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.
By Kurt Lawton
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While nitrogen prices have declined dramatically on the wholesale market, they have been slower to drop at the retail level. And with fertilizer prices so volatile you can count on a host of products flooding the market, promising to enhance nitrogen efficiency and/or boost yields. Some of the product claims are legit, but others are more questionable. Your dilemma is in deciding which ones to believe. That's where the NCR-103 committee comes in. Composed |
| Poly-coated granular fertilizer is one of many products promising to enhance nitrogen efficiency and boost yields. | of university agronomists, the group has attempted to quantify non-conventional/non-traditional products, soil amendments, growth regulators and soil fertility programs since the early 1980s. |
Measuring the merits. "We like to call ourselves the ‘magic dust' committee, because most of the time we try to determine if any of the hundreds of non-mainstream products have merit," says Peter Scharf, University of Missouri Extension agronomist. "We share data so we all don't have to test everything, because we can't.
"The good news for growers," he continues, "is that we have both a product listing of over 400 products and a searchable web site that lists actual research completed on these non-mainstream products (extension.agron.iastate.edu/compendium/index.aspx). "Now people have access to a research database of any product that meets certain minimum criteria, mainly two or more site years of research," he says.
While Scharf says most of these non-mainstream compounds provide little if any benefit, "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," Scharf says.
Top products. A variety of mainstream commercial stabilizers exist that can slow or minimize the biological process that changes nitrogen into a form that can be lost. We asked several committee members to offer their insight on the best mainstream products that can help growers achieve greater nitrogen efficiency. Urease inhibitors. The most common urease inhibitor is NBPT (N-(N-butyl) thiophosphoric triamide), a liquid that is applied to dry urea or mixed with UAN solution. It is sold under the trade name Agrotain. "This product is very solid, as it has given very consistent results with surface-applied urea, regardless of when it was used," Scharf says. "We've seen an average corn yield increase of 7 bushels per acre, and it is very consistent, unless you get a rain right away," he says. |
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University of Illinois agronomist and committee member Fabian Fernandez likes how Agrotain reduces the volatilization of urea or UAN. "It's a good product and does what it is supposed to do. The best chance for yield enhancement occurs when you are applying urea or UAN on the soil surface, especially when there is a lot of residue present. But if you have rainfall or the product is incorporated, you won't see much difference," he says.
Giles Randall, University of Minnesota agronomist, has learned the value of Agrotain over the years. "Where we have to apply a surface treatment in minimum tillage or where it is not incorporated, we customarily use Agrotain-treated urea. It minimizes volatilization of surface-applied nitrogen," he says.
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," Randall 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, Fernandez 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."
Nitrification Inhibitors. Another good product that helps protect fall-applied anhydrous ammonia, N-Serve, has been around for more than three decades. Randall has tested N-Serve over the past 15 years. "When we used N-Serve, corn yields increased 9 and 12 bushels per acre per year—and nitrate losses decreased by 14 and 15% by either fall nitrogen plus N-Serve or spring preplant nitrogen," he says.
Regarding the new microencapsulated UAN stabilizer product called Instinct, Randall has only one year of data on one location, so he would not comment on its efficacy yet. "It apparently showed good results in Iowa under their wet 2008 conditions." Scharf also has limited data from testing in Missouri, and so far has seen slight improvement in keeping more nitrogen in the ammonia form.
For more information on non-mainstream products, visit the web site and search by product name to view all university research. Only products with at least two years of testing are listed.
Source: http://progressivefarmer.com/tabid/1673/Default.aspx
