AshNet: Facilitating the use of wood ash as a forest soil amendment in Canada

Abstract

The growing demand for bioenergy has raised concerns about the sustainability of intensive forest biomass removal. Less attention has been paid to the ash generated when forest biomass is combusted to produce energy. In Canada, this ash is often landfilled, but in some countries, wood ash is applied to the soil to maintain or improve soil fertility and forest health. AshNet is a network of Canadian scientists, foresters, policy makers and industry representatives that has formed to address opportunities for and challenges to the use of wood ash as a forest soil amendment. To date, AshNet collaborators have produced a guide to navigating the regulatory approval process, and completed a techno-economic analysis of the costs associated with landfilling wood ash versus using it as a forest soil amendment. Practical methods for optimizing ash quality and applying it on forested sites are being investigated. Applications of wood ash are also being examined as a tool for emulating some of the effects of wildfire on soil chemistry. The results of research trials established by AshNet collaborators across Canada will be shared to help develop and refine forest management policies and practices surrounding soil applications of wood ash. Updates on AshNet's activities are available at (http://cfs.nrcan.gc.ca/projects/140 (English); http://scf.rncan.gc.ca/projets/140?lang=fr_CA (French)).

Short-term changes in spruce foliar nutrients and soil properties in response to wood ash application in the sub-boreal climate zone of British Columbia

“…Worldwide, bioenergy production is expanding to offset and reduce consumption of fossil fuels for heat and power (Hannam et al 2016). The combustion of wood by-products can provide an efficient, renewable energy source, but as bioenergy power generation increases, so does the amount of ash produced as a by-product (Helle et al 2009;Hannam et al 2016Hannam et al , 2017. In some European countries and some Canadian provinces, ash produced through bioenergy combustion is commonly recycled in forest ecosystems (Hannam et al 2016(Hannam et al , 2017.…”

“…The combustion of wood by-products can provide an efficient, renewable energy source, but as bioenergy power generation increases, so does the amount of ash produced as a by-product (Helle et al 2009;Hannam et al 2016Hannam et al , 2017. In some European countries and some Canadian provinces, ash produced through bioenergy combustion is commonly recycled in forest ecosystems (Hannam et al 2016(Hannam et al , 2017. In British Columbia, however, most of the wood ash produced in pulp and paper mills, sawmills, and bioenergy plants is considered a waste, and is landfilled (Nishio 2016;Hannam et al 2017).…”

“…In some European countries and some Canadian provinces, ash produced through bioenergy combustion is commonly recycled in forest ecosystems (Hannam et al 2016(Hannam et al , 2017. In British Columbia, however, most of the wood ash produced in pulp and paper mills, sawmills, and bioenergy plants is considered a waste, and is landfilled (Nishio 2016;Hannam et al 2017).…”

“…Addition of N via commercial fertilizers or N-rich organic amendments (e.g., biosolids, manures, and N-rich sludges) can help overcome this limitation. Motivations for ash application to forest ecosystems include potential enhancement of tree biomass, replenishment of harvested ecosystems with nutrients and base cations, and the emulation of natural disturbances such as wildfire (Hannam et al 2016(Hannam et al , 2017.…”

“…Chemical properties of wood ash vary widely, depending on composition of biomass residue, type of combustion system, and the point of collection (e.g., bottom or grate ash vs. fly ash) (Pitman 2006;Hannam et al 2017). Wood ash is often more soluble and has a higher pH than agricultural limestone, typically ranging from pH 9 to 13.…”