Ammonia Emissions from Broiler Litter and Laying Hen Manure Management Systems

Poultry farming accounted for an estimated 16% of ammonia emissions from UK agriculture in 1999. This study investigated the potential to reduce ammonia emissions by altering the ways in which poultry manures are managed. Ammonia loss measurements were made from complete broiler litter and laying hen manure management cycles (housing → manure handling → storage → land spreading). Ammonia losses were higher (probability image) from winter-housed broilers on straw (mean 2·0 g [NH3-N] h−1 500 kg−1[liveweight — lw]) than from those on woodshavings (mean 1·0 g [NH3-N] h−1 500 kg−1[lw]), but there were no differences in emissions (image) between different litter types⧸rates during storage and following land spreading. The overall balances of ammonia emissions from broiler litter during housing, storage and following landspreading were 28, 15 and 57%, respectively. In the laying hen housing studies, ammonia losses from weekly belt-scraping (mean 3·3 g [NH3-N] h−1 500 kg−1[lw]) were more than double (image) those from daily belt-scraping (mean 1·3 g [NH3-N] h−1 500 kg−1[lw]), with twice weekly belt-scraping estimated to reduce ammonia losses by ca. 50% compared with weekly cleaning. Ammonia losses from a commercial deep pit house (8·2 g [NH3-N] h−1 500 kg−1[lw]) were higher (image) than from belt-scraped (2·7 g [NH3-N] h−1 500 kg−1[lw]) or stilt (1·4 g [NH3-N] h−1 500 kg−1[lw]) houses, but there were no differences between manures from the three housing types (deep-pit, belt-scraped or stilt houses) during storage or following land spreading. The overall balance of ammonia emissions from laying hen manures during housing, storage and land spreading was 51, <1 and 48%, respectively. These findings indicate that strategies to reduce ammonia emissions from poultry farming would be most effective if focused on housing and land spreading practices where the greatest loss of ammonia occurs.