Fly-ash from a pulp and paper mill: A potential liming material for agricultural soils in Western Newfoundland.

Abstract

Most agricultural soils in Western Newfoundland are acidic and need lime to raise soil pH to be productive. Corner Brook Pulp and Paper Ltd produces a substantial amount of fly-ash, disposed of at a local landfill. This study was conducted to assess the potential for using fly-ash as a liming material for agricultural soil (pH 5.5) in Western Newfoundland. Heavy metal concentration in the soil and fly-ash were analysed and compared with soil and compost guidelines. As per quality guidelines, only part of the lime requirement can be substituted by fly-ash. The percentage may vary depending on initial soil pH and the desired pH for the crop to be grown. The total lime requirement can be met when fly-ash is applied combined with other soil amendments low in trace element concentration.

Paper mill wastes and biochar improve physiochemical properties and reduce heavy metals leaching risks in podzolic soils

“…There was no significant difference observed between biochar mended and unamended treatments for As, Cr and Mo, although the concentration of these heavy metals were lower in biochar amended treatments leachates compared to unamended treatments (table 7). The accumulation of these heavy metals might be due to rise in pH by enhancement of the metal's retention on the soil surface (Maheswaran 2019). The application of biochar with wood ash and paper sludge absorbed the heavy metals and reduced its concentration in leachates.…”

“…Crop growth and food production in boreal agroecosystems, including Newfoundland and Labrador (NL), Canada, are limited by short growing seasons, extreme weather, and poor soil conditions (Altdorff et al 2019. Most soils in boreal regions are podzols, characterized by high acidity, coarse texture, and poor inherent fertility due to heavy leaching of nutrients (Maheswaran 2019). Constant applications of liming materials and fertilizers are required to achieve optimal pH and fertility in these soils.…”

“…On one hand, wood ash is reactive in soil, increases soil pH and lowers the exchangeable soil aluminium (Al 3+ ) (Jala and Goyal 2006, Maheswaran 2019, Johansen et al 2021. Studies have shown that wood ash positively impacts soil physicochemical properties (Cherian and Siddiqua 2019), leading to improvement in soil structure, bulk density, total porosity, and water retention (Rautaray et al 2003, Sahu et al 2017.…”

“…Wood ash and paper sludge also contain elements, including limited amounts of essential plant nutrients, as well as heavy metals like arsenic (As), cadmium (Cd), chromium (Cr), cobalt (Co), lead (Pb), molybdenum (Mo) and nickel (Ni) (Camberato et al 2006, Maheswaran 2019, Farhain et al 2022. The main source of heavy metals in these waste products is the oil used during combustion, and contaminant levels can vary depending on the fiber source and the treatment process (Camberato et al 2006).…”

“…These include chemical oxidation, soil washing and bioremediation (Zhao 2020). Application of biochar, a carbonaceous material produced from the pyrolysis of organic feedstock, has been shown to limit the mobility and bioavailability of heavy metals (Karami et al 2011) and reduce the uptake of heavy metals by plants and leaching to groundwater (Maheswaran 2019). Biochar has a porous structure (Saha et al 2020), active functional groups (Zhang et al 2017), high pH (Vermooten et al 2019 and high cation exchange capacity (CEC) (Park et al 2011, Zhang et al 2017 which increase its affinity for heavy metals adsorption.…”