October 3, 2007 | By: Laura Skillman

One of the biggest challenges wheat farmers face is the timely application of nitrogen fertilizer to wet soils. Recent advances in slow release nitrogen fertilizer may be the answer, based on recent studies by University of Kentucky College of Agriculture scientists.

In 2002, Greg Schwab and Lloyd Murdock, soil scientists and members of the UK Wheat Science Group, began working with the then-experimental polymer-coated nitrogen product and have conducted subsequent studies. The new fertilizer was designed to reduce nitrogen loss from soil in corn production, but the two UK extension specialists thought it also held promise in the state’s wheat fields. 

“Timely nitrogen fertilizer applications on wheat are often difficult because of wet soil conditions in the early spring,” Schwab said. “By protecting the urea inside a high-tech plastic shell, it became possible to apply nitrogen to wheat in January without any significant reduction in yield or increased nitrogen loss compared to the common practice of applying two applications in the spring.” 

The experimental product, manufactured by Agrium Inc., is now commercially available in the state on a limited basis as ESN (Smart Nitrogen). The plastic polymer controls the release of nitrogen, making it available as the crop needs it and reducing nitrogen loss to the environment through leaching, volatilization and denitrification`. Schwab said Kentucky producers quickly are adopting ESN, especially for wheat on wetter soils. 

ESN usually costs about 10 cents more per pound of nitrogen. So, if a producer applies 100 pounds per acre, it would cost about $10 more per acre. Depending on how the farmer normally fertilizes, there could be one less trip through the field, resulting in savings of about $6 to $7 per acre. In addition, the producer can generally cover more acres per day with a dry product like ESN. 

“Wheat producers like ESN because it increases the nitrogen fertilizer application window making it easier to avoid soil wetness while reducing the number of trips through the field,” he said. “Because ESN limits environmental nitrogen loss and decreases the amount of fuel required to produce wheat, it is beneficial to everyone.”


Greg Schwab, 859-257-9780