Title: Methane emissions from a New Mexico dairy lagoon system Authors
Submitted to: International Symposium on Air Quality and Waste Management for Agriculture
Publication Type: Proceedings
Publication Acceptance Date: September 11, 2010
Publication Date: September 13, 2010
Citation: Todd, R.W., Cole, N.A., Casey, K.D., Hagevoort, R., Auvermann, B.W. 2010. Methane emissions from a New Mexico dairy lagoon system. In: Proceeding of the 2010 International Symposium on Air Quality and Waste Management for Agriculture, September 13-16, 2010, Dallas, Texas. ASABE Publication No. 711P0510cd. doi: http://asae.frymulti.com/azdez.asp?search=1&JID=1&AID=32618&CID=isaq2010&v=&i=&T=1 Interpretive Summary: Methane is a greenhouse gas that adds to the warming of the planet. Animal agriculture can be an important source of atmospheric methane. We need to improve our knowledge of how animal production systems add to methane emissions in order to reduce greenhouse gases. We studied a commercial dairy in eastern New Mexico, a part of the Southern High Plains that has a well-established dairy industry, and which is also located next to the growing dairy industry in west Texas. This typical dairy flushes cow manure into wastewater lagoons where conditions to produce methane exist. We measured methane concentration at the lagoons along with the speed, direction, and turbulence of wind. Then, we used a computer program that describes how gases move in the atmosphere to calculate methane lost from the lagoons. Background methane concentration was 1.8 parts of methane per million parts of air (ppm). Methane concentration increased over the lagoons, and ranged from 3 to 12 ppm, showing that the lagoons lost methane. We calculated that from 165 to 1184 micrograms per square meter per second were lost. Daily methane loss averaged 402 kilograms per hectare per day. This represented 0.21 kilograms of methane emitted for each cow in the dairy every day. Uncovered low-oxygen lagoons like these can be a significant source of methane at dairies. They offer an opportunity to reduce lost methane.
Technical Abstract: Methane is a greenhouse gas with a global warming potential 25 times that of carbon dioxide. Animal agriculture is recognized as a significant source of methane to the atmosphere. Dairies on the Southern High Plains of New Mexico and Texas are typically open lot, and major sources of methane are the dry enteric emissions from cattle and wastewater lagoons. Uncovered anaerobic lagoons are identified by the U.S. Environmental Protection Agency as a major source of methane in dairy manure management systems. Our objective was to quantify methane emissions from the wastewater lagoons of a commercial dairy located in eastern New Mexico. Research was conducted during seven days in August 2009 at a 3500-cow open lot dairy with flush alleys. Methane concentration over three interconnected lagoons (total area 1.8 ha) was measured using open path laser spectroscopy. Background methane concentration was measured using a back-flush gas chromatography system with flame ionization located upwind in the direction of prevailing winds. Wind and turbulence data were measured using a three-axis sonic anemometer. Emissions were estimated using an inverse dispersion model. Methane concentration over the lagoons ranged from 3 to 12 ppm, and averaged 5.6 ppm; background methane concentration averaged 1.83 ppm. Methane flux density ranged from 165 to 1184 ugm**-2s**-1. Mean daily methane flux density was 402 kg ha**-1 d**-1. Per capita methane emission rate averaged 0.211 kg head**-1 d**-1. Uncovered anaerobic lagoons were a significant source of methane emitted from this Southern High Plains dairy, and lagoons could be a significant control point for emission reduction.