USE OF MUNICIPAL SLUDGE TO RESTORE AND IMPROVE SITE PRODUCTIVITY IN FORESTRY - THE PACK FOREST SLUDGE RESEARCH-PROGRAM

Municipal wastewater residuals-sludge or biosolids-represent a major w aste by-product from society that must be managed in responsible ways, and not released into aquatic systems or allowed to contaminate groun d waters. Because of its high nutrient and organic matter content, slu dge can be beneficially recycled into forest sites for site improvemen t purposes. Research to date on forest application of sludge has been very encouraging, clearly demonstrating the validity of this managemen t technique. Forest sites typically display benefits in two ways: (1) an immediate growth response by both overstory and understory species; (2) a long-term improvement to the productivity of the site. However, for this practice to have broad utility and acceptance, it is critica l that the concerns of the regulatory agencies and general public be a ddressed regarding public health and environmental issues through cont inued research. These concerns include the fate of trace metals, inclu ding movement, uptake and potential phytotoxicity, and passage into wi ldlife and human food chain, the fate of pathogens, and leaching of ni trates into ground water systems. Many concerns are a result of miscon ceptions or misunderstandings of the potential problems involved and r equire working with these agencies and the general public through educ ation and demonstration programs. This paper addresses the opportuniti es and problems that researchers at the University of Washington, Coll ege of Forest Resources have encountered while working in forest sludg e applications during the past 20 years.