Land Application of Mechanical Pulp Mill Sludges in Alberta - Research and Operational Activities, 1998 Environmental Conference Proceedings

Terry M. Macyk

Alberta Research Council

Research regarding land application of mechanical mill sludges was undertaken by the Alberta Research Council in June 1991. The objective of the research is to provide industry, government regulators and the public with information on the impact of sludge application on agricultural and forest land and to provide a basis for adopting operational landspreading guidelines. The results of detailed sludge characterization work, greenhouse studies, decomposition work and column leaching studies demonstrated that land application was easible and provided

guidance for impleme tation of relevant and practically designed field studies. Two field trials were established to evaluate the impact of single and multiple applications of sludges from different mills on agricultural crops and soil quality in 1992 and 1993 and are monitored to obtain long-term data relative to crop yields and soil quality. The sludge amended treatments have demonstrated yield increases from two-to-five-fold greater than control nd thatincreased yields have been sustained for at least five growing easons. Three experiments were established in the forest beginning i 1993. The first involved application and incorporation of four rates of two sludge types in a replicated experiment on a recently harvested cut-block. Height and diameter increases up to 2.5 fold for white spruce (Picea glauca) and lodgepole pine (Pinus contorta var. latifolia) seedlings planted in the sludge amended plots compared to the control plots have been observed during the past five growing seasons. Another experiment involved application of three rates of sludge on frozen and non-frozen soil on haul roads, borrow areas, and wellsites to assess the efficacy of the sludge in reclaiming disturbed areas in the forest and returning forest productivity. The bulk density of the sludge amended haul road soils was reduced by 30%, soil water holding capacity was increased by 25% and lodgepole pine seedling growth increased three-fold over control treatments.