It’s difficult to find much current research on the interaction of corn with nitrogen and irrigation in the South, but if recent crop years are any indication, there could be more coming.

 “This past year, we averaged about 154 bushels per acre on corn this year in Mississippi, which was unbelievable,” says Jac Varco, Mississippi State University Extension soil scientist.

“When I first arrived in Mississippi, we were averaging 68 bushels per acre. In the beginning, corn was being grown in the hills, but now it’s being grown on cotton ground in the Mississippi Delta, and most is irrigated. We’ve switched soils, so yield potential has increased,” he says.

Speaking to a group of Alabama crop consultants recently, Varco says rates, timing and placement of nitrogen fertilization all are important considerations when producing corn.

“I don’t worry much about fertilization until I see the crop start to come up because the crop isn’t using any during germination. It has enough nitrogen in the soil and in the seed to get it through a couple of leaves of corn. By the time it has two leaves or so, I put on my first fertilization — usually about 50 percent.

“I would wait even longer if I could, but the corn is getting high and we’re usually using ground equipment, so we don’t have high-clearance equipment yet for side-dressing. Depending on how many acres you have to cover, the corn might be at V6 when you start and V8 when you finish,” says Varco.

In Mississippi, he says, growers have gotten away from using anhydrous ammonia. They’ve been weaning us off ammonium nitrate because people are using it for purposes other than to fertilize, and we’re losing it,” he says.

While fertilizer prices have decreased some, they still comprise about 40 percent of the cost of producing a crop of cotton or corn, he says. The next largest input crop is fuel.