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Serving: IA

Got Nitrogen? Many Farmers Asking That Question

They applied it last fall or earlier this spring, but now wonder how much has been lost due to wet weather.

You may have put nitrogen fertilizer down last fall or early this spring before the rains came. How can you be certain it's still there?

"Weather patterns this spring are very similar to those in 2004, which was one of the wettest springs we'd seen in 20 years," says Tracy Blackmer, director of research for the Iowa Soybean Association. "That year, our On-Farm Network studies showed that in some areas, as many as three out of four fields had reduced corn yields due to nitrogen deficiency, according to the end-of-season corn stalk nitrate testing."

Caught early enough, nitrogen deficiency can be corrected by sidedressing. You can wait until you see yellow corn plants in the field and then apply some extra nitrogen as a sidedress application. But how much should you apply?

Use the late spring soil nitrate test

"The most reliable way we've found to check for available nitrogen is to do a pre-sidedress soil nitrate test," says Blackmer. "You can test your soil and get a pretty good idea of how much N to sidedress per acre."

For information about the late spring soil nitrate test, go to and scroll down to page A-3.

The On-Farm Network enables farmers to conduct their own research on more than just nitrogen. Using the basic replicated strip trial guidelines, farmers can study any crop production practice or product they believe might help boost their profits, says Blackmer. "No matter what you'd like to study on your farm, this program can help. You don't have to rely on data from studies done on farms on the other side of the state, or in another state."

On-Farm Network can help you too

"Iowa farmers working with the On-Farm Network successfully completed 456 replicated strip trial studies in 2006," he says. "That included 180 trials involving nitrogen management and another 27 in which growers looked at the need for nitrogen fertilizer to supplement manure applications."

"Growers and their fertilizer and farm supply dealers also worked with us in completing 152 trials looking at fungicide use in corn and soybeans. Farmers also worked with us on over two dozen studies of corn rootworm controls, both Bt and chemical, in both rotated and in continuous corn."

Other studies gaining interest include the need for lime, a combination of insecticides and fungicides on soybeans, foliar feeding, the effectiveness of Bt in controlling corn borer, and the use of nematicides for soybeans.

Any farmer can participate in On-Farm Network studies. The only requirements are that they be willing to follow the ISA protocols and have GPS and a combine yield monitor. To participate in On-Farm Network studies, contact Patrick Reeg by e-mail at or by phone at 800-383-1423. Or by mail at 4554 114th St., Urbandale, Iowa 50322.

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