The nursery’s tillage radish/clover mix choked out weed pressure in this newly planted field. In winter, the vegetative matter creates a barrier to prevent winter weed seeds from germinating and taking hold.
McKay Nursery Company

For 118 years, McKay Nursery Company has been growing and digging trees on 1,800 acres of Wisconsin farmland. That takes a toll.

“Being an old nursery, we harvest a lot of bareroot and B&B material, which takes a lot away from the land,” says Tom Buechel, McKay’s head of production. “You start to lose a lot of soil properties.”

McKay’s land is mostly clay, which causes several issues. Compaction and erosion are problems that are exacerbated by traditional nursery production methods.

These challenges prompted the nursery to look for new solutions to cushion the land using a non-traditional cover crop. Annual tillage radishes are currently being used in agronomic settings to reduce soil compaction, hold nutrients, reduce runoff and reduce herbicide applications. Their ability to aerate the soil well below plow depth levels has intrigued farmers and opened the avenue for uses in other industries, including the nursery setting.

After visiting an agronomic farm with his local extension, the wheels started turning for Buechel. He wrote a grant for the Wisconsin specialty crop block grant program, titled “Using a novel cover crop blend to increase the sustainability of ornamental plant nursery production.” The project was awarded $35,000, and Buechel began work with the support of the Wisconsin Nursery Association and Bill Hoch at Montana State University, and Brent McCown at the University of Wisconsin-Madison. McKay picked three species that sometimes cause them fits to test the effectiveness of the cover crops — honey locust, oak, and spruce.

In the first year of the project, while the clover was being established, the radishes developed a dense canopy to suppress weeds and strong tap roots, breaking up hardpan and mining nutrients from the subsoil. When the radishes died in the winter, they decomposed, releasing nutrients and organic matter to help sustain the trees. The perennial clover took over as expected in the second year, in the absence of the winter-killed radishes. The clover formed a mat, reducing other weed pressure and creating an environment for beneficial insects. Buechel says there has been noticeably less erosion in the cover crop rows.

McKay is in its third and final year of the project, and the data collected suggests the potential benefits of this cover crop blend in nursery production far outweigh the expense of planting. Buechel says the areas using the radish/clover mix had improved plant health and appearance, reduced disease, lower chemical and labor inputs, and no reduction in plant growth.

In fact, caliper measurements taken on the oaks and honey locust revealed slight increases in the diameter of trees in the cover crop treatments.

“We’re seeing trees’ caliper a hair bit heavier, which has the potential to shave some time off of growing as well,” Buechel says.

This result differs from previous studies that found reduced growth in production fields using other species of cover crops. It’s a particularly important finding, because reduced growth has been one of the major barriers to the widespread use of cover crops in the nursery industry.

“One of the big advantages of cover crops is, because you’re encompassing a fairly big area, your chemical usage goes down to band treatment within the tree row,” he says.

McKay performed a chemical cost analysis, and found the cost per acre was halved in the cover crop rows.

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