Soil Formation

Welcome to class.

Soil is the uppermost or topmost layer of the earth. It is the part of the earth on which plants grow. It is the portion that sustains plant growth. There are three types of soil, they are: Sandy soil, clayey soil, and Loamy soil. Of these three types, the type that most supports plant growth is loamy soil. So loamy soil is said to be the best soil for planting.


  • Take a close look at the picture above which is showing types of soil. What can you observe? Write down your observation.

Factors Or Agents Of Soil Formation

Soil formation is greatly controlled by five major factors or agents. They are:

  • Climate
  • Parent Materials
  • Topography
  • Biotic(living organisms)

Climate: Climate is the average weather condition of a place over a given period of time. Elements of climate are rainfall, temperature, wind and pressure. These are all very important in soil formation.

  • Temperature: The alternating heating and cooling of rocks result in the continual expansion and contraction which eventually result in the rock and its components breaking down into small pieces to form soil.
  • Rainfall: The action of running water from rainfall causes the gradual wearing away of rocks during erosion to form soil.
  • Wind: High wind velocity in deserts carry with it other tiny rocks which collide with one another or with other rocks, resulting in the breaking down of rocks into tiny pieces to form soil.
  • Pressure: High pressure on a hanging rock may cause such a rock to fall and break into tiny pieces, resulting in the formation of soil

.Parent Materials: Parent materials constitute the major materials from which soil is formed. They are the three types of rocks, which are: Igneous rock, Sedimentary rock and Metamorphic rock.

Topography: This refers to the physical features of the land surface. The slope of a land affects exposure of the elements and distribution of the soil. The shape of the land influences the movement and amount of water in the soil.

A hanging rock
Agents of soil formation

Biotic Factors: The activities of microorganisms, animals and man influences the development of soil. Also the burrowing activities of some organisms like, rodents, termites, earthworms and crickets etc lead to the breaking down of rocks which eventually add up to the soil formation process.



  1. ———– is the uppermost layer of the earth on which plants grow.
  2. The average weather condition of a place is called.   a) Climate.   b) weather.   c) Rainfall
  3. All the following are living organisms except.   a) Rodents  b) Earthworm   c) Table
  4. Four factors of soil formation are a)————————-. b) ————————c) ————————–    d) ———————–

we have come to the end of the class. If you have any questions ask using the comment box. Thank you for your time.

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