Methane emissions from a dairy feedlot during the fall and winter seasons in Northern China

Accurately determining methane emission factors of dairy herd in China is imperative because of China’s large population of dairy cattle. An inverse dispersion technique in conjunction with open-path lasers was used to quantify methane emissions from a dairy feedlot during the fall and winter seasons in 2009–2010. The methane emissions had a significant diurnal pattern during both periods with three emission peaks corresponding to the feeding schedule. A 10% greater emission rate in the fall season was obtained most likely by the higher methane emission from manure during that period. An annual methane emission rate of 109 ± 6.7 kg CH4 yr−1 characterized with a methane emission intensity of 32.3 ± 1.59 L CH4 L−1 of milk and a methane conversion factor (Ym) of 7.3 ± 0.38% for mature cattle was obtained, indicating the high methane emission intensity and low milk productivity in Northern China.

► CH4 emission from the feedlot in China was associated with clear diurnal pattern. ► Methane conversion factor for mature cows in this feedlot was about 7.3%. ► This feedlot was characterized with relatively high methane emission intensity.