Deep Overburden Research Articles

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

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

MICROBIAL ACTIVITY AND MYCORRHIZAL POTENTIAL OF FOUR OVERBURDEN TYPES USED IN THE RECLAMATION OF EXTRACTED OIL SANDS

Slender wheatgrass and jack pine were grown in the greenhouse in cores containing a bottom layer of extracted oil sands with four overburdens individually layered over the sand. The overburdens included a muskeg peat, two shallow mineral overburdens and a deep overburden. Mycorrhizal development, microbial respiration and biomass and the degree of decomposition of slender wheatgrass roots in litter bags were determined in each plant species-overburden combination. Both ecto- and vesicular-arbuscular (VA) mycorrhizal inoculum was present in all four overburdens. The symbionts of slender wheatgrass were the "fine endophyte" and Glomus aggregatum. VA development was very low in peat whereas plants in the shallow overburdens became heavily mycorrhizal. Infection did not spread from the overburden layer to roots in the tailing sand. Jack pine roots in the peat and two shallow overburdens were heavily infected after 4 months. The most common symbiont was an ascomycete known as the E-strain. Microbial respiration was highest in the peat and was not influenced by plant species. Microbial biomass was also highest in the peat and much lower in the mineral overburdens. Only in the peat was the amount of microbial biomass larger with slender wheatgrass than with jack pine. Slender wheatgrass roots decomposed most rapidly in the peat overburden and least rapidly in the deep overburden. Key words: Microbial activity, jack pine, slender wheatgrass, mycorrhizae, reclamation, oil sands

Excavation of a mine shaft through deep overburden by natural freezing : CIM Bull, V75, N840, April 1982, P135–141

Excavation of a mine shaft through deep overburden by natural freezing : CIM Bull, V75, N840, April 1982, P135–141