The right con-till system

Conservation tillage offers farmers an opportunity to control erosion, improve profit and conserve moisture.

"For years we assumed that we had to turn under crop residue, especially on sandy soil, to prevent blowing problems and reduce weed populations," says Wayne Keeling, agronomist with the Texas Agriculture Experiment Station.

Keeling, who is stationed at Lubbock, has tested a number of conservation tillage systems since the early 1990s on an experimental farm near Lamesa and has found that reduced tillage systems not only provide conservation benefits but also offer the best yield and profit potential.

"We've learned that cultivation promotes soil moisture loss," Keeling says. "Also, bare soil promotes wind damage, especially in sandy soils. We can lose a lot of cotton seedlings to blowing sand.

Keeling and other researchers have studied a number of systems over the past decade.

"We've tried conservation tillage at several sites on the High Plains, using different crops and cropping systems,"

Field trials compare conventional cotton production and tillage systems to minimum- and no-till systems producing cotton and cover crops.

"The basic idea is using a cover crop or crop stubble to hold the soil during winter and then planting cotton the following spring," Keeling says. "We've used milo stubble, sudangrass, rye and wheat as cover crops, but we're getting the best yields and returns when using wheat or rye.

"Cotton planted into a spring-terminated wheat or rye rotation cover crop has so far produced the highest yields and the best net returns," he says. "During the last seven years, this system has consistently posted a 100 pound-per-acre yield advantage over conventional or minimum-till cotton.

"We use minimal water to get the fall cover crop established and rely on subsequent rainfall to keep it alive and growing."

Keeling says growers may invest a little more water and additional fertilizer in the cover crop if they graze cattle during the winter. "With cattle, we can justify a little more expense," he says.

Otherwise, he recommends using as little water and other resources as possible to establish the cover.

"We like to establish the wheat or rye into standing cotton stalks. Apply just enough water to get the crop up and then forget about it. Don't use excess water, just grow the cover."

Keeling says cotton planted into a wheat or rye cover "shines under tough starts and tough finishes. A dry fall will not permit a conventional cotton crop to catch up what it loses early in the season."

In Keeling's tests, conventional cotton has produced an average yield of 878 pounds per acre and minimum till has produced 898 pounds. Cotton planted no-till in terminated rye has averaged 994 pounds per acre.

"That system produces the best yield and the best economic benefit," he says.

"We've tested wheat and milo for harvest but we lost money on the grain crops. The best system is to terminate wheat or rye and plant cotton into the residue."

Keeling says tests with legumes for cover have not been as successful. "With legumes we get some nitrogen advantage," he says. "But it's harder to establish a stand and harder to terminate legumes. Also, with wheat or rye, we get standing stalks that help prevent wind damage."

Keeling says for years the primary challenge for conservation tillage was weed control but with new chemistry and equipment farmers can manage even problem weeds.

"Roundup Ready cotton varieties have provided us a lot of options," he says.

With choices including 2,4-D to kill winter weeds, Roundup to terminate the cover crop, Roundup over-the-top before the four-leaf stage and combinations of Roundup and residual herbicides, farmers can control most weed problems, he says.

Hooded sprayers that allow post-directed herbicide applications later in the season complete the system. "A hooded sprayer is an important part of a no-till operation," Keeling says. "We can use this equipment to apply Roundup and a residual herbicide to take care of morningglory and other problem weeds."

Economical cropping systems that conserve soil and moisture will continue to attract attention from researchers and farmers trying to find better ways to earn profits with limited water supplies and depressed prices.

Conservation tillage, Keeling says, "is getting to be a pretty good way to grow cotton."

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