In arid parts of the U.S. like the Texas Panhandle, quenching the thirst of crops has been increasingly difficult in recent years.
“Where we live, irrigation is everything,” says Braden Gruhlkey, who farms 5,000 acres of corn, wheat, cotton, sorghum for silage and seed milo with brothers Brittan and Cameron, and their father Bill, near Wilderado, Texas. “But now, we only irrigate about a third of our crops because the water is running out.
The Gruhlkeys draw water from the Ogallala Aquifer, which at current use rates could be 70% depleted by 2060, says a recent study by Kansas State University. They’ve drastically reduced the amount of water they pump and the acres they irrigate.
They’ve strip-tilled since 2007 and currently have 1,000 acres of strip-tilled corn under center-pivot irrigation ranging from 120-acre to 500-acre circles.
“We’ve gone from our wells pumping 800 gallons per minute to about 200 gallons per minute due to overuse in the area,” Gruhlkey says. “So we’ve looked at strip-till as a way to help maximize our water usage and still grow a good crop.”
They’ve succeeded on both fronts, with irrigated strip-till corn yields reaching 270 bushels per acre in spite of droughts and other adverse growing conditions.
Split Nitrogen Benefit
The Gruhlkeys typically build strips in fall and apply 70% of their phosphorous and 40% of their nitrogen needs with a 12-row Kuhn Krause Gladiator unit. They build strips about 7 inches wide and place fertilizer 6 to 8 inches below the soil surface.
Photo courtesy of Braden Gruhlkey
“We’re all liquid. We used anhydrous in the past, but feel we get a better bang for the buck with our current setup,” Gruhlkey says. “With our drier soil conditions, we’re concerned about denitrification. But I like our liquid system because if we’re applying 100 units in the field, I know we’ll have 100 units out there, instead of trying to guess how much anhydrous survived.”
They apply the remainder of their phosphorus in-furrow at planting through Keeton seed firmers — typically 3 to 5 gallons per acre of Pro-Germinator, a pop-up blend produced by Agro-Culture Liquid Fertilizers. To improve zinc deficiencies, they’ve also incorporated a small amount of the fertilizer into their micronutrient package, which is also applied in-furrow with the planter.
One advantage of the Gruhlkey’s fertility program compared to other strip-tillers is being able to apply in-crop nitrogen with the center pivots. They typically apply about 80 to 100 units to corn at V5 and V8 stages, then evaluate the need for another 20 units just before tassel.
“We’ve had excellent luck with splitapplication of our nitrogen, and because it’s just as good a sidedressing anhydrous, and it’s saving us from spending $30,000 on that equipment,” Gruhlkey says. “Plus, I like not having to make that trip through the field with the tractor, and we haven’t seen any yield loss with this method.”
Gruhlkey says they’ve harvested 260 to 270 bushels per acre of strip-tilled corn under irrigation.
“We’re fertilizing for 290 bushels per acre of corn and try to get 300 units of nitrogen applied,” he says. “That’s a high yield goal, but we’ve had fields get close, so we’re going to continue shooting for it.”
While the Gruhlkeys primarily no-till their dryland corn, recent split-planting experiments on their strip-tilled fields have improved yields and conserved water.
Last year, they tried split-planting, strip-tilled corn into wheat stubble, planting half the crop in mid-May under an irrigation circle, then coming back about 5 weeks later to plant other half.
“Our goal was to try and spread out peak water use and give us 5 to 6 weeks of time when the early corn was at tassel to apply double the water,” Gruhlkey says.
“Then we scaled back and focused on watering the late-planted corn during that peak time.”
Rather than apply the same amount of water on each field, he drastically reduced irrigation on the late-planted corn, and also reduced seed population. This was done to get a baseline yield comparison and assess the value of split-planting irrigated corn.
On the early-planted corn, Gruhlkey applied 28 inches of water and planted at a population of 31,000 seeds per acre. The combination resulted in about 250 bushels per acre.
For the late-planted corn, he scaled water application back to 12 inches and a population of 16,000 seeds per acre, which translated to about 150 bushels per acre.
“What I learned is that we could grow an decent crop with a lot less water, despite planting most of it in 90-degree heat and high winds, so I would call it a successful experiment,” Gruhlkey says. “We planted a little thin on the late-planted corn. Had we pushed populations a little higher and had more ideal conditions, we could have probably made 200 bushels per acre.”
Having the wheat stubble as cover helped preserve moisture in the strips, he adds. In past years, Gruhlkey struggled to maintain moisture in the soil profile with irrigated corn, but the wheat stubble reduced the need to run pivots nonstop.”
The Gruhlkeys have also experimented with strip-tilled cotton after corn to retain excess nitrogen left by stalk residue and create a more favorable early-growth environment.
“Cotton doesn’t have a high tolerance for cold and that can really impact germination,” Gruhlkey says. “With strip-till, we can have a nice clean seedbed and that ground warms up a lot faster.”
This year, strip-till was particularly beneficial to survival of a portion of the Gruhlkey’s cotton crop. After planting this past spring, they endured a May frost, which Gruhlkey thought was going to doom their crop.
“A lot of that cotton survived and is looking good,” Gruhlkey says. “I think that by strip-tilling it, we opened up that narrow area of soil that didn’t freeze, because it had already warmed up faster and we had better emergence.”