Laboratory measurements of ammonia volatilization from five nitrogen-containing fertilizers after surface application at different rates on a neutral to alkaline soil

Volatilization losses of NH3 from five fertilizers, namely (NH4)2SO4, LAN, urea, MAP and DAP were determined. The fertilizers were applied to a Bainsvlei soil of which the pH was adjusted to 6,5; 7,6; 8,3 and 9,1. The application levels were equivalent to 0, 15, 30, 60, 120 and 240 kg N ha−1. After a contact period of three days NH3 losses were determined. Ammonia was lost from all fertilizers under all treatments. The losses increased with increasing pH values and levels of application. These five nitrogen-containing fertilizers differ significantly from each other with regard to volatilization of NH3. They can be ranked in order of increasing NH3 losses as follows: LAN < MAP < (NH4)2SO4 < DAP < urea. These differences can be explained by the composition and properties of the fertilizers.