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Soybeans are planted on approximately eight million hectares (20 M acres) of highly erodible land (HEL) in the United States. Soybean crops have been recognized as deficient in supplying crop residues that reduce soil erosion. A new type of soybean tested at the Beltsville Agricultural Research Center, Maryland, can grow to heights of 1.8-meters (6 ft) or more. The development of the large biomass soybean (LBS) suggested the potential of increased crop residue production to reduce soil loss on erodible soybean lands. An evaluation was conducted of the soil conservation benefits of LBS versus conventional soybean using data from a three-year field experiment. LBS produced more crop residue dry biomass and provided a mean increase of 31 percent more crop residue cover in the spring before mulch tillage and 47 percent more after mulch tillage than conventional cultivars. Soil loss estimates for LBS were much lower than for conventional soybeans as simulated by a revised universal soil loss equation ...

The Goodwin Creek Research Watershed (21.3 km2) is located in the north central part of Mississippi in the bluff hills just east of the Mississippi River floodplain. Land use on the watershed has been surveyed annually and the percentage of cultivated land has decreased from 26% in 1982 to 12% in 1990. During this 9-year period the concentration of fines ( 2.0 mm) have decreased by 39%. The decrease in the percentage of cultivated land affects the sediment budget of the watershed in two ways. A source of readily eroded sediment is removed, and the energy of the flowing water available to erode and transport sediment is reduced. The reduced flow in the channels from the decrease in cultivated land in the watershed was probably the main cause for the lower transport rates of sand and gravel.