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Cover-up grows in popularity

Seeding cover crops to enhance basic rotations is a new frontier in Nebraska cropping systems, according to its adherents. Interest has grown in the past few years in trying seedings of one or two cover crops or a cocktail blend of several after wheat harvest in summer or even after taking off soybeans or corn in the fall. As yet, acreage remains limited.

At a glance

• Farmers build soil by using cover-crop cocktails.

• Blends of grasses, legumes and brassicas are used.

• They talk of multiple benefits, including capturing nitrogen.


“We are trying to provide a healthier soil for crops,” says Brian Berns of Bladen. “Cover crops do that by increasing soil biological activity and increasing organic matter. The key is having something growing for more months of the year. We’re feeding the soil microbes, bacteria and fungi, even the earthworms.”

Brian and brother, Keith, are no-tillers who’ve experimented with more types of cover crops than anyone in the state. They used a USDA Sustainable Agriculture Research and Education grant to do most of their evaluations.

They market a base seed mix, called Green Cover Soil Builder, which is a 10-pound-per-acre blend of grasses, legumes and brassicas. “We like a balance of these plants for the diversity and benefits they provide,” Brian says.

The Bernses’ base blend consists of sorghum-sudan, a grass; lentils and common vetch, legumes; and oilseed radishes, canola and a hybrid brassica. “You can add to this blend seed from your own farm, such as oats, sorghum or soybeans,” Keith says.

The mix increases soil biological activity and also provides forage for livestock. Plus, the legumes can fix nitrogen, while the brassicas scavenge any excess soil nitrogen, and their tap roots break up compaction and leave soil cavities that increase water infiltration.

The best route to success, at least for cover-crop blends, is planting them into wheat stubble, giving them a longer growing season for establishment.

Seeding a blend after soybeans or corn in the fall is riskier because of the shorter window for establishment, but it can still work if moisture conditions are adequate.

Winter annual grasses, such as wheat and cereal rye, provide erosion control and also can scavenge excess nitrogen. Then the following spring, after a burndown herbicide, they decompose and release nutrients for the next crop.

While cover-crop cocktails are relatively new, use of single or double cover crops isn’t. Producers chopping silage, particularly on light-textured soils, have for years seeded rye, wheat or triticale as a soil cover and for winter pasture, says Paul Jasa, University of Nebraska engineer. A number of cattle producers have planted turnips or other brassicas for forage.

Seed corn growers, who harvest earlier than other corn producers, have used brassicas, including turnips and radishes, to scavenge excess nitrogen. That’s intended to prevent leaching from fields that often are over-fertilized and over-irrigated, particularly if it’s seed corn rather than a regular corn-soybean rotation.

“Today, there is increasing interest in cover crops, but we’ve not established trends or clear-cut recommendations as to the best systems or best mixes,” Jasa adds.

The Berns brothers list the following benefits cover crops provide for no-tillers:

• protect from wind and water erosion

• build soil organic matter

• aid soil structure and capture carbon

• feed earthworms and soil microbes

• provide root structure to help precipitation penetrate deeper into the soil

• fix nitrogen with use of legumes

EQIP offers cover crop cost-sharing

Opportunities exist through Natural Resources Conservation Service programs to obtain a cost-share payment to apply cover crops.

Under the general Environmental Quality Incentives Program, there are two options, according to Brad Soncksen, assistant state conservationist for programs in the Lincoln office.

1. Seeding cover crops after a summer-harvested crop for erosion control and to improve soil quality.

2. Seeding cover crops as a seedbed preparation practice to control erosion prior to seeding grass in the fall.

Contact your local NRCS office for information about these programs and the types of cover crops recommended.

There was a Feb. 1 cutoff date for 2010 EQIP funds, but the program will take applications for later sign-ups.

NRD program tests aerial interseeding

To test the interseeding of cover crops into growing soybeans, the Lower Elkhorn Natural Resources District created an incentive program that includes 15 cooperators, each enrolling 40 acres. It specifically involves aerial application of a cover-crop cocktail — three to four legumes and winter wheat or cereal rye — in late August or early September, about the time of soybean leaf yellowing.

The three-year program ends in 2010, says Dan Gillespie, a no-till farmer and Natural Resources Conservation Services staffer in the Battle Creek office, who assisted the NRD.

“The goal of the mix of legumes is to utilize any nitrogen left unused by the harvested cash crop and then fix nitrogen in the spring after the residual nitrogen has been sequestered,” Gillespie says. “Rye also takes up nitrogen.”

With above-average rain the past few years, unused nitrogen has leached below the soil profile, and the cover-crop cocktail can prevent that leaching, he says.

The legumes need about 90 days before an average hard frost to do their work, so that’s why they’re seeded into growing soybeans rather than drilled after bean harvest. “We are attempting to see what cover-crop system works best for a corn-soybean rotation,” he says.

In the spring, Roundup is applied to kill the rye and any other overwintering legumes that were used.

Cooperators had moderate success establishing the cover in 2008. However, last year results were disappointing based on several factors — including lack of sunlight and warmth in the fall, wet soils in some areas, and dryness elsewhere. “This will be one of those three years out of 10 that I estimated it wouldn’t be a success,” Gillespie says.

In 2008, lentils were part of the legume mix, but were dropped in 2009 because they failed to establish well as a surface-applied seed. Oil-seed radishes and canola are other legumes in the mix.

The NRD paid roughly half the per-acre costs of $45 to $48, with seed and aerial application around 60% of the cost and the burndown herbicide and its application the remainder.

Cooperators encountered a few problems finding aerial applicators at the right time.


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COVER TESTERS: Brian (left) and Keith Berns have experimented with 17 cover crops and eight cover-crop mixes.

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DIGGING IN: Saline County Extension educator Randy Pryor shows an oilseed radish just pulled from the ground. Its taproot helps reduce soil compaction and leaves cavities for water infiltration.

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A HANDFUL: This is a Green Cover Soil Builder mix, from the Berns Brothers in Bladen, that includes seeds of common vetch, lentil, sorghum-sudan, pearl millet, oilseed radish, turnip, canola and hybrid Winfred Brassica.

This article published in the February, 2010 edition of NEBRASKA FARMER.

All rights reserved. Copyright Farm Progress Cos. 2010.