AMMONIA AND HYDROGEN SULFIDE CONCENTRATIONS AND EMISSIONS FOR NATURALLY VENTILATED FREESTALL DAIRY BARNS

Concentrations and emissions of ammonia (NH3) and hydrogen sulfide (H2S) data for two naturally ventilated freestall dairy barns, within a one-year window of a two-year measurement effort, are presented in this article. Barn I (B1) had a capacity of 400 fresh-lactating Holstein cows, while barn 2 (B2) had a capacity of 850 non-fresh-lactating Holstein cows. The 10 min mean concentrations of NH3 in the barns ranged from 0.16 to 2.85 ppm, while the concentrations of H2S ranged from 0.0 to 135.8 ppb. The concentrations of NH3 and H2S in the barns were significantly below the OSHA permissible and NIOSH recommended exposure levels with respect to safety and health concerns of farm workers. Air exchange rates ranged from 7 to 74 h(-1) during all measurement periods, which met and exceeded the standard minimum ventilation rate requirements for dairy barns. Ammonia emissions ranged from 15.1 to 36.7 g d(-1) AU(-1) (20.3 to 49.5 g d(-1) cow(-1)) with a mean of 21.6 g d(-1) AU(-1) (29.0 g d(-1) cow(-1)). Emissions of H2S, on the other hand, ranged from 0.0 to 1.5 g d(-1) AU(-1) (0.0 and 2.0 g d(-1) cow(-1)) with an overall mean of 0.51 g d(-1) AU(-1) (0.69 g d(-1) cow(-1)). In general, NH3 emissions correlated fairly well with temperature (R-2 = 0.29 to 0.51). However, the relationships between NH3 emission and wind speed were mixed, ranging from zero to moderately positive (R-2 = 0.01 to 0.46). Regression analyses did not indicate any significant relationships between H2S emissions and these environmental parameters.