Wood ash and paper sludge: potential liming and nutrient source for crop production in podzolic soils

Javed, Bilal (2021) Wood ash and paper sludge: potential liming and nutrient source for crop production in podzolic soils. Masters thesis, Memorial University of Newfoundland.

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Abstract

The Corner Brook Pulp and Paper Ltd (CBPPL) produces approximately 10,000 Mg of wood ash (WA) and 47,500 Mg of paper sludge (SL), annually, as waste byproducts. Among these wastes WA is landfilled as part of the disposal management program administered by the company whereas SL is burnt to generate steam for paper mill operations. This practice is not ideal due to high disposal costs and environmental concerns. In addition, WA and SL contains essential nutrients such as Ca, K and Mg that favors plant growth and could increase soil pH due to its calcium carbonate equivalent ability. One sustainable management practice is the land application of WA and SL to agricultural soil, increasing soil pH and enhancing crop growth and yield. Herein, we conducted greenhouse studies to evaluate the effect of WA and SL alone and in combination with biochar (BC) on growth, yield, nitrogen dynamics, and heavy metals mobility in the soil-plant system of annual ryegrass (Lolium perenne L.) and kale (Brassica oleracea L.). In study 1 soil with pH 5.7 and 2.7 % organic matter was used and in study 2, soil pH and organic matter were 5.2 and 4.5 % respectively. Results of the study 1 and 2 indicated that WA was effective in achieving the target soil pH of 6.3 and produced 71% and 42% more biomass than control in annual ryegrass, respectively. Similarly, WA application showed 28% and 27% higher yield than control in kale in both studies, respectively. BC addition significantly decreased 15 – 20 % Pb and Cd uptake in annual ryegrass and kale crops in both studies. Study results suggest that WA could be used as a liming and nutrient source and could be a substitute for limestone used in improving soil pH in agriculture production system. Furthermore, BC amendment with WA or SL could be a promising strategy in decreasing heavy metals uptake in agronomic and horticultural crops.

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