Estimating farm-gate ammonia emissions from major animal production systems in China

Ammonia (NH3) emissions from livestock production in China are an important contributor to the global NH3 budget. In this study, by estimating total nitrogen (N) intake based on herd structures and excreted N, a mass balance model was used to estimate NH3 losses from animal housing and manure storage facilities of dairy cattle, beef cattle, pigs, broiler and layer productions within animal farm gate and their corresponding NH3 emission intensities on the basis of animal products, N and protein in animal products. In 2009, NH3 emissions from pigs, layers, beef and dairy cattle and broiler production systems in China were 1.23, 0.52, 0.24, 0.21 and 0.09 million tons, respectively. The NH3 emission intensities were 26.6 g NH3–N kg−1 of pork, 28.1 g NH3–N kg−1 of layer eggs, 39.4 g NH3–N kg−1 of beef meat, 6.0 g NH3–N kg−1 of dairy milk and 4.6 g NH3–N kg−1 of chicken meat, or 1260 (pigs), 1514 (layers), 1297 (beef), 1107 (dairy) and 123 g NH3–N (broilers) kg−1 N in animal products. Of the sectors of NH3 emission, manure storage facilities and farmyard manure (FYM) in animal housing were the major contributors to the total NH3 emissions except for layers; housing emissions from slurry were also major contributors for dairy and pig production.