Alongside Kansas State University students and farmers she lectures at seminars, Anita Dille, Ph.D., beckons nature in her arsenal as a weed warrior.
Timing and strategy, while co-existing with regenerative agriculture practices, are paramount in battles to secure moisture and sunlight for crops, said the K-State professor of weed ecology who spoke at Soil Health U, sponsored by High Plains Journal.
Eager as any who make a living from the soil, Dille is on a covert mission to turn farming friends—nutritious soils, photosynthesis and others—against enemies, among them kochia, palmer amaranth (pigweed), water hemp, horse weed and cheatgrass—high on the list of middle America’s botanical villains.
A “tough one” in these parts is bindweed, a species so prolific in Kansas that Dille suggested the hard-to-eradicate plant could be dubbed the “state flower,” during the second annual Soil Health U, Jan. 23 to 24, in Salina.
Key to conquering their foes in an economical and responsible way, she said, is to give cash crops an advantage by limiting what predatory plants need to flourish.
Cover crops help the soil, add to biomass and provide forage for cattle and other critters, but Dille is working on using them to manage weeds by devising recipes for success.
“We need a diversified approach with a focus on preventing weed seed production,” Dille told her audience.
Among the attacks is to “emphasize continual production of weed competitions,” and “understanding the biology of weeds,” according to her presentation.
Choosing the right cocktail of cover crops, and having them flourishing in the field when pesky weeds are most thirsty and in need of nourishment, will help chip away at populations of unwanted plants.
But “there is no cookie cutter approach” to the process, said Larry Manhart, a farmer-rancher in Gove County. Dille concurs.
Rainfall on the Plains, for example, varies from year to year, and from fence row to fence row, requiring producers to adjust their plans accordingly. Droughts are common, but downpours are never out of the question, she agreed, and farmers must be able to adjust on the fly.
“What works in North Dakota isn’t necessarily gonna work in Kansas,” said Joel Suderman, a farmer-rancher in Marion County. He’s been using no-till farming practices for 20 years and cover crops for roughly five years.
“There are years we don’t get enough rain to feed our own cattle,” Suderman said.
What’s most consistent among Kansas’ conditions is its inconsistency, Dille said, and cover crop results can be the same, even in relatively close proximity.
Among the research data Dille shared was a study at the Northwest Research Center near Colby, and the K-State HB Ranch near Hays, both from 2016.
A control plot at Northwest Research Center contained 153 weeds per square meter that produced 212 grams of dry weed plant matter, compared to 258 and 95.4, respectively at HB Ranch.
The plot, with a mixture of triticale and oats, produced zero weeds near Colby. At HB Ranch, the same cocktail yielded 28 weeds and 0.7 grams of dry matter per square meter.
The spring pea, triticale, oat mix gave up 32 weeds and 7.4 grams of dry matter from weeds at the Colby center, but only six weeds and 0.2 grams at HB Ranch.
On the subject of when to plant cover crops, Dille learned that sowing them in the fall “is almost like insurance” against weeds because you have a better chance to getting rain during that time to get the cover crops established. Planting cover crops in the spring and fall saw a 50 percent or higher reduction in the number of weeds.
“Cover crops delay pigweed by a month, pushing the need to control them (chemically) until later,” Dille said, and by then, there is an added benefit of the growing crop being vibrant enough to assume a lead as they compete for sunlight, moisture and nutrients, and choke out the interlopers.
“We need to be thinking of getting a cover crop to have the greatest effects, to smother out the competition for things weeds need: Temperature, moisture, germination and time,” she said.
Some cover crops contain “allelopathic characteristics” that can have detrimental effects on other plants. DIBOA in cereal rye, “can suppress other plants,” Dille said. “Consider the timing of when those plants release those chemicals and when the weeds are germinating.”
Those efforts are working for Mark Heim, a farmer in Leavenworth County.
“We’ve been implementing no-till the last five years and cover crops three years, and we’ve seen a lot of weed seed suppression,” he said. “We’re seeing better use of less chemicals with cover crops, and also cattle to graze. I’m also very interested in building new soil organic matter.”
Dille suggested farmers “think out of the box. Change your rotations and time of planting. Know when key weeds germinate and emerge. There are optimal times to plant different cover crops to get the best control.”
Dille still yearns for more results after her research logs more growing seasons. Researchers have been studying cover crops for weed suppressions for the past decade, but “it’s really revamped up in the last three,” she said. “We’re doing more work on it, still studying and answering growers’ questions.”
Tim Unruh can be reached at [email protected].
