The potential for plants to trap emissions from farms with laying hens: 2. Ammonia and dust

The potential for plants to trap NH₃ and dust [particulate matter (PM)] discharged from a layer house through the exhaust fans was evaluated at The Pennsylvania State University Poultry Education and Research Center in August 2006. Poultry and livestock NH₃ emissions are a concern for air quality, surface deposition, and animal and human health. Particulate matter is a human health concern as well and is regulated by the United States Environmental Protection Agency in nonattainment areas. A vegetative buffer comprising 5 tree species was planted in pot-in-pot containers in 5 rows downwind from 4 henhouse fans, with 1 control row of plants upwind from the fans. When measured with a photoacoustic NH₃ detector at fan elevation (1.5 m), NH₃ concentrations decreased sharply (P < 0.0001) with greater distance, from 71.1 ppm at 0 m (at the fan) to 2.1 ppm at 5.5 m (between rows 2 and 3), 0.3 ppm at 10 m (after row 5), and 0.1 ppm at 50 m (control). This trend was also observed with colorimetric dosi-rubes and a photoacoustic detector at 0.3- and 3.0-m elevations. Significantly lower NH ₃ concentrations were recorded at both the 0.3- and 3.0-m elevations in the presence of the trees compared with when the trees were removed from their pot-in-pot containers, suggesting that a portion of the atmospheric NH₃ was being trapped by the plants. This was further supported by greater foliar N concentrations in plants when measured downwind from the fans (P < 0.0001). Dust concentrations sampled downwind from the fans were greatest at 2.5 m and decreased linearly to 50 m (P ≤ 0.0001). Plant PM _2.5, PM₁₀, and total PM washed from the foliage showed the same significant linear trend with greater distance from the fans. Plants also showed unique species differences in their capacity to trap and hold NH ₃ and PM that can be applied in practical recommendations. These findings indicated vegetative buffers are capable of trapping NH₃ and PM fan emissions from poultry facilities.