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In Table 13, soil erosion potential classes are shown in a five-class system ranging from Class1 - very slight potential for soil loss, i.e . 33t/ha/y .It should be emphasized that .the potential soil loss values shown in Tables 10, 11 and 13,were calculated for bare soil . Values for vegetated soils, in the Ville-Marie area, would be reducedconsiderably, by incorporation of the crop cover factor (C) and the management practice factor (P)in the USLE equation, .A = RKLSCP.Table 14 contains some C-values of typical crops and vegetative cover commonly found oncultivated soils of the Ville-Marie map sheet . P-values for some management practices are foundin Table 15 .How to determine potential erosion from the soil map or for field sitesSite or field-specific interpretations are utilized for on-farm or resource managementpurposes, by providing farm managers or extension personnel with a general indication of thepotential soil loss and the erosion-reducing effectiveness ofvarious crop and management systems.In order to estimate these values for a field, follow the procedure outlined below.1 . Determine the site conditions and associated U .S.L.E . factor values for the field.e .g . R-value for the Ville-Marie area = 80Soil type = Cane (K = 0.40 ; Table 10)Slope class - `c'; 7-12% slope, 300 m (LS = 1 .75 ; Table 11)Crop/vegetation cover - cereal grains (C = 0.27; Table 14)Conservation practices = none (P = 1 .0 ; Table 15)2 . Calculate the average annual soil loss (A)A = RKLSCP= 80 x .4 x 1.75 x .27 x 1= 15.1 t/ac/y (33 .9 t/ha/y)According to Table 13, 33 .9 t/ha/y (15 .1 t/ac/y) potential soil loss would be considered verysevere, and remedial measures should be considered .3 . A tolerable `A' value for deep agricultural soils is 11 t/ha/y (4 .9 t/ac/y) or less . A crop orvegetation cover with a lower C value than that used for cereal grains in the above example(e .g . C = 0.06 for hay and pasture in rotation; Table 14), would reduce erosion on this siteto a tolerable level of 7.5 t/ha/y (3 .4 t/ac/y) .