Spent Oil-sand Fertility Study

Physical and chemical analyses of spent sand indicate that this material is very infertile. The spent sand samples analysed had an average pH of 7.2 and low Na content indicating that there was no residual problem resulting from the NaOH used in the oil production process. Freshly processed sand however does have a high pH and higher Na contents. Overburden samples from several dump-sites varied considerably in soluble salt content (salinity), were of sandy loam textural class and had low organic N, NO3-N and extractable P contents. The variation in salinity found in these overburden samples suggests a need for extensive sampling and analysis of these materials prior to their inclusion in a full-scale reclamation program. These materials, if non-saline, would aid in seedbed construction, and retention of moisture and nutrients. Analyses of the organic materials (decomposed peat, raw sphagnum and sedge peats) indicate that they may supply plant nutrients (N and P) in addition to aiding in seedbed construction and moisture retention. Barley growth on spent sands, supplied with adequate NPK and S, in greenhouse experiments was adversely affected by additions of boron at 2 mg/Kg and beneficially affected by additions of Ca at 30 mg/Kg. Singular additions of other essential plant nutrients (Cu , Zn , Fe, Mn , Mo , Mg) had no significant effect on barley yield. In a similar experiment the yield of alfalfa was significantly decreased by addition of Cu at 5 mg/Kg. In a greenhouse experiment involving growth of barley on media comprised of spent sands, overburden and peat, barley yield was primarily governed by NPK addition but peat and overburden addition to spent sand did result in growth increase. In a greenhouse experiment involving the additions of sewage sludge, decomposed peat, sedge and sphagnum peats to spent sands, barley yields were significantly increased by the sludge, sedge and decomposed peat additions and decreased by the sphagnum peat additions. The deleterious effect of the sphagnum may be due to its low pH (4.1) and a competition for N between the plants and bacteria in the decomposition of sphagnum.