Unit 3.3-SOIL EROSION-Human Factors Responsible for Soil Erosion
What is Soil Erosion ?
Soil erosion is the process of removal of superficial layer of the soil from one place to another.Soil erosion leads to soil infertility as the top soil layer is lost and also ability of soil to hold water and sediment is reduced.
WORLD AREAS AFFECTED BY SOIL EROSION:
Human Factors Responsible for Soil Erosion are 1. Deforestation, 2. Overgrazing, 3. Faulty Methods of Agriculture
Soil erosion is the result of a number of factors, working in isolation or in association with one another. Apart from the natural factors such as torrential rainfall, resulting in swift flow of water, strong winds in dry areas, nature of soil and the physiography, man is an important factor responsible for soil erosion.
Man’s ill gudged activities such as deforestation, overgrazing and faulty methods of agriculture have made soil erosion a serious national problem. Besides diversion of natural drainage courses, wrong orientation of roads and railways, embankments and bridges have also led to soil erosion. Thus it is rightly said that soil erosion is essentially a problem created by man and also faced by man himself.
1. Deforestation:
With the increase in population, the pressure on forest resources is increasing with each passing day. This has resulted in reckless cutting of forests which has led to the problem of soil erosion. Roots of trees and plants bind the soil particles and regulate the flow of water, thus saving soil from erosion.
Therefore, deforestation invariably results in floods and soil erosion. The large scale damage to soil in Shiwalik range, the Chos of Punjab, parts of Haryana and the ravines of Madhya Pradesh, Uttar Pradesh and Rajasthan is largely due to deforestation.
2. Overgrazing:
Forests and grasslands provide much needed fodder for animals. During the rainy season, there is plenty of growth and animals get enough fodder. But during the long dry period, there is shortage of fodder and the grass is grazed to the ground and tom out by the roots by animals.
This leads to lose structure of the soil and the soil is easily washed away by rains. Moreover, soil is pulverised by the hoofs and teeth of animals, especially by sheep and goats and thus proves detrimental to top soil when heavy showers fall on it.
Soil erosion due to overgrazing is a common site in the hilly areas of Himachal Pradesh, Jammu and Kashmir and in the dry areas of Rajasthan, Madhya Pradesh, Maharashtra, Karnataka and Andhra Pradesh.
3. Faulty Methods of Agriculture:
Much of the soil erosion in India is caused by faulty methods of agriculture. The most outstanding are wrong ploughing, lack of crop rotation and practice of shifting cultivation. If the fields are ploughed along the slope, there is no obstruction to the flow of water and the water washes away the top soil easily. In some parts of the country, the same crop is grown year after year which spoils the chemical balance of the soil. This soil is exhausted and is easily eroded by wind or water.
Another outstanding example of faulty method of agriculture is the shifting cultivation practised in some areas in the north-eastern states of Arunachal Pradesh, Assam, Meghalaya, Manipur, Tripura, Mizoram as well as in Orissa.
It is sporadically practised in Andhra Pradesh, Madhya Pradesh, Chhattisgarh, Maharashtra, Кёга1а, Karnataka and Tamil Nadu. In this method, a piece of forest land is cleared by felling and burning of trees and crops are grown.
The removal of the forest cover leads to the exposure of the soil to rains and sun which results in heavy loss of top soil, especially on the hill slopes. Thus the soil becomes unfit for cultivation and the tribes move to another piece of land after 2- 3 years, returning to the earlier one after a gap of 10-15 years. In this way, the whole of the forest area is adversely affected by shifting cultivation resulting in intensive soil erosion in vast areas.
Soil Conservation Practices:
1. Conservational till farming (or) no-till-farming:
(Photo: No Till farming practices,without using any machinery)
In tradition method, the land is ploughed and soil is broken up and levelled to make a planting surface. This disturbs the soil and makes it susceptible to erosion. However, no-till-farming causes minimum disturbance to the top soil. Here the tilling machines make slits in the unploughed soil and inject seeds, fertilizers and water in the slit. So the seed germinates and the crop grows.
2. Alley cropping (or) Agro forestry:
It involves planting crops in strips or alleys between rows of trees of shrubs that can provide fruits and fuel wood. Even when the crop is harvested, the soil will not be eroded because trees and shrubs still remain on the soil and hold the soil particles.
3. Contour farming:
It involves planting crops in rows across the contour of gently sloped land. Each row acts as a small dam to hold soil and to slow water runoff.
4. Terracing:
It involves conversion of steep slopes into broad terraces, which run across the contour. This retains water for crops and reduces soil erosion by controlling runoff.
