Emissions of hydrogen sulfide from a western open-lot dairy.

Hydrogen sulfide (H2 S) emissions are considered hazardous to the environment. Animal agriculture operations must therefore report emissions exceeding a threshold to the National Response Center. Estimating the emissions from operations is needed because monitoring at all operations is not possible. However, little is known about H2 S emissions from open-lot dairy operations commonly found in dry regions. Daily mean H2 S emissions from a Texas open-lot dairy were relatively uniform over the year. Emissions were greatest during the fall when air temperatures were relatively high and vapor pressure deficits were low. Higher air temperatures and wind speeds and lower surface wetness corresponded with higher mean hourly emissions in winter, spring, and summer. Hourly mean emissions in the fall differed substantially from those of the other seasons. These high fall emissions appear to have been associated with unreported producer activity of hauling manure from the manure windrow storage onto the surrounding fields. Mean annual live animal basis emissions were 3.6 g d-1 hd-1 . Annual mean emissions for the entire 3,400 head dairy were 12 kg d-1 . The maximum measured daily emissions for this 3,492-cow dairy were 33.1 kg d-1 .