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SAI International School
Subject – Chemistry

Class - VII
Topic - SOIL: Natural Resource
Sub-topic - Properties of Soil

LESSON NOTES

Properties of Soil:

Some important properties exhibited by soil include the followings:

1. Texture of the Soil: Different soils have different textures. Texture refers to
the feel, appearance or consistency of the particles of a particular type of soil.
It is seen that sandy soil is gritty and loose, loamy soil is smooth and clayey
soil is smooth and sticky.

2. Percolation Rate of Soils: Percolation is the passing of a liquid or gas
through a porous material.

 Percolation rate for a given soil is the time taken by water to pass through
it.
 It helps us to study whether the soil would allow rapid drainage of water or
hold it for a long time.
 Soils with very small particles tend to retain water for longer periods.
 Such soils are poorly aerated and are not good for plant growth.
 Percolation rate can be calculated by using the given formula:

Percolation rate = Amount of water (ml)/ Percolation time (min)

3. Moisture content in different types of Soil:
 The amount of water present in a soil depends on its water-holding
capacity.
 Water holding capacity of sandy soil is less while that of clayey soil is
maximum.

Organisms found in Soil:

 Organisms like bacteria, fungi, algae or microbes live in the soil.
 They improve the fertility of the soil by decomposing the organic matter into
simple inorganic compounds and fixing the atmospheric nitrogen into
nitrogenous compounds.

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