Micronutrient concentrations vary between peat–mineral mix and substrates in revegetated sites in the Alberta oil sands

Adequate supply of micronutrients is essential for plant growth in reclaimed sites in the Athabasca oil sands region. The objectives of this study were to determine boron, iron, manganese, copper, and zinc concentrations in peat–mineral mix (PMM), tailings sand (TS), and overburden (OB) materials and to assess whether lodgepole pine (Pinus contorta) planted on PMM over TS and white spruce (Picea glauca) planted on PMM over OB had low foliar micronutrient concentrations. Micronutrient concentrations determined using LiNO3 and Mehlich-3 extractions were different between PMM and TS in the pine sites while only LiNO3 extractable boron was different between PMM and OB in the spruce sites (p < 0.05). Micronutrient concentrations varied in the order of boron > iron > manganese > zinc > copper in all soil layers with concentrations ranging from 0.04 to 39.56 µg g-1. The low foliar concentration of copper in pine and spruce was consistent with low LiNO3 extractable copper in the soil in both the pine and spruce sites. We conclude that the availability of micronutrients such as copper can become a potential limitation for revegetation of white spruce but not lodgepole pine. Further studies on soil management for improving Cu availability in reclamation materials are needed for improving the growth of spruce in reclaimed soils.