Winter broiler litter gases and nitrogen compounds: Temporal and spatial trends

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. Thirty-six grid samples were taken during a winter flock in Mississippi 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 NH3 flux on day 2 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 694 mg m−2 h−1 in H1 vs. 644 mg m−2 h−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 litter moisture and ammonium (NH4) 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.