RESUMO
We measured NH3 emissions from litter in broiler houses, during storage, and after land application and conducted a mass balance of N in poultry houses. Four state-of-the-art tunnel-ventilated broiler houses in northwest Arkansas were equipped with NH3 sensors, anemometers, and data loggers to continuously record NH3 concentrations and ventilation for 1 yr. Gaseous fluxes of NH3, N2O, CH4, and CO2 from litter were measured. Nitrogen (N) inputs and outputs were quantified. Ammonia emissions during storage and after land application were measured. Ammonia emissions during the flock averaged approximately 15.2 kg per day-house (equivalent to 28.3 g NH3per bird marketed). Emissions between flocks equaled 9.09 g NH3 per bird. Hence, in-house NH3 emissions were 37.5 g NH3 per bird, or 14.5 g kg(-1) bird marketed (50-d-old birds). The mass balance study showed N inputs for the year to the four houses totaled 71,340 kg N, with inputs from bedding, chicks, and feed equal to 303, 602, and 70,435 kg, respectively (equivalent to 0.60, 1.19, and 139.56 g N per bird). Nitrogen outputs totaled 70,396 kg N. Annual N output from birds marketed, NH3 emissions, litter or cake, mortality, and NO2 emissions was 39,485, 15,571, 14,464, 635, and 241 kg N, respectively (equivalent to 78.2, 30.8, 28.7, 1.3, and 0.5 g N per bird). The percent N recovery for the N mass balance study was 98.8%. Ammonia emissions from stacked litter during a 16-d storage period were 172 g Mg(-1) litter, which is equivalent to 0.18 g NH3 per bird. Ammonia losses from poultry litter broadcast to pastures were 34 kg N ha (equivalent to 15% of total N applied or 7.91 g NH3 per bird). When the litter was incorporated into the pasture using a new knifing technique, NH3 losses were virtually zero. The total NH3 emission factor for broilers measured in this study, which includes losses in-house, during storage, and after land application, was 45.6 g NH3 per bird marketed.