Factors affecting ammonia volatilization from broiler litter

Loss of ammonia (NH3) from broiler litter degrades air quality, decreases litter fertilizer value, and can have negative health consequences for birds and their caretakers. Rates of NH3 emission from broiler houses are complicated by interrelated management and environmental factors such as air temperature, humidity, house style, ventilation rate, bird age, litter conditions, litter characteristics, and cleanout schedule. Wide variations in emission rates necessitate further investigation of litter characteristics and abatement techniques. The research was designed to clarify the impact of moisture effects that are critical to NH3 emissions for poultry litter, in conjunction with bedding type and temperature. Experiments were conducted on litter samples in the laboratory using an acid trap method for determining NH3 losses. Statistical models were developed for predicting NH3 release from each bedding material and within the range of litter moisture and temperatures found in commercial broiler houses. This allowed development of relationships that describe the effects of bedding, moisture, time, and temperature on litter NH3 generation that have not been published previously.;First, type of bedding material was investigated within a limited scope of moisture contents. The results indicated that increasing moisture increases NH3 generation from litter. Literature supports the phenomenon that greater litter moisture content up to a point elicits greater NH 3 release. At the original moisture content, sand and vermiculite litters generated the most NH3 whereas wood shavings, commercial, and rice hull litters emitted the least NH3.;Second, an extended range of litter moisture contents (20--55%) was investigated while including temperature (18.3--40.6°C) effects. Experiments were conducted using built-up commercial broiler litter from multiple flocks. Response surfaces were parabolic cylinders, indicating maximum NH 3 production was between 37.4 and 51.5% litter moisture depending on temperature. Comparing the temperature extremes, the maximum NH3 was up to 7 times greater at 40.6 vs. 18.3°C. This research defines intermediate critical moisture levels in broiler litter where NH 3 is maximized, providing target areas for researchers and the poultry industry to develop management scenarios to reduce NH3 production from litter.