Writer: Tim W. McAlavy, (806) 746-4051,t-mcalavy@tamu.edu
LUBBOCK — Most cotton producers on the Texas Plains saw their crop management strategies lead to naught last year, due to the withering drought.
If dry conditions persist this year, producers should think about “retooling” their strategies, two agronomists and an irrigation specialist told farmers at a March crops conference here.
“I wouldn’t be too pessimistic about the chances for a repeat of last year s drought…not yet anyway,” said Dr. Dan Krieg, South Plains farmer and a Texas Tech University professor of plant and soil science. “We didn’t receive much winter rainfall, but we normally average less than 5 inches of rainfall from November through April in the Lubbock area.
“What we count on is getting up to 13 inches of rain between May and October, right during the cotton growing season. But even in the best rainfall years, keep in mind that our evaporation potential is four times greater than our normal average rainfall.”
Most South Plains soils can hold 15 to 20 inches of moisture in the four-foot soil profile, Krieg said. But the Plains’ high evaporation potential means producers should water their crop wisely and do all they can to preserve their land s limited moisture-holding capacity.
“Cotton reaches its peak water demand 90 to 100 days into the growing season, when the crop is in peak bloom,” he added. “With average rainfall and a well capable of pumping 3 gallons per minute per acre, we can meet that water requirement.
“But there is no benefit in watering beyond peak bloom. In fact, research on the South Plains has shown that watering after peak bloom, when the first bolls begin to open, actually lowers the crop’s yield potential.”
Retrofitting center pivot sprinklers to maximize irrigation efficiency and increase a crop’s water use efficiency also aids crop survival during dry years, said Dr. Leon New, a Texas A&M professor of ag engineering and Extension irrigation specialist based in Amarillo. “If you haven’t yet adopted Low Energy Precision Application (LEPA) technology on your pivots, I encourage you to do so.
“A LEPA pivot equipped with drag socks on its drop lines, running in a field with furrow dikes, achieves 95 to 98 percent irrigation efficiency. In other words, it loses only 2 to 3 percent of the water pumped to evaporation it’s the most efficient system we have.”
LEPA systems equipped with bubble-mode nozzles are second in irrigation efficiency, followed by LEPA systems equipped with spray-mode nozzles, he said.
LEPA Conversion and Management, a Texas Agricultural Extension Service publication (B-1691) written by Drs. New and Guy Fipps, explains how to convert center pivots for LEPA. It is available on the Internet (http://agpublications.tamu.edu/pubs/eengine/b1691.pdf ) or through county Extension offices.
“Skip-row watering (irrigating every other row) is another good water management strategy. And if you are concerned about watering the crop uniformly, I recommend installing pressure regulators and pressure gauges on a pivot s drop lines,” New said. “Pay close attention to the pivot’s nozzles, too. You may get better results simply by re-nozzling one or two drops, or an entire pivot.”
Re-evaluating all crop inputs is another way producers can stay competitive and survive another dry crop year, said Dr. Randy Boman, cotton agronomist with the Texas Agricultural Extension Service in Lubbock.
“Don’t buy and apply unnecessary fertilizer. Know what’s in your soil (run a thorough soil test) and apply only the nutrients your crop needs. Your soil test should check for nitrogen, phosphorus, potassium, sulphur and zinc,” he said. “Remember that it takes 50 to 60 pounds of actual nitrogen to produce each bale of cotton in your yield goal. And be sure to credit residual soil nitrates against the crop’s nitrogen requirement. Don’t apply more nitrogen than the crop needs.
Furrow diking, using a cover crop such as wheat during the fallow winter season, or practicing minimum tillage in dryland fields are good individual practices to conserve soil moisture, improve yields and boost returns per acre, the agronomist said.
“Take a good look at your seeding rate, too. Higher rates mean higher cost. Higher seeding rates also produce more barren plants — plants that use fertilizer but produce no lint,” he noted. “If you are seeding more than 20 pounds per acre, think about cutting back. Cotton seeded at 15 pounds per acre returned the best yields in our 1998 seeding rate field trial in Swisher County.”
Boman also encourage producers to plant at least two or more adapted cotton varieties and to make objective performance comparisons when selecting varieties to plant.
The crops conference was hosted by Southwest Farm Press and sponsored by the Texas Agricultural Extension Service, Texas Agricultural Experiment Station, USDA’s Agricultural Research Service, and Plains Cotton Growers, Inc.
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