If the field test plots at the LSU Ag Center's Northeast Research Station in St. Joseph, La., are any indication, corn growers across the state may be due for a bountiful harvest this fall.

Rick Mascagni, Louisiana corn research agronomist, says, “Right now, the corn in our test plots has the potential to produce an average yield in excess of 200 bushels per acre. One or two more timely rains will make this crop.”

Weather conditions in northeast Louisiana, thus far this year, he says, have been ideal for corn production. “If the timely rains and relatively cooler daytime temperatures in the lower 90s continue we may set some yield records this year,” he says. “We're having such a good season. The potential is there for some of the state's corn acreage to produce outstanding yields above the 200-bushel mark. You don't have too many years like this with near-perfect temperatures and rainfall, though.”

This year's corn outlook is a welcome change from the past few years when Louisiana's corn growers experienced decreased yields due to extended periods of high temperatures and drought during the growing season.

It was the hot, dry growing conditions of the past three years that prompted Mascagni to initiate a study to better define the effects of irrigation on corn hybrids planting into poorly drained, clay-type soils. “Much of the corn acreage in Louisiana is on soils that typically exhibit moisture stress at some time during the growing season. The clay soils may be more drought-prone than other soil types,” he says.

Mascagni says his research results from 2000 indicate that plant stress, particularly lack of soil moisture and high temperatures, predispose the corn plant and grain to yield reduction, seed quality problems, and aflatoxin contamination.

What he has also found thus far is about a 30-bushel per acre yield increase with irrigation. One-year data from a field experiment in Jonesville, La., in 2000 produced average per acre corn yields ranging from 82.9 bushels in non-irrigated plots to 115 bushels in the plots irrigated when the soil moisture deficit reached 1.5 inches; to 95.5 bushels in the plots irrigated when the soil moisture deficit reached down 2.5 inches.

“Apparently, adequate water for maximum yield was not provided by the 2.5-inch deficit treatment,” he says. There were five irrigation treatments for the 2.5-inch moisture deficit compared to eight for the 1.5-inch deficit treatment.

In most years, you can expect a yield response from irrigation on the clay soils. It all depends on how much rainfall you get during the critical growth stages,” Mascagni says. “We saw a big yield increase with irrigating last year, even though our top corn yield wasn't that high due to a late planting date.”

While Mascagni says it is always ideal to irrigate corn in Louisiana, there are instances where growers can produce yields over 100 bushels per acre without irrigation capabilities.

“On Mississippi River alluvial soils, which are fairly deep soils, corn producers can potentially make 100 bushels or better with careful management, even without irrigation,” he says. “In most years, you can still make an economical yield on the clay soils, if you plant the corn early.”

However, specialists with the Louisiana State University Agricultural Center do not recommend planting corn into Macon-Ridge soils without irrigation capabilities. “That soil type is very shallow and acidic, with a natural hardpan at about 12 to 15 inches, which restricts rooting depth. The Macon-Ridge soils dry out quickly and basically need a rain every three or four days to produce corn,” Mascagni says.

To increase corn yield potential on clay soils, with or without irrigation capabilities, Mascagni recommends planting by early to mid-March, and planting adapted hybrids at recommended seeding rates (planting the recommended seeding rate and following the recommended plant population guidelines). “You don't want too many plants out there competing for available soil moisture.”

In his irrigation studies, Mascagni is also studying the effects drought-like conditions during the growing season have on the development of the aflatoxin fungus. In the research study, he inoculates corn with Aspergillus flavus, the aflatoxin-producing fungus, and then analyzes grain samples for aflatoxin at harvest.

Normally, he says, the number one factor in the development of aflatoxin is drought. However, the data from 2000 didn't provided any definitive trends, despite the fact that the crop was heavily stressed due to hot, dry weather conditions throughout the growing season.

“Last year, even with the stress conditions, there were no obvious trends, so we're going to look at it again this year,” he says.


e-mail: doreen_muzzi@intertec.com