Since 1980, a group of university agronomists have conducted tests to separate fact from fiction on the effectiveness of products to boost nitrogen efficiency in corn, and in 2011, findings of the group from previous years were revised and re-released.
In an announcement from the University of Missouri, Nutrient Management Division of Plant Sciences in the College of Agriculture, Food and Natural Resources, Peter Scharf, Extension agronomist, said that the group started by looking at non-mainstream products but "we are starting to include more research on some of the mainstream products that have been proven to provide benefits. Many of us work on fertilizer enhancers, extenders, nitrogen transformation inhibitors and slow release products as well, and we're looking to expand our scope to officially include these products.
One of the products in university trials was ESN from Agrium. The following findings are what the group of university agronomists compiled. As with any group of agronomists, one believes one thing and another one believes something else and sometimes questions arise that can best be answered by company representatives in showing if a product was used according to the specific recommendations or if the agronomist was trying to push the envelope on use practices. The following is what was issued in the University of Missouri look at ESN:
Controlled-Release Urea. The most common trade name is Agrium's ESN (Environmentally Smart Nitrogen). It is a poly-coated granular fertilizer that undergoes a chemical or microbial (moisture and temperature) decomposition to make nitrogen available.
"We have worked with ESN for five years, comparing it to regular urea," Giles Randall, University of Minnesota, says. "In Minnesota, ESN has performed better than urea when applied in the fall, but our spring applications show similar results to urea. Consequently, we're comfortable with the fall application being an acceptable practice in south-central Minnesota."
In Missouri, Scharf says they have seen more benefit when ESN is applied in early spring on corn, as compared to at-planting applications. "We also had research on a 30-acre field that showed very profitable use of ESN when applied to low-lying (higher moisture) portions of fields up to a 25-bushel yield bump. So we're thinking of exploring variable source application where we use multi-bin machines to hold both urea and ESN, and create a map to apply different products where needed."
In Illinois, Fabian Fernandez, University of Illinois, likes the ESN technology because it protects urea from both volatilization and nitrification. "Granted, the efficacy of these products is dependent on soil temperature and water for activation. When applied in a wetter-than-normal spring, ESN protects nitrogen from loss compared to urea. With adequate growing-season conditions, ESN releases nitrogen when the crop needs it. In dry years it can take too long for nitrogen to release, creating potential nitrogen deficiencies."