Direct Measurements of Greenhouse Gas Emissions from Ground Level Area Sources in a Dairy Operation

Abstract

A new protocol similar to EPA method TO-14A was used to quantify and report variations in greenhouse (GHG) emissions from different ground level area sources (GLAS) in a free-stall dairy in central Texas during summer and winter. A week-long sampling was performed during each season. Seventy five and 66 chromatograms of air samples were acquired from six delineated GLAS (loafing pen, walkway, barn, silage pile, settling basin and lagoon) of the same dairy during summer and winter, respectively. Three primary GHGs were identified from the dairy operation during sampling period and the gas chromatograph (GC) was calibrated for methane (CH4), carbon dioxide (CO2), and nitrous oxide N2O. Estimated overall emission factors (EFs) for CH4, CO2 and N2O during summer for this dairy were, 100, 2192, 2.9 kg hd-1 yr-1, respectively. In winter, estimated overall EFs for CH4, CO2 and N2O for this dairy were, 19, 2726, 1.3 kg hd-1 yr-1, respectively. Overall CH4 and N2O EFs in summer were about 5.2 and 2.2 times higher than those in winter for this free-stall dairy. This seasonal variation was due to ambient temperature, dairy waste loading rates, and manure microbial activity of GLAS.