The effect of different intermediate amendments on pH, ammonia, carbon dioxide and methane emissions from composting poultry deadstock

The study of ammonia, carbon dioxide and methane emissions from composting deadstock and other agricultural wastes has been a topic of great interest lately due to their effects on air quality. Previous deadstock composting research has shown that ammonia emissions are strongly affected by increasing pH of the pile above 8. To verify these findings and ascertain the uncertainty in the data, a project was initiated to look at composting poultry deadstock while using different amendments within the pile and observing the effects on the gaseous emissions. It is also of interest whether or not pH can be utilized as a best management practice parameter in composting.;Each pile was constructed using two layers of spent hen carcasses with one layer below and one above the intermediate amendment. Three different intermediate amendments were used in the experimental design with triplicates of each pile to assist in data verification and statistical analysis. The control pile was constructed solely of fresh woodchips for the base, intermediate amendment and cap material. The two additional pile designs were constructed in the same manner, however, the intermediate amendment consisted of either poultry compost (PC), a lower pH material, or poultry litter (PL), a slightly higher pH material.;Air samples were collected using a dynamic flux chamber designed to fit over the composting bins with fresh air drawn across the pile face at a known volumetric flow rate of approximately 370 m3/hr. Results indicate that as the pH of the pile goes above 8, the ammonia emissions also increase. The PL piles had the highest ammonia emissions as compared to the control and PC piles which had similar emissions. It was determined that pH is not an effective best management practice parameter as the initial pH of the amendments, specifically the control and PL piles, were very similar initially but resulted in conflicting results. However, the. PC piles which had an initially acidic pH did have much lower ammonia emissions that were similar to the control piles. Temperature, moisture, carbon and nitrogen content were monitored throughout the sampling period to provide additional information on the pile characteristics. Results from these parameters indicate composting poultry deadstock does produce variable results that are influenced by changes within the piles that are not always foreseen. In addition to ammonia, carbon dioxide, methane, nitrogen oxide and dioxide were monitored throughout the experiment.