A Greenhouse Study of Grass Response on Composite Tailings Discharged from Alberta Oilsands Mine. Wu and Wang. 2011

The oilsands operations produce large amount of Composite Tailings (CT) mixture of sand, Mature Fine Tailings (MFT) and pond water which is saline-sodic, with Na+, Ca+, SO4 2-, and Cl- being the dominant ions. CT can be classified as slightly salinity soil with 7.3Using plants to increase the bearing capacity by soil evaporation and plant leaves transpiration and root fiber reinforcement has been identified as a mechanism. However, directly seed plant species on soft CT deposits are still challenging. A greenhouse study was designed to determine the suitability of five grass species (Bluejoint, Creeping red fescue, Hairy wild rye, Northern wheatgrass, and Slender wheatgrass) for dewatering CT and to evaluate the application of direct seeding techniques on vast CT deposits. This study assessed germination, early plant growth, and survival of selected grass species directly seeded by applying modified broadcast seeding covered with very thin layer of CT; hydroseeding with mulch; slurry seeding with mixture of seeds and freshly produced CT. In addition, the effect of 20-8-20 fertilizer on grass germination and early plant growth were also assessed.

Results suggested that two native grass species, Northern wheatgrass and Slender wheatgrass, survived on CT and performed reasonably well during the first growing season. Slightly saline tailings cause Hairy wild rye stunted growth. Slender wheatgrass and Northern wheatgrass grew to 30.4 cm and 23.9 cm, respectively, produced the highest biomass and leaf area and could be used to improve dewatering CT deposits. Modified broadcast seeding, slurry seeding, and hydroseeding with mulching techniques are applicable for early stage of reclaiming vast CT deposits in the field.

Wu, S., D. Sego, A. Naeth and B. Wang. 2011. “Greenhouse Study of Grass Response on Composite Tailings Discharged from Alberta Oilsands Mine,” in: 5th Mining and the Environment International Conference, Sudbury, Ontario, June 25-30, 2011. Sudbury: Laurentian University.

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