Land Degradation: Causes and Control |Soil Pollution

In this article we will discuss about the causes and control of land degradation.

Causes of Land Degradation:

In addition to pollution, soil and land face several other problems. These include erosion, deforestation and overgrazing, flooding and water logging, salination, desertification and ill- planned urbanization. It is estimated that if the present rate of soil depletion and land degradation continues, about one-third of arable land will be destroyed by the end of the present century.

Erosion:

Removal of top, fertile layer of soil is called soil erosion. The agencies responsible for it are water, wind, ocean waves, glaciers, rains, over-grazing, over-cropping, and improper tilling. In fact, erosion occurs both in dry and wet regions and results in floods.

In India, soil erosion is a serious problem in northern and north-eastern regions. Soil erosion is a global problem especially in countries like Nepal, India, China, Spain, Australia, U.S.A., USSR and Central Asia.

Deforestation and Over-Grazing:

In India, these are the main causes of soil erosion. An estimate suggests that nearly 40,000 hectares of land are affected by wind and water erosion. The quality of top soil loss in India is about 18.5% of the total global loss. India has highest number of livestock in the world, the pressure of grazing, therefore, is intensively higher.

Roots of grasses, plants and trees are excellent binding material and keep the soil intact. Disruption of grass cover by plough, intensive grazing, deforestation, etc., loosens the soil making it suitable for being washed away by wind or rain.

Shifting Cultivation:

It is also one of the causes of land degradation. Many tribal communities, particularly in the north-eastern India, follow the practice of cutting trees, burning them and raising crops on resulting ashes called jhuming. This practice is most prevalent in Jhum forests covering an area of about 30,000,000 km². It degrades forests and disturbs soil stability.

Desertification:

It results from erosion of top soils, shifting of sand dunes by wind and over­grazing in lands sparsely covered by grass. Many deserts are believed to be man-made.

In addition to above causes, various developmental activities like rapid urbanisation and human settlements, construction of dams, canals, mining, roads, railways, airports and establishment of industries have considerably reduced the areas of fertile and productive crop lands, woodlands and grasslands. All these have, thus, aggravated the problem of land degradation.

Control of Land Degradation:

Degradation of land can be controlled by adopting following measures:

1. By restoring forests and grass cover, soil erosion and flood can be checked.

2. Shifting cultivation can be replaced by crop rotation practices. Mixed cropping or developing plantation crops would improve soil fertility and support a larger population.

3. Adequate drainage should be made to prevent salinity of soil.

4. Salt affected lands can be recovered by bleaching them with more water.

5. Sufficient plantation of appropriate plant species can prevent shifting sand; mulching or covering the area with artificial protective covering also prevents shifting sand.

India is basically an agricultural country. Out of India’s total land mass of 305 million hectares nearly half is waste land, hence, nearly 143 million hectares are used for agricultural purposes.

From remaining, nearly 18 million hectares are under urban productive use, 21 million hectares are rocky or snowcapped, 17 million hectares are culturable waste lands,’23 million hectares are fallows, 83 million hectares are forests and pasture lands.

Due to rapid increase in population the demand of land for agriculture, settlement and industry is increasing rapidly but, on the other hand good land is shrinking considerably because of soil degradation problems. Obviously, the only solution of the problem appears to develop the waste lands so that they may be used by man for their various needs.

The waste lands are grouped into two categories, viz., culturable and unculturable waste lands. The culturable waste lands are those which can be brought to use by their development and reclamation.

Examples of such lands are ravinous and gullied lands, surface water-logged land and marsh, saline lands, forest lands, strip lands, industrial waste lands, shifting cultivation areas, etc.

The unculturable waste lands are those which cannot be used. Examples of such lands are barren rocky areas, steep slopes, snow-capped mountains, glaciers, etc. So, the development and reclamation of culturable waste lands can increase the availability of productive land.

No doubt, reclamation of waste lands involves high expenditure, expertise hands and manpower. Even then, proper steps within the financial means must be undertaken by the Government agencies immediately which will definitely solve the crisis of productive land to some extent.