Soil resources

SOIL RESOURCES
  • Soil is the most finite and valuable resource upon which we depend for our basic amenities of life. So, we should preserve soil by all means. The total area of India is 328.73 mha. of which the potential area is 264.5 mha. About 187.8 m ha of land have been degraded due to water shortage, wind erosion, salinity, alkalinity and water-logging. Soil is thin covering over land containing organic materials, living organisms, air and water.
  • Soil is a renewable source. But it is regenerated at a very slow rate i.e., 2.5 cm soil for 200-1000 years. Soil becomes non-renewable resource when the rate of erosion is faster than the rate of renewal. A cross section of soil horizon is called soil profile.

Abuses

  • The rapid increase of population results in demand for limited land resources which are subject to degradation. Land degradation takes place due to natural and man-induced or arthropogenic activities. Natural causes are soil erosion, land slide, volcanoes, earthquakes, floods, droughts and desertification.
  • Man induced causes are deforestation, mining, over-irrigation, dam construction and use of more fertilizers. The flood havoc witnessed in Mumbai and Tamilnadu (Nov.2005) was perhaps due to increase in global temperature and green house gases. The average annual erosion rate of land is 20-100 times more than renewal rate.

Man-induced landslides

  • Overirrigation of slopes for farming
  • Diversion of surface water onto sensitive slopes
  • Cutting of trees and forest fires along the slopes
  • Construction work along the slopes
  • Hydroelectric projects, large dams, reservoirs, construction of roads and railway lines and mining.
  • Mining combines with natural factors for landslides Example: Land slides between Rishikesh and Byasi on Badrinath Highway due to construction of roads and mining.

Soil erosion

  • Top soil moves from one place to another resulting in loss of fertility of soil. One third of world’s croplands is getting eroded. Two thirds of degraded lands lie in Asia and Africa. Soil erosion takes place due to normal erosion by natural process and accelerated erosion by overgrazing, deforestation and mining.
  • Two types of agents cause soil erosion. The first one is climatic agent (water and wind) and the other is biotic agent (overgrazing by 35% damage to soil, mining and deforestation by 30% and unscientific modern farming practices by 28%)

Desertification

  • The croplands are converted into desert like land. The desertification may be moderate (10-25% drop in productivity), sever (215-50% drop) and very severe (more than 50% drop).
  • The causes for desertification are overgrazing, disforestation, surface mining, quarrying , unscientific farming, overcultivation, low rainfall, more drought and global warming.
Last modified: Tuesday, 8 March 2011, 11:52 AM