Comparison of pine and miscanthus biochar physicochemical properties and impact on <i>Escherichia coli</i> populations in broiler litter

Abstract

<b><sc>Abstract.</sc></b> The broiler industry‘s rising adoption of antibiotic-free production requires alternative pathogen control strategies. Biochar is carbonized biomass that has been shown to reduce E. coli in soils and waste water; however, the effect of biochar on E. coli in broiler litter is unknown. The objectives of this study were to evaluate the physicochemical properties of pine and miscanthus biochar and determine their impact on E. coli populations in broiler litter compared to poultry litter treatment (PLT). Biochar specific surface area (SSA), pore volume, and pore diameter were measured via BET analysis and chemical composition was analyzed via ultimate analysis. Baseline E. coli abundance was determined in the broiler litter prior to biochar addition (day 0). Pine and miscanthus biochars were then mixed at inclusion rates of 0, 5, 10, 20, 25, and 30% w/w with litter and PLT was surface applied. Treatments were incubated and E. coli was enumerated at days 2 and 7. Pine biochar had higher SSA, pore volume, and carbon content than miscanthus. E. coli counts in pine biochar inclusion rates of 20, 25, and 30% were lowest overall, however, they were not significantly different than the control (0%). Pine‘s higher pyrolysis temperature likely produced more stable biochar with recalcitrant carbon unavailable for bacterial growth. E. coli abundance was highest in PLT treated litter and counts significantly decreased over time for all treatments. Results from this study indicate that higher pyrolysis temperatures of woody materials create biochar that can reduce E. coli populations in broiler litter.