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Emission of greenhouse gases, including nitrous oxide (N2O), from open beef cattle feedlots is becoming a concern. Research measuring emission rates of N2O from open beef cattle feedlots, however, has been limited. This study was conducted to quantify the N2O emission rate from pen surfaces in a commercial beef cattle feedlot in Kansas. Static flux chambers with a diameter of 30 cm were used to measure the flux from the pen surface as affected by pen surface conditions (i.e., moist/muddy, dry and loose, dry and compacted, and flooded) on 10 sampling days from July to November 2010. Air samples were collected from the chambers headspace at 0, 15, and 30 min using syringes and analyzed with a gas chromatograph. From the N2O concentrations, N2O emission fluxes were calculated. For each pen surface condition, N2O emission flux varied considerably with sampling day. Emission flux also varied with pen surface condition, with the moist/muddy surface having the largest median emission flux (7.18 mg m-2 h-1), followed by the dry and compacted, dry and loose, and flooded surfaces with median emission fluxes of 0.18, 0.17, and 0.09 mg m-2 h-1, respectively. This study quantified N2O emission rates from pen surfaces in a cattle feedlot; further work is investigating factors that influence emission rates.