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49 plant-available P (Bauer et.al., 1978; Power et.a., 1978). Some of these shales <br />may initially contain adequate amounts of plant-available N as exchangeable <br />NH4+ (Power et.al., 1974). However, after several growing seasons a <br />N-deficiency can occur as this N supply is depleted. Total N, other than <br />exchangeable NH4in shales may be high but in terms of a growing season, <br />very little becomes plant-available (Reeder and Berg, 1977). <br />According to Berg (1980), based on a general knowledge of N and P in semi-arid <br />grassland soils and limited experimental information, it is suggested that suffi- <br />cient N will be available on topsoiled areas for plant establishment. Substan- <br />tial perennial plant growth response to fertilizer N, is often prevented by the <br />response of vigorous annuals and grasses which tend to out compete slower growing <br />forbs and woody species. Thus use or amount of use of fertilizer N should be <br />based on a compromise to extablish optimum vegetative cover for site stability <br />and productivity while at the same time avoiding curtailment of species diver- <br />sity. Soil tests are of little help in determining fertilizer N requirements be- <br />cause of interference from carbon in shales or coal associated with coal mines. <br />• Replaced topsoil on many mine sites is characteristically low in available nutri- <br />ents, especially nitrogen, according to agronomic standards. As previously dis- <br />cussed however, fertilizers can only benefit plant growth if water isn't limit- <br />ing. If a site has low productivity because of low moisture availability as is <br />common in the arid west, fertilizer will not significantly improve growth. More- <br />over, agronomic criteria for determining the adequacy of soil nutrient levels <br />should be used cautiously for native species since they often have lower nutrient <br />needs (Stoddart, et al 1975)(Heady, 1975)(Hodder, 1976). Fertilizer treatments <br />at Trapper Mine are discussed in Sections 3.6.2.3 and 3.6.3.3 of this applica- <br />tion. <br />3.6.1.2 Erosion <br />The second identified major reclamation concern for Trapper Mine is the control- <br />ling of erosion. Erosion is a natural phenomenon that has always occurred. <br /> <br />3-55 <br />WISED FEB 13 V