Methane emissions from swine houses in North Carolina

Abstract

Gaseous methane (CH4) emissions were determined during the winter and summer from `farrow-to-finish' (FF) swine production houses and during the summer from a `farrow-to-wean' (FW) house in 1998 in the coastal plains of North Carolina. The houses were instrumented with sensors to determine cycling of the individual forced-ventilation fans. Laser spectrometry was used to measure CH4 concentration differences between the intake and exhaust points of the houses. Differences in CH4 concentrations were combined with fan operation data to calculate CH4 fluxes from the houses. During the cold winter measurement period, CH4 fluxes averaged 6.9 g CH4animal−1d−1 in the FF house. During summer measurement periods, CH4 fluxes were much greater and averaged 33 and 46 g CH4animal−1d−1 from the FF and FW houses, respectively. The much larger emissions during the summer than winter, indicate that CH4 house emissions were primarily from fresh feces and the underground storage/wash pits containing lagoon effluent; and not directly from the animals since temperature would have little affect on direct animal emission. Emission factors based on animal units (au) of 454 kg animal−1 were much greater at the FW farm with a pull-plug waste management system (7–8 day wash cycle) than at the FF farm with a periodic flush system (8 h wash cycle).