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Cover crop trial tries tillage radish

By Heather Thorstensen
hthorstensen@agrinews.com

Date Modified: 11/09/2011 4:39 PM

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MAYER, Minn.— The Schuettes' neighbors probably weren't sure what has been growing for the last few months on a field near Mayer.

Dean Schuette is taking part in a cover crop demonstration project that is trying out tillage radishes. A 17-acre area was planted to spring wheat and harvested this year. On Aug. 10, seven of those acres were planted to tillage radish, seven acres went to a mix of tillage radish, oats and field peas and three acres weren't seeded for a control area.

Schuette intends to follow his normal fertility plan on the three plots as well as on 34 acres that had soybeans on it this year. He'll plant corn in 2012 to the entire 51-acre field and compare the plots' yields to see if any show an increase in corn yield.

Schuette is sharing the cost of the project with Rural Advantage, a non-profit organization with a mission to promote connections between agriculture, the environment and rural communities.

Jill Sackett, a University of Minnesota Extension educator and conservation agronomist with Rural Advantage, said tillage radishes have long roots that can grow up to six feet long. The roots help to break up soil compaction.

"They act as an organic tillage implement," Sackett said.

When the radishes decompose, they increase soil organic matter and leave holes in the soil surface that allow water and air to infiltrate the ground.

This is Schuette's first time trying cover crops. He was intrigued by tillage radishes because he noticed his soil compaction was increasing.

"I'm hoping for better soil health," he said. "I want to see how much it loosens the soil."

Field peas, used on the combination plot, are legumes like soybeans that fix atmospheric nitrogen in the soil that next year's corn will use.

Cover crops in general are good for soil conservation, to prevent losing rain water to overland flow and to sequester carbon, said Mark Zumwinkle, a soil scientist with the Minnesota Department of Agriculture.

Schuette went over his wheat stubble with shallow disc equipment, then used a grain drill with a grass seeder attachment to plant cover crops. The drill planted the oat-pea mix and the grass seeder handled the tillage radish seeds.

He used 9-10 pounds per acre of tillage radish seed on the all-radish field. On the combination field, he used 4 pounds per acre of tillage radish with 70 pounds per acre of an oat-pea mix. He estimates the two plots each cost $30 to $35 per acre to plant.

His largest radishes have grown to more than 12 inches long. A more common size is 8 inches to 10 inches.

The bigger radishes seem to be coming from the plot with the oat-pea mix. Schuette said that could be because radishes there are seeded thinner.

The seed he used came from Albert Lea Seed. Matt Leavitt, a sales agronomist for the company, said they've sold more than 60,000 pounds of tillage radish seed this year.

"We've sold more this year than we ever have," he said.

To be effective cover crops, tillage radishes need time to grow before they're killed by cold weather. It doesn't pay to plant them after Aug. 18, said Zumwinkle, so they don't work well in a crop rotation after corn or soybeans. They would be better suited to following small grains, sweet corn, canning vegetables or corn silage, said Leavitt.

Tillage radishes are part of the brassica family, like canola and forage turnips.

Schuette Family Farm is run by Dean and his wife, Ann, with their son Ryan and his wife, Beth. Their cost-share project was made possible with grants received by Rural Advantage and Practical Farmers of Iowa from the Sustainable Agriculture Research and Education program.