We talk of land degradation when human actions, as well as natural occurrences, result in long-term loss of land services in terms of its natural and ecosystem functions. Restoration of degraded lands and soils are often possible, but time is needed for that piece of land to fully recover all or some of its value and nutrients. Land degradation is known to be a cause and effect of climate change.
There are direct and indirect effects of land degradation. Directly, soil loses its organic carbon and nutrients. It also loses its ability to store and regulate water both at the land surface and water table level. It is the ability to sustain below-the-surface life-forms are also hurt. Indirectly, land and soil degradation it can potentially disrupt the water cycle in that area. Degraded land may be exposed to the sun’s direct action, which can have the effect of the flow of surface and groundwater.
Though soil erosion is a natural process, it is facilitated by human actions that remove the land cover and expose it to rainwater or wind. Pollution by deforestation, mining, farming (including grazing) and construction are the main causes of soil erosion. Erosion wipes away top-soils, which is usually made up of soil organic matter and nutrients. Top-soils also has good water holding abilities because of the porous nature of it. Wind erosion is the major problem in West Asia, with as much as 1.45 million km2 (that is about one-third) of the region affected.
Soil fertility is reduced when the land is polluted. This degradation involves the loss of plant nutrients such as nitrogen, phosphorus, potassium and organic matter, all of which determine the health and resilience of ecosystems. Nutrient depletion is a major biophysical factor limiting crop production in many places. Usually, the application of fertilizers can help improve crop yield, but again, it leaves further chemicals in the soils, that end up in water tables. Typically, nutrient depletion is caused by wet climates, coupled with soluble nutrients that are easily leached and the removal of crop residue after the planting season.