“Anhydrous ammonia is the cheapest source of nitrogen per pound of nitrogen, urea is next, then urea ammonium nitrate solution, and then ammonium nitrate is the most expensive,” says Varco.

“With cotton, at 100 pounds of nitrogen from anhydrous ammonia or ammonium nitrate, you’ll spend $29 or so more per acre if you go with the liquid over anhydrous ammonia.

“If you switch to corn at 200 pounds of nitrogen, you’ll spend close to $60 per acre. When you do it on paper, anhydrous ammonia looks good.”

Mississippi has been changing, he says, in terms of the crops being planted.

“Not too long ago, we had 1.25 million acres of cotton.  Now we have 800,000 acres of corn, 500,000 to 600,000 acres of cotton, and cotton is expected to go down.

“When you switch to corn, it doesn’t take as much labor as with cotton. But we’re trading labor costs for fertilizer nitrogen costs. You’re spending $59 more acre for that extra 100 pounds of nitrogen required by corn. You go from a 100-pound nitrogen rate with cotton to a 200-pound rate with corn,” says Varco.

Ammonium nitrate is efficient on most soils in Mississippi as a broadcast spread, he adds. “Urea usually takes a higher nitrogen rate to get the same yield as ammonium nitrate.

“If you did an economic comparison, ammonium nitrate is probably at about 175 to 180 — the nitrogen rate you should apply — whereas urea is closer to the 200-pound rate.

“UAN solution is knifed into the soil, and it’s very efficient, producing almost 200-bushel corn with 150 pounds of nitrogen.

Mississippi State University has a general recommendation of 1.3 pounds of nitrogen per bushel of yield goal for corn, says Varco.

“More and more wells are being dug in Mississippi each year, and we’re depleting the aquifer, even in the state’s Delta region. With furrow irrigation in the Delta, it seems that when we flush our soils, we’re flushing the nitrogen.”

Since Mississippi growers are banding nitrogen, Varco says research has been conducted to look at the best place for putting that band.

“We’re spacing nitrogen 6, 12 and 18 inches from the row, so with 38-inch rows, we’re almost in the middle.

“A lot of our growers and the Extension Service recommend that we put nitrogen in the middle. Part of the reason for that is that it’s easy for tractor drivers to do it and not damage the crop. The knife will be in the middle and won’t prune roots.”

Treatments included 15N labeled fertilizer applied at 6, 12 and 18-inch distances from the corn row using both surface and subsurface-banded application.

Following university recommendations, fertilizer nitrogen was split-applied, with 50 percent put down at planting followed by 50 percent at the V6 corn growth stage.

The research showed that with subsurface banding, there wasn’t much difference in banding at 6 and 12 inches from the row, says Varco.