1986-12-08_GENERAL DOCUMENTS - M1977493 (2)

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