Yan et al. (2003b) focused their literature analysis on ureainduced
NH3 emissions because urea is the most common chemical
fertiliser used by farmers in South and South East Asia (urea and
ammonium-based fertilisers form approximately 85% of all nitrogen
fertilisers applied to paddy fields in Northeastern Thailand).
They proposed a model of urea-induced NH3 emissions that depends
upon the timing and mode of application, which, in turn,
have a strong influence on the volatilisation rate. In spite of a
paucity of data, the same authors also proposed NH3 emission
factors for other nitrogen-based fertilisers. These models were
used, with adjustment to a 120-day cropping season.