Effects of Blending Dairy Manure Compost and Canola Meal on Pellet Quality and Nutrient Concentrations

Abstract

HighlightsNutrient contents and unit density were positively correlated with canola meal blending ratio.Pellet durability, bulk density, and length were inversely correlated with canola meal blending ratio.Pellets produced from compost and 20% canola meal blend were 67% denser than the compost.Pelleting dairy manure and canola meal blends improved nutrient transport and storage.Abstract. The potential for adverse environmental impacts from excess manure nutrients generated in regions with large concentrations of animal production is enormous and real. The goal of this research was to investigate ways of alleviating such threats via pelleting and blending of excess dairy manure nutrients to enhance their value, utilization, transport, and storage. In this study, composted dairy manure was blended with canola meal in ratios ranging from 0% to 40% canola meal prior to pelleting. The pre-pelleting moisture content was set at 21% (wet basis) and an 8 mm diameter die was selected for pelleting, based on previous studies. The effect of canola blending ratio was evaluated against moisture content, unit and bulk densities, recovery, durability, and nutrient concentrations (total nitrogen and phosphate) of the resulting pellets. Results indicated positive correlations between the blending ratio and pellet recovery (r = 0.83), moisture content (r = 0.75), unit density (r = 0.74), total nitrogen (r = 0.99), and phosphate (r = 0.87). In contrast, inverse correlations were observed between the blending ratio and pellet durability (r = -0.93), bulk density (r = -0.99), and length (r = -0.76). No significant differences were observed between the blending ratio and all these parameters for blending ratios of 0% to 15%. However, data indicated significant differences between pellet durability and recovery at blending ratios above 20%. Overall, this study showed that blending dairy manure with up to 15% canola meal significantly (p < 001) improved the nutrient value, storage, and transport. Keywords: Blending, Dairy manure, Durability, Environmental pollution, Pelleting.