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Today, we will learn about soil.
What is soil?
How is it formed?
What is its importance to us?
We all live on the planet earth.
Have you ever thought
why is the life possible on the earth?
Life is possible on the earth
because of air, water, sunlight and the soil.
These are necessary elements for the life.
So, why is the soil necessary?
Soil is a necessary element of the life
as all the plants grow on the soil.
We know plants are primary source of food
for all of us.
Soil also is the home for many insects,
and, small animals like the rabbit
which makes burrough,
or the snake
which lives in holes.
Some houses like the kutcha houses
are also made up of mud
or the soil.
Apart from this, we get
many minerals from the soil
such as
calcium,
magnesium,
potassium, etc.
But,
what is the soil actually?
How is it formed?
You surely will have this question in mind,
who can form such a huge amount of soil?
Let us see it in detail.
Millions of years ago,
the earth was made up only of rocks.
There was no soil,
hence, no plants and no life.
Slowly the huge rocks broke into small pieces
due to action of rain,
frost, heat and the wind.
This process of break down
of huge rocks into smaller pieces
is called
Weathering.
Weathering takes place as rocks are broken down
into progressively smaller pieces
by the effects of
weather.
Slowly,
tiny plants and green moss
grew on the broken pieces of the rocks.
When these plants died,
their remains were added to rock pieces
and the soil was formed.
Weathering continued
and the bigger trees started to grow.
And, slowly the animal life began on the earth.
It took millions of years
for the soil to form.
Soil forms the top layer of earth.
The soil itself is not the same throughout.
It also has a layered structure.
The top most layer of the soil
is called the Top soil.
It is very fertile
plants grow in it.
Below the Top soil is the Sub soil.
It is hard with mostly small rocks.
Below it is Weathered rock fragments
where there is little or no plant or animal life
The bottom most layer is the Bedrock
which is the starting stage of the earth, millions of years ago.
It has only big rocks.
In short,
the soil is a mixture of broken rocks and minerals,
living organisms,
the decaying organic matter.
Let me tell you a small joke!
Can you guess
why did the gardener plant his money?
Guess, guess, guess!
No idea!
He wanted the soil to be rich!
This decaying organic matter
present in the top soil
is called Humus.
Humus is dark, soft and rich in nutrients.
Humus layer which is the top most layer of the soil,
is formed in millions of years.
It is very useful
as you can see all plants grow well in this layer of the soil.