11:32 am - Monday May 28, 2012

Land Degradation

Land degradation is a process in which the value of the biophysical environment is affected by one or more combination of human-induced processes acting upon the land. It is viewed as any change or disturbance to the land perceived to be deleterious or undesirable. Natural hazards are excluded as a cause, however human activities can indirectly affect phenomena such as floods and bushfires.

Land DegradationCauses of Land Degradation

  • Land degradation is a global problem, largely related to agricultural use. The major causes include:
  • Land clearance, such as clearcutting and deforestation
  • Agricultural depletion of soil nutrients through poor farming practices
  • Livestock including overgrazing
  • Inappropriate Irrigation and overdrafting
  • Urban sprawl and commercial development
  • Land pollution including industrial waste
  • Vehicle off-roading
  • Quarrying of stone, sand, ore and minerals

Effects of Land Degradation

The main outcome of land degradation is a substantial reduction in the productivity of the land. The major stresses on vulnerable land include:

  • Accelerated soil erosion by wind and water
  • Soil acidification and the formation of acid sulfate soil resulting in barren soil
  • Soil alkalinisation owing to irrigation with water containing sodium bicarbonate leading to poor soil structure and reduced crop yields
  • Soil salination in irrigated land requiring soil salinity control to reclaim the land
  • Soil waterlogging in irrigated land which calls for some form of subsurface land drainage to remediate the negative effects
  • Destruction of soil structure including loss of organic matter

Overcutting of vegetation occurs when people cut forests, woodlands and shrublands—to obtain timber, fuelwood and other products—at a pace exceeding the rate of natural regrowth. This is frequent in semi-arid environments, where fuelwood shortages are often severe.

Overgrazing is the grazing of natural pastures at stocking intensities above the livestock carrying capacity; the resulting decrease in the vegetation cover is a leading cause of wind and water erosion. It is a significant factor in Afghanistan.

Agricultural activities that can cause land degradation include shifting cultivation without adequate fallow periods, absence of soil conservation measures, fertilizer use, and a host of possible problems arising from faulty planning or management of irrigation. They are a major factor in Sri Lanka and the dominant one in Bangladesh.

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