The Universal Soil Loss Equation, developed at the USDA National Runoff and Soil Loss Data Center at Purdue University in a national effort led by Walter H. Wischmeier and Dwight D. Smith, was published in 1965 in USDA Agriculture Handbook 282. Based on extensive erosion data from studies throughout the USA, it provides a quick approach to estimating long-term average annual soil loss and is comprised of six factors: rainfall and runoff, soil erodibility, slope length, slope steepness, cover and management, and support practice. It was the first empirical erosion equation not tied to a specific region of the United States, and it has been used in more than 100 countries to guide conservation planning, assess soil erosion for conservation policy development, and estimate sediment yield. It has helped save millions of tons of soil, helping to feed the world's population and protect the environment from sediment produced by soil erosion.

Photo: courtesy Purdue University

West Lafayette, Indiana · USA