What Mike Werling does when he combines more than a dozen species of cover crops into one seeding mixture isn’t new. Werling, of Decatur, Ind., is one of several veteran no-tillers who add various cover crop species to speed up the return of healthy soil, especially on challenging fields.
Dave Brandt of Carroll, Ohio, began no-tilling in 1971. He started using cover crops in 1978, long before the soil health movement took on a life of its own. When Brandt visits farmers across the U.S., he talks about adding in more species of cover crops as you gain experience to capture more benefits. He also talks about selecting the right variety of each cover crop for your area.
Roger Wenning of Greensburg, Ind., also experiments with mixtures of multiple species of cover crops. Brandt has visited his farm, and the two have stood in cover crop plots of multiple species, explaining to crowds of farmers why they believe so strongly that cover crops improve soil health.
See and believe
If you ever go to a field day on Wenning’s farm, there will be a soil pit. Wenning loves to dig pits where cover crops have grown so others can see the deep rooting power of cover crops for themselves.
Jeremy Henry of Connersville, Ind., hasn’t been no-tilling or using cover crops nearly as long as these other farmers, but he’s fast becoming a true believer. He recently held a field day, complete with soil pits, in two different types of cover crop plots — one with broadleaves growing on top and one with grasses growing.
Henry hasn’t worked up to trying cocktail mixes as extensive as what Werling and the others use, but he’s branching out, starting with a base of annual ryegrass, cereal rye and radishes, and adding more species as he goes.
Why cocktail mixes
"My goal is to get four types of cover crop species out there working for me,” Werling says. “Each provides a different benefit. Several species root deep. All protect the soil in the fall, although ones that typically winter-kill won’t provide as much protection in the spring.”
Some are better at capturing nitrogen left over after the crop season than others, Werling notes. Some form nitrogen if they can grow long enough in the spring. Various species bring along their own specific types of organisms that work in the soil, he says.
Werling’s 14-way mix, which he seeded in 2016 in some fields, included legumes, grasses, brassicas and broadleaves.
Here’s a breakdown of what he used, with pounds per acre of each one included in the mix.
1. Legumes: Cowpeas, 8 pounds per acre; sunn hemp, 2; Cahaba vetch, 5; yellow sweetclover, 2; crimson clover, 2.
2. Grasses: Oats, 4 pounds per acre; sorghum-sudangrass, 4; pearl millet, 2.
3. Brassicas: Radishes, 0.5 pound per acre; rapeseed, 0.3; turnips, 0.3.
4. Broadleaves: Buckwheat, 5 pounds per acre; sunflowers, 1; flax, 2.
That totals up to 38.1 pounds per acre. This past year, he substituted soybeans for flax. “My goal is to seed 40 to 44 seeds per square foot,” Werling notes.
Werling grows oats because there’s a good market in his area. He often seeds this cover crop mix in late July or early August, after oats. Others seed it in late summer, after wheat. Some species must be seeded earlier than others to get enough fall growth to provide benefits.
Seeding cover crops can be challenging, especially if it’s a mixture with various shapes of seeds. Werling has used an air seeder available for rent in his area.
Henry, who uses simpler mixes, built seeders: one for his corn head and one for his grain head. He’s limited on time because he works off the farm, so he seeds off the combine.
Bill Johnson, Purdue University Extension weed control specialist, hasn’t necessarily been a fan of cocktail mixes. However, he’s beginning to see where they might fit.
“With multiple species in the mix, you have better odds that at least some will grow and provide a decent stand,” he notes. His concern about stands relates to possible herbicide carryover from herbicides applied in corn and soybean rotations.
Cover crop species vary in plant-back restrictions after various chemicals. With multiple species in the mix, you stand a better chance of having some species that won’t be affected by active ingredients in herbicides that still might be present in the soil, Johnson observes.
Soil pit lesson
Dena Anderson, with the USDA Natural Resources Conservation Service, jumped into the pit at Jeremy Henry’s field day. Before people arrived, she marked earthworm channels with orange golf tees. She marked rooting depth with green golf tees. One pit was dug across a plot of radishes and other species, including various clovers. Henry seeded these plots in late summer.
Anderson found roots several feet deep in the soil. The roots came from cover crops, because they were the only thing growing there, she says.
She pointed out how rooting depth varied, and how soil biology that developed around roots also varied. There was definitely a difference between radishes and clover, she notes. Yet both were providing benefits.
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