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ATTACHMENT 6 infiltration. Microbial decomposition of [he organic matter at a rate of 1 to 2X per year will release nutrients to growing plants, a process especially important in providing N for the plant. 2.27 Nitrate Available N in the soil is expressed as soluble nitrate, NO Additional N will be mineralized from organic matter during a growing season. 3If the soluble NO -N is 10 or more ppm, normal growth of plants could be expected. This criteria indicates that 9 samples contain adequate N. Most of the samples are deficient in available N so a response to added fertilizer N during revege- tation periods would be expected. 2.28 Lime requirement and sulfide The pH values of the surface soils indicated a favorable range for plant growth. Lime will not be required. The analyses for sulfide are low and indi- cate that acidity problems will not develop on these soils. 2.3 Physical properties Measurements~of physical properties of the topsoil were not made; how- ever, estimates of Ghese properties may be inferred from observations of texture, • -\ structure, color, erosion, and vegetation. The soil in mapping unit 1 (figure 1 2.3) will have a lower water holding capacity, a measure of available water for plants, than the soil in mapping unit 4. Soils in the other two mapping units will be intermediate. In general the high organic matter content of these soils has created a good soil structure which is associated with high rate of water infiltration and a good stability against erosion. Vegetation strongly protects the soil from erosion, which is almost absent in the lease area. 2.4 Erosion hazard of disturbed topsoil Established vegetation protects the topsoil Erom erosion. As mining operations will remove the vegetation and transfer the topsoil to the over- burden, the chances for erosion will increase greatly. The best control measure will be to reduce the slope by grading to retard runoff. After the final grading, however, the application of a surface stabilizer such as a straw mulch at 1 or 2 tons per acre could be used to reduce erosion from water and wind. Other techniques of surface stabilization might also be used to the same end. 2.5 Value of topsoil in reclamation Of the various surface treatments which UII might use, a discussion of topsciling is most appropriately presented in the context of this study. A cover of topsoil on the overburden will increase the rate of water infiltration in those areas where the overburden has a low rate of water infiltration. This property of the topsoil will increase the storage of water in the root zone to reduce runoff that leads to erosion. 9