Question 1 What is meant by soil erosion?
Question 2 What are the causes of soil erosion?
Question 3 What are the effects of soil erosion?
Question 4 What is meant by soil pollution?
Question 5 How can soil pollution be prevented?
Question 6 How can soil erosion be prevented?
The removal of fertile top soil land by wind or water is called soil erosion.
Soil erosion occurs easily in those areas of land which are not covered by vegetation (trees and other plants) or have very little vegetation.
1) Due to the binding of soil particles by the roots of trees and plants, the blowing wind and flowing rainwater are not able to carry away top-soil and hence soil erosion does not occur. The soil not covered by vegetation (trees and other plants) is easily eroded because there are no roots of trees and plants in it which can bind the soil particles together and prevent them from being carried away by strong winds or flowing rainwater.
2) If there is vegetation (trees and other plants) on land, then much of the falling rain hits the trees and plants before it hits the soil. The cover of vegetation softens (or reduces) the effect of heavy rains on the soil. The soil does not become loose easily and the flowing rainwater is not able to carry away top-soil. Due to this, soil erosion does not occur. If there is no vegetation (trees and other plants) on land to soften the effect of heavy rains, the bare soil becomes loose quickly by the force of falling rainwater and erodes easily. This is because, being loose, it is easily carried away by flowing, rainwater or strong winds.
Cause of Soil Erosion
Soil erosion is caused mainly by the large scale cutting down of forest trees and other plants.(which is called deforestation).
A large number of forest trees are cut down everyday for obtaining wood for burning as fuel (firewood), for building purposes (timber) and for the manufacture of paper.
When the forest trees and other plants are cut down, then the top soil gets exposed and becomes loose because there are no roots to bind soil and no cover to soften the effect of falling rain. Blowing wind and flowing rainwater can then carry away this loose soil easily causing soil erosion.
Effects of Soil Erosion
The important effects of soil erosion are as follows:
1) Soil erosion can turn lush green forests into deserts and spoil the environment: When the fertile top-soil in a forest gets removed by soil erosion, then the infertile sub-soil is left behind. No forest plants can grow in this remaining infertile soil due to which the once lush green forest can gradually turn into a desert.
2) Soil erosion can lead to famines (excessive scarcity of food): When the fertile top-soil is removed by soil erosion, then the food crops do not grow well in the remaining infertile soil. And due to bad crops, there is an excessive shortage of food-grains in that area.
3) Soil erosion can cause floods: The soil carried away from land by the flowing rainwater gradually deposits on river beds (decreasing their depth). So. when it rains heavily, the river cannot take away all the rainwater quickly Due to this, river water overflows from its banks and causes severe floods by submerging surrounding areas.
Prevention of Soil Erosion
Soil erosion can be prevented in the following ways:
1) Soil erosion can be prevented by preventing large scale cutting down of forest trees. The large scale cutting down of forest trees is called deforestation. So soil erosion can be prevented by deforestation.
2) Soil erosion can be prevented by afforestation (large scale growing of forest trees in place of cut down trees).New trees should be planted in place of the cut down trees. And this tree cover will prevent soil erosion of the forest land.
3) Soil erosion can be prevented by increasing the green cover (vegetation) around us by planting more trees and plants ourselves.
The contamination of soil with waste materials (especially used polythene bags and plastics), pesticides, fertilisers, acid rain and industrial chemical wastes, etc., is called soil pollution.
The various sources of soil pollution and their effects are as follows:
1) Dumping of waste materials (such as polythene bags plastics, glass and metal objects) causes soil pollution. Some waste materials (like paper and vegetable wastes) rot after some time and become harmless. But the waste materials such as polythene bags and other plastics (plastic bottles, etc.) do not rot on their own and remain as such indefinitely. They also kill the living organisms. The used glass and metal objects also do not rot in nature and cause soil pollution.
2) The use of pesticides in agriculture causes soil pollution: Pesticides are the poisonous chemical substances which are sprayed on standing crops to save them from the harmful insects and diseases. So, the grains, fruits and vegetables grown in this polluted soil contain pesticides. When we eat such contaminated grains, fruits or vegetables, the pesticides present in them enter our bodies and damage our health in the long run.
3) The excessive use of fertilisers in agriculture causes soil pollution: Chemical fertilisers are added to soil in the fields to increase food production. The excessive use of chemical fertilisers makes the soil acidic or alkaline. When the soil becomes highly acidic or alkaline it is said to be polluted. This soil becomes unfit for the growth of crop plants.
4) Acid rain causes soil pollution: Acid rain makes the soil highly acidic. This acidic soil becomes toxic or poisonous) for plant growth. In this way, pollution caused by acid rain makes the soil less fertile.
5) Dumping of industrial wastes causes soil pollution: Many industries (or factories) dump their waste products containing harmful chemicals on soil. These chemicals cause soil pollution and harm plants which grow in it and the cattle which graze on it.
Prevention of Soil Pollution
The soil pollution can be prevented in the following ways :
(1) The use of polythene bags should be avoided to prevent soil pollution. This can be done by using bags made of paper, cloth or jute.
(2) Plastic objects should be sent to factories for recycling to prevent soil pollution. Discarded glass and metal objects can. also be recycled.
(3) The use of pesticides in agriculture should be minimised to reduce soil pollution.
(4) The use of excessive chemical fertilisers should be avoided in agriculture to prevent soil pollution.
(5) Steps should be taken to reduce the emission of acidic gases like sulphur dioxide and nitrogen oxides from factories which cause acid rain.
(6) The industrial chemical wastes should be treated properly to make them harmless before dumping into soil.