Submitted to: Proceedings of the Workshop on Agricultural Air Quality: State of the Science
Publication Type: Proceedings
Publication Acceptance Date: 4/1/2006
Publication Date: 6/5/2006
Citation: Miles, D.M., Rowe, D.E., Owens, P.R. 2006. Concurrent measurement of litter gas flux and nutrients with air and litter properties in poultry houses to improve emission estimates. Proceedings of the Workshop on Agricultural Air Quality: State of the Science. p. 914-920.
Interpretive Summary: During a winter broiler flock, a static chamber method was used to capture volatilized ammonia to learn more about the surface chemistry of the litter and how litter and gas parameters change over the floor area. Litter properties and gas flux varied throughout the broiler houses. House management, feeder/waterer placement and bird activity influence litter gas flux and nutrient level. Data trends agree with established relationships for the influence of pH, moisture, and temperature on gas emissions. However, aberrations in the physical condition of the litter should be considered and quantified in future emission models. Litter amendments are the primary means for altering litter pH. They are effective, but time limited. Bird age affected litter temperature; the larger birds appeared to insulate the litter base which may somewhat negate seasonal effects on emissions. Caked areas in the house produced lower ammonia flux, but differed in moisture content based on location. Cake moisture was lower near feeders and waterers but higher near the exhaust fans. Further studies of the spatial variability are expected to lead to new best management practices that would require input from broiler managers to prevent detrimental consequences for the birds. Zone litter treatment during the flock is one example.
Technical Abstract: Accurate predictive models for animal feeding operation air emissions require inclusion of a wide range of conditions. For broiler chickens, management practices vary considerably, complicating emission measurements. This research characterized the spatial variability of litter gas flux including ammonia, nitrous oxide, carbon dioxide, and methane as well as litter nutrients, such as total Kjeldahl nitrogen, water extractable phosphate, ammonium, and nitrate, in two solid sidewall commercial broiler houses where 12 flocks were previously grown. In the 146 m by 12.8 m houses, grid samples (36 points) at 5 m across and 12 m down the house were taken during a winter flock on day 2 and 45. On day 45, eight additional samples were taken near the feeders and waterers (F/W). Gas flux estimates at each site were derived from timed gas concentrations measured using a photoacoustic multigas analyzer and an inverted chamber. Geostatistical contour plots indicate ammonia flux on day 2 was elevated in the brood area of house one (H1) where litter and air temperatures were highest. For this date, a commercial litter treatment in the brood area of house two (H2) held the ammonia flux near zero for approximately 45% of the brood area. Day 45 ammonia flux levels were similar in each house; averaging in H1 694 vs. 644 mg m-2 hr-1 in H2. Ammonia flux, litter moisture and pH were diminished at the F/W locations. Low moisture is suspected as a result of addition of dry matter from feed spillage. On day 45, areas of extensive cake near the exhaust fans in H2 provided the lowest recorded litter pH, highest moisture and essentially zero ammonia flux. For broiler health, pathogen persistence makes high litter moisture undesirable. The results indicate that house management and bird activity influence litter gas flux and nutrient level. General data trends agree with established relationships for the influence of pH, moisture, and temperature on gas emissions. However, irregular physical conditions of the litter must be considered and quantified to improve emission estimates.