KAWA MULTIMEDIA PUBLICATIONS
Causes of desertification
i. Cultivation of marginal lands
ii. Cultivation of steep slopes /sides.
iii. Over stocking which may lead to overgrazing.
iv. Population pressure on existing land that led to opening of virgin land.
v. Wanton destruction of trees.
Desertification occurs in cropland (both irrigated and nonirrigated), pasture, and woodlands. Loss of soil, deterioration of soil, and loss of natural vegetation all lead to desertification. Drought, a period of unusually dry weather, can cause loss of vegetation, which in turn leads to desertification. Poor land management and increasing population are factors that promote increased irrigation, improper cultivation or overcultivation, and increased numbers of livestock. These events alter the land and the soil, diminish the resources, and increase the chances of desertification.
Desertification has sometimes been mistakenly described as the expansion of deserts into non desert areas. Pictures of sand dunes engulfing agricultural lands encourage this misconception, but this type of desertification is rare. Arid and semiarid lands can be degraded even if there is no adjacent desert. Drought has also mistakenly been called the primary cause of desertification. Desertification can occur without drought, and drought can occur without resulting in desertification. Droughts are short-term and cyclical. By themselves, they do not degrade the land. However, they intensify the pressures that lead to mismanagement of land, plant, and water resources.
While dryland rainfall is low on average, it is extremely variable from year to year and from place to place. Native plants and animals have adapted to this variability. For example, the seeds of many desert plants can remain dormant through several years of drought, waiting for a good rain to sprout. In order to survive in this harsh environment, humans must adapt their activities as well. However, many factors, including population growth, poverty, politics, disrupted social institutions, and the pursuit of short-term economic opportunity, may work together to promote unsustainable practices.
Ironically, the availability of water for irrigation can cause desertification. Nearly all irrigation water contains some salt. If an irrigation system lacks a good drainage system, then the salt accumulates in the soil. Eventually, the salt reaches levels toxic to most plants. This problem is now jeopardizing about one-third of the world’s irrigated land. For example, in the Euphrates Valley of Syria, irrigation costs dropped with the introduction of diesel pumps in the 1940s, encouraging development of new croplands. By 1980 half the land area had extremely high salt concentrations and a large part of the area had been abandoned.
A political change in Mauritania was largely responsible for the desertification that began there in the 1960s. Prior to Mauritania’s gain of independence in 1960, Mauritanian pastoralists could freely move south into Senegal during times of drought. The border established at the time that independence was gained restricted these traditional movements. This blockage increased competition for the limited forage available and resulted in overgrazing during times of drought. The consequence was a general decline in nomadic pastoralism, or livestock rearing, and an increase in Mauritania’s urban population.
Cultivation of the land, especially overcultivation or the introduction of nonnative plant species, can lead to the loss of topsoil and degradation of the soil. Before the Dust Bowl in the 1930s, high wheat prices and favorable climatic conditions in the Midwestern United States encouraged early 20th-century settlers to convert native grasslands to cropland. The native grasses had held the fine-grained soil in place in spite of recurrent droughts and strong winds.
The crops planted by the settlers, however, were adapted to neither drought nor wind. When the drought came in the 1930s, the crops failed. Without the cover of crops to protect the soil, the soil began to blow away. In many places, 8 to 10 cm (3 to 4 in) of topsoil vanished in the wind. When the rains returned, the farms were less productive due to the loss of much of their nutrient-rich topsoil. The crop failures and subsequent declines in production ruined many farms. As in other arid lands, many families had few options other than migration. Those people who remained adopted new soil conservation practices, and they were also protected by a new system of government crop subsidies and insurance.
ii. Cultivation of steep slopes /sides.
iii. Over stocking which may lead to overgrazing.
iv. Population pressure on existing land that led to opening of virgin land.
v. Wanton destruction of trees.
Desertification occurs in cropland (both irrigated and nonirrigated), pasture, and woodlands. Loss of soil, deterioration of soil, and loss of natural vegetation all lead to desertification. Drought, a period of unusually dry weather, can cause loss of vegetation, which in turn leads to desertification. Poor land management and increasing population are factors that promote increased irrigation, improper cultivation or overcultivation, and increased numbers of livestock. These events alter the land and the soil, diminish the resources, and increase the chances of desertification.
Desertification has sometimes been mistakenly described as the expansion of deserts into non desert areas. Pictures of sand dunes engulfing agricultural lands encourage this misconception, but this type of desertification is rare. Arid and semiarid lands can be degraded even if there is no adjacent desert. Drought has also mistakenly been called the primary cause of desertification. Desertification can occur without drought, and drought can occur without resulting in desertification. Droughts are short-term and cyclical. By themselves, they do not degrade the land. However, they intensify the pressures that lead to mismanagement of land, plant, and water resources.
While dryland rainfall is low on average, it is extremely variable from year to year and from place to place. Native plants and animals have adapted to this variability. For example, the seeds of many desert plants can remain dormant through several years of drought, waiting for a good rain to sprout. In order to survive in this harsh environment, humans must adapt their activities as well. However, many factors, including population growth, poverty, politics, disrupted social institutions, and the pursuit of short-term economic opportunity, may work together to promote unsustainable practices.
Ironically, the availability of water for irrigation can cause desertification. Nearly all irrigation water contains some salt. If an irrigation system lacks a good drainage system, then the salt accumulates in the soil. Eventually, the salt reaches levels toxic to most plants. This problem is now jeopardizing about one-third of the world’s irrigated land. For example, in the Euphrates Valley of Syria, irrigation costs dropped with the introduction of diesel pumps in the 1940s, encouraging development of new croplands. By 1980 half the land area had extremely high salt concentrations and a large part of the area had been abandoned.
A political change in Mauritania was largely responsible for the desertification that began there in the 1960s. Prior to Mauritania’s gain of independence in 1960, Mauritanian pastoralists could freely move south into Senegal during times of drought. The border established at the time that independence was gained restricted these traditional movements. This blockage increased competition for the limited forage available and resulted in overgrazing during times of drought. The consequence was a general decline in nomadic pastoralism, or livestock rearing, and an increase in Mauritania’s urban population.
Cultivation of the land, especially overcultivation or the introduction of nonnative plant species, can lead to the loss of topsoil and degradation of the soil. Before the Dust Bowl in the 1930s, high wheat prices and favorable climatic conditions in the Midwestern United States encouraged early 20th-century settlers to convert native grasslands to cropland. The native grasses had held the fine-grained soil in place in spite of recurrent droughts and strong winds.
The crops planted by the settlers, however, were adapted to neither drought nor wind. When the drought came in the 1930s, the crops failed. Without the cover of crops to protect the soil, the soil began to blow away. In many places, 8 to 10 cm (3 to 4 in) of topsoil vanished in the wind. When the rains returned, the farms were less productive due to the loss of much of their nutrient-rich topsoil. The crop failures and subsequent declines in production ruined many farms. As in other arid lands, many families had few options other than migration. Those people who remained adopted new soil conservation practices, and they were also protected by a new system of government crop subsidies and insurance.