Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/19/2005
Publication Date: 1/1/2006
Citation: Miles, D.M., Owens, P.R., Rowe, D.E. 2006. Spatial variability of litter gaseous flux within a commercial broiler house: Ammonia, Nitrous Oxide, Carbon Dioxide, and Methane. Poultry Science. 85:167-172. Interpretive Summary: As animal feeding operations are being scrutinized with respect to gas emissions, the public, regulators, and researchers are looking for methods to quantify these gases. Though some data exists that provide gas concentration within poultry houses, little data exists to characterize the evolution of the gases for developing a prediction model. At 36 points within a commercial broiler house, ammonia, carbon dioxide, nitrous oxide and methane were measured at the surface of the poultry litter (wood-bedding material and manure left by previous flocks). Litter properties including temperature, moisture, and pH were concurrently measured with the gases. Sampling dates during the summer flock were the first day and day 21 (the middle of the growout). Ammonia from the litter seemed most affected by temperature and was greater on the first day of the flock. Carbon dioxide and methane were greater at the middle of the growout in areas where litter moisture had increased. These results show that in addition to litter properties, house management and bird age affect litter gas products and should be considered in process-based models for emissions. Also, gas products vary across the surface of the litter so that single point measurements in the house may not be indicative of the actual levels and should be used cautiously when estimating emissions.
Technical Abstract: Twenty-eight flocks were grown on litter in a tunnel ventilated, curtain-sided commercial broiler house prior to this summer flock. Grid measurements were made using a photoacoustic multigas analyzer to assess the spatial variability of litter gases: NH3, N2O, CO2, and CH4, on d 1 and 21. The pooled results for the brood and non-brood areas of the house were: (1) NH3 flux was greatest in the brood area at d 1, averaging 497 mg/(m2 hr), and had a mean of 370 mg/(m2 hr) in the vacant end of the house; (2) at d 21, the non-brood area had the greater average NH3 flux, 310 mg/(m2 hr), with 136 mg/(m2 hr) in the brood area; (3) N2O and CH4 fluxes were less than 60 mg/(m2 hr); and (4) on d 1, brood CO2 flux was 6190 mg/(m2 hr) compared to 5490 mg/(m2 hr) in the opposite end of the house. On d 21, these values increased to 6540 and 9684 mg/(m2 hr) for the brood and non-brood areas. Ammonia flux seemed most affected by litter temperature. Carbon dioxide and CH4 increased from placement to mid-growout, corresponding to increased moisture especially near the fans. Contour plots were developed using geostatistical software to visually assess the spatial disparity among the measurements. This research provides a unique view of gas flux variation within the house. Co-linear factors such as house management, bird size/age, and amount of deposition are significant factors for litter gas flux and should be considered in comprehensive models for emission estimates.