Soil – The upper most soft layer of the earth in which plants grow is called soil.
Note: 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.
Composition of soil or soil contains: There are five component of soil.
Rock particles
Water
Air
Humus
Living organisms
- 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.
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.
Humus – Those organic materials made up of remains of plants and animals it generally found in the top soil are called humus.
Manure – Those substances is made up of decayed plants and animals waste, which supply nutrients to the soil are called manure.
Types of soil
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.
Soil erosion – The process by which the top fertile carry way by fast moving wind as water is
Called soil erosion.
OR
Displacement of top fertile soil by fast moving air or water is called soil erosion.
Factors of soil erosion: There are three factors of soil erosion.
Running water
Moving winds
Human activities
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.
Deforestation – The cutting of large part of forest is called deforestation.
It is Occur for construction of roads, rail, tracks, building and field and need for wood and fuel.
The roots of plants wind soil particles together and do not allow them to be carried away by water and wind hence, plants check 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
Growing cover crops –
We can raise boundaries along the fields by growing bushes and trees to check moving winds to carry way the top soil.
When the fields remain barren for a few months after cultivation moving wind and water start soil erosion.
So farmers should grow grass or creepers on the field until they grows new crops.
It checks soil erosion.
Terrace farming –
This is used in hilly areas.
In this process the slopes of the hills are cut on the steps (terrace) for farming.
These steps made on the slopes slow down the flowing water.
As the water flow slows down, some soil from one step is left on the next step that reduces the amount of soil lost.
Afforestation – The process of growing plants in a planned manner is called afforestation.
It is the most effective methods for soil conservation in both plains and hills.
Constructing embankments and dams –
Flood is one of the important factors responsible for soil erosion.
We can prevent the flood by constructing the embankments along river banks.
Dams are constructed to hold extra water of rivers during monsoon season.
Important –
Sandy soil cannot hold much water because it is made up sands in large amount.
The farmers add manure to the soil because it increases the capacity of growing crops.
We should not through the polythene bags, glass, plastic etc in the field because it gets polluted the soil.
