PLANT GROWTH IN FOUR OVERBURDEN TYPES USED IN THE RECLAMATION OF EXTRACTED OIL SANDS

Abstract

Two shallow mineral overburdens, a deep mineral overburden and a peat overburden from northern Alberta were examined to determine effects of each on the growth of jack pine and slender wheatgrass. Plants were grown in the greenhouse in 30-cm-deep cores in which the overburdens were placed in either 5- or 15-cm-deep layers over oil sand tailings. For comparison with current reclamation practices, cores containing a mixture of sand, peat and deep overburden were also used. The growth of slender wheatgrass was best in the peat and very poor in the deep overburden. Jack pine also grew very poorly in the deep overburden but reasonably well in the other three overburdens. There was extensive root development of both species in the sand layer beneath all four overburden types. Increasing the depth of peat from 5 to 15 cm resulted in a decrease in the growth of both plants whereas increasing the depth of the mineral overburdens had favorable effects. The amount of available P was much higher in sand under the 5-cm layers than sand under the 15-cm layers. Iron and Mn uptake was suppressed with the thick layer of peat. Mixing 15 cm of peat with deep overburden and sand did not affect the growth of slender wheatgrass but reduced shoot production of jack pine. Key words: Reclamation, oil sands, jack pine, slender wheatgrass, plant growth, peat