For dryland crops, maximize ‘free’ water
Because of the heat, frequent dry spells, low-humidity and high-evaporation conditions in northwest Kansas and southwest Nebraska, farmers like Dietrich Kastens need to harvest as much “free” water as possible. At Kastens Farms in Herndon, Kan., where only 21.5 inches of rain fall annually, everything is about effective use of precipitation in this predominately dryland operation.
“We need to harvest water, not sunlight. We have plenty of the latter out here,” says Kastens, referring to the High Plains. He farms with his father, Terry (a retired Kansas State University ag economist), his uncle, Gary, and three employees in Rawlins and Cheyenne counties in Kansas and Hitchcock county in Nebraska. “Keeping rainfall where it falls is key to our region. Our yields are based on the percentage of water captured.”
At a glance
• Farmer conserves moisture for dryland crops in Nebraska and Kansas.
• Farm uses no-till, and wheat stubble is key in rotations.
• Use of new technologies also helps them save resources.
That means residue is king. The operation has been entirely no-till for 10 years.
Flexible rotations also are part of their systems approach to using free water efficiently. The base rotation consists of wheat, corn, sorghum and peas and, in some cases, wheat, corn, sorghum, fallow wheat, corn and peas.
“An excellent wheat crop is the foundation of our rotation,” Kastens says. “The wheat stubble year is critical. With high-yielding wheat in a rotation, we can still see wheat residue in sorghum fields three years down the road, and the field peas have allowed us to eliminate fallow, while preserving the yields and residue volumes associated with fallow wheat.”
Additionally, a stripper header that’s been used since 2005 leaves taller, more uniform wheat stubble.
Half of the acres are in a spring crop every year and half in fall crops to take advantage of year-to-year moisture variations.
Using yield models and moisture measurements from KSU research farms in the western part of the state, Kastens estimates that they can obtain a 100-bushel corn yield with 40% moisture efficiency. That’s using 40% of the moisture that falls from preplanting through harvest.
“That’s OK, but not necessarily good. If we can push that up to 60%, we could realize 148-bushel corn on average, based on the models,” he explains. “But there are challenges in moving up. First we have to figure out where we’re losing moisture and then how to conserve more of it.”
With plenty of residue, runoff and drainage aren’t problems. The culprits are evaporation, especially in the short fallow period behind wheat, and the consumption of water by weeds.
Kastens Farms is experimenting with several cover crops for those typical fallow periods. For instance, in the fallow months after wheat harvest in early July, much of the summer remains, and ultimately only 30% to 40% of the precipitation is stored annually, with the remainder lost to evaporation.
“Perhaps rather than leaving it fallow, we’d be better off growing something during this window. A shallow-rooted millet or a pea crop could take advantage of 60% to 70% of the moisture that would otherwise be lost. And if either crop uses less than that, the remainder might be stored and protected by the cover crop shading. The additional residue and macro-pores created with this crop might make the overall system more water-use efficient over the long run without sacrificing short-term yields,” Kastens says.
Kastens Farms also has focused on increasing cropping intensity. “In traditional wheat-fallow rotations, a piece of ground only has a crop one out of two years. Eco-fallow, with wheat, corn and fallow in rotation, is 65% crop intensive. A crop every year is 100% crop intensive,” Kastens says.
He adds, “We made huge gains in water-use efficiency over the past 20 years through these practices.”
They also place a heavy emphasis on science and technology adoption.
Autoguidance, section control on planters and sprayers, variable-rate seeding, and fertilizer are part of their cropping program. “Minimizing overlap in planting or spraying by shutting off planter units or nozzles also help us use soil moisture wisely,” he adds.
Kastens Farms is an ongoing experiment in a systems approach to maximizing crop production and managing input costs, using innovative rotations, no-till and the latest in ag technologies, all ingredients in using precipitation more effectively.
This article published in the February, 2012 edition of NEBRASKA FARMER.