Corn just isn’t corn without a good shot of nitrogen, primarily in the form of anhydrous ammonia. But high costs of nitrogen that mandate the need for efficient use, as well as the prospect for stronger environmental regulations, may give a jumpstart to looking at alternative forms of nitrogen application on corn, sorghum, and wheat.

Earlier this year you may have been forced to buy or commit to anhydrous ammonia for the 2009 corn crop. As the dollar fell in value, the price of nitrogen climbed. Now, with the dollar increasing in strength, the price of nitrogen is falling. Regardless of where you may have locked in a price, you probably are going to apply it with the greatest efficiency possible. It is sort of like spreading gold dust across your fields.

Agronomists and fertility specialists at the University of Missouri and University of Wisconsin have been testing increased efficiency fertilizers, to determine productivity, profitability, crop quality and environmental impacts across the Cornbelt. Their focus was on the management of the new technology offered by polymer-coated urea (PCU). The polymer coating will degrade at varying rates once spread on the ground and exposed to the elements. The supply or release of fertilizer coordinated with plant demand should optimize fertilizer-use efficiency. (Details)

The researchers found average yields from research in Iowa, Kansas, Nebraska, Minnesota, Missouri, and Wisconsin for anhydrous ammonia and urea plus a nitrification inhibitor was similar to the PCU controlled release fertilizer. Corn yields ranged from -12 to +22 bushels per acre comparing anhydrous ammonia with PCU. Other tests ranged from -16 to +9 bushels per acre comparing urea plus an inhibitor with the PCU. The researchers reported, “Variability in response to enhanced-efficiency fertilizer sources has been related to rainfall timing following fertilizer application, rainfall amounts, rainfall frequency, fertilizer incorporation, and soil texture.” Corn yields increased 13 bushels per acre if the PCU was incorporated.

Urea management on no-till fields can be difficult due to the volatilization loss. However, when the urea was coated with the polymer and knife injected, yields were comparable, even with heavy rains that would have limited the volatilization loss.

Included in some of the other findings about polymer coated urea (PCU):
1) Fall applications of PCU and anhydrous yielded 17 and 20 bu/acre greater than urea, respectively; while fall applied PCU yielded 11 bu/acre greater than urea in northern Iowa.
2) No difference among N sources was detected when urea, PCU, and anhydrous were applied pre-plant.
3) Deep placement of fall applied PCU increased yield 16 bu/acre more than deep banded urea, 28 bu/acre greater than broadcast applied PCU, and 8 bu/acre greater than ammonia plus N-serve in 2005.

At the bottom line is the fact a polymer coated urea will be more costly than conventional fertilizers, however some Conservation Security Programs within NRCS may provide some funding to offset costs. EQIP and CSP programs could provide $7-10 per acre for using an efficiency product such as PCU. Retailers may have only limited supplies due to costs and storage issues, however, the methamphetamine problems with anhydrous ammonia may restrict its handling. Polymer coated fertilizers have a consistent analysis and a decreased need and time for sidedressing efforts.

Summary:
Increased costs of nitrogen as well as need for better management of nutrients may increase the potential for using polymer coated urea as an alternative. Consistent in quality and more benign on the soil surface because of its coating, PCU has been shown to produce equivalent yields in corn that had been treated with anhydrous ammonia. PCU is going to be more expensive because of the added manufacturing, however its application efficiency and potential to draw NRCS cost-share funds, may result in greater acceptance.