The University of Tennessee is developing a corn nitrogen calculator which will be available this winter as a link on the UT Web site: UTcrops.com. According to Tennessee Extension corn specialist Angela Thompson, the concept for the calculator is based on a similar tool currently used in the Midwest which incorporates nitrogen response data for corn rotated with corn or soybeans in several Midwestern states. “They were able to develop a nitrogen response curve in corn for Midwestern growers.”

The calculator “is an additional tool allowing the grower to take into account the economics of the situation we’re facing now with high nitrogen prices,” Thompson said. “So instead of putting down a certain amount of fertilizer based on yield potential, the calculator bases the decision on how much you can actually afford to put on depending on the price of your fertilizer and the price you will receive for your corn. We’re trying to bring economics into the situation.”

The calculator is based on three years of study on corn as a rotational partner with cotton, soybeans and corn and for corn following soybeans under irrigation. Rates ranged from zero to 275 pounds of nitrogen, carried to yield.

Most of the studies were conducted at the Milan Research and Education Center at Milan. There was another site in middle Tennessee at the Highland Rim Research and Education Center, in Springfield, Tenn.

One objective of the study was to generate new nitrogen response data for corn in Tennessee, according to Thompson. “Most of our recommendations for nitrogen are based on much older hybrids that are no longer sold and were planted at lower plant populations. Things are different today, so we wanted to see if our nitrogen response would be different with the new hybrids.

“We’ve had one very dry year, one pretty dry year, and one normal year for corn, so we’re kind of weighted toward nitrogen response under drought conditions. We’ll repeat everything again next year, and hopefully, we’ll have a little more rain and somewhat of a more normal year.

“Users can go online, plug in the price of corn they’re expecting and the cost of their nitrogen source and the calculator will provide a target nitrogen rate that they can afford to put on for their particular situation.”

Other variables entered into the calculator include any rotational crop with corn, irrigated or not. “We’re trying to keep it pretty simple,” Thompson said.

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