roblem if current cultivation practices continue, because corn is relatively poor at holding soil, the corn-growing lands ¡V about 7.5 percent of all lands in cultivation, producing roughly one-fifth of the world¡s grain ¡V will fare the worst . As this consequence occrued, people will have to acquire more land by flating forests and hills, this has already became a harmful circulation. Although much remains to be laearned about the physical c!
             onsequences of soil erosion in terms of future productivity and environmental quality, economic assessments using available data for the purpose of public policy analysis must be made.
             In the final stage in a slow and insidious process of land degradation and erosion, is desertification which starts with the loss of vegetative cover and ends with the destruction of the the soil¡s fertility and its transformation into barrin desert. The most vulnerable soils are to be found in the dry tropices . In most people¡s view, nomadic pastoralism and traditional peasant ag
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