The Soils of Brant County - Agriculture and Agri-Food Canada

Soil Map Unit Erosion PotentialThe soils map of Brant County delineates, among otherthings, unique combinations of soil materials and associatedslope gradient and pattern . The combinations of soil and slopeproperties depicted on the soil map are called map units . Table11 illustrates all the combinations of soil and slope that occuron the Brant County soil map. For each of these soil map units,the corresponding slope effects (LS), soil erodibility (K) values, .and average annual soil loss (A) values for bare soil conditionsare reported . Guidelines for establishing LS-values, soil erodibilityvalues and soil erosion potential classes are found inTables 12, 13, and 14 .Table 11 also illustrates the soil erosion potential classesfor each soil map unit for bare soil, corn, and small grain landuses .Site-specific Assessment of Soil Erosion PotentialFigure 14 is a soil erosion nomograph that was designed tofacilitate site-specific assessment of soil erosion potential . Thenomograph may be employed with information contained inthe Brant County Soil Survey Report to assess potential soilloss for various crops and slope conditions, as well as for differentsoil conservation practices .The nomograph is agraphical solution of the universal soilloss equation for the soils of Brant County. Potential soil erosionlosses for a site can be obtained as follows :(a) determine the soil erodibility value from the soil surveyreport (Table 11) or by the method described by Wischmeieret al . (19) ;(b) determine LS-value from on-siteevaluation of slope gradientand slope length . Use LS chart of Wischmeier andSmith (20), to arrive at LS-value (Table 14) ;(c)(d)draw a line between the site-specific K-value and LS-valueto determine the intercept with the pivot line (Figure 14) ;site-specific soil loss potentials for all the land uses listedon the nomograph may be determined by drawing a linefrom the land use under question, through the soil-slopeintercept on the pivot line to the potential soil loss axis.A sample calculation is illustrated as follows :Soil K-value- Conestogo soil = .30Site LS factor = 1 .0Draw a line between K and LS values and find the interceptwith the pivot line. What is the potential soil loss for thesesoil and slope conditions for : a) a soybean crop and b) anorchard crop?A line is drawn from the soybean and orchard crop valueslocated on the land use axis through the intercept on thepivot line to cross the potential soil loss axis . The soybeancrop grown onthese soil and slope conditions has amoderatelysevere erosion potential, while the orchard crop has anegligible soil loss potential .The soil erosion nomograph provides a rapid method toassess the effect of many land uses on soil loss potentials forsite-specific soil and slope conditions . By altering the LS factorto reflect different slope lengths (Table 14), the soil erosionnomograph can also be useful to test field consolidation alternativesthat minimize soil loss potentials . The soil erosionnomograph (Figure 14) in combination with soils informationfrom the Brant County Soil Survey Report can provide muchinformation for farm soil conservation planning .