Litter ammonia generation: Moisture content and organic versus inorganic bedding materials

Negative impacts on the environment, bird well-being, and farm worker health indicate the need for abatement strategies for poultry litter NH₃ generation. Type of bedding affects many parameters related to poultry production including NH₃ losses. In a randomized complete block design, 3 trials compared the cumulative NH₃ volatilization for laboratory-prepared litter (4 bedding types mixed with excreta) and commercial litter (sampled from a broiler house during the second flock on reused pine wood chips). Litters were assessed at the original moisture content and 2 higher moisture contents. Broiler excrement was mixed with pine wood shavings, rice hulls, sand, and vermiculite to create litter samples. Volumetrically uniform litter samples were placed in chambers receiving humidified air where the exhaust passed through H₃BO₃ solution, trapping litter-emitted NH₃. At the original moisture content, sand and vermiculite litters generated the most NH₃ (5.3 and 9.1 mg of N, respectively) whereas wood shavings, commercial, and rice hull litters emitted the least NH₃ (0.9-2.6 mg of N). For reducing NH₃ emissions, the results support recommendations for using wood shavings and rice hulls, already popular bedding choices in the United States and worldwide. In this research, the organic bedding materials generated the least NH₃ at the original moisture content when compared with the inorganic materials. For each bedding type, incremental increases in litter moisture content increased NH₃ volatilization. However, the effects of bedding material on NH₃ volatilization at the increased moisture levels were not clearly differentiated across the treatments. Vermiculite generated the most NH₃ (26.3 mg of N) at the highest moisture content. Vermiculite was a novel bedding choice that has a high water absorption capacity, but because of high NH₃ generation, it is not recommended for further study as broiler bedding material. Controlling unnecessary moisture inputs to broiler litter is a key to controlling NH₃ emissions.