Last week, at the invitation of Dr. Ellen Jordan (Extension Dairy Specialist, Dallas), I made a short presentation at the annual Dairy Outreach Program Area (DOPA) workshop in Stephenville.  Dairy producers in the Central Texas (Erath, Comanche, Johnson, Bosque, and Hamilton Counties) and East Texas (Hopkins, Rains, and Wood Counties) DOPAs  are required under their state water-quality permits to obtain a certain number of continuing-education units each year.  Because these CEU programs are a regulatory requirement, they’re usually well attended, and this year’s was no exception:  somewhere around 45 dairy producers assembled at the Texas A&M AgriLife Research and Extension Center at Stephenville for a chicken-fried steak lunch and four hours of CEU-eligible instruction.

My remarks centered on air emissions from open-lot dairies, including dust, greenhouse gases, and ammonia.  Here are the highlights:

• Ammonia emissions matter because:
  1. Ammonia can combine with other atmospheric gases (mainly sulfates and nitrates) to form very small particles that stay airborne a long time and contribute to stresses on the human respiratory system.
  2. Ammonia emissions represent an effectively unrecoverable loss of expensive nitrogen, for which dairy producers pay quite a lot when they buy alfalfa hay or crude-protein supplements.
  3. The human nose often recognizes ammonia’s characteristic “note,” and the general public therefore associates ammonia emissions with unpleasant odors.
• By far, most of the ammonia emitted by open-lot dairies comes from the open lots instead of the lagoon(s).
• Controlling ammonia emissions is, first and foremost, a matter of optimizing the level of crude protein fed to the herd.  Protein intake that exceeds the animal’s maintenance and milk-production requirements is eventually excreted onto corral surfaces, typically as urea, and is rapidly lost to the atmosphere as gaseous ammonia.
• After feed optimization, the next most important practice to reduce ammonia emissions is to intercept manure-borne nitrogen before it accumulates on the corral surfaces and undergoes the wetting-drying cycles that drive so much of the emissions process.  Scraping manure from feed alleys instead of flushing it into a lagoon allows a dairy producer to capture the manure nitrogen and use it beneficially as an organic fertilizer on grass or row crops.
• Methane, a potent greenhouse gas, comes primarily from the anaerobic lagoons on a dairy.  Again, intercepting manure before it goes into a lagoon allows a producer to reduce methane emissions and build soil organic matter via land application of manure.
• Lots of dust-related research over the past five or ten years has centered on bioaerosols and their implications for both occupational and public health.  Dairy producers should pay close attention to this body of research; it’s not going away any time soon.

Here is a link to my slide deck:  Auvermann slides 20160407 .

I’m deeply indebted to Dr. Rick Todd of USDA-ARS at Bushland, TX, for providing me with much of the ammonia- and methane-related research on which I based those portions of my remarks.

Here is a link to the Texas Dairy Matters web site, a site hosted by the Texas A&M AgriLife Extension Service’s dairy program.