Abstract
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 (NH₃) and nitrous oxide (N₂O) emissions were quantified using 2.2 m³ 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 NH₃ and N₂O 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 nitrification- denitrification 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.