Wood ash as a forest soil amendment: The role of boiler and soil type on soil property response

Abstract

Pugliese, S., Jones, T., Preston, M. D., Hazlett, P., Tran, H. and Basiliko, N. 2014. Wood ash as a forest soil amendment: The role of boiler and soil type on soil property response. Can. J. Soil Sci. 94: 621–634. Wood ash is produced in large quantities in Canada as a by-product of the pulp and paper, sawmill, and bioenergy industries and it is anticipated that its disposal in landfills will not be a viable option. An alternative option may be to use it to amend forest soils. Wood ash is a complex mixture and its composition depends on several variables, including the combustion parameters of the boiler in which it is generated. We present an analysis of the amendment of two Canadian forest soils (a Brunisol from the Great Lakes–St. Lawrence and a Luvisol from the Carolinian forest regions of Ontario) with six different wood ashes collected from different biomass boilers through short-term controlled incubations. We show that following an 8-wk incubation period, amendment of the soils with wood ash led to small to moderate increases in soil pH, but had little effect on soil microbial activity and biomass. The concentration of important base cations such as calcium, magnesium and potassium as well as phosphorus generally increased in both soil types following amendment with different ash. This practice can return nutrients lost from forest ecosystems during harvesting; however, effects were found to be boiler-specific. Lastly, we show that four ash types led to small increases in cadmium in either soil; the concentration of all other measured heavy metals was not significantly increased following amendment, and in certain cases decreased, particularly with lead. The only potentially negative aspect encountered was elevated sodium, particularly with ash from one boiler, but unacceptable Na-absorptivity ratios were not exceeded. These results demonstrate that with proper characterization and selection of wood ash type and application rates, amendment of Canadian forest soils with wood ash may benefit forest ecosystems and is unlikely to disrupt the chemical and biological processes in soil environments.

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

“…Following ash application, increases in soil pH, CEC, % BS and exchangeable Ca, Mg, K, and Na, were expected (Pitman 2006;Augusto et al 2008;Pugliese et al 2014), but were actually only significant in LFH samples. Increases tended to be greater following gasifier ash application, as compared with boiler ash, likely due to its higher CCE and mineral content.…”

“…Some charcoals may reduce N availability to plants through net N immobilization (Deenik et al 2011). Pugliese et al (2014) reported a small reduction of NH 4 + -N, but an increase in NO 3 − -N concentration, following addition of high-carbon (∼16% total C) ash (equivalent to 5 Mg ha −1 ) to soils in laboratory incubations. Omil et al (2013) reported slightly reduced N mineralization rates in sandy loam soil following additions of high-carbon ash, but foliar N concentrations in mature Monterey pine stands (1-2 yr following one or three annual doses at 4.5 Mg ha −1 ) were not changed by ash addition.…”

“…Elements are recycled, allowing for continued biogeochemical cycling in the biosphere. Reduced acidity may increase availability of P, % base saturation (% BS), and pH-dependent cation exchange capacity (CEC) of soils (Pitman 2006;Augusto et al 2008;Pugliese et al 2014). Increased pH has been associated with increased rates of microbial activity, organic matter mineralization, ammonification, and nitrification (Zimmerman and Frey 2002;Saarsalmi et al 2014).…”

Wood Ash Improved Soil Properties and Crop Yield for Nine Years and Saved Fertilizer

“…Beneficial effects of 25 Mg ha -1 wood ash supplemented by N fertilizer were observed on barley biomass and seed yield (Patterson, Acharya, Thomas, Bertschi, & Rothwell, 2004a) and canola seed yield (Patterson, Acharya, Bertschi, & Thomas, 2004b) in central Alberta. In an incubation study in central Canada, wood ash increased the pH, Ca, Mg, K and P of a Brunisol and a Luvisol, but had little effect on their microbial activity and biomass (Pugliese et al, 2014). In a review, Demeyer, Nkana, and Verloo (2001) attributed the plant growth benefits on wood ash-amended soils to increases in the availability of P, Ca, Mg, K, and B, and decreases in Al and Mn toxicity.…”

“…On an acid agricultural soil in northwest Alberta, lime and wood ash increased microbial biomass and C mineralization as well as changed the functional structure of bacterial communities (Lupwayi, Arshad, Azooz, & Soon, 2009); and the soil pH increase was in the order: wood ash = lime, while the order for available P and aggregation of soil was wood ash > lime (Arshad et al, 2012). In central Canada, wood ash increased pH, Ca, Mg, K and P but had little effect on microbial activity and biomass of a Brunisol and a Luvisol in an incubation study (Pugliese et al, 2014); and the liming products that significantly raised the soil pH also increased Ca, P and K concentrations in a 3 year field study (Lalande, Gagnon, & Riyer, 2009). In a 3-year field study on Gray Luvisol and Dark Brown Chernozem soils on organic farms in northeastern Saskatchewan, annual application of wood ash at 1 Mg ha -1 increased soil pH, extractable P, sulphate-S and exchangeable K; and tended to increase light fraction organic C and N in soil (Malhi, 2012a).…”