Use of Wastewater and Compost Extracts as Nutrient Sources for Growing Nursery and Turfgrass Species Robert C. Michitsch,* Calvin Chong, Bruce E. Holbein, R. Paul Voroney, and Hua-Wu Liu ABSTRACT Nutrient salts present in liquid by-products following waste treat- ment are lost resources if not effectively recycled, and can cause envi- ronmental problems if improperly disposed. This research compared the growth response and mineral nutrient status of two nursery and two turfgrass species, hydroponically supplied with nutritive by- product extracts derived from anaerobically digested municipal solid waste (MSW) and aerobically composted organic wastes from the mushroom and MSW industries. Forsythia (Forsythia 3 intermedia ‘Lynwood’) and weigela (Weigela florida ‘Red Prince’), and creeping bentgrass (Agrostis palustris Huds.) and Kentucky bluegrass (Poa pratensis L.), were grown in nutrient solutions/extracts prepared from: (i) half-strength Hoagland’s #2 solution (HH; control), (ii) Plant Products liquid fertilizer (PP; g kg 21 : 180 N; 39 P; 224 K), (iii) spent mushroom compost (SMC), (iv) MSW compost (GMC), and (v) intra- process wastewater from the anaerobic digestion of MSW (ADW). Additional nutrient solutions (SMC-A, GMC-A, and ADW-A) were prepared by amending the original solutions with N, P, and/or K to concentrations in HH (mg L 21 : 105 N; 15 P; 118 K). Plants receiv- ing the SMC-A extract grew best or at least as well as those in HH, PP, and the amended GMC-A and ADW-A solutions. This study indicated that, with proper amendments of N, P, K and other nu- trients, water-soluble constituents derived from organic waste treat- ment have potential for use as supplemental nutrient sources for plant production. O RGANIC components constitute more than 70% of the 30 3 10 6 metric tons of municipal solid waste (MSW) generated annually in Canada (Marshall, 2004). These nutrient-rich residuals represent a lost resource if not reused, for example, for fertilizing plants (Gill and Rainville, 1994; Mancino, 1994; Nava, 2001), and pose detrimental environmental risks if improperly disposed. Recent initiatives toward a zero-waste society (Seldman, 2004) have encouraged research to evaluate the recy- cling and reuse of such waste products. In previous studies, municipal wastewaters have suc- cessfully been used to grow turfgrass (Mancino, 1994; Beltrao et al., 1999), trees, legumes, and grains (Hussain and Al-Saati, 1999), and other horticultural crops (Monnet et al., 2002). Landfill and industrial wastewaters have proven successful in the production of clover and cress (Vasseur et al., 1998), ryegrass (Revel et al., 1999), and corn and rice (Singh and Mishra, 1987). Waste- waters generated during anaerobic digestion of mu- nicipal and industrial wastes have been reported as potential nutrient sources for crops, turfgrasses, and landscaping applications (Riggle, 1996; Little and Grant, 2002). Turfgrass fertilized with compost or its extracts had longer root length and increased root density than nonfertilized plants, and exhibited less incidence of dis- ease (Anonymous, 2001; Scheuerell and Mahaffee, 2003). Furthermore, Purvis et al. (2000) found up to 77% reduction in essential plant nutrient needs by recir- culating nutrients in containerized nursery production, exemplifying the potential for agricultural and horti- cultural waste reuse, reduction and conservation, and overall cost savings. The growth and nutrient status of vegetative species, grown in anaerobic digestion wastewater (ADW), spent mushroom compost (SMC), and municipal compost (GMC), were evaluated in comparison to traditional (HH) and commercial (PP) hydroponic solutions. The prepared waste solutions were independently amended to N, P, or K levels of HH (as required) as additional comparisons. Both ADW, a liquid by-product of the Super Blue Box Recycling Corporation (i.e., SUBBOR) process, which produces biogas and stabilized organic residuals from the anaerobic digestion of MSW (Vogt et al., 2002), and SMC, an abundant by-product of mush- room cultivation (Chong and Rinker, 1994), are highly nutritive. However, while both waste sources have indi- cated generally positive results in growing vegetables (Wang et al., 1984; Rhoads and Olson, 1995; Stewart et al., 1998a; 1998b), woody ornamentals (Chong and Rinker, 1994, McLachlan, 2001), and grasses (Guo et al., 2001), they have also caused phytotoxic responses due primarily to high salt or foreign compound contents (i.e., phenolic and volatile fatty acids, fumigants, fungicides, etc.). GMC, a nutritive extract of MSW compost, was evaluated for comparison. This research assessed the potential for reusing by- product extracts derived from the anaerobic (ADW) or aerobic digestion of MSW (GMC), or the aerobic di- gestion of mushroom cultivation solid wastes (SMC), to grow selected woody and turfgrass species. Hydroponic culture was utilized due to its usefulness to rapidly iden- tify plant growth problems/sensitivities to nutrient defi- ciencies (or toxicities) due to direct contact of soluble R.C. Michitsch and R.P. Voroney, Dep. of Land Resource Science, and C. Chong, Dep. of Plant Agriculture, Univ. of Guelph, Guelph, ON, Canada, N1G 2W1. B.E. Holbein and H.-W. Liu, Super Blue Box Recycling Corporation (SUBBOR), Suite 401, 2275 Lakeshore Blvd. W., Etobicoke, ON, Canada, M8V 3Y3. Robert C. Michitsch, present address, Nova Scotia Agricultural College, c/o R. Michitsch, 20 Tower Rd., Truro, NS, Canada, B2N 5E3. Received 8 Dec. 2005. *Corre- sponding author (rmichits@dal.ca). Published in J. Environ. Qual. 36:1031–1041 (2007). Technical Reports: Waste Management doi:10.2134/jeq2005.0453 ª ASA, CSSA, SSSA 677 S. Segoe Rd., Madison, WI 53711 USA Abbreviations: -A, amended; ADW, anaerobic digestion wastewater; EC, electrical conductivity; EDTA, ethylene-diamine-tetra-acetic acid; GI, growth index; GMC, municipal compost; HH, half-strength Hoagland’s #2 solution; ICP, inductively coupled plasma; INL, internode length; MSW, municipal solid waste; PP, Plant Products liquid fertilizer; SMC, spent mushroom compost; SUBBOR, Super Blue Box Recycling Corporation. Reproduced from Journal of Environmental Quality. Published by ASA, CSSA, and SSSA. All copyrights reserved. 1031