Comparative rooting of deciduous landscape shrub cuttings in media amended with paper mill biosolids from four different sources

Abstract

Scarcity of landfills has resulted in increasing need for alternative disposal or reuse of industrial organic wastes such as paper mill sludge (biosolids). The objective of this study was to evaluate and compare the rooting response of stem cuttings from six species of deciduous landscape shrubs [coralberry (Symphoricarpos × chenaultii Rehd. 'Hancock'); flowering almond (Prunus triloba Lindl. 'Multiplex'); honeysuckle (Lonicera × xylosteoides Tausch. 'Clavey's Dwarf'); mock orange (Philadelphus × virginalis Rehd. 'Minnesota Snowflake'); purple-leaf sandcherry (Prunus × cistena N. E. Hansen); and viburnum (Viburnum dentatum L.)] under mist and 50% shade (outdoor lath) in flats filled with 100% perlite medium, or perlite mixed with 15, 30, 45 or 60% of fresh paper mill biosolids, by volume, of one of four sources (Atlantic, Domtar, Thorold, and QUNO). There was little or no adverse effect of the biosolids, despite wide variability in rooting response due to species, source and/or level of biosolids. Regression analyses indicated that, with few exceptions, the percent rooting, mean root number per rooted cutting, and length of longest root per cutting increased linearly or curvilinearly, or was unaffected, when regressed over level of biosolids. Optimum amounts of biosolids in the rooting medium ranged from 30 to 60% by volume. The electrical conductivities of the biosolids-amended media were acceptable (0.1–0.3 dS m−1) for rooting of woody cuttings and pore space characteristics were comparable to, or exceeded those of, perlite. Key words: Ornamentals, landscape plants, propagation, organic waste, paper mill sludge, waste recycling