Methane emissions from southern High Plains dairy wastewater lagoons in the summer
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Methane is a greenhouse gas with a global warming potential 25-fold that of CO 2 , and animal agriculture is recognized as a source of CH 4 to the atmosphere. Dairy farms on the southern High Plains of New Mexico and Texas (USA) are typically open lot, and sources of CH 4 are enteric emissions from cattle and wastewater lagoons. Uncovered anaerobic lagoons are identified by the US Environmental Protection Agency as a source of CH 4 in dairy manure management systems. Our objective was to quantify summer CH 4 emissions from wastewater lagoons of a commercial dairy farm in eastern New Mexico. Research was conducted during 8 days in August (2009) at a 3500 cow open lot dairy farm with flush alleys. Methane concentration over three lagoons (total area of 1.8ha) was measured using open path laser spectroscopy. Background CH 4 concentration was measured using a back-flush gas chromatography system with flame ionization. Wind and turbulence data were measured using a three-axis sonic anemometer. Emissions were estimated using an inverse dispersion model. Methane concentrations in the air over the lagoons ranged from 3 to 12ppm, and averaged 5.6ppm, with a background CH 4 concentration of 1.83ppm. Methane flux density (i.e., emission rate/unit area) ranged from 165 to 1184g/m 2 /s, with a mean daily CH 4 flux density of 402kg/ha/d. Methane emission rate averaged 0.211kg/head/d. Uncovered anaerobic lagoons were a source of CH 4 emitted from this southern High Plains dairy farm, and lagoons could be a control point for emission reductions. This article is part of the special issue entitled: Greenhouse Gases in Animal Agriculture - Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors; K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson. 2011.