Soil – The upper most soft layer of the earth in which plants grow is called soil.
The life cannot exsit without the soil.
Beacuse we cannot live without plant and plant cannot live without soil.
Importants of soil:
Soil gives firm support to plant and helps them to grow.
It provides water and minerals to the plants.
It provides shelter to different kinds of animals like earth worms, rat, snake, insect, centipedes and millipedes etc.
Soil is also used to make bricks, pots and toys etc.
Formation of soil:
The formation of soil started with the breaking of rocks into small particles due to action of heat, rain, wind and water.
The process of soil formation step by step-
Step- 1:
The rocks are basic particles of soil that breaks into small particles due to action of natural force (sun, rain and wind).
The sun heats up the rocks and cold wind cools them down, rain water enter their crevices due to the heat up the sun this rain water changes into water vapors and puts pressure.
Fast moving winds also put pressure to the rocks.
Gradually, the rocks become weak and break down the action of natural forces on the rocks is called weathering.
Step-2:
With the time, the small particles break into smaller pieces.
Step-3:
Air and water work on these pieces and carry then here and there.
In this process the smaller rock particles become tiny particles.
Step-4:
Gradually, organic matter like dead plants or their parts and dead animals mix up with the tiny rocks particles and from humus.
In this way soil is formed.
Note:
Organisms like earth worm, Insects, centipedes, millipedes etc tern the soil through shifting and create spaces which allow air and water to enter the soil.
Hence these are called farmer’s friend.
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Layers of soil
Top soil:
This is the uppermost layer which is dark in colour due to presence of humus.
It contains dead and decaying bits of plants and animals.
Plants grow in this layer. Roots of the plants spread well and get fixed in it.
This is the most fertile of all the layers.
The colour of top soil may vary from place to place.
Subsoil:
It is below the top soil and is lighter in colour.
The particles of soil in this layer are bigger than the top soil.
It is not suitable for the growth of plants.
Bedrock:
Further down, the soil particles are still bigger and it mostly contains stones and rocks.
Types of soil
According to the size, colour and texture of the soil particles, soil can be divided into Three types.
Sandy soil Clayey Soil Loamy Soil
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It contains sand in large amount
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It is formed with very fine particles of rock
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It is a mixture p of both sand and clayed.
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Sandy soil – A soil which contains sand in large amount and humus in small amount is called sandy soil.
Properties of sandy soil:
Its water holding capacity is not much.
It has a lot of air in the space between the particles.
It has very small amount of humus.
This type of soil is found in desert and near rivers.
Note: It is comfortable for the agriculture of cotton, paddy, wheat and vegetables etc.
Clayey – A soil that is formed with very fine particles (smooth) of rock is called clayey soil.
Properties of clayey soil:
Its water holding capacity is very much.
It has no space for air between the particles.
It has hegeleble amount of humus.
It is used by potters to make pottery.
Loamy soil – A soil that is mixture of both sand and clayed is called loamy soil.
Properties of loamy soil:
It contains a lot of humus.
It holds both air and water.
It is very fertile.
It holds small amount of water.
Composition of soil or soil contains: There are five component of soil.
- Rock particles – It refers to small particles of broke rock of different shapes and sizes.
- Water – water is also present in between the pores of the soil particles.
- Air – Air is present between the soil shapes. It is essential for the survival of living organisms.
- Humus – It is also present in soil that is organic matter essential for plant grows.
- Living organisms – soil also contains a variety of living organisms like earth worm, Insects, centipedes, millipedes etc.
Soil erosion – The process by which the top fertile carry way by fast moving wind as water is called soil erosion.
Causes of soil erosion: There are three factors of soil erosion.
Running water –
This is the main causes of soil erosion.
The force of rain water and rivers washes away the top soil and deposits it to some other places.
Flood is also an important cause of soil erosion both in plain and hills area.
In hilly areas the water flows down swiftly and carries away the top fertile soil.
In plain rivers same times beings to eat up their sides due to this severe damage.
Moving winds –
Soil erosion is also occurs by fast moving wind.
It carries away top fertile soil and manure from field.
Soil erosion by wind is common in dry regions like Rajasthan and some parts of Gujarat.
Human activities –
Human activities like deforestation is also cause of soil erosion.
Soil conservation – The process of protecting soil erosion is called soil conservation.
It is very important because the formation of soil is extremely slow process and soil erosion is fast process.
Methods of soil conservation: There are four methods of soil conservation.
Growing cover crops
Terrace farming
Afforestation
Constructing embankments and dams
