Experiences with Wastes and Composts in Nursery Substrates

Abstract

<jats:p>During the past 20 years, the Ornamental Nursery Research Program at the former Horticultural Research Institute of Ontario (now part of the University of Guelph) has been conducting applied research dealing with environmentally friendly and sustainable nursery production practices with emphasis on container production. The use of farm, industrial, and consumer waste by-products as amendments in nursery substrates has been a major focus. The program has evaluated hundreds of potting mixes derived from individual or combined, raw or composted waste by-products including spent mushroom compost, turkey litter compost, paper mill sludge, municipal waste compost, corrugated cardboard, apple pomace, wood chips from pallets, pulverized glass, and various types of tree barks. With few exceptions, all the above waste by-products tested under our cultural conditions provided acceptable to excellent container-growing media, often in amounts exceeding 50% and sometimes up to 100% by volume in No. 2 containers (6 L), even despite initially elevated and potentially toxic contents of soluble salts [expressed in terms of electrical conductivity measured up to 8.9 dS·m<jats:sup>-1</jats:sup> in 1 substrate: 2 water (by volume) extracts] in many of the substrates. A key to these successful results is that salts leach quickly from the containers to benign levels (∼1.0 dS·m<jats:sup>-1</jats:sup>) with normal irrigation practices. High initial pH in most waste-derived substrates (up to 8.9) has had little or no discernible effect on growth of a wide assortment of deciduous nursery species. By-products such as paper mill sludge and municipal waste compost with soluble salts contents typically ranging from 0.8 to 2.0 dS·m<jats:sup>-1</jats:sup>, also provide acceptable rooting media provided salts are leached before use to values ≤0.2 dS·m<jats:sup>-1</jats:sup>. The porosity and aeration characteristics of waste-derived substrates tend to be comparable to, or better than, those of bark.</jats:p>

The effect of paper sludge and biochar addition on brown peat and coir based growing media properties

“…A number of studies have shown that several organic residues such as urban solid wastes, plant wastes, sewage sludges, paper wastes, spent mushroom, coconut coir and even green wastes, after proper composting, can be used with variable results as growing media in lieu of peat (Abad et al, 2005;Chong, 2005;Garcia-Gomez et al, 2002;Maher et al, 2007;Méndez et al, 2011;Ostos et al, 2008).…”

Evaluation of biochar-anaerobic potato digestate mixtures as renewable components of horticultural potting media

“…Peatlands in the northern hemisphere store approximately onethird of world's CO 2 (Gorham, 1991), and there is increasing public concern over their destruction during peat harvest (Barkham, 1993;Robertson, 1993;Zaller, 2007;Blok and Verhagen, 2009;Jayasinghe et al, 2010). The utilization of farm, industrial and consumer waste by-products as components of nursery substrates has been extensively investigated during the past several decades, with a wide variety of materials having been examined (Chong, 2005;Krucker et al, 2010;Vaughn et al, 2013).…”

Leaching composted lignocellulosic wastes to prepare container media: Feasibility and environmental concerns

“…Saline composts can be successfully improved by using different techniques: (1) by leaching the compost with tap water before growing media preparation (Chen et al, 1984;Lohr et al, 1984;Marfà et al, 1998;Szmidt and Conway, 1995); (2) by leaching the compost when filling up the container with one (or several) starting irrigation(s) (Chong, 2005), or with standard nutrient solution (Mazuela et al, 2005), before transplanting; (3) by leaching the compost-based medium with the customary irrigation programs applied during the crop growing season, especially when using shallow containers (Chong, 2005;Hernández-Apaolaza et al, 2005;Papafotiou et al, 2004); and, (4) by mixing the compost with other nutrient-poor, non-saline materials (e.g. Sphagnum moss peat, pine bark, etc.)…”