Air pollution is increasingly being linked to human health effects in terms of cost of illness as well as the occurrences of pulmonary and cardiac diseases. Ammonia and fine particulate matter are two contaminants that are emitted by agricultural operations and that contribute to the general burden of illness due to atmospheric exposure. Production commodity groups thus need a sound scientific knowledge regarding their agricultural air emissions so that future discussions, decisions and policies can be made in a rational and logical manner.
Emissions from farming enterprises are extremely complex and interrelated. Emissions to the air can occur from all stages including the animal housing unit, the manure storage, and the subsequent field application of the manure. The aim of the overall study is to conduct an integrated investigation of different poultry operations (broiler and/or layer) as a whole system to quantify the strength of sources as well as their interrelationship for a suite of air contaminants, including ammonia, greenhouse gases (methane and nitrous oxide), size fractionated particulate matter (PM10 and PM2.5), and gaseous and particulate anion and cation concentrations. This project, which represents the third year in the study, focused on the emissions of ammonia and particulate matter from poultry houses.
To date, emission factors for ammonia and particulate matter have been published for broiler facilities. As an example, for a summer broiler flock, the estimated ammonia emission rate was 120.8 g/day/AU and particulate matter emission rates, as PM10 and PM2.5, were 5.2 and 1.0 g/day/AU respectively (PM10 refers to particulate matter with aerodynamic diameters of less than 10 mm, or the coarse fraction; PM2.5 refers to particulate matter with aerodynamic diameters of less than 2.5 mm, or the fine fraction; and AU represents an animal unit taken as 500 kg live weight). These emission factors developed for the release from housing facilities are seasonally dependent as ventilation rates vary accordingly. The expertise and knowledge gained with broiler operations is now being applied to layer facilities.
Methane (CH4) and nitrous oxide (N2O) emissions from an outside broiler litter storage bunker were measured and emissions factors developed. On a mass of litter basis, the estimated annual emission rates of CH4 and N2O from the exposed litter surface in the bunker were 19 and 3.3 g/(kg of litter), respectively. These emission factors are somewhat dependent on the depth of the litter in the bunker, the mass of volatile solids within the litter and the season of the year.
Experiments aimed at estimating the loss of NH3 to the atmosphere after surface broadcasting of broiler litter on soil surfaces indicate that 22 per cent of the ammonium (as N) in the litter was lost 72 hours after application and 25 per cent after 132 hours.
Composting of chicken carcasses is also a source of NH3 to the atmosphere. Flux chamber experiments on static compost piles have indicated that different amendment materials used, such as broiler litter, finished compost and fresh wood chips, can affect the levels of NH3 generated and released from the pile. The controlled experiments clearly showed that broiler litter emitted the most NH3 while finished compost emitted the least over time. Elevated NH3 releases can lead to odour concerns as well as the loss of nutrients. To read more about this project, please visit www.poultryindustrycouncil.ca.