High Litter Moisture Content Suppresses Litter Ammonia Volatilization

Authors: Miles, Dana; ROWE, D - Mississippi State University; CATHCART, T - Mississippi State University

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/21/2011
Publication Date: 6/1/2011
Citation: Miles, D.M., Rowe, D.E., Cathcart, T.C. 2011. High litter moisture content suppresses litter ammonia volatilization. Poultry Science. 90:1397-1405.

Interpretive Summary: With global food demand expected to increase 100% in the next 50 years, urgency to combine comprehensive strategies for sustainable, efficacious, and environmentally sensible agronomic practices has never been greater. One effort for U.S. meat bird management is to reduce ammonia volatilization from litter to create a better growing environment for the birds, improve production efficiency, retain nitrogen in litter for fertilizer value, and negate detrimental environmental impacts of ammonia loss to the air. To investigate temperature and moisture effects on litter ammonia, experiments were conducted using commercial broiler litter that had moisture contents of approximately 20 – 55%, while controlling temperature from 18.3 – 40.6 °C. These conditions mimic the range found in commercial houses. A statistical model was used to develop surface response plots. The surfaces were parabolic cylinders, indicating a critical moisture level at which ammonia no longer rises but is diminished as moisture continues to increase. The critical moisture level lies between 37.4 and 51.1% litter moisture depending on temperature. Increasing temperature consistently increased ammonia generation. Comparing the temperature extremes, the maximum ammonia was up to 7 times greater at 40.6 °C vs. 18.3 °C. The upper moisture limit at which ammonia release is maximized and subsequently arrested as moisture continues to increase had not been previously defined for commercial broiler litter. The poultry industry and researchers can use these results as a decision tool to enable management strategies that limit ammonia production.

Technical Abstract: With global food demand expected to increase 100% in the next 50 years, urgency to combine comprehensive strategies for sustainable, efficacious, and environmentally sensible agronomic practices has never been greater. One effort for U.S. meat bird management is to reduce NH3 volatilization from litter to create a better growing environment for the birds, improve production efficiency, retain N in litter for fertilizer value, and negate detrimental environmental impacts of NH3 loss to the air. To derive fundamental effects of temperature and moisture on litter NH3 volatilization over the range of conditions found in commercial houses, experiments were conducted using commercial broiler litter that had moisture contents of approximately 20 – 55%, while controlling temperature from 18.3 – 40.6 °C. Litter samples (100 g) were placed in 1-L containers that received humidified air at approximately 113 mL/min. Volatilized NH3 in exhaust air was captured in H3BO3 traps. Ammonia loss (log10 transformation) was modeled via an equation using linear coefficients for temperature and moisture, an interaction term for temperature X moisture, and a quadratic term for moisture. The surface responses resembled parabolic cylinders, indicating a critical moisture level at which NH3 no longer rises but is diminished as moisture continues to increase. The critical moisture level lies between 37.4 and 51.1% litter moisture depending on temperature. Increasing temperature consistently increased NH3 generation. Comparing the temperature extremes, the maximum NH3 was up to 7 times greater at 40.6 °C vs. 18.3 °C. The upper moisture limit at which NH3 release is maximized and subsequently arrested as moisture continues to increase had not been previously defined for commercial broiler litter. The poultry industry and researchers can use these results as a decision tool to enable management strategies that limit NH3 production.