pedogenesis, soil morphology, and soil classification, while edaphology studies the way soils influence plants, fungi, and other living things....
, whose other aspects include the soil morphology
Soil morphology

Soil morphology is the field observable attributes of the soil within the various soil horizons and the description of the kind and arrangement of the horizons....
, classification
Soil classification

Soil classification deals with the systematic categorization of soils based on distinguishing characteristics as well as criteria that dictate choices in use....
 (taxonomy
Taxonomy

Taxonomy is the practice and science of classification. The word comes from the Greek language ', taxis and ', nomos .Taxonomies, or taxonomic schemes, are composed of taxonomic units known as taxa , or kinds of things that are arranged frequently in a hierarchical structure....
) of soils, and their distribution in nature, present and past (soil geography and paleopedology
Paleopedology

Paleopedology is the discipline that studies soils of past geological eras, from quite recent to the earliest periods of the Earth's history. Paleopedology can be seen either as a branch of soil science or of paleontology, since the methods it uses are in many ways a well-defined combination of the two disciplines....
).

rate of chemical weathering
Weathering

Weathering is the decomposition of earth Rock , soils and their minerals through direct contact with the planet's atmosphere. Weathering occurs in situ, or "with no movement", and thus should not be confused with erosion, which involves the movement of rocks and minerals by agents such as water, ice, wind, and gravity....
 increases by 2-3 times when the temperature increases by 10 degrees Celsius (18 °F). Climate also affects which organisms are present, affecting the soil chemically and physically (movement of roots).

Organisms
The organisms living in and on the soil form distinct soil types.






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Pedogenesis or soil evolution (formation) is the process by which soil
Soil

Soil is the naturally occurring, unconsolidated or loose covering on the Earth's surface. Soil is composed of particles of broken rock that have been altered by chemical and environmental processes including weathering and erosion....
 is created. It is the major topic of the science of pedology
Pedology (soil study)

Pedology is the study of soils in their natural environment. It is one of two main branches of soil science, the other being edaphology. Pedology deals with pedogenesis, soil morphology, and soil classification, while edaphology studies the way soils influence plants, fungi, and other living things....
, whose other aspects include the soil morphology
Soil morphology

Soil morphology is the field observable attributes of the soil within the various soil horizons and the description of the kind and arrangement of the horizons....
, classification
Soil classification

Soil classification deals with the systematic categorization of soils based on distinguishing characteristics as well as criteria that dictate choices in use....
 (taxonomy
Taxonomy

Taxonomy is the practice and science of classification. The word comes from the Greek language ', taxis and ', nomos .Taxonomies, or taxonomic schemes, are composed of taxonomic units known as taxa , or kinds of things that are arranged frequently in a hierarchical structure....
) of soils, and their distribution in nature, present and past (soil geography and paleopedology
Paleopedology

Paleopedology is the discipline that studies soils of past geological eras, from quite recent to the earliest periods of the Earth's history. Paleopedology can be seen either as a branch of soil science or of paleontology, since the methods it uses are in many ways a well-defined combination of the two disciplines....
).

Climate


Climate regulates soil formation. Soils are more developed in areas with higher rainfall and more warmth. The rate of chemical weathering
Weathering

Weathering is the decomposition of earth Rock , soils and their minerals through direct contact with the planet's atmosphere. Weathering occurs in situ, or "with no movement", and thus should not be confused with erosion, which involves the movement of rocks and minerals by agents such as water, ice, wind, and gravity....
 increases by 2-3 times when the temperature increases by 10 degrees Celsius (18 °F). Climate also affects which organisms are present, affecting the soil chemically and physically (movement of roots).

Organisms


The organisms living in and on the soil form distinct soil types. Coniferous forests have acidic leaf litter and form what are known as inceptisols
Inceptisols

Inceptisols are a soil order in USDA soil taxonomy. They form quickly through alteration of parent material. They are older than entisols. They have no accumulation of clays, Iron, Aluminum or organic matter....
. Mixed or deciduous forests leave a larger layer of humus, changing the elements leached and accumulated in the soil, forming alfisols
Alfisols

Alfisols are a soil order in USDA soil taxonomy. Alfisols form in semiarid to humid areas, typically under a hardwood forest cover. They have a clay-enriched subsoil and relatively high native fertility....
. Prairies have very high humus accumulation, creating a dark, thick A horizon
Soil horizon

A soil horizon is a specific layer in the soil which measures parallel to the soil surface and possesses physical characteristics which differ from the layers above and beneath....
 characteristic of mollisols
Mollisols

Mollisols are a soil order in USA soil taxonomy. Mollisols form in semi-arid to semi-humid areas, typically under a grassland cover. They are most commonly found latitudinally in a band of 50th parallel north of the equator, although there are some in South America, South-Eastern Australia and South Africa....
.

Parent Material


The rock from which soil is formed is called parent material. The main types are: eolian, glacial till, glacial outwash, alluvium, lacustrine parent material and residual parent material, or bedrock. Pedologists use the following formula for understanding soil formation:

s = f (cl, o, r, p, t, ...)

where s - soil properties; cl - regional climate; o - potential biota, r - topography; p - parent material; t - time; ... - additional variables.

See also

  • CLORPT
    Clorpt

    Clorpt or Corpt is a mnemonic for Hans Jenny 's famous state equation for soil formation:S = f* S is for soil,* cl represents climate,...
  • Parent material
    Parent material

    Parent material, in soil science, means the underlying geological material in which soil horizons form. Soils typically get a great deal of structure and minerals from their parent material....
  • Soil horizon
    Soil horizon

    A soil horizon is a specific layer in the soil which measures parallel to the soil surface and possesses physical characteristics which differ from the layers above and beneath....
  • Soil production function
    Soil production function

    Soil production function refers to the rate of bedrock weathering into soil as a function of soil thickness.A general model suggested that the rate of physical weathering of bedrock can be represented as an exponential decline with soil thickness:...
  • Topography
    Topography

    Topography is the study of Earth's surface shape and features or those ofplanets, Natural satellite, and asteroids. It is also the description of such surface shapes and features ....