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Soil Properties UPSC| Biogeography| Physical Geography

Soil properties can be categorized into three parts:

  • Physical Property
  • Chemical Property 
  • Biological Property 

Physical property:

It includes the following:

Soil Colour:

  • For example, Black soil, Red, Yellow, Gray, etc soil.
  • Soil color gets from Parent rock and vegetation. It also shows the pH values of the soil.

Soil texture:

  • Soil texture can be defined as a description of soil particles.
  • It refers to the proportion of the different size particles such as sand, silt, clay, etc.
  • As per texture soil can be categorized as Sandy, Silty, loamy, clay soils.
The following are the decreasing order of soil size particles:
  • Gravel[ largest in the size]
  • Sand
  • Silt
  • Clay[smallest particle size]


  • Porosity refers to Inter particles space in the soil.
  • Pores help to retain air, water, and microorganism.
  • The soil has a large pore is called porous soil.
  • The porosity of sandy soil is approximately half of the of clay soil; that is why clay soil has larger water or air holding capacity than sandy soil.
  • More porosity means more water or air holding capacity.
Soil Permeability:
  • Permeability means the rate of moisture or air gets passes between the space of soil.
  • We can notice that water gets passes easily in the sandy soil and not in the clay soil; hence sandy soil is more permeable than clay soil.
  • More porous soil is the least permeable.

Soil structure:

  • Soil structure describes the way in which soil particles are grouped together into a black, layer, or different structure.
  • For example, 
  • During summer; Clay soil becomes blocky; hence the structure of clay soil is blocky.
  • Sandy soils found in the Rajasthan region are Grainy in structure.
  • Columned structure; black soils are columned in structure as they developed verticle cracks during the dry season.
  • Plate Structure: Horizontal space between particles. Each year river valleys in the flood plains, make the layer structure of khadar deposits.

Chemical properties:

  • The chemical property of the soil is generally determined by pH values. pH values of the soil are related to the ability of soil to supply nutrients to plants.
  • pH is based on the relative concentration of relative hydrogen( H+) ions. Acidity increase with the increase of H+ concentration and pH values decrease.
  • Soil is called acidic if the pH values are less than 6.5.
  • Soil is called alkaline if the pH value is more than 7.
  • Maximum nutrients are available to plants when the pH value of the soil lies between 6.5 and 7.
  • An example of Acidic soil is Podzol and Forest Soil found in the Taiga region characterized by pH values of 3 to 5.
  • Laterite soil or Latosol is neutral soil having pH values of nearly 7.
  • Prairies and Chestnut soil in the temperate regions are slightly alkaline soil.

Biological properties of the soil:

  • Soil contains many organisms and microorganisms that help to enrich air, water, and humus in the soil.
  • Bacteria presence in soil indicates the neutrality of the soil.
  • Fungi presence in the soil indicates the acidic nature of the soil.
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