Question.
Discuss the factors involved in soil formation and their role in the global distribution of soils. ( 64th BPSC, 2019)
Answer:
The uppermost part of the earth's crust is made up of loose weathered materials, these loose weathered materials are called soil. Soil is the result of the action of the atmosphere, hydrosphere, lithosphere, and biosphere.
The following are five factors involved in soil formation:
- Parent materials
- Topography
- Climate
- Biological activities
- Time
Parent materials:
- Soil formation starts from weathering of parent rocks. Soil gets chemical values such as pH values and physical values such as color, soil texture, soil structure, soil porosity, and permeability.
Topography:
- On the plain surface, the soil is generally thick. On the steeper side of the land, very thin soil developed.
Climate:
- Temperature and precipitation are two active agents of climate that help in the soil formation processes such as weathering, erosion, and transportation.
- High temperature and high precipitation enhance the weathering, biological, and erosional activities.
For example,
- there is a very thick weathered mantle present in the equatorial region due to high temperature and precipitation.
- Soil is generally thin in the desert and polar regions due to the absence of sufficient rainfall and temperature respectively.
Biological activities:
Vegetation and animals release acids that enhance chemical weathering. Flora and fauna, both are favorable for soil formation.
Time:
The length of time determines the maturity of soil profile( thickness) development.
For example,
- Very thin soil is found in newly developed landforms.
- Thick soil is found in old landforms.
The below image explains the thickness of soil on the earth's surface.
Mainly climate plays an active role in soil formation and global distribution.
- Laterite soils develop in the presence of high temperatures and heavy rainfall in the equatorial region.
- Desert soil develops in presence of high temperature and very scanty rainfall in the desert areas.
- Chestnut soil develops in presence of moderate temperature and rainfall in the Mediterranean region.
- Taiga soil with low humus content develops in the presence of heavy rainfall and low temperature in the higher latitude.
Try to solve the following questions:
- How does natural vegetation affect the formation of in situ soils? ( UPSC 2015, 150 words, 10 marks)
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