|Todd, Richard - Rick|
|HAGEVOORT, ROBERT - New Mexico State University|
|CASEY, KENNETH - Texas A&M Agrilife|
|AUVERMANN, BRENT - Texas A&M Agrilife|
Submitted to: Atmospheric Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/26/2015
Publication Date: 3/4/2015
Citation: Todd, R.W., Cole, N.A., Hagevoort, R., Casey, K.D., Auvermann, B.W. 2015. Ammonia losses and nitrogen partitioning at the southern High Plains open lot dairy. Atmospheric Environment. 110:75-83 http://dx.doi.org/10.1016/j.atmosenv.2015.02.069.
Interpretive Summary: Ammonia (NH3) is a gas in the atmosphere that can contribute to reduced air quality and negatively impact sensitive ecosystems. One source of NH3 is from manure at dairies that concentrate cows in small areas. Dairy farmers need to know how much NH3 is lost from their dairies in order to meet EPA regulations. There are many different types of dairy. Dairies on the southern High Plains typically house thousands of cows in outdoor corrals called an open lot. Cow manure collects on the open lot. Constructed lagoons also collect some of the manure. We measured the NH3 that was lost to the atmosphere from both the open lot and lagoons at a typical dairy in eastern New Mexico. We found that 92% of the NH3 was lost from the open lot. On average, each cow in the dairy was responsible for 332 grams of NH3 lost every day. Each cow at the dairy, on average, consumed 612 grams of nitrogen (N) in their daily diet, and 44% of that N was lost as NH3. Most of the NH3 came from the N in cow urine that was excreted on the surface of the open lot. Conditions were very good for NH3 loss during our study; warm summer days, large adult cows, and most manure left on the open lot. Dairies that handle manure more intensively typically have lower NH3 loss than what we found. This highlights how important it is to handle manure effectively at dairies so that NH3 loss is minimized.
Technical Abstract: Animal agriculture is a significant source of ammonia (NH3). Cattle excrete most ingested nitrogen (N); most urinary N is converted to NH3, volatilized and lost to the atmosphere. Open lot dairies on the southern High Plains are a growing industry and face environmental challenges as well as reporting requirements for NH3 emissions. We quantified NH3 emissions from the open lot and wastewater lagoons of a commercial New Mexico dairy during a ten-day summer campaign. The 3500-cow dairy consisted of open lot, manure-surfaced corrals (22.5 ha). Lactating cows comprised 80% of the herd. A flush system using recycled water intermittently removed manure from feed alleys to three lagoons (1.8 ha). Open path lasers measured atmospheric NH3 concentration, sonic anemometers characterized turbulence, and inverse dispersion analysis was used to quantify emissions. Ammonia fluxes (15-min) averaged 56 and 55 µg m-2 s-1 at the open and lagoons, respectively. Ammonia emission rate averaged 1072 kg d-1 at the open lot and 89 kg d-1 at the lagoons; 92% of NH3 was emitted from the open lot. Per capita emission rate of NH3 was 306 g cow-1 d-1 from the open lot (41% of N intake) and 26 g cow-1 d-1 from lagoons (3% of N intake). Daily N input at the dairy was 2139 kg d-1, with 44, 36, 17 and 2% of the N partitioned to NH3 emission, manure/lagoons, milk and cows, respectively. Type of housing and manure management critically affects the source and magnitude of NH3 loss from dairies.