Talking about nitrogen

Hello everyone! It’s finally warm, and it seems more like summer this week. Crops are growing, and now everyone is trying to get caught up. The delayed planting season has raised questions for Illinois farmers, such as, “How does this affect future grain prices?”, “Do I need more nitrogen?”, “Should I have planted more beans?” and so on.

Nitrogen is always a hot topic at the University of Illinois Extension, and this year is no exception. Many Illinois farmers are wondering if the wet weather has affected nitrogen loss at a significant rate and if re-application is necessary. Fabian Fernandez, University of Illinois assistant professor of soil fertility, has been fielding lots of questions regarding nitrogen and wet weather this month.

According to Fernandez, the key factors in determining whether additional nitrogen is needed are the soil type, source of nitrogen used, time of application, and amount of precipitation since fertilization. “In silt loam or fine textured fields with poor drainage, if you had excessive rain (and water sat on the field long enough to kill the crop) about two weeks after applying a urea and ammonium nitrate solution (UAN) or four or more weeks after applying anhydrous ammonia, you might consider applying 50 to 100 pounds of nitrogen per acre for the new corn crop. This situation occurs most often in low areas of a field,” he said.

Fernandez says that in sandy or light-textured soils that have had seven or eight inches of rain two weeks after applying UAN or four weeks after applying anhydrous ammonia, it is likely that a substantial part of that nitrogen was leached out of the root zone. In this situation you might also consider applying between 50 and 100 pounds of nitrogen per acre. In silt-loam or fine-textured soils with poor drainage where a large rain event caused ponding for one to three days and UAN was applied at least two weeks before or anhydrous ammonia at least four weeks before the time of waterlogged conditions, then consider applying 30 to 50 pounds of nitrogen per acre.

According to Fernandez, if a farmer side-dressed UAN or urea and had heavy rains the next day, nitrogen loss may be excessive only on sandy soils. A farmer’s experience with the particular field is important, but the best measure of whether enough nitrogen is available is the response of the crop. “One simple way to test whether the crop has sufficient nitrogen is to establish a reference strip. If you are planning to apply additional nitrogen, an easy way to do this is to apply at a higher rate in one strip in each field. If you can see the differences between the strip and the rest of the field, it likely indicates that more nitrogen is needed,” he said.

I would like to bring attention to the excellent website farmdoc.uiuc.edu . I know that many of you are familiar with this site, but if you haven’t taken a look, this would be a great time. This extremely useful Web site provides comprehensive and integrated risk management information and analysis. Subject matter sections include finance, marketing and outlook, management, law and taxation, crop insurance, FAST tools, prices and weather, and policy. This Web site has been a valuable tool for many Illinois producers and agricultural professionals and is constantly updated to provide current and relevant economic farm information.

The Bureau County 4-H fair dates are July 23-25 so please plan on attending. The extension office is geared up for the 2009 4-H fair, and we are looking forward to the many excellent projects that the Bureau County 4-Hers enter, display, and show every year.

Sherry Hockings, University of Illinois Extension