SOIL EROSION MAP OF INDIA
Soil erosion is the process of removal of superficial layer of the soil from one place to another.Soil erosion leads to soil infertility as the top soil layer is lost and also ability of soil to hold water and sediment is reduced.
WORLD AREAS AFFECTED BY SOIL EROSION:
(SEE SOIL EROSION MAP OF INDIA BELOW)
--------------------------------------------------------------------------------------------------------Types of Soil Erosion:
Human Factors Responsible for Soil Erosion are 1. Deforestation, 2. Overgrazing, 3. Faulty Methods of Agriculture
Soil erosion is the result of a number of factors, working in isolation or in association with one another. Apart from the natural factors such as torrential rainfall, resulting in swift flow of water, strong winds in dry areas, nature of soil and the physiography, man is an important factor responsible for soil erosion.
Man’s ill gudged activities such as deforestation, overgrazing and faulty methods of agriculture have made soil erosion a serious national problem. Besides diversion of natural drainage courses, wrong orientation of roads and railways, embankments and bridges have also led to soil erosion. Thus it is rightly said that soil erosion is essentially a problem created by man and also faced by man himself.
1. Deforestation:
With the increase in population, the pressure on forest resources is increasing with each passing day. This has resulted in reckless cutting of forests which has led to the problem of soil erosion. Roots of trees and plants bind the soil particles and regulate the flow of water, thus saving soil from erosion.
Therefore, deforestation invariably results in floods and soil erosion. The large scale damage to soil in Shiwalik range, the Chos of Punjab, parts of Haryana and the ravines of Madhya Pradesh, Uttar Pradesh and Rajasthan is largely due to deforestation.
2. Overgrazing:
Forests and grasslands provide much needed fodder for animals. During the rainy season, there is plenty of growth and animals get enough fodder. But during the long dry period, there is shortage of fodder and the grass is grazed to the ground and tom out by the roots by animals.
This leads to lose structure of the soil and the soil is easily washed away by rains. Moreover, soil is pulverised by the hoofs and teeth of animals, especially by sheep and goats and thus proves detrimental to top soil when heavy showers fall on it.
Soil erosion due to overgrazing is a common site in the hilly areas of Himachal Pradesh, Jammu and Kashmir and in the dry areas of Rajasthan, Madhya Pradesh, Maharashtra, Karnataka and Andhra Pradesh.
3. Faulty Methods of Agriculture:
Much of the soil erosion in India is caused by faulty methods of agriculture. The most outstanding are wrong ploughing, lack of crop rotation and practice of shifting cultivation. If the fields are ploughed along the slope, there is no obstruction to the flow of water and the water washes away the top soil easily. In some parts of the country, the same crop is grown year after year which spoils the chemical balance of the soil. This soil is exhausted and is easily eroded by wind or water.
Another outstanding example of faulty method of agriculture is the shifting cultivation practised in some areas in the north-eastern states of Arunachal Pradesh, Assam, Meghalaya, Manipur, Tripura, Mizoram as well as in Orissa.
It is sporadically practised in Andhra Pradesh, Madhya Pradesh, Chhattisgarh, Maharashtra, Кёга1а, Karnataka and Tamil Nadu. In this method, a piece of forest land is cleared by felling and burning of trees and crops are grown.
The removal of the forest cover leads to the exposure of the soil to rains and sun which results in heavy loss of top soil, especially on the hill slopes. Thus the soil becomes unfit for cultivation and the tribes move to another piece of land after 2- 3 years, returning to the earlier one after a gap of 10-15 years. In this way, the whole of the forest area is adversely affected by shifting cultivation resulting in intensive soil erosion in vast areas.
Soil Conservation Practices:
1. Conservational till farming (or) no-till-farming:
In tradition method, the land is ploughed and soil is broken up and levelled to make a planting surface. This disturbs the soil and makes it susceptible to erosion. However, no-till-farming causes minimum disturbance to the top soil. Here the tilling machines make slits in the unploughed soil and inject seeds, fertilizers and water in the slit. So the seed germinates and the crop grows.
2. Alley cropping (or) Agro forestry:
It involves planting crops in strips or alleys between rows of trees of shrubs that can provide fruits and fuel wood. Even when the crop is harvested, the soil will not be eroded because trees and shrubs still remain on the soil and hold the soil particles.
3. Contour farming:
4. Terracing:
It involves conversion of steep slopes into broad terraces, which run across the contour. This retains water for crops and reduces soil erosion by controlling runoff.SOIL EROSION MAP OF INDIA
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