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ATTACHM1tENT 6 <br />•; . <br />Recent studies have shown that topsoil and mulches reduce erosion from <br />denuded slopes (Pleyer, L. D., W. H. Wishmeier and W. H. Daniel, 1971. Trans. of <br />the ASAE 14:138-141; Meyer, L. D., W. H. Wishmeier and G. R. Foster, 1970. Soil <br />Sci. Soc. Amer. Prot. 34: 923-931). Topsoil may increase the effectiveness of <br />revegetation procedures. Lt could improve seed germination and provide moisture <br />and nutrients during the critical early stages of growth, especially in estab- <br />lishing grasses and shrubs. <br />2.6 Depths of topsoil associated with various kinds of vegetation <br />In general, a recurring pattern of landscape and vegetation occurs <br />across the mining area which appears [o be closely related to soil depth and <br />available water for plants. The shallow and sandy soils (mapping unit 1 in <br />figure 2.3) will hold less available water. As a result they support thinner <br />stands and shorter vegetation. In the West Panel oakbrush is scarce in these <br />soils as well as those in mapping unit 2. Service berry, antelope bitterbrush, <br />and big sagebrush occur mainly as shrubs in these shallower soils as well as <br />various grasses. <br />Oakbrush thrives in the deeper loess soils of mapping unit 4 in the East <br />Panel. In contrast, oakbrush is absent in the silty clay soils derived from <br />exposed shale in mapping unit 3. These soils essentially support grass with <br />very few shrubs. Water penetrates slowly in these soils and a greater portion <br />of the precipitation runs off than from adjacent loess soils. Therefore, storage <br />• of water in the root zone is low in these silty clays and mainly near the surface <br />- where the grasses utilize it. This pattern of vegetation and soil may indicate <br />~° that problems could arise in attempts to revegetate with shrubs (browse) in areas <br />of the East Panel where some of the overburden has a high clay content and a low <br />permeability to water. <br />3. Evaluation of overburden <br />UII plans to divide the lease area for mining operations into a West <br />Panel and an East Panel. A similar division will be followed in this report <br />since certain problems connected with using the overburden as a growth medium <br />for plants are quite different in the two panels. More serious problems are <br />anticipated with the overburden in the East Panel; however, this section contains <br />the best and deepest topsoil. <br />The West Panel contains core holes CR 213 to CR 218; the East Panel in- <br />cludes core holes CR 219 to CR 224. <br />~ In general, problems may be expected in using the overburden at the sur- <br />face as a medium for plant growth if it contains a high clay content, a high <br />exchangeable sodium percentage (ESP), a low amount of organic matter, a high <br />concentration of soluble salts, or it has a high pH. <br />An indication that a problem may be encountered in growing plants should <br />not be interpreted to mean that no growth will occur. A problem with the over- <br />burden as a medium for plant growth indicates, in general, a deviation from <br />• normal growth, i.e. a reduction in yield or in seed germination. The amount of <br />reduction to be considered as serious or significant will depend on [he land use. <br />An assumption is made in evaluating the overburden that the normal drag- <br />line operations will remove the overburden above various coal layers (two to six <br />10 <br />