Early growth response of container-grown selected woody boreal seedlings in amended composite tailings and tailings sand

Successful reclamation of saline-alkaline sites may be enhanced by revegetating with species that are tolerant to factors that limit normal plant growth. Boreal woody plants tested in this study have shown promise for use in saline habitats. This study was conducted to assess the effects of amendment treatments (peat, pulp waste, agriboost®, a combination of pulp waste and fly ash, and mineral fertilizer) on the early growth of three hybrid poplar clones and three coniferous species. Twelve-week and 18-week container-grown hybrid poplar clones and coniferous species, respectively, were monitored for 12 weeks in pot culture in both composite tailings (CTs) and tailings sand (TS) materials obtained from the oil sands plant, Syncrude Canada Ltd., Ft. McMurray, Alberta. These substrates with low nutrients, organic matter, and water-holding capacities, were amended with different organic materials at different rates. Growth, as assessed by the volume increment in both substrates, was generally better for the first 6 weeks than for the last 6 weeks. Growth was reduced during the last 6 weeks due to nutrient depletion over time in these impoverished substrates. Overall, for both substrates, the mineral fertilizer, 20%, 40% and 60% peat were the best amendments treatments for poplar clones with NM-6 being the most productive clone. For coniferous species, 20% and 40% pulp or peat appear to be the best amendment treatments, with lodgepole pine being the most productive species. The inflexion point of the regression functions were found around 30% rate of the amendment materials. The results also indicated that peat and pulp waste were the best amendment treatments for both hybrid poplars and coniferous species whereas the agriboost and mix (combination of pulp waste and fly ash) were the worst.