Title: Greenhouse gas emissions from beef cattle feedlot pen surfaces in Texas during fall Authors
Submitted to: Biological Engineering (ASABE)
Publication Type: Abstract Only
Publication Acceptance Date: June 7, 2013
Publication Date: N/A
Technical Abstract: Accurate estimation of greenhouse gas (GHG) emissions, including nitrous oxide and methane from open beef cattle feedlots is an increasing concern given the current and potential future reporting requirements for GHG emissions. Research measuring emission fluxes of nitrous oxide and methane from open beef cattle feedlots, however, has been very limited. This study was conducted to quantify the nitrous oxide and methane flux rates from pen surfaces at two commercial beef cattle feedlots in Texas during fall. Fluxes from the pen surfaces were measured using 200 mm diameter, non-flow-through non-steady-state (NFT-NSS) chambers on 20 sampling days at 12:00 noon from October to December 2012 in four, five day measurement campaigns. Air samples were collected from the chambers' headspace at 0, 10, 20 and 30 min using syringes, transferred to evacuated vials and analyzed using a gas chromatograph. The nitrous oxide and methane concentrations, emission fluxes were calculated using the Quad method. Nitrous oxide flux rates varied considerably across the pen suface generally being higher on manure mounds and on the edge of manure mounds. Median nitrous oxide emission fluxes for each five day measurement period were 0.01, 0.06, 0.05, and 0.03 mg m-2 h-1, respectively. Methane emission fluxes were generally low under the dry conditions experienced during the study but were considerably higher from moist areas and somewhat higher over manure mounds. Median methane emission fluxes for each five day measurement period were 6.92, 1.06, 3.59, and 0.34 mg m-2 h-1, respectively.This study quantified nitrous oxide and methane flux rates from pen surfaces in a cattle feedlot during fall; further ongoing work is investigating flux rates in other seasons and further factors that influence emission rates.