The National Air Emissions Monitoring Study’s Southeast Layer Site: Part IV. Effects of Farm Management

Abstract

<abstract><title><italic>Abstract.</italic></title> The effects of house lighting, forced molting, manure removal, and flock replacement on air pollutant concentrations and emissions from high-rise tunnel-ventilated layer houses were evaluated. Air pollutants included ammonia (NH₃), carbon dioxide (CO₂), and particulate matter (PM, including PM₁₀, PM_2.5, and total suspended particulate, TSP). Emission rates were determined based on ventilation rates and pollutant concentrations, which were monitored for two years. House lighting schedules, molting, manure removal, and flock replacement activities were documented by the producer. Hen activity was monitored continuously using commercial motion detectors and was observed to be much higher during light periods as compared with dark periods. The TSP and PM₁₀ emissions during light periods were about five times greater than during dark periods, whereas NH₃ and CO₂ emissions during light periods were about 20% higher. The NH₃ and CO₂ concentrations and emission rates decreased during molting and then increased afterward. Ammonia emission was directly proportional to hen body weight and feed consumption. Compared with NH₃, CO₂ concentrations and emissions showed more variations during molting. During manure pit cleanouts, NH₃ and CO₂ emissions decreased from 0.62 to 0.21 g d^-1 hen^-1 and from 78 to 64 g d^-1 hen^-1, respectively. After the manure pits were emptied, NH₃ and CO₂ emissions increased steadily during the first 3 to 7 d of manure accumulation and then remained relatively constant. Manure pit cleanout activities caused high PM emission. Particulate matter emission decreased gradually after the pits were cleaned. No significant changes in egg production, mortality, water consumption, or feed consumption were observed during manure removals. When compared with occupied houses, empty house emission rates of PM₁₀, TSP, and NH₃ each decreased by more than 90%, and CO₂ decreased by more than 70%.