Circular Valorization of Pulp and Paper Mill Biosolids for Sustainable Soil Management and Crop Production in Cold-Region Agroecosystems

Sustainable valorization of pulp and paper mill biosolids (PPMB) can improve soil fertility and reduce reliance on synthetic fertilizers in cold-region agriculture. This two-year field study assessed PPMB as a soil amendment for canola ( Brassica napus L.) and wheat ( Triticum aestivum L. ) in Northern Manitoba, Canada. Six treatments; control, urea, mixed PPMB, and three PPMB–urea combinations; were tested in a randomized complete block design. PPMB application reduced soil bulk density by 15-20% compared to urea and increased soil organic carbon by up to 21% under mixed PPMB. Microbial respiration responses were variable, and yield outcomes for both crops were comparable to or higher than urea. Redundancy analysis showed positive links between improved soil attributes and yield. The findings indicated that PPMB can sustain crop production and improve soil health in cold climates, supporting circular bioeconomy applications in northern agriculture.