Desertification

Desertification

Desertification is a type of land degradation in drylands in which biological productivity is lost due to natural processes or induced by human activities whereby fertile areas become increasingly more arid. It is the spread of arid areas caused by a variety of factors, such as through climate change (particularly the current global warming) and through the overexploitation of soil through human activity.

Throughout geological history, the development of deserts has occurred naturally; however, when deserts emerge due to unchecked depletion of nutrients in soil that are essential for it to remain arable, then a virtual "soil death" can be spoken of, which traces its cause back to human overexploitation. Desertification is a significant global ecological and environmental problem with far-reaching socio-economic and political consequences.

From NASA

Temporary Drought or Permanent Desert?

Desertification. The word invokes images of sand dunes blowing over abandoned farms as some irresistible, dark force steadily transforms fertile fields into an inhospitable wasteland. The United Nations’ official definition says desertification is land degradation in typically dry areas resulting from various factors, including climatic variations and human activities. But for Prince and many other scientists studying desertification, this definition is too broad. “The definition encompasses things like drought, overgrazing, and inadvisable cropping,” says Prince. All of these conditions do suppress the ability of the land to support plant growth. “But if it starts to rain and vegetation returns, what do you call it?” Is the land still desertified?

Scientists are beginning to say that desertification is a reduction in the productivity of the land that is not reversible. In other words, the land is desertified when it can no longer support the same plant growth it had in the past, and the change is permanent on a human time scale. Many things can cause desertification. Drought, overgrazing, fire, and deforestation can thin out vegetation, leaving exposed soil. If the nutrient-rich topsoil blows or washes away, plants may not be able to return. Overfarming or drought can change the soil so that rain no longer penetrates, and the plants lose the water they need to grow. If the changing force is lifted—drought ends or cattle are removed, for example—but the land cannot recover, it is desertified. The loss of productive land for a season or even a few years is one thing, but to lose it effectively forever is clearly far more serious.

Strategies to reduce desertification

Prevention is much more cost-effective than rehabilitation. Desertification can be reduced by adopting the following strategies:

  • Planting more trees - the roots of trees hold the soil together and help to reduce soil erosion from wind and rain.
  • Improving the quality of the soil - this can be managed by encouraging people to reduce the number of grazing animals they have and grow crops instead. The animal manure can be used to fertilise the crops grown. Growing crops in this way can improve the quality of the soil as it is held together by the roots of plants and protected from erosion. This type of farming is more sustainable.
  • Water management - water can be stored in earth dams in the wet season and used to irrigate crops during the dry season. This is an example of using appropriate technology to manage water supplies in the desert environment.
  • Magic stones (or bunds) are circles of stones placed on the ground to hold water on the soil rather than letting it run quickly over the surface.
  • Drip irrigation is where water drips slowly onto the ground from pin-sized holes in a hose lying on top of the soil. This minimises water loss, maximises effectiveness and can be delivered via a solar pump.

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