The revegetation of tailings sand slopes that result from tar sands extraction pose many problems. The tailings material has a low moisture holding capacity, contains low amounts of plant nutrients and is potentially very erodable.
Large areas of tailings material have been successfully revegetated by Great Canadian Oil Sands Limited by employing a 15 cm thick amendment of peat on the surface. Even 5 years after seeding with grasses and legumes these areas must receive regular fertilization to maintain a good surface cover.
In new experiments the tailings sand surface was amended with peat or peat/overburden mixtures. A good surface cover was rapidly established by the addition of N, P, K and S containing fertilizers. Most efficient use of the fertilizers occurred when 80 kg-N, 35 kg-P, 75 kg-K and 20 kg-S were added per hectare rather than when larger amounts were added. Rapid plant growth enabled erosion to be kept at a minimum. Losses of plant nutrients through leaching and surface water runoff were not serious in relation to the amounts added as fertilizer. Additional application of fertilizer later in August did not increase dry weight yield but did enhance nutrient uptake into the plant tops. Dry weight production of tops and roots was about the same in the first year of growth. Root growth was largely restricted to the surface 15 cm of peat and overburden.