Degradation by improper resource utilisation

DEGRADATION BY IMPROPER RESOURCE UTILISATION AND MAINTENANCE

The lowering of quality, fertility and productivity of land by various factors such as salination of soil, soil erosion, desertification, shifting cultivation and developmental activities etc. is called land degradation. It is caused by five main factors :

(i) Developmental activities:

Many developmental activities such as rapid urbanisation, human settlement, mining, construction of roads, dams, canals, railways, airports, playgrounds, industries cause loss of large areas of fertile and productive land.

(ii) Soil erosion:

It is the removal of top, fertile, mineral rich soil layer by water, floods, wind, ocean waves, glaciers, felling of trees, overgrazing on slopes or some arid soils, over cropping and improper farming techniques etc. It occurs in both wet and arid regions. Roots of grasses are excellent binding material and keep the soil intact and free from soil erosion.

(iii) Desertification:

It is the change of fertile soil into a non productive desert soil. It is due to the shifting of sand dunes by strong winds, or by deforestation, soil erosion or overgrazing in lands sparsely covered by grasses. Many deserts in the world are man-made. Afforestation is the only solution to prevent desertification.

(iv) Shifting cultivation:

In many tribal communities of tropical and subtropical regions of Africa and Asia, it is a practice of slashing, cutting down trees, burning the felled trees and raising crops on the ash formed. This practice is called 'Jhum Cultivation' in north east India. This destroys forests and causes soil erosion.

(v) Salination of Soil:

Increase in the concentration of soluble salts in the soil is called salination. Origin or development of saline soil depends upon following factors:

(a) Poor Drainage of Soil: Salts dissolved in irrigation water accumulate on the soil surface due to inadequate drainage especially during flood.

(b) Quality of Irrigation Water: The ground water of arid (dry, barren having not enough rainfall to support vegetation) regions are generally saline in nature. The irrigation water may be itself rich in soluble salts and add to salinity of soils.

(c) Excessive use of basic fertilizers: Excessive use of alkaline fertilizers like sodium nitrate, basic slag, etc may develop alkalinity in soil.

(d) Saline nature of parent rock materials: If soil develops from saline nature of parent rock materials, soil would be saline.

Control of degradation : Degradation can be checked by the following measures :

(i) Reforestation and plantation of grassess can check soil erosion, floods and water logging.

(ii) Crop rotation and mixed cropping improve fertility. It would increase production, which would support large population.

(iii) Salinity of the soil can be checked by providing adequate drainage.

(iv) Desertification can be checked by artificial bunds or covering the area with suitable soil binding vegetation.