Wet weather pushes soybean planting into tall, growing cover crops

  • Published: Wednesday, May 22, 2019

COLUMBIA, Mo. – Cool, wet weather is forcing more farmers to consider how to plant soybeans into tall, mature cover crops this spring.

This might be the year that farmers want to consider “planting into the green,” says University of Missouri Extension nutrient management specialist John Lory. Planting into the green refers to no-till planting of soybean into growing cover crops.

Many growers terminate cover crops early in the season when the cover crop is less than knee-high. This lets cover crop biomass break down quickly before planting. “We’re well past that this year,” Lory says.

Lory, who heads the Missouri Strip Trial Program, says the program’s research shows only a small yield loss when planting soybean into the green. Strip trials from the past three years show a 1-2 bushel per acre loss at some locations. The yield differences could be attributed to factors such as voles or poor seed-to-soil contact going over terraces, he says.

Farmer cooperators in the Strip Trial Program have planted soybean into cover crops that were waist- to head-high with minimal yield loss. “I had never seen this done until working with farmers in the Strip Trial Program,” Lory said.

MU Extension specialist Greg Luce, a member of the strip trial team, agrees. He works with farmers who have practiced planting soybean into the green with good results. Cereal rye is the No. 1 seeded cover crop. Some farmers report better results from planting into green rather than dead residue. “Planting soybean prior to terminating the cover crop has proved to be successful for many growers,” Luce says.

Many growers are most comfortable with terminating the cover crop early then waiting a couple of weeks before planting. However, this year’s extremely wet field conditions have forced farmers to consider planting into living cover crops, Luce says. In areas with claypan soils, this may help the soil dry out and warm up quicker. Late termination before planting may result in a mat of tough, dead cover crop residue that will slow drying of the field and might be harder to plant into than the live cover crop.

Most farmers adjust their methods from year to year, field to field, as they learn what works for their operation, says Luce. As growers gain experience, they tweak their management to get the best results from the cover crop.

Planting into thick or tall green cover crops might require some adjustments to the planter and attachments, says Charlie Ellis, MU Extension field specialist in agricultural engineering. Farmers with older equipment may struggle with heavy residue.

Ellis makes these recommendations:

-Don’t get too far ahead of planting with the sprayer. Only spray what you can get planted. If you spray and cannot plant, the dying vegetation does not remove moisture from the ground. It loses stem strength, falls and creates a mat on the soil. The mat will prevent sun and wind from drying the soil.

-Check planter disk openers and closing wheels to make sure they are in good condition to no-till into cover crops. Depending on cover crop conditions, you might need different styles of closing wheels.

-Planters need to be leveled for good depth control and closing wheel operation.

-Check seeding depth frequently and plant soybean deep enough to get good seed-to-soil contact and seed slot closure. Ellis suggests a 1.5-inch depth.

-Use GPS-guided equipment if you have it available. Marker tracks on older equipment may be difficult to see.

-Limit planting speed to prevent excessive row unit bounce and variable planting depth.

MU Extension weed scientist Kevin Bradley offers information on spraying cover crops in “Burning Down Cover Crops Effectively,” available as a downloadable PDF at weedscience.missouri.edu/extension/slideshows.cfm.

“Don’t let your decision on whether to burn down your cereal rye cover crop before or after planting be based on a belief that we can’t kill it with herbicides—because we can,” says Bradley. “We still have the ability to control cereal rye that is heading out with glyphosate products like Roundup or other mixes such as glyphosate plus clethodim.”

The Missouri Strip Trial Program (striptrial.missouri.edu) is a collaboration of farmers, MU Extension, and the Missouri corn and soybean merchandising councils and their checkoffs. If you are interested in strip trials or want more information on managing cover crops, contact your local extension agronomist or agricultural engineer.

Writer: Linda Geist

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John Lory

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