Characteristics of wood wastes in British Columbia and their potential suitability as soil amendments and seedling growth media

摘要

In British Columbia, alternative uses for poor-quality wood-waste fines (approximately 50 mm or less) are being sought to replace traditional methods of disposal, including landfilling and burning without energy recovery. As a complement to associated field trials to assess the potential suitability of woody wastes as soil amendments, we determined chemical, physical and spectroscopic characteristics of a variety of wood wastes, co-composts and wood chips and carried out a plant (Betula papyrifera) bioassay. Chemical properties and C-13 NMR spectra indicated similarity to other woody wastes, and suitability for site rehabilitation if applied under conditions to avoid excessive leachate. Seedlings grew poorly in the wood waste materials (final height < 4 cm), except for co-composts prepared with municipal biosolids (final height 93 cm). Seedlings also grew poorly in wood chips unless fertilizer was added, indicating that nutrient deficiencies were the primary cause of the poor growth in wood chips. Even with nutrient addition, seedling growth was low in the finest wood chips (< 10 mm), probably as a consequence of retention of excessive moisture. This problem could be overcome by applying larger particles or by incorporating the wood chips into soil rather than leaving them as a surface mulch. In conjunction with results from field trials, these results support the application of woody wastes for site rehabilitation, where in situ mixing with mineral soil should reduce bulk density and improve water-holding capacity, and fertilization can compensate for N immobilization by wastes with high C:N ratios.