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

Ammonia (NH 3 ) emissions from livestock production in China are an important contributor to the global NH 3 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 NH 3 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 NH 3 emission intensities on the basis of animal products, N and protein in animal products. In 2009, NH 3 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 NH 3 emission intensities were 26.6 g NH 3 –N kg −1 of pork, 28.1 g NH 3 –N kg −1 of layer eggs, 39.4 g NH 3 –N kg −1 of beef meat, 6.0 g NH 3 –N kg −1 of dairy milk and 4.6 g NH 3 –N kg −1 of chicken meat, or 1260 (pigs), 1514 (layers), 1297 (beef), 1107 (dairy) and 123 g NH 3 –N (broilers) kg −1 N in animal products. Of the sectors of NH 3 emission, manure storage facilities and farmyard manure (FYM) in animal housing were the major contributors to the total NH 3 emissions except for layers; housing emissions from slurry were also major contributors for dairy and pig production.