Page 70 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

4. How is soil polluted? How can it be prevented?

Ans. Soil is polluted because of following reasons :

Industrial Waste: Disposal of chemicals, heavy metals, and other pollutants from
factories.

Agricultural Activities: Overuse of pesticides, herbicides, and fertilizers.
Urbanization: Construction and waste dumping.

Mining Activities: Extraction processes that leave harmful residues.

Deforestation: Removal of vegetation that leads to soil erosion and degradation.
Improper Waste Disposal: Dumping of household and hazardous wastes.

We can prevent soil pollution by following the steps below :
Proper Waste Management: Treating and disposal of industrial and household waste

properly.

Sustainable Agriculture: Using organic farming practices, reducing chemical usage,
and employing crop rotation.

Reforestation: Planting trees and maintaining vegetation cover to prevent erosion.

Pollution Control: Implementing regulations to control emissions and effluents from
industries.

Use of Biodegradable Products: Reducing the use of non-biodegradable materials.

Public Awareness: Educating communities about the importance of soil conservation
and pollution prevention.

5. Describe the different layers of soil profile.
Ans. (a) Horizon or Topsoil : A-horizon or the topsoil is the topmost layer of the soil. It

is very soft and porous. It contains large amounts of humus and minerals and

can retain water easily. This topsoil is home to many living organisms, such as
worms, insects and rodents. Topsoil is a very useful part of the soil. It is where

the plants grow.
(b) Horizon or Subsoil : It lies beneath the top soil. It does not contain humus but

minerals are found here in large quantities. B-horizon or subsoil has a hard

texture, is light in colour and is more compact than the topsoil.
(c) Horizon : It is the third layer of the soil which consists of small rocks with cracks

in them. The rocks which are found in this layer are partly weathered.

(d) Bedrock : Below C-horizon is the bedrock. This is the last layer of the soil. It
contains huge rocks that are not weathered as they are not exposed to sunlight

or wind. The bedrock cannot be dug as it is very hard in texture.

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