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Published online by Cambridge University Press: 10 May 2010
A perspective
Soil erosion is one of the most serious environmental problems in the world today, because it seriously threatens agriculture and the natural environment. Adequate food supplies depend on productive land. Over one thousand million humans today are malnourished – more than ever before in the history of human society. Today 5.5 thousand million humans exist on earth, and an additional 250 000 humans are born each day and must be fed.
More than 97% of the world's food comes from the land rather than the oceans and other aquatic systems, with an ever-increasing portion being derived from steep lands in tropical climates. Therefore, the control of soil erosion for a sustainable agriculture and environment is essential for all programs of food security and environmental conservation.
At a time when agricultural efforts are focused on increasing food production, soil degradation worldwide is increasing. The dimensions of land degradation are alarming; it affects from 30 to 50% of the earth's land surface. In some areas the productivity of eroded soils cannot be restored, even with heavy applications of fertilizers and other fossil energy inputs. (Severely eroded soils can be restored in some cases with enormous investments including adding either 2000 tonnes/hectare [t/ha] of quality soil or 500 tonnes [dry]/ha of rotted cattle manure to the soil.) In addition, water resources and aquatic environments are degraded because of sediments and other pollutants washed from the land.
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