Ammonia volatilization from ammonium sulfate as sulfur source

Surface application of ammonium sulfate (AMS) as S source to soils with pH ≥7.0 is subjected to ammonia (NH 3 ) volatilization. However, AMS volatilizes less NH 3 than urea does. In soils with pH <7.0, unlike urea, very little NH 3 volatilization from AMS occurs. The associated N with AMS may enhance early biological N fixation by leguminous crops as compared to S sources without N such as polyhalite.