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Published November 18, 2013, 11:41 AM

Benefits of cover crops

Southwest Minn. farmers see the benefits first hand.

By: Julie Buntjer, Forum News Service

LAKEFIELD, Minn. — When Jerry Ackermann had some of his crop drown out this spring, he opted to plant purple-topped turnips and tillage radish on the prevented plant acres.

These are the same crops he’s tried in each of the last three years to seed into fields of standing corn and soybeans to provide cover during the winter months and break up the hard layers in the soil.

On Nov. 13, during a cover crops field day at his farm, Ackermann showed how the turnips and radish he planted in early July grew to mammoth proportions, while a variety of speakers discussed how those plantings are helping to improve soil health, soak up nitrogen and increase rain water infiltration.

Ackermann is one of several farmers in the area experimenting with cover crops. His reason for doing so, he told the more than 40 people in attendance, is because “I don’t want to see any nutrients get away from me.”

Jerry Perkins, on the other hand, says he has planted cover crops because they feed the microorganisms in the soil.

Both Perkins and Ackermann participated in a Heron Lake Watershed District program this year in which the district received a National Wildlife Federation grant to assist farmers growing cover crops. In early September, they and a few other farmers in Jackson and Nobles counties aerial-seeded fields of standing corn and soybeans with cover crop seeds such as the purple-topped turnips, tillage radish and cereal rye, among others.

“The roots are really loosening things up,” Ackermann says of the impact he’s seen thus far with the cover crop plantings.

With some of his acres enrolled in the Environmental Quality Incentive Program, Ackermann plans to continue cover crop plantings for at least the next five years.

“We put out cereal rye, which doesn’t grow that much in the fall, but it comes up in the spring,” Ackermann says.

“When I look at those yield maps, I’ll be doing more next year, I can tell you that,” he adds, saying he’s considering cover seeding all of his soybean acres next year in cereal rye.

Andy Nesseth, of Extended Ag Service in Lakefield, has been doing soil grid testing on the Ackermann farm in recent years, and notes that while there were no significant changes in fertility on the soil where cover crops were planted, there were more soil nitrates present. From 2012 to 2013, the amount of nitrates in the soil went from 78 pounds to 208 pounds per acre.

“That’s quite a difference,” Nesseth says.

The measurements in 2013 were taken about 2½ to three weeks later than the 2012 measurements because of weather issues, which could have accounted for some of the added nitrates in 2013. Still, Nesseth says there were visible improvements in soil tilth and water structure on the land where cover crops were grown.

Challenges

Some of the greatest challenges noted Nov. 13 with planting cover crops is relying on Mother Nature to bring timely rains in the fall to get the cover crops established. To perhaps take advantage of rains earlier in the growing season, one attendee asked whether the cover crops could be planted earlier than the Aug. 10 guideline.

Ackermann says there could be problems if crops are planted earlier because of the canopy of corn and soybeans and the lack of sunlight that would reach the seedbed to promote growth.

Timing of cover crop plantings is one of the greatest obstacles, but Jill Sackett, a University of Minnesota Extension educator who has worked with cover crop management for several years, says seed selection is also important.

“The more diverse plants you have out there, the more diverse your soil microorganisms are going to be,” Sackett says.

That said, seed can be rather expensive. For instance, tillage radish seed currently costs $3.45 per pound. It’s recommended that the radish seed be planted at a rate of 8 to 15 pounds per acre. Meanwhile, winter rye is about 34 cents per pound, and oats are 42 cents per pound.

“If you have a mixture of cover crops, then chances are you’re going to have something grow on the site,” Sackett says, adding that farmers should consider both warm and cool season crops. “Almost anytime you have a cover crop, you’re going to decrease soil erosion.”

Management of cover crops in the spring can range from spraying to tillage, although as Sackett pointed out, crops such as the tillage radish leave little residue in the spring.

“There will be basically nothing left next spring,” she says. “That root is mainly water, and the freeze-thaw is going to get rid of it. Earthworms like it, too.”

Sackett says planting cover crops isn’t something farmers should do “on a whim,” but instead should be researched and recorded if implemented.

Tony Thompson, one of the farmers in attendance who has experimented with cover crops, says, “Every time we’ve measured yield, we’ve had a yield cost. We know there are benefits, but they’re hard to measure.”

Stephanie McLain, Natural Resources Conservation Service District conservationist, says cover crops are a tool and something farmers should consider. Not only will cover crops improve soil health, but by keeping a living root in the soil for as long as possible, she says it improves biology for the bugs that live in the soil.

“We need to diversify,” she says. “The more diverse roots in our soil, the more diverse biology we have.”

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