Soil conservation district looks at benefits of cover crops

CLARA CITY, MINN. -- Winter can come hard to the Minnesota prairie, but never so early that cover crops cannot be used to improve and protect the soil.

Cover crops
Cover crops did not impede harvest in this corn field in Renville County. They continue to improve the soil and its fertility after the crop is removed while reducing the potential for erosion and sequestering carbon. Submitted photo.

CLARA CITY, MINN. - Winter can come hard to the Minnesota prairie, but never so early that cover crops cannot be used to improve and protect the soil.

"We do have the potential here,'' said Holly Hatlewick, district manager with the Renville County, Minn., Soil and Water Conservation District. "It is not just something that grows further south. We have that potential to have that living root on the landscape.''

Hatlewick spoke in December at the Hawk Creek Watershed Project meeting in Clara City. She shared the results of the second year of cover crop test plots in Renville County. The Renville County Soil and Water Conservation District and the Hawk Creek Watershed Project have been working with cooperating farmers.

Along with sponsoring test plots for research, the Renville County SWCD offers a cost-share program to encourage farmers to experiment with cover crops on their own. This year roughly 1,100 acres were seeded, according to Hatlewick.

The watershed project and conservation district want to encourage farmers to plant cover crops.


"You can't just fix everything with cover crops, but they are really a key component to improving soil health, water quality and reducing erosion,'' Hatlewick said.

Cover crops also benefit wildlife, said Jeff Miller, assistant wildlife manager with the Minnesota Department of Natural Resources. They provide feed for wildlife in the winter, he explained.

Whether cover crops catch on as a part of farming practices in west central Minnesota will depend largely on the question raised at the Dec. 2 watershed meeting by farmer Brandon Smith. Do cover crops provide sufficient economic value in this climate to justify the expense and challenges of dealing with them?

The University of Minnesota is working with the Renville County and Redwood County Soil and Water Conservation Districts to collect data from the test plots in both counties to answer that question, according to Hatlewick. There's plenty of data from Illinois and Iowa to answer that question in the affirmative. Studies in the two states have shown that farmers can reduce their nitrogen input costs by 20 to 40 percent with the use of cover crops.

But there is much more to it than just calculating fertilizer costs, according to Hatlewick.

"It's a long-term benefit you have to be thinking of when you're looking at cover crops,'' she said. Cover crops provide a cumulative benefit to a field by improving the fertility of the soil and improving its permeability, allowing it to retain more moisture.

Test plots were planted in Renville County in late summer. They included mixes of rye, clovers, rapeseed and brassica. Ryes and brassicas scavenge nitrogen from the soil, and release it for next year's crop as they decompose. The brassicas, which includes radishes, also opens the soil. The clovers fix nitrogen in the soil.

The cover crops help with the nutrient cycles in the soil by feeding the organisms in it. "Your soil is a living organism just like us so it needs food. It needs to be fed,'' she said.


Cover crops have the added benefit of pest suppression. They help keep weeds and pests in the soil in check. They also help sequester carbon.

The cover crops in Renville County were planted amidst rows of corn and soybeans. A wet fall helped produce cover crops that thrived as the soybeans and corn yellowed and shriveled.

Hatlewick said the test plots demonstrated that cover crops can work in corn and soybean rotations in our area. It was possible to seed the cover crops while the corn and soybeans were growing with minimal damage. The presence of cover crops did not hinder or adversely affect the harvest of the crops.

She noted that cover crops are especially suited for fields where crops are harvested early, such as peas and sweet corn. They are easily seeded once these crops are harvested.

Cover crops can also provide late-season forage for livestock. Hatlewick said there are some opportunities to take advantage of this in Renville County.

The cover crops retained their green mast this year through November. The hard, cold winds of December kill the cover crops, with one exception. A winter rye was planted in one test field. It will hold its green and provide soil protection into the spring, when it will need to be terminated with a herbicide, according to Hatlewick.

She is hoping the conservation district and watershed project can continue a third year of test plots in 2017. Along with answering the economic questions surrounding cover crops, the test plots are helping acquaint staff and local farmers with the real-life challenges that need to be overcome.

Hatlewick and others pointed out a need for specialized devices that farmers can add to their equipment to seed the crops. Due to the time constraints farmers face in late summer and the fall harvest period, there may be a need for independent contractors who could perform the seeding, it was noted at the meeting.


Dean Dambroten of the Hawk Creek Watershed Project made available 10 acres on his farm in Renville County's Wang Township for test plots. He said the Watershed Project has been encouraging some of the area's agronomists and cooperatives that provide field services to farmers to offer cover crop seeding services.

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