Woosaree, J & Anderson, HB 2012, 'Revegetation of tailings sand without a soil cover in the Alberta oil sands', in AB Fourie & M Tibbett (eds), Mine Closure 2012: Proceedings of the Seventh International Conference on Mine Closure
, Australian Centre for Geomechanics, Perth, pp. 197-206, https://doi.org/10.36487/ACG_rep/1208_19_Woosaree
Reclamation in the oil sands in Alberta is a high priority and can be challenging. Suncor Energy is in the process of reclaiming one of its consolidated tailings (CT) ponds (Pond 5). The CT is being capped with a layer of petroleum coke to accelerate the creation of a trafficable surface, and then with tailings sand. As these CT dewater, a temporary reclamation vegetative cover over the tailings sand was needed to stabilise the sand against water and wind erosion prior to final reclamation. Criteria for native plant species selection for the cover crop were based on their ability to grow rapidly, be drought and possibly salt tolerant and provide a vegetation cover for at least three years. This study aims to assess the potential of some native grasses to directly grow and stabilise tailings sand and to determine nutritional requirements for optimal growth.
The study was initiated in 2010 (Woosaree et al., 2010). Year 2011 provided an opportunity to study how well these native species continued to adapt and grow on direct tailings sands and if the underlying coke layer from the tailings ponds, presented any limitation to plant growth and survival.
Results indicated higher aboveground biomass and percent cover for the native grass seed mix than June grass or fringed brome grass alone. The higher biomass is most likely due to the nature of the species, with June grass being a low stature species compared to the native mix. Fringed brome plants were sparse within the plots, most likely as a result of low emergence in 2010. The greatest benefit of an organic amendment such as alfalfa pellet application appeared to be moisture retention, giving the seeded species a head start to germinate. Root depths measured ranged from 11 to 26 cm allowing the plants to tap deeper into below ground moisture. Plants in the control plots had less vigour, yet were still surviving despite no fertilisers or pellets being applied. A fertiliser rate above 50 kg N/ha did not have a positive effect on the plants.
Soil available nitrogen measured in the fall of 2011 was below detectable level. However, plant tissue analysis showed total nitrogen of 1–2.3%. Atmospheric deposition of N and microbial association with the plant roots could contribute to N availability. Microbial analysis revealed six nitrogen fixing bacteria and one plant growth-promoting bacteria to be associated with the native species roots. This study will help to select suitable species for inclusion in seed mixtures for final reclamation.
BGC Engineering Inc (2010) Review of reclamation options for oil sands tailings substrates, Oil Sands Research and Information Network, University of Alberta, School of Energy and the Environment, Edmonton, Alberta, OSRIN Report No. TR–2, 59 p.
Campbell, C.R. and Plank, C.O. (1998) Preparation of plant tissue for laboratory analysis, Reference Methods for Plant Analysis, Y. Yash and P. Kalra (eds), Soil and Plant Analysis Council, Boca Raton: CRC Press, 1998, pp. 39–41.
Chapman, K.J. and Das, S.B. (2010) Survey of Albertans’ value drivers regarding oil sands development and reclamation, Oil Sands Research and Information Network, University of Alberta, School of Energy and the Environment, Edmonton, Alberta, OSRIN Report No. TR-3, 13 p.
Grayston, S.J., Griffith, G.S., Mawdsley, J.L., Campbell, C.D. and Bardgett, R.D. (2001) Accounting for variability in soil microbial communities of temperate upland grassland ecosystems, Soil Biology & Biochemistry, Vol. 33, pp. 533–551.
Greer, C., Lefrançois, E., Quoreshi, A., Khasa, D., Fung, M., Whyte, L. and Roy, S. (2007) Alder-Frankia symbionts enhance the remediation and revegetation of oil sands tailings, viewed 16 May 2012.
Horneck, D.A. and Miller, R.O. (1998) Determination of total nitrogen in plant tissue, Reference Methods for Plant Analysis, Y. Yash and P. Kalra (eds), Soil and Plant Analysis Council, Boca Raton: CRC Press, 1998, pp. 81–83.
Jackson, R.B. and M. Caldwell (1992) Shading and the capture of localized soil nutrients: nutrient contents, carbohydrates, and root uptake kinetics of a perennial tussock grass, Oecologia 91, pp. 457-462.
Knops, J, Bradley, K. and Wedin, D. (2002) Mechanisms of plant species impacts on ecosystem nitrogen cycling, Ecology Letters, Vol. 5(3), pp. 454–466.
Maynard, D.G., Kalra, Y.P. and Crumbaugh, J.A. (2008) Nitrate and exchangeable ammonium nitrogen, C.R. Martin and R. Carter (eds), Canadian Society of Soil Science, Boca Raton: Lewis Publisher, pp. 98–105.
Onwuchekwa, N.E. (2012) Enhanced revegetation and reclamation of oil sand disturbed land using mycorrhizae, M.Sc. Thesis, Department of Renewable Resources, University of Alberta, Edmonton, Alberta, 102 p.
Paskey, J. and Steward, G. (2012) The Alberta oil sands, journalists, and their sources, Oil Sands Research and Information Network, School of Energy and the Environment, University of Alberta, Edmonton, OSRIN Report No. TR-17, 33 p.
Salifu, K.F., Woosaree, J., Wells S. and Anderson, J.B. (2011) Innovative techniques to improve reclamation practices in Alberta oil sands, in Proceedings Sixth International Conference on Mine Closure (Mine Closure 2011), A.B. Fourie, M. Tibbett and A. Beersing (eds), 19‒21 September 2011, Lake Louise, Canada, Australian Centre for Geomechanics, Perth, Vol. 1,
SAS Institute Inc. (2010) SAS Release 9.3 (64-bit) for Windows 7, SAS Institute Inc., Cary, N.C.
Tilman, D. (1986) Nitrogen-limited growth in plants from different successional stages, Ecology, Vol. 67(2), pp. 555–563.
Visser, S., Griffiths, C., Parkinson, D. (1984) Reinstatement of biological activity in severely disturbed soils – effects of mining on the microbiology of three minespoils and the microbial development in the minespoils after amendation and planting. Alberta Land Conservation and Reclamation Council, Report RRTAC 84-4, Volume I, 283 p.
Wedin, D.A. (1990) Nitrogen cycling and competition among grass species, Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN, 92 p.
Wedin, D.A. and Pastor, J. (1993) Nitrogen mineralization dynamics in grass monocultures, Oecologia, Vol. 96, pp. 186–192.
Woosaree, J. and Hiltz, M. (2010) Cover crop program for tailings sand stabilization, prepared for Suncor Energy. Alberta Innovates Technology Futures, Vegreville, Alberta, 25 p.
Woosaree, J. and Yang, J. (2012) Assessment of microbial growth from pond 5 cover crop research, Prepared for Suncor Energy. Alberta Innovates Technology Futures, Vegreville, Alberta, 10 p.