Most High Plains cotton farmers don't need to read the frequent reports outlining the decline of the Ogallala aquifer. They've watched over the past decade as irrigation wells produced less and less, forcing many to change the way they irrigate.
They've adapted. Some have switched a few acres to subsurface drip irrigation; most have converted overhead sprinkler center pivot units to more efficient low energy precision application (LEPA) systems; and a growing number are altering tillage practices or crop configurations to stretch dwindling water resources as far as possible.
Brandon Pointer, a 25-year-old Lamb County farmer, irrigates with what he calls “light water,” wells that deliver from 400 gallons to 480 gallons per minute. He needed all those wells could deliver this year with only 7 inches of rainfall during the growing season.
“The center pivot systems ran continuously from June until the first week of September,” Pointer said.
He plants cotton in a minimum tillage system and says the cover crop helps hold water from rainfall and irrigation. He said the cover also saved part of his crop this year.
“We had a lot of wind in the spring,” said crop consultant Denis Flowers. “The rye stubble protected the seedling cotton from wind and sand damage.”
“The cover crop also puts organic matter back into the soil,” Pointer said. “That helps hold water and we don't lose moisture to tillage in-season.”
Rye over wheat
Pointer prefers rye to wheat as a cover crop. “It grows faster in the cold months and we can kill it a little easier in the spring. Also, I think the rye stubble stands up a bit better.”
He'll plant rye from mid-to-late December and will “turn the wells back on to get it up. I may need to water it twice, but we have to establish the crop to get adequate cover.”
He terminates the crop with Roundup and says Roundup Ready cotton varieties make the minimum tillage system work.
Pointer also has a 20-acre block in drip irrigation. He has about 3.5 gallons of water per acre for the drip system.
“We believe we have potential to increase yields with drip irrigation,” Flowers said. “We saw some drip beat four bales per acre last year.”
“I'll try to put in some more drip next year,” Pointer said, “where we have light water. I figure I'll need to make more than a bale or a bale-and-a-half per acre as cheap as cotton is.”
He said drip systems cost from $700 to $1,000 per acre to install.
David Carter also relies on a light water source to irrigate his Hockley County cotton farm. He uses a minimum tillage system as well, planting cotton back into old crop stubble.
“A cover crop in this area is an iffy proposition,” Carter said. “Low moisture is a limiting factor. We barely have enough moisture to make one crop, much less a cover crop. From December through May we had no rain. If we get behind on moisture, we never catch up.”
Carter may try to alter his cropping system next year to conserve water. “I'm thinking about planting half a center pivot circle in wheat and half in cotton. I'll harvest the wheat and leave that land fallow throughout the summer. That leaves me more water for the cotton.”
Mike Gresham, another Hockley County cotton farmer, has made a significant investment in drip irrigation. He has 640 acres in drip and plans to add more. He's making his third drip crop but expects yields to be off a bit from last year because of poor early-season growing conditions including high winds, cool temperatures and drought.
Crop consultant Darrell Kitten said dry soils early created germination problems.
“We had trouble getting water to move up in this sandy soil,” he said. “Moisture tends to move downward.”
Gresham hopes drip will bump yields to three bales per acre or better. “Last year we saw a bale per acre advantage with drip,” Gresham said. “I used about the same amount of water I would have run through a pivot but I made more cotton.”
Narrow rows help
After early season setbacks, the crop recovered. “We set the systems so cotton was watered twice a day,” he said. He also applied nutrients through the system.
Ronnie Wallace, Seminole County farmer, says narrow rows are helping conserve moisture in cotton and peanuts.”
“I've read research reports indicating potential for a significant yield increase with 30-inch row spacings,” Wallace said.
He said the narrow rows allow a canopy to develop sooner, shading the soil and dropping soil temperatures. “I think we use less water,” he said. “I recorded a 103-degree temperature on my truck thermometer on the highway near one of my cotton fields this summer. When I drove into the cotton fields, the temperature dropped to 94. Underneath the canopy, I'm sure the temperature was even lower.
“I'll know how it yields after harvest but I expect a 10 percent to 20 percent advantage.”
Wallace uses center pivot irrigation, including one 2,607-foot-long LEPA system with LDP nozzles. “Each nozzle has a pressure regulator.”
Wallace has an unusually good water supply, 2,200 gallons per minute, but he makes certain he uses it as efficiently as possible. He applied 1.5 inches of water every six or seven days from late June until the first of September. “I think we got an inch and a half of rain during that time,” he said.
Dawson County farmer Mike Tyler has a bit less water, about 700 gallons per minute, but he's making it go as far as possible with LEPA irrigation and cover crops.
“Mulch helps hold moisture,” he said. “Two years ago I experimented with wheat in the bottom of the row. Instead of four rows of wheat, I put only two in some rows. We had a good rain and where we had two rows of wheat, water ran out of the field into the bar ditch. With four rows, none ran out. The water we got we held with four rows of cover crop in the rows.”
Tyler says minimum tillage shouldn't cost a farmer moisture, if he gets some rain. “If it doesn't rain, he may lose some moisture to the cover crop.”
He's used a minimum tillage system for more than 10 years and says he would not want to farm without it. “It's just no longer a question whether we'll plant minimum till or not,” he said.
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