Predicting Rainfall Erosion Losses: A Guide to Conservation PlanningDepartment of Agriculture, Science and Education Administration, 1978 - 58 Seiten The Universal Soil Loss Equation (USLE) enables planners to predict the average rate of soil erosion for each feasible alternative combination of crop system and management practices in association with a specified soil type, rainfall pattern, and topography. When these predicted losses are compared with given soil loss tolerances, they provide specific guidelines for effecting erosion control within specified limits. The equation groups the numerous interrelated physical and management parameters that influence erosion rate under six major factors whose site-specific values can be expressed numerically. A half century of erosion research in many States has supplied information from which at least approximate values of the USLE factors can be obtained for specified farm fields or other small erosion prone areas throughout the United States. Tables and charts presented in this handbook make this information readily available for field use. Significant limitations in the available data are identified. |
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20 percent antecedent soil moisture average soil loss chart column combined computed Conservation continuous fallow corn cover and management crop residues crop system cropland cropping and management cropstage period deposition derived developed disk distribution energy erosion control erosion index values estimating evaluated farming field slope figure gradient handbook Inceptisols intensity irregular slopes isoerodent map kaolinitic land slope legume less lowa meadow metric mulch No-till nomograph obtained Pct Pct Pct percent cover percent slope percentages plant plot plowed practices procedure rain rainfall erosion index rainfall patterns reduce residual effects residue mulch ridges rotation row crop row spacing runoff runoff water sediment sediment yield seedbed seeding segments selected silt loam slope length Soil and Water soil loss data soil loss equation soil loss ratios soil loss tolerance Soil Science specific storm strips subfactor table 13 tillage tion U.S. Department USLE vegetation watershed Watkinsville Wischmeier
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Seite 8 - K, the soil erodibility factor, is the soil loss rate per erosion index unit for a specified soil as measured on a unit plot, which is defined as a 72.6-ft length of uniform 9-percent slope continuously in clean-tilled fallow.
Seite 8 - C, the cover and management factor, is the ratio of soil loss from an area with specified cover and management to that from an identical area in tilled continuous fallow.
Seite 12 - Slope length is defined as the distance from the point of origin of overland flow to...
Seite 6 - Calculated at from one to five tons per acre annually, depending on soil and climatic conditions, this figure represents the maximum level of soil erosion that will permit a high level of crop productivity to be sustained economically and indefinitely.
Seite 8 - L = the slope-length factor: The ratio of soil loss from the field slope length to that from a...
Seite 34 - P values: A For 4-year rotation of row crop, small grain with meadow seeding, and 2 years of meadow. A second row crop can replace the small grain if meadow is established in it. B For 4-year rotation of 2 years row crop, winter grain with meadow seeding, and 1-year meadow. C For alternate strips of row crop and small grain. " Adjust strip-width limit, generally downward, to accommodate widths of farm equipment.
Seite 8 - A is the computed soil loss per unit area, expressed in the units selected for K and for the period selected for R . In practice, these are usually selected so that A is...
Seite 5 - Therefore, planning for the control of sediment requires knowledge of the relations between those factors that cause loss of soil and those that help reduc; such losses on croplond.
Seite 26 - County is 100. £ - is the ratio of soil loss from land cropped under specified conditions to the corresponding loss from tilled, continuous fallow.
Seite 10 - A. = slope length in feet; 0 = angle of slope; and m = 0.5 if the percent slope is 5 or more, 0.4 on slopes of 3.5 to 4.5 percent, 0.3 on slopes of 1 to 3 percent, and 0.2 on uniform gradients of less than 1 percent.