Utility of wood ash, paper sludge and biochar for the mitigation of greenhouse gases emissions from acid boreal soils

• Published in: Journal of environmental management 2023-03, Vol.330, p.117202, Article 117202
• Main Authors: Medaiyese, Ayodeji O., Wu, Jianghua, Unc, Adrian
• Format: Article
• Language: English
• Subjects: Agriculture; Boreal soils; Carbon Dioxide - analysis; Charcoal; Greenhouse gases; Greenhouse Gases - analysis; Microbial activity; Mineral nitrogen; Nitrous Oxide - analysis; Paper sludge; Sewage; Soil; Wood ash
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2022.117202

Land-use change in the boreal forest region leads to agriculture to be carried out on acid, shallow and low fertility soils. To correct soil fertility and promote crop productivity, manure and inorganic fertilizers are added, increasing the risk for greenhouse gas emissions (GHGE). To reduce the reliance on synthetic soil amendments while taking advantage of locally relevant industrial by-products, wood ash (WA) and paper sludge (SL) have been proposed as soil amendments for a range of soil types. We posited that amending soils with WA, SL and biochar will improve soil health parameters and fertility of boreal soils. Microbial activity resulting to nitrogen losses and availability were assessed. WA had a stronger ameliorative effect on acid boreal soils compared to SL. Both WA and SL increased soil microbial biomass and basal respiration resulting in higher net mineralization and thus significant increases in CO2 emissions. Co-application of urea with WA or SL further increased net mineralization compared to when used independently. Conversely, the biochar's effect was short-lived and not significant. Nevertheless, addition of biochar was shown to reduce CO2 emissions in all cases except in WA amended soils. No significant differences were observed in CH4 emissions across all treatments. WA and SL may improve soil fertility and quality but could also contribute significantly to GHG emissions in acid boreal soils. Further research is recommended to assess the mitigating effect of various biochar feedstocks on GHG emissions when co-applied with WA and SL. •The effect of wood ash and paper sludge on acid soils was tested in incubation tests.•Both increased the soil microbial biomass, respiration, and net mineralization.•Greenhouse gas emissions were larger for paper sludge amended soils.•Supplementing biochar to wood ash increased soil CO2 fluxes.•Supplementing biochar to paper sludge or limestone ash reduced soil CO2 fluxes.