CORN Newsletter: 2009-06, March 16, 2009

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C.O.R.N Newsletter 2009-06
March 16, 2009 - March 31, 2009

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Potential for Nitrogen Loss on Wheat in Saturated Soils of Northern Ohio
by Edwin Lentz


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Many producers have been asking about the loss potential of topdressed nitrogen on wheat prior to the heavy rains and flooding in northern Ohio. Unfortunately, a large part of it may have been lost. Ohio State University research completed in 2003 revealed that loss of N from a single N application prior to spring green-up may have yield reductions of 19% compared to applications between initial greenup and early stem elongation. In that year, nitrogen was applied in the first part of March about 10 – 14 days ahead of greenup. The risk is greater when the frost is not completely out of the soil. (Frost was still in the soil before this rain event.) This allows the upper surface to stay wetter and large amounts of water movement to occur as surface runoff (carrying fertilizer). The risk would be greater for an application closer to the rain events; thus recent applications may be more at risk than those in early February. It just depends whether or not the fertilizer got worked into the upper soil surface and attached to the soil before a heavy water event (rain, ground thawing, and so forth). Our research showed that when these loss conditions are present, all forms of fertilizer will be lost (we had ammonia sulfate, 28%, and urea in the study). Even though we do not have data on ESN, our expectation is that if it was laying on the surface where the coated fertilizer could move with the water (float), it too would probably experience a loss under these conditions.

Now the difficult part, how can you tell if any had been lost? There is no quantitative way -- only best guess scenarios. If a producer has a high nitrogen check strip they can compare nitrogen treatments (most likely they do not). You can use a chlorophyll meter but interpretation a little tricky since no check strip (to account for varietal greenness) -- I like scores in the 40's with the meter. The best bet is probably a visual comparison between the suspected nitrogen-loss field and fields with later nitrogen applications. If by Feekes 6 it appears to be significantly less green, then consider an additional 50 - 60 pounds of N, for fields that have a potential for 100 bushels. I do not have the research to back this up and I am using my experience from N rate curves, splits and other N management work. The one thing a producer should remember is that they don't have to get in a hurry to apply more nitrogen. They can easily wait until Feekes 6 without sacrificing yield. In addition, it might be a good time to consider an on-farm experiment to address the question. Check with your County Extension AgNR educator about setting up an on-farm experiment.

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C.O.R.N. is a summary of crop observations, related information, and appropriate recommendations for Ohio Crop Producers and Industry. C.O.R.N. is produced by the Ohio State University Extension Agronomy Team, State Specialists at The Ohio State University and Ohio Agricultural Research and Development Center. C.O.R.N. Questions are directed to State Specialists, Extension Associates, and Agents associated with Ohio State University Extension and the Ohio Agricultural Research and Development Center at The Ohio State University.

Information presented above and where trade names are used, they are supplied with the understanding that no discrimination is intended and no endorsement by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.

All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Keith L. Smith, Director, Ohio State University Extension.

TDD # 1 (800) 589-8292 (Ohio only) or (614) 292-1868


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