’Flowers + Limited Irrigation
Tuesday, November 1, 2011
filed under: Irrigation/Water Use
Given that he’s grown the crop since 1995, Bob Hoeme can legitimately be tagged as one of west central Kansas’ “veteran” sunflower producers. So it may seem odd, then, that the Scott City farmer didn’t harvest a single acre of sunflower this fall.
Rotational considerations lay beneath Hoeme’s lack of sunflower acreage in the 2011 growing season. About 40% of his acres are under irrigation (mainly sprinkler, some gravity), and corn takes top priority there. “They just didn’t fit this year on my irrigated ground,” he says.
Hoeme did plant a small dryland field to sunflower last spring, but then Mother Nature decided to get ornery. While most of his crop land is under no-till, this particular field was plowed ground with virtually no surface residue. Right after planting in mid-June, two hard half-inch rains fell back to back. Then the thermometer shot upward, and the field ended up with a heavy crust. A July 7 replant fared no better, as daytime soil surface temps climbed into the 120-125 degree range. Poor emergence and a “weedy mess” sealed the deal, and the only yield came in the form of an insurance payment.
The experience hardly soured the Scott County producer on this crop, however. He fully intends to be back in ’flowers in 2012 – both irrigated and dryland. “I like sunflower in a rotation with irrigated corn,” Hoeme affirms. “With that deep taproot, it will go down and ‘mine’ below the corn roots. If you get them off to a good start, they’ll go a long way into the summer before they need more attention.”
Like other High Plains irrigated producers, Hoeme is acutely tuned in to the Ogallala Aquifer’s ability to meet the pumping demands placed upon it. This season – with its minimal rainfall and high temperatures across a large part of the Southern Great Plains – did not help. “Usually we’ll notice the irrigation wells beginning to pump down in mid-August,” he notes. “This year, it started around August 1 because it was so dry last winter that everyone started up their pivots to pre-irrigate prior to planting corn. They ran them for two to three weeks, shut them off to plant; then started up again after planting was done. And they ran continuously [until early September].”
Hoeme raises continuous corn under a 120-acre pivot whose capacity is 550 gallons per minute. He operates a half-mile pivot on another 360 acres, where he often rotates in sunflower. That pivot has four irrigation wells running into it, with a total pumping capacity of about 900 gpm. “Another pivot (148 acres) is around 400 gpm, and I split that up into half-pivot fields,” he explains.
Placing sunflower into a limited-irrigation situation has worked well for Hoeme through the years. “I’ve tried to go in after corn in the fall and plant wheat and irrigate, but sunflower has been a much better crop after corn than wheat. You still get your income in the same year; it’s just in October-November from the sunflower rather than in July from the wheat.”
Hoeme, who plants between June 10-20, typically pre-irrigates the ’flowers — for two reasons: to aid emergence “because no-till behind corn is not perfect planting conditions,” and to incorporate the herbicide. His weed control program consists of a preplant glyphosate burndown, coupled with a preplant application of Spartan Charge. (Depending upon weed pressure, he’ll sometimes tack on a postemerge Select treatment for shattercane, volunteer corn or other grasses.)
Hoeme’s ’flowers under split pivots have to get by on the pre- treatment and any natural precipitation until after the corn’s irrigation needs have been met. By then, they’re usually approaching the seed fill stage. “They normally get through the summer in pretty good shape; but they’re needing a couple inches of water to finish off – especially if we haven’t had any rain,” he says.
Hoeme’s track record confirms the program works. His average yields under the limited irrigation across the years have run around 2,500-2,600 lbs/ac, with oil contents typically in the mid-40s. In better years (such as 2010), his dryland sunflower has yielded up to a ton per acre.
Bob Hoeme summarizes the agronomic benefits from sunflower in his rotation by focusing on its efficiency in utilizing both water and leftover nutrients from the preceding corn crop. And those benefits extend back to the following no-till corn, he believes. “Sunflower’s deep taproot ‘tills’ the subsoil,” Hoeme observes. “I really think it helps the corn yield under irrigated conditions.”
Biggest challenges? Like any producer, achieving the right population and consistent seed spacing rank at the top of Hoeme’s sunflower production priorities in every season. A new challenge, however, has been the threat from glyphosate-resistant kochia. Grower experience and Kansas State University surveys have found an increasing number of resistant populations — including in the Scott County area.
“When you’re limited on what you can use for burndown prior to planting sunflower, this is going to be a problem; it already is,” Hoeme states. While Spartan has some activity on the kochia, the best answer for now, he believes, is to manage the weed effectively in other rotational crops.
— Don Lilleboe