How do okra, squash and sweet clover for dinner sound? For your soil, that is. These two common vegetables and old-fashioned legume are gaining new acclaim among cover croppers, said Keith Berns, co-owner of Green Cover Seed, based in Nebraska.
Each one brings something new and valuable to the table, from the okra plant's compaction-busting roots to the bee-attracting pollen of the Hubam sweetclover. The vegetables are especially alluring to adventurous farmers, Berns said. "They're not only good agronomically for the soil, but it's also very rewarding -- or just fun -- to go out to your cover-crop field and bring back something you can eat at supper time."
Okra can be a divisive vegetable among its human consumers -- people either love it or hate it. But its relationship with your soil is far less controversial, Berns said.
"It has a very, very deep taproot for breaking up compaction layers, similar to sunflowers but even better," he said. "It's exceptionally heat- and drought-tolerant. Okra also stands very well during the winter, with a durable stalk that's excellent at catching snow." It can even provide some feed for cattle, which can eat the pods and strip the leaves, he adds.
Berns purchased the first okra seed for the company to sell in 2015 and promptly sold out of all 10,000 pounds of his stock. In 2016, cover croppers cleaned him out of 50,000 pounds. The vegetable has proved so popular with customers, the company planted 70 acres to harvest just for seed for the 2017 season.
Okra is well-suited to small-grains rotations, such as wheat or oats, where farmers can get it started in the summer. As an indeterminate species, the aggressive and fast-growing plant can start producing its edible pods within six weeks and will keep growing up until the first frost.
The resulting stalks can tower up to 6 feet tall and trap much-needed snow cover and moisture during the winter. "For guys out West who are hot and dry, it's a very good addition to a warm-season [cover-crop] mix," Berns said. A little goes a long way. Berns recommended adding just a pound or less per acre of okra to your mix.
If you want to eat those spiny okra pods, grab them early when they're just 3 inches long and still tender. The pods turn hard and fibrous as they grow.
THE THIRD SISTER
The synergistic and agronomic benefits of growing squash alongside beans and maize was so well-known to Native American farmers that they called them the "Three Sisters."
"We've been planting corn and beans for years, but no squash," Berns noted. "So we joke that we've finally found the long-lost third sister."
Adding a squash cover crop to a commercial corn and soybean rotation is probably not possible because the squash grows best in summer months. However, it fits nicely into warm-season mixes after small-grains crops, just as okra does, and requires less than a pound per acre within a warm-season mix to do its job. "It has an amazing ability to fill in blank spots in a field," Berns said of the plant's sprawling vines. Cows should find the fruit quite edible, and it won't survive the winter, so volunteers aren't likely to be a problem.
Berns stumbled across the idea of using squash species as a cover crop only by accident. A vegetable seed supplier had unintentionally mixed two different types of squash species in a seed shipment, making the resulting mix worthless to vegetable growers. Berns swooped in and bought the mix, which included zucchini and a type of Lebanese squash.
He liked the resulting cover crops so much, he added it to Green Cover Seed's stock. "As a totally different plant type from the typical cover crops, you're really adding a lot more diversity" to your soil community, Berns said of the unique squash mix.
Most sweet clovers are biennial, meaning the seed requires an overwintering period before it will bloom and won't provide full growth and blossoms until its second season. That makes them tricky to use as cover crops. Enter Hubam annual sweetclover, a white-flowering legume that blooms annually and thrives in the Deep South.
"Most clovers do really poorly in the heat of summer, but because this is primarily a Southern clover, it's been selected to handle the heat and does very well in Texas, Nebraska and Kansas summers," Berns noted.
He recommended adding it to warm-season cover-crop mixes where it will stand out for its fast growth, nutrient-scavenging deep roots, abundant forage crop and the addition of nitrogen to the soil. The clover has a long history in the U.S.; Nebraska farmers recognized the value of sweetclover species in soil improvement for beet and potato crops as far back as the mid-1900s.
It's regaining popularity now because its fragrant white flowers attract both pollinators and beneficial predatory insects. "Beekeepers love this clover," Berns said.
The Hubam sweetclover makes a good addition to pollinator strip seed mixes, he said. "There's a lot of interest in planting pollinator strips through the middle of fields or along the outside edges, and farmers need things that are going to bloom and flower, and attract insects. Hubam is a really important part of that, since very few clovers bloom in summer."
Adding a new cover-crop species to your operation or larger cover-crop mixes can be tricky. A number of institutions have created cover-crop calculators that help growers determine how much seed is needed for any given species, taking into account your nutrient or soil-health needs, as well as geography, cash crops and soil types. You can find two such calculators from Green Cover Seed at http://bit.ly/… and from the Midwest Cover Crops Council at http://bit.ly/….
Emily Unglesbee can be reached at Emily.firstname.lastname@example.org
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