Diurnal Fluctuation and Movement of Atmospheric Ammonia and Related Gases from Dairies1
- R. E. Luebs,
- K. R. Davis and
- A. E. Laag2
Simultaneous 24-hour air sampling, 0.8 km upwind from the nearest cows in a large dairy area (145,000 cows) and 11.2 km upwind from the dairy area, showed distillable N (mostly NH3) concentrations of 190 and 6 µg/m3, respectively. An average distillable-N concentration of 540 µg/m3 was measured during a 24-hour sampling at the downwind corral fence of an isolated 600-cow dairy. These data indicate significant N loss from dairy waste by NH3 volatilization. The significance of the effects of these higher atmospheric concentrations on NH3 absorption by soils, surface waters, and crops remains to be fully evaluated. Meteorological factors, particularly temperature inversions in the atmosphere and wind, along with proximity to the waste, greatly affected atmospheric concentrations of distillable N. A marked diurnal fluctuation with low concentrations in the afternoon and high concentrations at night were frequently recorded in the large dairy area. Higher nighttime values were related to temperature inversions in the atmosphere. A reversed diurnal pattern with the high afternoon and low nighttime concentrations were recorded at the isolated-dairy site. Close proximity to the source and a high horizontal flux of distillable N with afternoon winds were important factors in this diurnal pattern. Winds averaging 9.3 km/hour transported distillable N 500 m from the isolated dairy at a height of 1.2 m.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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