Submitted to: Atmospheric Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/21/2007
Publication Date: 3/1/2008
Citation: Miles, D.M., Rowe, D.E., Owens, P.R. 2008. Winter broiler litter gases and nitrogen compounds: Temporal and spatial trends. Atmospheric Environment. 42:3351-3363. Interpretive Summary: Understanding how animal activities, management, and barn structure affect litter gases and nutrients is fundamental to developing accurate emission models for meat-bird facilities. Investigating changes in gas generation at the litter surface during a flock and over the floor area of commercial broiler houses advanced comprehension of causative factors. Visual display of the litter surface measurements was accomplished using contour plots for ammonia flux estimates, as well as litter parameters like total nitrogen, moisture content, pH and temperature. At the end of the growout, the most notable trends were found as characteristic differences in the compacted litter, known as cake. Low ammonia flux was common to the caked areas. However, cake between the feeders and waterers had low moisture compared to surrounding litter and cake near exhaust fans, a dynamic area for birds due to light infiltration. The importance of cake formation over the litter surface and differences based on location, both related to bird activity and house structure, should be considered in NH3 mitigation strategies.
Technical Abstract: Understanding how animal activities, management, and barn structure affect litter gases and nutrients is fundamental to developing accurate emission models for meat-bird facilities. This research characterized the temporal and spatial variability of litter ammonia (NH3) and nitrous oxide (N2O) flux via a chamber method, as well as determined litter nitrogen (N) compounds by intensive sampling in two commercial broiler houses on aged litter. In a MS winter flock, 36 grid samples were taken on days 2, 22, and 45. On day 45, eight additional samples were taken near the feeders and waterers (F/W). Geostatistical contour plots indicate day 2 NH3 flux was elevated in the brood area of house one (H1) where litter and air temperatures were highest; a commercial litter treatment held the NH3 flux near zero for approximately 45% of the brood area in house two (H2). Day 45 NH3 fluxes were similar, averaging in H1 694 vs. 644 mg m-2hr-1 in H2; both houses exhibited greater NH3 flux near the cooling pads. Ammonia flux, litter moisture and pH were diminished at the F/W locations. Heavy cake near the exhaust fans provided the lowest recorded litter pH, highest moisture and litter ammonium with no NH3 flux at the flock’s end. Trends in litter condition based on bird activity were evident, but individual differences persisted between the houses. The importance of cake formation over the litter surface and differences based on location, both related to bird activity and house structure, should be considered in NH3 mitigation strategies.