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Erosion Runoff Study cont. <br />Page 2 <br />and 69.6E respectively. Adjacent rangeland pre-mine sites provided <br />61.37. herbaceous cover. The total number of plant species on indi- <br />vidual treatments 1-4 were 30, 35, 36 and 35 respectively. Species <br />abundance on premine sites was 50 total plant species. <br />The plots planted to permanent vegetation in 1980 showed both the <br />greatest cover percentage and best establishment of targeted peren- <br />nial vegetation (Table 4). invader plant species are more dominant <br />in the winter wheat plots that were planted to perennials the fol- <br />lowing year. <br />3.0 Rill and Gully Erosion Calculations <br />Given the vegetation information provided and the various factors for the <br />USLE, quantitative estimates of the erosion potential for Che various <br />treatments and adjacent premine sites can be calculated. The (R) rain- <br />', fall and runoff factor was modified in the following equations to account <br />for peak losses in early spring. As the winter progresses, the soil <br />becomes increasingly more erodible as the soil moisture profile is being <br />filled. The surface structure of the soil is being broken down by <br />repeated freezing and thawing, as well as puddling and surface scaling <br />taking place. The calculated estimate of R was obtained by taking !.5 <br />times the local December-through-March precipitation measures as inches <br />of water and added to the Tabled R value shown in SCS Agronomy Note i`50 <br />~. "Universal Soil Loss Equation." The K factor was from the SCS soil sur- <br />vey estimate for erodibility of Savage soils 16-61% slope. <br />The following equations were calculated to predict erosion amounts on <br />study plots 1) prior [o any conservation practices performed, 2) immedi- <br />ately following conservation practice performance, and 3) three years <br />following conservation practices and permanent vegetation establishment. <br />The rainfall and runoff factors, soil erodibility factors and LS factors <br />were constant for all treatments with varying numbers for the cover and <br />erosion control practice Eac[ors. The following equations are predicCed <br />values in tons of soil lost/acre/year: <br />A = RKLSCP <br />Soil lost in tons/ac/yr immediately following [opsoiling up and down the <br />slope with no conservation practices performed = <br />~ 36 x .32 x 13 x .47 x 1 = 70.4 tons/ac/yr <br />Soil lost in tons/ac/yr immediately following conservation practice per- <br />formance on: <br />{ conc. <br />