You'll have to excuse Bruce Turnipseed if he feels a little snakebit about his subsurface drip irrigation (SDI) system. He's convinced it will raise cotton yields and increase irrigation efficiency. He'd just like a reasonable year to test it on the Hockley County farm he operates with his father, Travis, near Levelland, Texas.

This will be the third crop he has planted over underground tape (175 of the more than 2,100 acres he farms with his father will be watered with drip irrigation this year).

“We started with 40 acres three years ago,” Bruce says. “We got hailed out the first year. Last year, armyworms ate us up.”

He was somewhat encouraged each year, however. “The first year, we planted grain sorghum behind the hailed-out cotton,” he says. “We made 6,000 pounds per acre, and a field next to it made 500 to 600 pounds.”

He says the armyworm-infested crop last year yielded 540 pounds per acre, not great for irrigated cotton, but a sight better than the 45 pounds that came off a dryland field adjacent to it.

“I'd just like a decent year to test this system,” he says.

He says water use, so far, has been about equal with center pivot, mostly low energy precision application (LEPA) systems. “But we use water more efficiently. We can apply two-tenths of an inch every 24 hours and put it where the plant can pick it up. We also put nitrogen through the system and have it available where and when the cotton needs it.”

Travis says evaporation losses are significantly less and timing improves dramatically. “We waited five and a half weeks for a side row system to apply just seven-tenths to 100 acres. We can apply two-tenths to one-fourth inch with drip every 24 hours and use less water. We will need one less irrigation on that field.”

Water savings will be a key issue in the future, he says. “We know our wells are not half as good as they were 10 years ago. We have to use systems that are more efficient. LEPA provides efficient irrigation, but we still lose water to evaporation, especially in hot, dry conditions.

“The fertilization option, which allows us to put nutrients where we need them, also aids efficiency.”

“We save more than water,” says Bruce. “We use less labor, less fuel and less time with drip systems.

“Drip system also works well with minimum-tillage operations. We like to plant two rows of wheat in the bottom of the cotton furrows. We get sand and wind protection and also put organic matter back into the soil.”

They switched to minimum-till cotton three years ago, “after starting on a small-scale,” Bruce says.

The Turnipseeds say landlords have been receptive to installing SDI systems. “Our landlords own all the tape,” says Bruce. “One wants to install drip on another 50-acre tract and experiment with both 40-inch and 80-inch tape spacings to see which is best.”

Most of the systems in operation now are spaced 80 inches apart. “We have a 10-acre field with 40-inch spacing,” Bruce says. “That does offer flexibility to plant vegetables at some point. And we're seeing how much difference the widths make.”

All tape is installed from 12 inches to 14 inches deep.

The Turnipseeds anticipate the system will last 25 to 30 years.

“The key is maintenance,” Bruce says. “It's especially important to maintain the filter systems and to keep foreign matter and algae out of the lines. Every year, we'll put acid through the system to lower the water pH and that keeps the algae out. It also helps eliminate root intrusion, without hurting the crop.”

“We have two wells that produce only 200 gallons per minute,” he says. “That's not enough to row water and the fields are not conducive to pivots.”

The only barrier to installing more drip irrigation is expense balanced against low cotton prices.

“If the economy would improve, we'd like to add more,” Bruce says.

“We'd like to replace pivots with drip if prices were better. I own some land that I'd consider putting drip on,” Travis says.


e-mail: ron_smith@intertec.com