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<br />With the exception of Test Plot 1 (6" treatment) greatest species numbers are generally <br />observed with increasing soil depth. Interestingly, the reference area is represented by <br />only three perennial species with greater than 3% relative cover, malting it tied for <br />' lowest number of species. This is not unexpected in native plant communities where it <br />is common to be rare, and rare to be common (Krebs, 1972, Ricklefs, 1973). The <br />sampling does indicate that in terms of establishing long lasting perennial species <br />' numbers, the revegetation has been successful on the Test Plots. <br />' 4.2 1993 Soil Sampling Analysis and Discussion <br /> Analysis of the soil samples collected from the Test Plots in 1993 revealed several <br />' interesting trends (Table 37). The chemical makeup of the samples will be discussed in <br /> terms of the primary parameters, hydrogen ion concentration (pH), electrical <br /> conductivity (EC), and sodium adsorption ratio (SAR). It will be most productive to <br />' evaluate the parameters by depth from the surface within and between Test Plots as <br /> depicted in Figures 23-27. The primary concern with soil chemistry in the Test Plots <br /> and on the RDA in general is the potential for migration of growth inhibiting inorganic <br /> salts (especially sodium) from the refuse upward into the plant root zone. <br />' It was generally noted in the field during sampling that the soils were very dry and hard <br />from the surface to approximately 18-20" in depth. Below that depth there appeared to <br /> be more ambient moisture in the soil column. The coal refuse, when encountered was <br /> uniformly dry to the touch. One possible hypothesis to explain the chemical constituent <br /> values and concentrations obtained during sampling is that the upper soil levels remain <br /> generally dry throughout the year, lacking sufficient moisture penetration to move salts <br />' up through the soil column. With a more consistent moisture regime at greater soil <br /> column depths, there is greater ion mobility, potentially accounting for higher EC, <br /> cation, and SAR values at the lower soil column levels. <br /> <br /> 4.2.1 pH <br />I pH values were relatively consistent across depth and Test Plots. Values ranged from <br /> 8.0 to 8.4 in the 0-6" depth, 8.1 to 8.3 in the 6-12" depth, 8.2 to 8.4 in the 12-18" <br /> depth, 8.2 to 8.4 in the 18-24" depth, and were constant at 8.4 in the 24-48" depth <br />' (Table 37, Figure 36). Only a very minor increase with soil depth can be broadly <br /> identified. All reaction values were modestly alkaline, typical of alluvial/colluvial soils <br /> in the western United States. All soil samples were within acceptable levels for use in <br />' reclamation (Montana DSL, 1988, New Mexico CSMC, 1989, Wyoming DEQ, 1989, <br /> Utah DOGM, 1988). <br />1 <br />' S8 <br />