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4 - 50 <br />• Vegetation is difficult to establish on soils with high SAR which indicates potential instability <br />and water transmission problems (USDA, 1978). SAR values range from less than one to 57.3. <br />Most soils have values less than 5.0 and are rated good to fair. Most subsoils are rated good to <br />fair. The Havre soil, however, is rated poor below 1.5 inches. <br />Electrical conductivity is a measure of soil salinity. Excessive salts restrict plant growth, <br />create problems in establishing vegetation and therefore also influence erosion and the stability <br />of the surface. EC values range from less than one to 27.2 mmhos/cm. Most of the soils have <br />values less than 5.0 mmhos/cm. and are rated good for salinity. The saline phase of the Havre <br />soil is rated fair to poor in the subsoil. <br />Toxic materials such as boron enter the food chain and are toxic to animals that eat the <br />vegetation (USDA, 1978). All soils in the permit area are rated good for boron; no values <br />exceeded 1.0 ppm. <br />Excessively high or low pH causes problems in establishing vegetation and as a result of <br />influences erosion and stability of the surface (USDA, 1978). Most soils have good or fair pH <br />values throughout. The substratum of the alluvial soils and Havre soils have moderately to <br />strongly alkaline pH values. <br />The available water capacity also is important in establishing vegetation. Soils with low <br />available water capacity may require irrigation for establishment of vegetation (USDA, 1978). <br />AWHC was estimated based on field texture and percent coarse fragments NSDA, 1974). Most <br />of the soils are rated good for AWHC. The disturbed land material and the alluvial land soil are <br />rated good and fair, respectively. Some subsoils have fair ratings. <br />The stability of the soil depends upon its erodibility by water and wind and it's strength. <br />Water erodibility is indicated by the K factor; wind erodibility is rated according to the wind <br />erodibility group. K values for soils of the permit area are calculated for Wischmeier's equation <br />of soil erodibility (Wischmier, 1971). Most soils are rated good throughout for water erodibility; <br />the K factor for the Havre soil is fair, The Alluvial land soil is rated poor. Wind erodibility group <br />is based on soil textural class and lime content and rated by SCS criteria NSDA -SCS, 1974). <br />The surface layers of most soils are rated good or fair throughout. The roadfill material is rated <br />. good. The Alluvial land soil is rated poor. <br />M~ Volume 1 4-29.96 <br />