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

Abstract

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.