Do the math. With fertilizer prices still at near record highs, farmers may look at management approaches and new products that promise to increase efficiency, especially for nitrogen. But are specialty products the answer or merely costly alternatives that do little to meet plant nutrient needs? It may depend on soil needs, crop type and tillage practices, as well as moisture and other climate conditions beyond farmers’ control.

At the very least, producers should look at research into products and practices that promote improved nutrient efficiency, says a Texas Extension specialist.

Mark McFarland, Regents Fellow, professor and a Texas A&M AgriLife Extension Service soil fertility specialist, says farmers are concerned about making the most of their increasingly expensive nitrogen investment, but he cautions them to analyze costs and benefits before buying products promoted to improve nitrogen efficiency.

He points farmers to a recent study conducted throughout the South and reported byCharles Mitchell, Extension agronomist, Auburn University; and Deanna Osmond, Extension leader and professor in soil science at North Carolina State University.

That study looked at several nitrogen products applied to various crops in Alabama, Arkansas, Florida, New Mexico, Oklahoma and Texas. The study is available in the Southern Regional Cooperative Series Bulletin (http://aurora.auburn.edu/repo/bitstream/handle/123456789/44121/scsb-416.pdf?sequence=2) .  It is the first article under “News” at: http://srwqis.tamu.edu/

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The researchers said, “Minimizing nitrogen fertilizer rates while maintaining crop yields is essential both for improving agricultural profitability and reducing environmental consequences of farming, such as leaching and runoff from agricultural crop fields, which can be major sources of nitrogen to streams, rivers, and estuaries in the Southeast.”

They added that recent significant increases in nitrogen prices have sharply increased crop production costs, motivating farmers to look for alternative nitrogen sources.

“For most farmers, the only potential nitrogen alternatives (to inorganic fertilizers) include planting legumes as winter cover crops (which can deplete soil moisture needed for the primary crop) or applying animal manures (which are not available in all production areas). Another option is applying slow release nitrogen fertilizers, which have the potential to improve nitrogen use efficiency in corn and other field crops and, thereby, enhance both production economics and environmental protection.”

Traditional nitrogen sources come with challenges, the report says. “Ammonium nitrate (34-0-0) formerly was the standard but has become difficult to find and transport. Solid urea-ammonium sulfate blend (33-0-0) is very acid-forming and subject to volatilization. Solid urea (46-0-0) has a high risk of volatilization losses during hot, dry summer months when surface applications are not incorporated. This is especially true when urea is applied on crop residue in a high pH soil.

“Reduced tillage and high-residue management in row crops often require surface application of some materials. Liquid urea-ammonium nitrate solutions (UAN) are currently the most popular nitrogen source for row crops.”

Other alternatives include nitrification inhibitors (e.g., Nitrapyrin), available for many years but used mainly in the Midwest where fall-applied anhydrous ammonia is popular.

“Recently, urease inhibitors (e.g., Agrotain) have been marketed to help manage urea-based nitrogen fertilizers. Many new polymer coated products are on the market to control the release of nitrogen from both liquid and dry urea-based materials.”