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.
Causes 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.
