Page 101 - ACTIVE SCIENCE 4 TOC

Factual Study
A ir
The air in the soil has less oxygen
All the organisms that live in the soil
require air to breathe. Therefore, soil also and more carbon dioxide. This
contains oxygen and carbon dioxide which carbon dioxide escapes from the soil

remain trapped in small holes or cavities cavities and helps to replenish the
within the soil. Another gas found in the soil atmospheric levels of carbon dioxide.
is nitrogen, which is taken up by the plants for their growth. The air in the soil
is more humid as compared to the atmospheric air and has a higher proportion of

carbon dioxide in comparison to oxygen. This is because the organisms living in
the soil use most of the oxygen to breathe and exhale carbon dioxide.

Water

Water is a very important component of the soil. It is used by the plants and soil
organisms to survive. Water also dissolves many substances and nutrients in it.

L iving Things

There are many living organisms in the soil like
earthworms, microorganisms, tiny insects which help
in the development of humus. Earthworms help in
circulating air through the soil by making burrows.

The excreta of the earthworm is used as food by other
microbes.

Factual Study 45% Rock Material Living Things in Soil

Soil acts as a filter for 25% Air

underground water as it 25% Water
filters out pollutants.
5% Organic Material and living things

Activity 12.1

To identify various components of soil

Visit a nearby garden or a park. Look closely at the soil and make the following
observations:

1. What is the colour of the soil?

2. How does it smell like?
3. Hold some soil in your hand and note what it feels like.

4. Is the soil moist or dry?

108 Active Science-4