Emission of Volatile Organic Compounds as Affected by Feedlot Location, Moisture, and Temperature

Abstract. This study investigated the effects of within pen location, moisture, and temperature on odor emissions from manure derived from diets containing 30% distillers grain. Pen surface material was collected from three within pen locations. Material was consolidated for each specific location. Approximately 6.0 kg of pen material from was mixed with water to represent dry, wet, and saturated conditions. Material was packed into pans and incubated at a specific temperature for four days. All compounds had greater emissions at 35 o C than at lower temperatures except indole. The greatest volatile fatty acid (VFA) and aromatic emissions occurred under dry conditions while wet and saturated conditions produced greater sulfide emissions. Generally, VFAs and aromatics are more soluble than sulfide compounds; therefore, when water was present, these compounds remained in solution. Sulfide contributed 87.3% of the total odor activity value (OAV) when averaged across all treatments. Wet conditions at the bunk and drainage area may consistently have redox potentials not favorable for DMDS and DMTS production. Wetting and dry cycles typical at the mound may have redox potentials during wet periods favorable for sulfide production and during dry periods have potential favorable for VFA and aromatic production. This may explain why the mound accounted for over half of the OAV. Sulfide contribution to the OAV is further illustrated by each within pen location, moisture content and temperature. Sulfide emissions dominated (i.e., > 75%) the other compounds with the exception of dry condition where the VFA, aromatic and sulfide contribution were evenly distributed.