Influence of Amendments and Soil Depth on Available Nutrients and Microbial Dynamics in Contrasting Topsoil Materials Used for Oil Sands Reclamation

  • Author / Creator
    Howell, Daniel Mark
  • As of December 2013, the cumulative area disturbed by oil sands mining in NE Alberta was 896 km2 out of an estimated final footprint of 4,800 km2 – all of which will require reclamation. Expensive handling costs and scarce soil resources necessitate judicious management and application of salvaged topsoils and soil amendments such that the post-mining landscape re-establishes an “equivalent land capability” of pre-disturbance conditions. Soil microbial communities and microbially mediated nutrient availability are largely overlooked in reclamation analyses, despite their potential in providing a sensitive measurement of ecosystem processes. Our study measured nutrient availability and microbiological parameters in directly-placed forest floor mix (FFM) and peat mix (PM), which were compared to natural reference sites. The study was divided into two components: 1) assessing fertilizer and charcoal amendments (reclamation to d ecosite); and 2) assessing topsoil application depths (reclamation to a/b ecosite).

    1) The principal study on CNRL’s Reclamation Area-1 (RA-1) compares a fertilizer amendment on PM and FFM. Our study added a charcoal amendment to simulate natural soil additions from wildfire; and compared reclaimed treatments to recently burned and unburned natural reference sites. Microbial biomass-carbon was greatest in natural and reclaimed organic soils. Burning and charcoal amendments tended to increase metabolic quotient, indicating potential nutrient stress or decomposition inefficiency. Nutrient profiles differed mostly between natural and reclaimed sites, followed by sites receiving fertilizer. Fertilization increased inorganic-N availability by two orders of magnitude above unfertilized treatments, while P and K availability were below natural variation.
    2) Syncrude Canada’s Aurora Soil Capping Study provided Shallow and Deep topsoil application depths of PM and FFM which were compared to a control receiving no topsoil and a harvested analogue (Harvest). Soil respiration rates were greater in FFM and Harvest than in PM treatments, with no difference attributable to subsoil type or placement depth. Phospholipid fatty acid analysis (PLFA) and community level physiological profiles (CLPP) measured microbial community structure and function, respectively. Non-metric multidimensional scaling (NMS) ordinations revealed the greatest similarity between FFM and Harvest for available nutrients, PLFA and CLPP analyses. Deep FFM application shared greatest PLFA similarity to Harvest, but Shallow FFM was more similar in CLPP. Shallow PM was more similar than Deep for all parameters measured. PM indicated greater total inorganic N and S availability, and deficiencies in P and K compared to FFM and Harvest.

  • Subjects / Keywords
  • Graduation date
    Fall 2015
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.