Enrichment of the Atmosphere with Nitrogen Compounds Volatilized from a Large Dairy Area

A dairy cow population of 143,000 in an area of 150 km2 enriched the atmosphere with distillable N (mostly NH3) over an area in excess of 560 km2. Over an area of 35 km2, where cow population density was approximately 1,600 cows/km2, the concentration of distillable N in the atmosphere was between 20 to 30 times greater than at a control site outside the dairy area. Highest concentrations of N were associated with wet corral surfaces and favorable evaporative conditions. Approximately 20% of the total N absorbed by acid‐surface traps in the dairy area was nondistillable N while filtered air samples contained 5% or less. Rainfall delivered three times as much N to the land surface inside than outside the dairy area.