Desertification Desertification is the spread of desert-like conditions in arid and semi-arid areas, due to human influence and/or climatic change. Some of the natural causes of desertification are wind erosion, climatic conditions, and scarce water supply. There is a grave difference between areas where vegetation has been retained and surrounding vegetation. For example, “Nefta in southern Tunisia, the coverage of vegetation inside an area fenced 60 years ago is 85%, in contrast to 5% outside the area.” Approximately one-third of the earth’s land surface is semi-arid or arid. This is the land where desertification occurs; not in any of the natural desert zones.
“Were these lands to continue to support agriculture, their output could be worth at least $20 billion a year..the expense of rehabilitating the degraded lands, and of halting the spread of deserts, need no more than $2.5 billion a year.” Even though the governments refuse to put money into the fight against desertification there is still hope through many agricultural foundations that aid poorer countries. If this money is used wisely then the causes of desertification may be stopped. Desertification is caused not only by nature but also by human factors (over-grazing, poor irrigation, deforestation, and over-cultivation) all of which are preventable. Livestock, in many continents, overgrazes and flattens vegetation. Arid areas, such as the Sahel (“Desertification was brought to the world’s attention by the Sahel disaster..”), the dry plains of India, and semi deserts of Turkey can usually support a small number of people and their livestock without permanent damage. The land often recovers when the animals move on but when there are too many sheep, goats, and cattle everything is eaten (including twigs and bark). When rain finally does fall it is too late; trees, shrubs, and grass are all dead. Parts of North and Central America, and most of Australia is at the risk of desertification due to inadequate stock raising techniques (see map). This factor, which is a main cause of desertification, is preventable.
Disease-resistant varieties of animals (can survive drought and eat little) should be kept by farmers in marginal lands. “They cause less harm to the environment than do more exotic breeds.” Another strategy is to make laws on the periods of grazing. This will give over-worked pastures time to recover. The final method I would suggest is to plant vegetation which helps to restore soil fertility. “Legume grasses, such as clover and alfalfa,” are suggested in GAIA, An Atlas Of Planet Management. Improper irrigation sterilizes the earth with salts and alkalis. Canal irrigation is the method used in many poorer countries to supply the crops with water.
Much of northern and southern Africa is at high risk of desertification because of this and other poor irrigation techniques (see map). Better use of the scarce water available in these countries must be practiced. Drip or sprinkler irrigation should be used in place of canals. “This method (sprinkler) reduces water losses by evaporation and to weed growth along ditch-banks.” By converting to the sprinkler method the soil will increase its fertility and crops will prosper. In addition to this, fertilizers and pesticides should be combined with the water since it will be cheaper in the long run. Drip irrigation is where the water is directly put on the crops. This wastes little water since the water is not used by weeds.
By improving the irrigation in many areas this helps to halt the desertification process. Deforestation is causing desertification when people harvest trees and woody plants for fuel. In many of these regions there is a huge number of people whose only source of fuel for heating their homes and cooking their food is wood. Once all the available dead wood has been collected, , trees are cut down. Consequently, there is nothing to protect the soil. It turns to dust and is soon washed away or blown away by the wind.
Places such as Kenya are at high risk of becoming desert due to this destruction of trees (see map). In order to prevent this, many trees, such as the leucaena, should be planted. These trees are excellent for use as fuel since they “grow swiftly..and because they fix their own nitrogen, help to restore soil fertility.” If these type of trees were planted the worry of an encroaching desert would lessen since trees would always be available to chop for firewood. Over-cultivation occurs when many marginal lands are cleared and ploughed in farming attempts. Too many farmers are drifting into marginal lands and rob the land of the little richness it has to offer.
There should be an intensified use of the good land. Crops should be grown in rapid succession and perhaps multicropping should be practiced (a method where more than one crop is produced on the same land). By improving irrigation (previously mentioned) the good land can also be put to better use. Marginal lands should produce crops which can prosper without long periods of rain. These crops include, “millet, sorghum, amaranth, certain beans, and fast maturing maize”. Almost half of Asia is at high risk and one-third is at moderate risk of desertification (see map).
If the proper steps were taken to utilize the full potential of rich quality land and the poor quality land were allowed to replenish itself, then the desertification process would slow down dramatically. Desertification is caused by a combination of natural and human factors. If steps are not soon taken by many countries they may find their people starving to death in large numbers. Over-grazing is a major cause of desertification and can be stopped by keeping genetically advanced species of animals which eat less vegetation. Poor irrigation (another human cause) should be corrected by converting from canal to sprinkler or drip irrigation which will put the small amounts of water available to better use. Deforestation is obviously caused by humans and can be slowed or lessened by planting trees which grow quickly in large numbers (leucaena trees).
Finally, the over-cultivation of marginal lands is a man made cause of desertification. This can be stopped by putting good land to greater use, therefore allowing the poor land to recover. The earth, as a whole, will suffer if the human causes of deforestation are not eliminated. BIBLIOGRAPHY 1. Encyclopedia Britannica. Deserts.
Chicago: William Benton., 1981. 2. George, Uwe. In The Deserts Of This Earth. New York: Harcourt Brace J ovanovich Inc.,1977.
3. McGraw-Hill Encyclopedia Of Science And Technology. Desertification.New York: McGraw-Hill Inc., 1982. 4. Molyneux, John, and Marilyn Mackenzie.
World Prospects. Ontario: Prentice-Hall Canada Inc., 1987. 5. Myers, Dr. Norman. GAIA An Atlas Of Planet Management.
New York: Anchor Press, 1984. 6. Seager, Joni. The State Of The Earth Atlas. Toronto: Simon and Schuster Inc., 1990.
ENDNOTES McGraw-Hill Encyclopedia Of Science And Technology, Desertification (New York: McGraw-Hill Inc., 1982) 126. Dr. Norman Myers, GAIA An Atlas Of Planet Management (New York: Anchor Press, 1984) 46. Myers 47. Myers 59. Myers 59.
John Molyneux, and Marilyn Mackenzie, World Prospects (Ontario: Prentice-Hall Canada Inc., 1987) 94. Myers 59. Myers 59. Joni Seager, The State Of The Earth Atlas (Toronto: Simon And Schuster Inc., 1990) 36, 37.