Extent, severity and causative factors of land degradation in the Sudan

This paper examines the status of land resources in the Sudan after over half a century of unsustainable use. Several studies indicate that about 120 million ha of land, including 64 million ha of soils, are degraded to varying degrees. A remarkably high correlation seems to exist between human population densities and degraded soil in different aridity zones. The most degraded zones were the arid and semi-arid zones where 76% of the human population of the Sudan live. Wind erosion was the most widespread soil degradation type in the arid zone, while water erosion was dominant in the semi-arid zone. Chemical deterioration through nutrient loss was affecting all climatic zones. The central clay plains and the ironstone soils of south-west were the least degraded soil types. Overgrazing is the most widespread cause of soil degradation, particularly around permanent settlements and watering centres, affecting about 30M ha (47%) of the total degraded areas. Clearance of forests and woodlands cover for firewood and charcoal making and overexploitation of vegetation is the second cause of soil degradation affecting 22M ha. Cropping without appropriate nutrient inputs have degraded about 12M ha, particularly in small-scale farming on sandy and loamy soils. When these processes of resource mismanagement coincided with the recent recurrent droughts, collapse of the economic base of fragile areas took place. (C) 1998 Academic Press Limited.