SOIL BIOGEOCHEMICAL PROCESSES AND FINE ROOT DYNAMICS OF VEGETATION IN LFH MINERAL SOIL MIX AND PEAT MINERAL SOIL MIX ORGANIC CAPPING MATERIALS USED FOR OIL SANDS RECLAMATION

• Author / Creator

  Jamro, Ghulam M

• Peat mineral soil mix (PMM) and LFH, identifiable litter (L), fragmented litter (F) and humus (H), mineral soil (MS) mix are organic capping materials commonly used over overburden (OB) and tailings sand (TS) substrate materials in oil sands reclamation. These organic capping materials have different biological properties and nutrient availabilities due to differences in the carbon to nitrogen (C to N) ratio, exogenous organic input and organic to MS ratio. Substrate materials inherently possess high pH, electrical conductivity (EC) and soil compaction. The main goal of this research was to evaluate biogeochemical and fine root processes affected by required reclamation practices for oil sands reclamation. Soil sampling was conducted from 0 to 10 and 10 to 20 cm soil depth from June to October in 2011 and 2012 and N availability and enzyme activities were analyzed. Organic substrate type and diversity effects on microbial processes including carbon dioxide (CO2) emission, enzyme activities, available N and community level physiological profiles (CLPPs) were evaluated in a laboratory experiment using three organic substrates (glucose, acetic acid, alanine). The organic substrates were applied singly and in a mixture of two or three in an LFH-MS and a PMM. Effects of organic to MS ratio on biogeochemical processes were evaluated in a laboratory experiment using five ratios of LFH or peat to MS at 0:100, 30:70, 50:50, 70:30 and 100:0. Fine root properties such as root length density, surface area, total root biomass and rates of root production, turnover and decomposition of lodgepole pine and white spruce planted on the PMM placed over TS and OB substrates, respectively and were assessed from May to October in 2011 and 2012. The N availability and N-acetyl glucosaminidase, arylamidase and protease activities were greater in LFH-MS than in PMM, decreased along the soil depth and were influenced by the time of sampling. These differences were attributed to the lower C to N ratio in LFH-MS than in PMM. The addition of fresh labile C through root exudates and litter fall likely induced the N availability and enzyme activities in fall rather than in summer. The addition of organic substrates (laboratory study) significantly segregated CLPPs from the control (no substrate) in LFH-MS and PMM. The significant increase in enzyme activities, available N through increasing the organic substrate diversity, was likely associated with changes in CLPPs and a reduction in C to N ratio with a substrate addition in LFH-MS and PMM. The mixing of organic single substrates enhanced the CO2 emission rate and NO3--N concentration only in LFH-MS and PMM. The laboratory study results revealed that the β-glucosidase, cellobiohydrolase, phenol oxidase and leucine aminopeptidase activities, CO2 emission rates and available N were increased along the increasing organic to MS ratio regardless of LFH and peat. The increase in soil processes was due to changes in C to N ratios and pH along with increase in organic to MS ratios. Fine root length density, fine root production and turnover rates were increased along the low < medium < high productivity level in pine stands, and were positively correlated with tree height and diameter at the breast height. Fine root surface area was the only parameter that was increased along the productivity gradient in spruce. These differences were attributed to negative relationships of EC and soil compaction with root properties in pine and spruce, respectively. The root decomposition did not change along the productivity level of both pine and spruce species but was affected by the time of incubation, due to differences in species and OB and TS properties. The LFH-MS is a better soil quality organic capping material than PMM due to N availability and enzyme activities; however, the availability of LFH-MS is limited for reclamation. Hence, the ratios of organic to MS for optimization, particularly LFH, help to take advantage of available LFH material. Alternatively, augmenting LFH-MS with PMM can overcome the limitations of both materials, as indicated from organic substrate diversity and organic to MS ratios in this research. An evaluation of the effects of substrate properties on fine root properties can help improve current reclamation practices.

• Subjects / Keywords

  • LFH-mineral soil mix
  • Biogeochemistry
  • Oil sands reclamation
  • Organic capping materials
  • Fine roots
  • Soil Enzymes
  • Ratio of materials

• Graduation date

  Fall 2016

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3Q23R948

• 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.