Evolution of the universal soil loss equation

SUPPOSE this were 1934. You need to estimate the soil erosion on an area of land or compare the erosion resulting from different land uses. Where would you start? You have no relationships for computing the erosion and few data on which to base your estimations. How would you proceed? This dilemma faced soil conservationists less than a half century ago. Yet today we can readily make accurate estimates for many conditions. There are still opportunities for improvement, but erosion prediction certainly has come a long way in the last 50 years. How did this progress come about? Let's review the research history leading to development of the universal soil loss equation (USLE) (5, 12, 24, 25, 32-34, 38, 46-48, 50). Early erosion experiments A German scientist, Ewald Wollny (49), has been called a “pioneer in soil and water conservation research” (2). In the last quarter of the 19th century, Wollny conducted extensive investigations of the soil physical properties affecting runoff and erosion. Among the factors he studied were steepness of slope, plant cover, soil type, and direction of exposure. He also investigated factors affecting percolation, transpiration, and evaporation in soils, and he studied the effects of compaction on soil …