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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

G. M. Jamro. 2016.

Abstract

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.