Chapter - 6
Soil
️ Soil :-
Soil is a valuable resource of nature. It is on the most important part of the earth's crust.
Soil is that upper part of the earth's surface, which is formed by climatic and bio-chemical process by mixing the broken particles of rocks and rotten parts of vegetation .
Soil formation: -
Formation of Soil – The process of soil formation is very complex. The factors affecting soil formation are:
Parent material or parent material: The parent material that makes up soil is obtained from rocks. Soil is formed only by the break-up of rocks.
Relief:- Relief has an important place in the process of soil formation. In areas with steep slopes, the speed of water flow is faster and soil formation is hindered. Deposits are more in areas with less relief. And the soil layer becomes thick.
Climate :- Due to the huge regional difference found in different elements of climate especially temperature and rainfall, different types of soils have been born.
Natural Vegetation:- The actual process of soil formation in any region and its development begins with the growth of vegetation.
Time : It takes several thousand years for the formation of a small layer of soil.
️ Soil Types :-
- alluvial soil
- laterite soil
- black soil
- red/yellow soil
- dry soil
- saline soil
️ Alluvial soil :-
- The vast plains of North India are made up of this soil.
- Water + Odor = Water will bring some particles with it.
- Sediment + silt + pebble + gravel + stone + organic matter = alluvial soil.
- Mostly found in India.
- This soil is formed by sediments brought by rivers.
- most fertile.
- It is found in river valleys, deltaic regions and coastal plains.
- It is high in potash and low in phosphorus.
- The color of this soil varies from light gray to ash gray.
- It is found in the Ganges-Brahmaputra plains in India.
️ Black Soil :-
- It is formed from lava obtained from volcanic activity.
- It is also called sand soil.
- It is a fertile soil.
- Cotton is cultivated in this, hence it is also called cotton soil.
- Elements like lime, iron, magnesium and alumina are found in it and there is a lack of phosphorus, nitrogen and organic elements.
- Area: Most of the Deccan Plateau, some parts of Maharashtra, Gujarat, Andhra Pradesh and some parts of Tamil Nadu.
- When this soil becomes wet, it swells and becomes sticky.
️ Red / Yellow Soil :-
- The color of this soil is red.
- This soil is not very fertile.
- It lacks nitrogen, organic matter and phosphoric acid.
- Due to being hydrated, it appears yellow.
- This soil is found in the eastern part of the southern plateau.
- Area :- Odisha, parts of Chhattisgarh, Middle Gangetic plains.
- Fine-grained red and yellow soils are fertile.
- Soils of high land with coarse particles are infertile.
️ Laterite Soil :-
- Laterite is derived from a Latin word 'letter'.
- Literal meaning - brick
- Area: Areas of high temperature and heavy rainfall.
- It is formed by the process of leaching due to the gradual change of dry and wet seasons in the monsoon climate.
- This soil is not fertile.
- It is low in nitrogen, lime, phosphorus and magnesium.
- This soil is found in the hilly areas of West Coast, Tamil Nadu, Andhra Pradesh, Orissa, Assam and Rajmahal hills.
- Laterite soils are used to make bricks for building houses.
️ Dry Soil :-
- Its color varies from red to raisin.
- It is sandy and saline.
- The salt content in the soils of some areas is so high that salt can be obtained by evaporating their water.
- These soils lack moisture and humus due to dry climate, high temperature and rapid evaporation.
- These soils are infertile because they contain less amount of humus and organic matter.
- Layers of pebbles are found in the lower beds due to the increase in the amount of lime towards the bottom.
- Due to the formation of layers of pebbles at the bottom of the soil, the seepage of water is limited.
- Therefore, when irrigated, moisture is always maintained in these soils for the continuous growth of plants.
- These soils have developed in western Rajasthan with typical dry topography.
️ Saline Soil :-
- Found in arid and semi-arid and waterlogged areas and Anoops.
- Their structure ranges from sandy to loamy.
- These are also called as barren soils.
- Sodium, potassium, magnesium are more fertile and no type of vegetation grows.
- Due to dry climate and poor drainage, the salt content of these increases.
- In the Rann of Kutch, along with the south-west monsoon, salt particles come which get deposited on the upper surface in the form of a crust.
- Filling of sea water in the delta region encourages the development of saline soils.
- The fertile alluvial soils are also becoming saline in areas of intensive agriculture with excessive irrigation, especially in the areas of Green Revolution.
️ Soil degradation :-
- Decline in soil fertility.
- In this the nutritional level of the soil falls.
- The depth of the soil decreases due to erosion and misuse.
- Soil degradation is the main factor in the depletion of soil resources in India.
️ Soil erosion :-
The destruction of the soil cover due to natural and human causes is called soil erosion.
On the basis of the factor of soil erosion, it can be classified into wind-borne and water-borne erosion. Erosion by wind occurs in arid and semi-arid regions, whereas erosion by running water is more on the slopes, we again keep it in two categories :-
Layer Erosion:- Removal of the soil layer after heavy rains.
Drainage Erosion:- Deep drains are formed by running water on steep slopes. The ravines of Chambal are an example of this.
Major causes of soil erosion :-
Factors responsible for soil erosion :-
- deforestation
- over-irrigation
- excessive use of chemical fertilizers
- Man-made construction work and faulty farming practices.
- Uncontrolled grazing.
Measures to prevent soil erosion: -
- tree planting .
- Contour line plowing.
- Control over grazing.
- Limited irrigation.
- Proper use of chemical fertilizers.
- Adoption of scientific farming method.
️ Soil Conservation :-
Soil conservation is the prevention of soil erosion and maintaining its fertility.
What should be done to ensure the conservation of soil?
Soil Conservation Measures :-
- Do not cultivate the land with slope gradient of 15 to 25 percent.
- Terraced farm.
- Sasyavartan means growing crops with manipulation.
️ Soil Conservation Measures :-
Plantation Trees:- Plants, shrubs and grasses help in preventing soil erosion.
Contour Linear Plowing and Weeding:- Plowing and weeding according to the contour lines on steep slope land obstructs the flow of water and the soil does not flow with water.
Control of pastoralism: - Due to the large number of animals in India, they roam freely in the empty fields. Soil erosion can be stopped by stopping or controlling their grazing process.
️ Right methods of agriculture: - By adopting the right methods of agriculture, soil erosion can be stopped.
