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pH values'- pH (.O1M CAC12 solution and paste) (Tables 2.7-6 and 2.7-7 and Map <br />M40) <br />Overburden pH is probably one of the most important factors to be considered in <br />attempts to reclaim mine spoils. Several different methods can be used in test- <br />ing pH of soils, however, some methods are more desirable in reference to vegeta- <br />tive response. Two different methods were used for evaluating pH. <br />A water extract pH and a .O1 molar CaClz solution extract pH were taken Eroa <br />the cores. The water extract method tends to cause pH readings [o be high <br />'" because sodium compounds will ionize in water and therefore raise the pH. In a <br />CaC12 solution extract, the pH will be consistently lower when sodium compounds <br />are present and the results are more meaningful from an agronomic standpoint <br />(Olsen, 1974). <br /> In defining the desirable limits of pH, the Soil Conservation Service (1971) has <br />' divided pH ranges into [he Following three categories. <br />a. pH Class A (6.0-8.5) will support a wide variety of climatically adapted <br />woody or grass plants. <br />b. pH Class B (more than 8.5) will support only the most salt and alkali toler- <br />ant plants; topsoil application may be necessary; plant establishment will be <br />difficult. <br />c. pH Class C (4.0-6.0) topsoil application may be necessary. <br />A pH of Class A is obviously [he most desirable from a reclamation standpoint <br />even though all mine spoils will be topsoiled. All other pH values would have to <br />be adjusted within [his range to have a good plan[ response, especially for those <br />species of plants with an extensive root system (shrubs, etc.). <br />pH values present in the overburden strata prior [o weathering are presented in <br />Table 2.7-7 and are depicted in [he cross section Map M40. Tab 1e 2.7-8 provides <br />the measured pH values from samples that were exposed [o weathering. <br /> <br />2-386 <br />