Grower wants more efficiency with drip irrigation

Tom Killian hopes the subsurface drip irrigation he installed under his near 40-acre pecan grove doesn't increase yields.

“I've seen no difference in the three acres I've had under drip for several years and the trees I've been watering with sprinklers,” Killian says. “I certainly can't document any difference and I hope we don't see any.

“I didn't install drip irrigation to increase yields; I prefer to keep production as consistent as possible and do all I can to remove nuts from the trees in years when they are loaded.”

Killian's goal, he says, is to improve efficiency and use a bit less water on his Lubbock, Texas, grove.

Killian says the alternate year bearing pattern of native pecan species creates production and marketing problems. And he says a heavy crop one year means a light one the next. Stress of producing high yields prevents the trees from making much the following year.

That's why he prunes heavily on bumper crop years and why he hopes irrigation improvements doesn't disrupt his schedule.

He started with just that three-acre plot five years ago.

“I liked it. With sprinklers, I have to move equipment out of the way to harvest or do much of anything else under the trees. With drip I don't have to move anything.”

He has spaced trees about 60 feet apart and tries to put on eight to ten acre-feet of water per year. “The sprinklers couldn't keep up with the demand,” he says. “I had a hard time covering the area with the sprinkler system.”

He got interested in drip systems at a production meeting and worked with a local distributor, Jerry Funk, to put in the first three acres. He found that he could water that section in about one-third less time than it took to water a similar plot with sprinklers.

“I thought I could get by with less water using the drip system,” he says.

Water has become a limiting factor for pecan production in the Southern High Plains as water tables diminish from increased agricultural and municipal demand. “It's also a substantial part of production costs. I hope to see a significant difference in water use with increased efficiency,” Killian says.

The success of those first three acres convinced Killian to convert the entire grove to drip irrigation. “I planned to do a few acres a year until I got everything converted,” he says.

“But I applied for funds from the Environmental Quality Incentive Program from the Natural Resources Conservation Service and qualified. With that funding I decided to convert the entire grove to drip at the same time.”

He says the conversion created some inconveniences this year but “nothing I couldn't work around.”

By early April Killian had the system installed but did not have all the automatic features turned on.

He says the system will require management adjustments. “I've noted some inconveniences. The tape, buried only five inches deep, limits cultural practices.

“I can't disk, for instance, and I can't move trees around the way I would like to. And I'll always have to maintain the tape.”

But he has no real reason to cultivate. “I get a natural cover crop throughout the grove to prevent erosion and I keep vegetation in check with Roundup.”

He has found other ways to improve efficiency. “I'll run most of my nitrogen through the tape,” he says. ‘I don't have that system ready to go yet but I will be able to apply fertilizer to the 40 acres through the system.

“I use about 400 units of nitrogen per year and had applied it about 50 pounds per acre at a time, several times a year. Now, I'll apply nutrients almost continuously.”

He'll use a flow meter to measure water use. “I've been using four or five acre-feet of water and it's expensive to lift that much water and apply it. And application is somewhat inconsistent. Now, I'll know exactly how much water I use.”

He says the drip system allows him to keep ample water on the grove during critical growth periods.

“I learned the hard way to water late into the season,” he says. “I'll shut off the system around mid-October and then water heavy after harvest.”

To qualify for the EQIP funds, Killian had to provide NRCS with an accurate plan depicting acreage and an irrigation layout.

“We submitted what we were doing, got a design and NRCS approved the project,” Killian says.

He says Funk worked with NRCS to develop a map and irrigation layout. NRCS used an aerial map and special software to plot the grove. Global positioning system technology provided accurate data for system layout and for certifying the acreage for EQIP funding.

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