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~; <br />• <br />PRINCIPLES OF SOIL EROSION CONTROL: RANGELANDS <br />by <br />Kenneth C. Renardl <br />The control of erosion on rangeland ie certainly not an easy problem for <br />the land manager/environmentalist. The zeason the land is prohably being used <br />as range 1s because of come limitation in the resource base such as poor soil <br />(shallow or mineral deficiency), excessive slope (and eorzasponding high <br />erosion hazard), limited precipitation and in turn, limited soil protection by <br />vegetation. A further significant factor in the eroalon control problem on <br />rangelands involves the low economic value on a unit basis of aueh land vhich <br />limits the options for investments in many types of treatments vhich have been <br />found to be•effeetive on cultivated land. And finally, the erosion on ran- <br />, geland includes that from both wind and voter ao that both contribute to the <br />loss of the precious soil base. <br />Having spent moat of my career working with water erosion problems on <br />rangeland, I hope to emphasize eater erosion on rangelands while recognizing <br />that the same fozeea ^nd processes aze involved with wind erosion, the <br />transport medium being the mayor difference. <br />Erosion and sedimentation by eater involve processes of detachment, <br />( • transport and deposition of soil particles. She mayor forces are from <br />raindrop impact and valet flowing over the land surface. The faetozs affect- <br />ing erosion can be expressed in equation farm as: <br />Er - f (C1, Sp, To, SS, K) (1) <br />where Er - erosion; f - function of ( ); C1 - climate; Sp - soil properties; <br />'~ To - topography; SS ~ •oil surface condition including vegetation; and M <br />human netivltlea. A fairly detailed treatment of the theoretical aspects of <br />each of these factors vas presented by Aanard and Footer (1983) and Foster <br />(1982). Neither time or space permit repeating aueh material here. Rather I <br />want to disease what !a being dons regarding two approaches to estimate upland <br />erosion by eater, namely a revision of the Universal Soil Loss Equation ,LISLE, <br />(Vischmeier and Smith, 1965 6 1978) and the 17ater Erosion Prediction Project, <br />7 VEPP, a technology intended to replace the LISLE. <br />^` Although it is now over 20 years since the original LISLE handbook vas <br />published, the technology has bean available and widely used in USDA for <br />i almost four decades. The LISLE la an expression of the functional relationship <br />shown 1n equation 1. Developed from extensive field experimentation, the US LE <br />Snvolvee six terms, the product of vhich furniches an estimate of the average <br />annual eroclon from a field area. <br />A-RKLS C Y (~) <br />f • <br />lies. Hydraulic Engr., Arldland Vatershed .yanagesent Research L'nit, L'SDA-ARS, <br />:000 E. Allen Rd., :ueson, AZ 85719 <br />JO <br />e <br />