Ammonia concentrations and emission rates at a commercial poultry manure composting facility

Abstract

Composting facilities are essential parts of most manure-belt (MB) poultry houses in the U.S., but their NH3 concentrations and emission are not well understood. This may affect farm operation safety and limit the development of NH3 mitigation and management strategies. The study aimed to quantify NH3 concentrations and hen-specific emission rates (ER) at a commercial poultry manure composting facility and to understand their diurnal and seasonal variations. Two large tunnel-ventilated composting buildings with twelve 122-cm exhaust fans were chosen as the study site, which received manure from four on-site manure-belt layer barns. The inlet and exhaust NH3 concentrations at the compost building were monitored quasi-continuously for one month per season for two years. Ammonia ERs were calculated based on the NH3 concentrations and building ventilation rates. The average daily mean ± SD of the NH3 concentrations in spring, summer, fall, and winter were 114 ± 20, 144 ± 35, 115 ± 13, and 141 ± 25 ppmv, respectively. Seasonal and diurnal variations existed in both NH3 concentrations and ERs. The daytime NH3 ER was significantly higher than that of night time. These results showed that NH3 emissions from composting facilities are considerably high, and thus mitigation strategies are needed to further reduce NH3 from the whole MB layer facility system.