Mitigation of gaseous nitrogen losses during composting of beef cattle bedded manure using rice husk biochar

This study evaluated the efficacy of rice husk biochar (RHB) for mitigating gaseous nitrogen losses and enhancing nitrogen retention during the composting of Hanwoo (Korean native cattle) bedded manure.A 58-day pilot-scale trial was conducted using six 800 L intermittently turned compost piles: three control piles without biochar and three amended with 10% RHB (w/w, dry basis).Ammonia (NH 3 ) and nitrous oxide (N 2 O) emissions were quantified using 2.2 m 3 flux chambers, alongside monitoring of internal pile conditions.RHB amendment significantly enhanced organic matter decomposition, with volatile solids reduction reaching 27.5% in RHB compared to 19.3% in control (p<0.05).Compared to the control, the RHB treatment reduced cumulative NH 3 and N 2 O emissions by 33.4% and 25.2%, respectively, over the composting period (p<0.05).Consequently, total nitrogen retention was improved by 29% in the RHB treatment (p<0.05).The enhanced nitrogen conservation is attributed primarily to RHB's porous structure, which provided adsorption sites for ammoniacal nitrogen, thereby reducing volatilization losses and potentially influencing nitrificationdenitrification pathways.The findings demonstrate that incorporating 10% RHB into intermittently turned composting systems offers a practical strategy to improve nitrogen use efficiency and environmental sustainability in Hanwoo bedded manure management.