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• • <br />0 1474 Plots. Dr. Larry Brown, of AMAX, designed and implemented <br />4 x 4 factorial experiment using various application rates of <br />sawmilll wastes and sewage sludge (with replications) in the spring <br />of 1974 on both fragmented rock plots and tailing plots. The <br />objectives of the experiment were to compare the two growth media <br />and determine optimum quantities of sewage and wood wastes used as <br />soil amendments for revegetating the Urad tailing ponds. <br />The experimental design crossed three application rateas of sewage <br />(5, 10, and 20 tons/acre) and one rate of nitrogen l60 lb/acre) <br />with two rates of sawdust (4 and 8 tons/acre), one rate of wood <br />chips (20 tons/acre), and a control. A11 plots were seeded with <br />the "Climax" seed mixture, uniformly treated with 300 lb of P205 <br />acre, and received light daily irrigation for germination and <br />establishment. <br />The plots have nev n tatistically analyzed The different rates of <br />wood waste application did not produce significant observable differences in <br />the quantity or quality of vegetation. Different application rates of <br />sewage on rock waste produced obvious differences from inception. Five <br />tonslacre of sewage produced better vegetation than no sewage but 10 and <br />20 tonslacre of sewage yielded the best results. No maintenance was <br />performed on these plots until the sixth growing season, 1979. A71 <br />treatments including the unamended rock are surviving and being <br />qualitatively monitored. <br />To date, 1981, approximately 125 acres of waste rock coverin~l the Urad <br />tailing have been successfully revegetated using 30 tons/acre of sewage and <br />20 tons/acre of wood chips (Figure 9-1). <br />Exposed sulfide tailing oxidizes, producing acidic runoff unless treated <br />with lime. As expected, this happened at the Urad tailing test plots. The <br />1972, 1973 and 1/2 (tailing) of the 1974 plots were reclaimed along with the <br />rest of the tailing area. No effort was made to neutralize the acidity <br />7 <br />