Fig. 4. Ammonia emission rates (g heifer^–1 d^–1). Present study compared with published studies. Footnoted references: (1) Compiled from literature review of Monteny and Erisman (1998), dairy cow type not provided. (2) Measured from cement barn floor and reported for 450 kg dairy cow by Amon et al. (2001). (3) Manure (including straw) and reported for 500 kg dairy cow by Demmers et al., 1998. (4) Compiled from literature review by Anderson et al.(2003) and reported as kg cow^–1 yr^–1. (5) Simulations by Rotz and Oenema, 2006 and revised by Rotz (personnal communication, 22 Jan. 2007). (6) Hourly emissions reported by Pedersen (2006) scaled to daily emissions. (7) Simulations by Pinder et al. (2004). (8) Monthly emissions reported Hutchings et al. (2001) scaled to daily emissions.