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

Abstract

A new protocol similar to EPA method TO-14A was established to quantify and report variations in greenhouse gas (GHG) emissions from different ground level area sources (GLAS) in a free-stall dairy in central Texas. The objective of the study was to estimate and compare methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) emission factors (EFs) from different GLAS using this new protocol during summer. A week-long sampling was performed during summer and seventy five chromatograms of air samples were acquired from six delineated GLAS (loafing pen, walkway, barn, silage pile, settling basin and lagoon) of the same dairy. Three primary GHGs were identified from the dairy operation during sampling period and the gas chromatograph (GC) was calibrated for CH4, CO2, and N2O. The GHGs concentrations measured at different GLAS during summer were ranged from 4.043.4 to 24931298, 383131 to 31073878, and 0.060.03 to 1.62.0 ppmv for CH4, CO2, and N2O, respectively. These variations in measured gas concentrations within each GLAS were widely varied due to spatially variable manure loading rates at different GLAS in a dairy operation. Average CH4, CO2 and N2O EFs estimated from different GLAS were ranged from 0.10 to 60.5, 21 to 1767, and 0.002 to 2.73 kg hd-1 yr-1, respectively, during summer. Estimated overall EFs for CH4, CO2 and N2O during summer for this dairy were, 10056, 21921510, 2.93.5 kg hd-1 yr-1, respectively.