ABSTRACT
Soil erosion is one of the most important and challenging problems for natural resource managers worldwide. It is the main source of sediment that pollutes streams and lls reservoirs. The World Wildlife Organization states that “half of the topsoil on the planet has been lost in the last 150 years” (https://www.worldwildlife.org/threats/soilerosion-and-degradation). Some estimates of erosion rates in the 1970s, while perhaps somewhat exaggerated, were as high as 4 billion tons annually in the United States (Schwab et al. 1994). The USDA-NRCS estimated that in the United States soil erosion on cropland decreased 41 percent between 1982 and 2010. Water (sheet and rill) erosion declined from 1.67 billion tons per year to 982 million tons per year, and erosion due to wind decreased from 1.38 billion to 740 million tons per year (USDA-NRCS 2013). It has been estimated that soil erosion costs the United States between $30 and $44 billion annually (Pimental et al. 1995; Uri 2001, Morgan 2005). In contrast to developed countries, such as the United States, many developing countries experience much higher erosion rates that often tend to be increasing rather than decreasing. Informative account of factors that inuence soil erosion and the food and environmental threat posed by soil erosion are provided by Pimental (2006) and Ypsilantis (2011).
