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<br />ham, 1966). Both the topsoil and refuse materials of the study <br />sites were below 5 ppm and may benefit from the addition of <br />phosphorus fertilizer to aid plant growth. <br />Although the nutrient requirements of native species are not <br />well documented, they are generally less than that of agricultur- <br />al crops and minimal levels for agriculture may be suffucient for <br />native species. N and P nutrient deficiencies have also been <br />reported on coal refuse in the Northern Great Plains regions <br />(Bauer et a1.,1978). Fertilization experiments on refuse for <br />revegetation in that area have had varied results. In one <br />experiment, fertilization was shown to increase shrub vigor <br />ratings but overall survival of P fertilized and nonfertilized <br />shrubs was not statistically different. In other experiments on <br />refuse in North Dakota, N fertilization was shown to increase <br />grass and legume yields while P fertilization had no effect. <br />Agriculture crops generally show a response to potassium <br />fertilizer on the soils containing less than 50 ppm potassium <br />(Ulrich and Ohki, 1966). Only one sample of topsoil analyzed <br />indicated potassium to be under this level. Old refuse material <br />contained significantly less potassium than the topsoil. New <br />refuse material also contained less potassium than the topsoil <br />but more than the older refuse material. Although potassium <br />levels are less in the refuse materials, there still appears to <br />~~ <br />2-5 <br />