Loss of nitrogen (N) as ammonia gas (NH3) is known as volatilization. While volatilization directly from soil can occur, such loss is generally relatively small compared to the amount that can be lost from fertilizers. Volatilization losses can be significant with granular urea and urea-ammonium nitrate (UAN) sources, but the amount of loss varies greatly depending on placement of the fertilizer, soil pH, soil texture, and climatic conditions after application.

The most commonly available nitrogen fertilizer sources used in Virginia are urea, liquid urea-ammonium nitrate (UAN) solution, and ammonium sulfate. Ammonium nitrate is also available in some areas but its use is low relative to urea and UAN solution. Understanding the properties of these fertilizers enables managers to make better decisions as to the most effective way to use these fertilizers as well as to make economic comparisons.

Liquid nitrogen fertilizers have typically been surface applied. This method of application places the fertilizer where the urea nitrogen component of the solution is susceptible to volatilization losses.