Understanding Nitrogen Loss: Volatilization

In addition to leaching and denitrification, volatilization is one of the three main nitrogen loss mechanisms. Volatilization is the loss of applied nitrogen to the atmosphere as ammonia gas. To understand how to reduce this form of nitrogen loss, it’s important first to understand how and why it occurs.

Volatilization causes and effects

The greatest losses occur from surface application of fertilizer containing urea, including UAN solution, manure, and blended dry fertilizers, particularly on high pH and/or high temperature soils during hot, windy weather or on dense crop residue. Most of the nitrogen volatilization typically occurs in the first seven to fourteen days after a top-dress fertilizer application, if moisture is present to start the conversion of urea to ammonia, but losses may extend for a longer time depending on conditions.

As soil pH increases from 6.5 to 7.5, volatilization losses double from 10 to 20 percent for urea left on the surface for four days. Since there are so many influencing factors, predicting volatilization and the extent of its impact can be difficult.

Getting ahead of mother nature

While most growers are trying to get their fertilizer out before it rains, those who use ESN have more application flexibility. The beauty of ESN is that it can be applied early, when there is no rain in sight. The granules are in the field, waiting for the rain and premium conditions to begin a slow release of nitrogen. The protective coating means that even in excessive precipitation, the nitrogen won’t run off into the ditches.

ESN also protects against volatilization more effectively than urease inhibitors and for a longer time. Because ESN protects nitrogen for an extended time, there’s no need to try to plan around the weather, whether too dry or too wet. Urea released from ESN is less susceptible to volatilization because only a small amount is released at a time, which maintains a lower urea concentration and prevents the temporary rise in pH around the fertilizer granule that is responsible for causing ammonia volatilization. And growers get the added benefit of protection against other nitrogen losses, like leaching and denitrification, not provided by urease inhibitors.

Are you interested in learning more about ESN? Get in touch with your local rep to find out if ESN is right for your farm.