Erosion and soil productivity in Africa

ASIA probably has suffered more from human-induced soil erosion than any other continent. As one of the first to describe the impacts of erosion on early civilizations, Walter Lowermilk noted the extensive damage in the eastern Mediterranean, Iran, and China ( 30 ). He emphasized the loss in soil productivity that had reduced the human carrying capacity a thousand or more years ago. Likewise, Eric Eckholm's well-documented account of environmental degradation cites erosion losses in deteriorating mountain areas as a major contributor to a chronic reduction in food production in developing countries (10. Eckholm said that mountainous Nepal may have the world's most acute erosion problem, caused primarily by deforestation to provide cropland and timber. Soil erosion is a natural process that can be accelerated by human activity. Once accelerated, erosion can threaten food production potential. Of all the human-induced land degradation problems, the permanent loss of soil productivity due to erosion is the worst on a global scale. Degradation of vegetation, salinization, loss of soil organic matter and fertility, crusting, and compaction usually are reversible. Pesticide pollution frequently is reversible, although it may require several years. Heavy metal and nuclear waste contamination may not be reversible …