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High corn yields in hot, dry fields

High corn yields in hot, dry fields

• Forecasters are pretty much in agreement that the La Niña weather phenomenon will continue through early spring for the lower Southeast. • Generally, during a La Niña, warmer and drier conditions exist until the May/June period when it essentially falls apart.

With the certainty of a dry spring looming, there are several things corn growers can do to better manage their crops for the weather ahead, says David Wright, University of Florida Extension agronomist.

Forecasters are pretty much in agreement that the La Niña weather phenomenon will continue through early spring for the lower Southeast, says Wright, meaning warm, dry conditions that’ll be reminiscent of those seen in 2011.

Ironically, the data shows that corn producers with irrigation make higher yields during a La Niña phase, he adds. “In an El Niño, corn yields are usually below normal if you’ve got irrigation. You normally don’t see the record corn yields like we saw in 2011. However, if you are not an irrigated grower, that is not the case.

“Throughout north Florida, Georgia and Alabama, with irrigation, we usually have higher corn yields during a La Niña weather pattern.

“But we still have large amounts of non-irrigated corn in the U.S., especially when you get into the northern parts of the states, and I’m not sure this always would be the case,” says Wright.

Compared to last year at this time, drought severity in the lower Southeast is much worse, he says. “A lot of our winter crops look okay, as far as wheat and winter grazing, but many people have been working in swamps and cleaning out ponds because there is no water.

“A lot of irrigation wells dried up this past year. In south Georgia and north Florida, we’re in an extreme drought situation now.

“We’re in a long-term drought situation, along with parts of Texas and Oklahoma. That means more than six months of drought. We actually came out of 2010 about 20 inches below normal in rainfall.

“We came out of 2011, at least in the Florida Panhandle, at about 30 inches below normal. So we’re a total of about 50 inches below normal in rainfall.”

Most corn in the lower Southeast is planted in February or March, says Wright, which places the main pollination period in May.

“During this period last year, we were in a severe drought across north Florida, southern Georgia, southern Alabama and on out into Texas. So we had to do a lot of irrigation during this time period if we wanted to make adequate corn yields.”

Some growers made more than adequate yields in 2011, says Wright.

“In Georgia, we saw about 350 bushels per acre, and the second highest corn yield in the U.S. was made by a Georgia grower.

“We had irrigated growers around the Live Oak, Fla., area in deep sand, with 500 to 700 acres, who averaged 275 bushels per acre. That’s unheard of for that part of the country, but it happened.”

Some of the factors behind these high yields were high photosynthesis and low plant disease, he says.

“We didn’t have to worry about fertilizer leaching because we didn’t have enough rain. But we did have more potential for aflatoxin, with the hot, dry weather.”

Steps for success

In anticipation of warmer and drier conditions, there are several things corn growers can do to manage for good yields, says Wright.

Killing cover crops early will help, he says.

“In many cases, I’ve seen non-irrigated farmers let cover crops grow late, and by the time they start planting, there’s no moisture to get the crop up.

“Some growers utilize heavy cover crops, and that’s one way to conserve moisture and prevent weeds, except for volunteer peanuts, which seem to come up through anything.

“A heavy mulch can delay the need for an irrigation by a day, sometimes two days, which can make a significant impact on water use throughout the year.”

Heavy mulches also help to increase organic matter, says Wright. When following pasturelands, organic matter is quite a bit higher, and it will hold moisture and nutrients.

He also advises that growers split their pivots among crops.

“Corn generally has higher water requirements earlier in the season than other crops, such as cotton and peanuts. If you know your wells are limited in the amount of water they’ll produce, put half of it in a crop that requires water at a different time. You can cut off the water for a time.”

Also, says Wright, plant fields based on electrical conductivity.

“Research in cotton has shown that as the electrical conductivity is increased, this usually means the soils are heavier or at least have higher water-holding capacity, and this can make a difference. Some of our soils may hold as much a 2 inches of water.”

Another suggestion, he says, is banding fertilizers at planting whether it’s dry or liquid. “Be very careful about putting anything in-furrow. Banding works especially well in sandy soils.”

Growers also should consider following winter grazing wherever possible, says Wright.

“We have data that has shown cattle do compact the top 6 inches of the soil, but as you go down into the soil profile — 3 feet deep — there was a tremendous increase in the root mass where cattle had grazed.”

If you have nematodes in your fields, use nematicides, he says. In fields where grass crops can be grown, you can have higher levels of nematodes that definitely will impact yield.

“Controlling other pests is also important. Plant something after corn harvest to keep down weeds,” he advises.

Drought-tolerant hybrids also will help, as will adjusting plant populations, says Wright.

“We have made 200-bushel corn with 12,000 plants per acre. If you know you’re going to be in stress situations, it’s better to be at 26,000 than 36,000.

“If you are shooting for those high yields and you have the irrigation capability, look at some of the higher populations. Usually, plant population is not the main yield-limiting factor. It’s usually drought, fertility and other things.”

Ripping under the row also has proven to be very beneficial, especially in stress situations, he says.

“As you go through the season, you’ll usually get behind on irrigation at some point, and this can make a tremendous difference, but rip early.”

Growers with irrigation also might consider a second crop, says Wright.

“If you have irrigation, it allows you to plant a second crop, and we’ve had growers who made 280-bushel corn followed by 34 or 40-bushel soybeans. If you’re timely, it can work.”

If you’re in a non-irrigated situation, he says, plant later.

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