Understanding nitrogen loss: Volatilization

Nitrogen loss through 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.

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.

“Sometimes it’s too wet and sometimes it’s too dry,” says ESN Marketing Rep Kelly Dupont. “From a grower’s standpoint, they have to try to time those applications.”

While most farmers are chasing the rain, trying to get their fertilizer out before it rains, growers who use ESN have more application flexibility.

“Where ESN fits in, is we have a product that you can put out when there’s no rain in sight,” Dupont says. “With ESN, you could have done it last week, or two weeks ago, and you will know that it’s out there. If the weather is dry, you don’t have to worry about the volatilization and losing it, and if you get a whole bunch of rain, ESN has that protective coating on it, and it’s not going to run off into the ditch.”

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 you get the added benefit of protection against other nitrogen losses, like leaching and denitrification, not provided by urease inhibitors.

To learn how ESN reduces nitrogen loss, click here.

To learn about the controlled release difference, click here.

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