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In ISU research, ESN and urea were hand-applied in late fall at rates of 0, 40, 80, 120, 150 and 180 lbs. N/acre. Urea-only treatments were applied in late April for comparison. The previous crop was soybean both years.
“The crops were planted in May both years and were machine-harvested in October,” says Killorn. “Yields were weighed in the field and adjusted to a moisture content of 15.5%.”
The ESN treatments yielded 177 bu./acre, compared to 166 bu. for straight urea applied in the fall. Killorn says the spring urea treatments yielded 172 bu. “The difference in yield between fall ESN and spring urea treatments wasn’t statistically significant, but the difference between these two treatments and the fall urea treatments was significant,” he says.
Steve Ebelhar, University of Illinois (U of I) agronomist, says growers can expect to pay an additional 10¢/lb. of N for the ESN-coated urea. He says Agrotain would likely add 4-5¢/lb. of N.
He says growers should consider the different N technologies in some cases. “If you’re growing no-till corn, Agrotain seems to help a lot with surface-applied urea and UAN,” he says. “Our studies show it certainly reduces the amount of N lost. ESN also gives good protection. It can prevent N losses due to denitrification, leaching and volatilization.”
U of I research looked at numerous N and slow-release/stabilizer combinations. In no-till corn, the new technologies showed strong results in 2008 studies statewide, says Ebelhar, who works mainly in southern Illinois.
For example, in 10 different N-source applications on no-till corn in 2008, an ESN broadcast application produced a 197-bu. yield, compared to 193 bu. for a UAN side-injected application, a 179-bu. yield from a UAN+AgrotainDF application and 175 bu. for a UAN+AgrotainPlus application, all significantly better than UAN surface-dribble applied that resulted in corn yield of 160 bu.
From 2006 to 2009, ESN broadcast on no-till led to a 142-bu. yield average. That compared to 140 bu. for UAN sidedressed, 132 bu. for urea+Agrotain and 130 bu. for corn broadcast with SuperU. All of these were significantly better than urea alone at 121 bu. (For a more detailed list of the of the U of I research results, go to http://frec.cropsci.illinois.edu/2009/report2/.)
“It appears that many of the N sources in this study may provide significant improvements in N-use efficiency,” says Ebelhar. “These differences appear to be more important with no-till than conventional-till systems.”
Several locations had higher-than-normal rainfall prior to N application, which caused problems with planting at optimal timing, he says. “At both locations, heavy urea losses occurred from the surface applications,” says Ebelhar. “Products containing Agrotain tended to significantly reduce these N losses, presumably from volatilization.
“Sidedressed injection of UAN or application of ESN also significantly reduced N losses and increased yields. UAN sources had less loss of N than urea.”
Lyle Paul, U of I agronomist for northern regions, worked with Ebelhar on the N technologies research. “We’ve seen that Agrotain works well if N is applied during dry weather,” he says. “If you get a half inch of rain, that will usually incorporate N into the soil.”
Paul says that in DeKalb, IL, three-year N studies, ESN applied in the late fall yielded 217 bu. of corn, while spring-applied ESN yielded 230 bu. Straight urea yielded 221 bu. from the fall application and 229 bu. from a spring application. Corn receiving ammonium sulfate and ammonium sulfate and urea combination had similar corn yields. SuperU had 233-bu. yields from spring application and 223 from N applied in the fall.
Kentucky studies have shown 15-20-bu. increases in yields from Agrotain technology, he says.
There are several other N stabilizers on the market, including N Serve from Dow. Discuss the value of N stabilizers with your local Extension agronomist or crop consultant for the best advice under your circumstances.