Most volatilization from urea typically occurs during a two- to three-week period after application. Volatilization depends on the rate of urea hydrolysis (see Chemical Reactions; Equation 1), and the rate at which the ammonium is then converted to ammonia gas (Equation 2) that volatilizes if near the soil surface.

How long before urea evaporates?

If the soil is totally dry, no reaction happens. But with the enzyme urease, plus any small amount of soil moisture, urea normally hydrolyzes and converts to ammonium and carbon dioxide. This can occur in two to four days and happens more quickly on high pH soils.

Does urea degrade over time?

Enzymatic degradation of urea

Urea is a very stable molecule with a half-life (t_½) of approximately 40 years at 25 °C, and therefore, it is not spontaneously hydrolyzed (degraded) in solution (Callahan et al. 2005; Shaw and Bordeaux 1955).