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8 <br />chemical-vegetative procedure has proved effective during the past 4 years o; <br />six different tailings ponds, <br />The hydroseeding procedure, as normally used, encompasses blowing a <br />slurry of wood chips or paper pulp with admixed seeds and fertilizer over th <br />surface to be stabilized. After the seeds germinate, the wood chips or Pape <br />pulp serve as protection for the seedlings and inhibit blowing of sands. La <br />oratory research at the Salt Lake City Metallurgy Research Center has shown <br />that hydromulching can conserve water in sandy tailings material. Although <br />the addition of one-half ton of mulch per acre showed an improvement of only <br />1 percent less water evaporated than the control plot in 9 days' time, the <br />addition of 1 and 2 tons per acre reduced water toss by 4 and 9 percent, <br />respectively. Matting serves the same purpose as the wood chips for that <br />method. Usually the area is planted with seeds and fertilizer and then 3-fc <br />wide strips of excelsior-filled matting are staked continuously or. at 3-foot <br />intervals over the planted area. Matting is used most commonly on the slopi <br />surface of tailing dikes to inhibit slippage of the sands. <br />Preliminary Vegetative Testing <br />Bureau of Mines research was designed to develop improved methods for <br />achieving better initial germination and more rapid growth than was common r <br />mill tailings. Preliminary Bureau work was concerned with selecting proper <br />vegetation, testing microscopic plant forms for stabilization potential, sti <br />ing the interaction of fertilizers with residual heavy minerals and salts-cc <br />tained within the wastes, improving the structure of the wastes to enhance <br />vegetative growth, and developing a combination chemical-vegetative procedu; <br />to obviate the problems of highly reflective surfaces and sandblasting. Pe: <br />tinent studies are here described. <br />~ecies Selection <br />Seeds of many species were tested for germination and growth in repress <br />alive samples of various types of tailings. Both domestic and wild plant <br />species were evaluated in as-received tailings and with various fertilizer <br />amendments. Almost always, the domestic species were more reliable germina <br />tors than wild species and thus easier to test. Plants that showed conside <br />able promise include the following: Sweet clover, various varieties of <br />alfalfa, winter wheat, rye, barley, various wheatgrasses (western, crested, <br />intermediate, tall, pubescent), other grasses (sorghum, love, Kentucky blue <br />orchard, etc,), and shrubs such as big sagebrush, rubber rabbit brush, and <br />Siberian pea tree. A special barley, Charlottetown 80 (grown on Prince Edw <br />Island, Canada), has .been grown in acidic wastes at a pU as low as 3.0. <br />Preliminary tests using Indian ricegrass (Oryzopsis hymenoides), a har <br />native grass, as a stabilizing plant were encouraging, Tests show that the <br />roots of these plants are surrounded by a capsule of sand grains containing <br />bacteria which are capable of fixing molecular nitrogen. The tube of sand <br />when separated from the roots shows a positive nitrogen fixation reaction, <br />whereas the clean roots are negative. Tests are underway to determine the <br />ation mechanism which may derive from the bacteria or other micro-organism: <br />the sand sheath,6 <br />bSubsequen[ research has identified the causative bacteria as Bacillus pOlvn <br />