Prairie farmers new to soybeans and corn are still figuring out how to adapt their practices to these crops. Researchers at the University of Manitoba are doing the same.
Dr. Yvonne Lawley is part of three projects examining soil and residue management of soybeans and corn. The first project looked at seeding soybeans into wheat residue.
“As soybeans move farther west, they’re moving into areas which are usually no-till or minimum till areas,” says Lawley. Farmers are tilling to warm soil for seeding, she adds.
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Researchers wanted to know whether soybeans could handle residue. Greg Bartley, a grad student at the University of Manitoba, undertook the two-year project as part of his grad studies. In the fall of 2013, Bartley and colleagues set up several treatments in large plots at the university’s Carman research station, including tall wheat stubble, short wheat stubble, disced stubble, strip till in wheat stubble and a fall rye cover crop.
In 2014 and 2015, soybeans were seeded into each treatment, under ideal temperatures, says Lawley. “We saw some yield differences between the two treatments, but not as dramatic as we thought.”
In 2014, yields ranged from 29 to 39 bushels per acre. Fall rye yielded the lowest. Strip-tilled and tall stubble hit 39 bushels. Discing yielded 35 bushels and the short stubble 34 bushels.
In 2015, researchers used a new row cropper better equipped to handle residue. Lawley says they think they had more hair-pinning the previous year. They ended up with a better fall rye stand in 2015. Most importantly, there was no real difference in yields between treatments — they all hit 53 to 54 bushels per acre.
Lawley sees a good news story emerging from this research. Farmers don’t need to switch out of no-till for soybeans, she says. “But we need to adapt how we manage residue prior to soybeans.”
On-farm research
Researchers are also running on-farm trials looking at the effects of different tillage on soybean and corn residue.
Researchers and cooperating farmers are planting soybeans into corn residue for one project. The other project is looking at either corn or wheat seeded into soybean stubble.
Both trials include treatments using a tandem double discer and vertical tillage. The corn residue trial also looks at strip tillage, while the soybean residue trial includes no-till.
Lawley says vertical tillage treatments include treatments making vertical cuts, chopping residue, and leaving a lot of residue on the surface. But they’re also using vertical tillers the way many Western Canadian farmers do “which is basically to be a high-speed disc. They’re incorporating residue aggressively and doing it fast,” says Lawley.
Each site uses the same vertical tiller to either till aggressively or to leave more residue on the surface, she says. The tillers have a wavy cutting coulter on the front and rolling baskets at the end to smooth and finish the surface.
Researchers didn’t see any differences between treatments in the soybean residue management experiments. They measured crop emergence, plant stand, and yield in the corn and wheat crops grown in the soybean residue.
In the corn residue project, emergence was the same across all treatments, said Patrick Walther via email. Yield was the same at the Winkler site.
Walther said strip till yielded similar to double discing and low disturbance vertical tillage at the MacGregor site. High disturbance vertical tillage yielded a little higher. But the differences were very small, he said, and of low statistical significance.
“This is a sneak peak of one season, so I cannot make any conclusions yet,” he said.
They do see differences in soil temperature and moisture in both the soybean and corn residue trials. The soil is warmer when the residue is buried, Lawley says. The no-till treatments have cooler daytime highs and warmer temps at night than other treatments.
The strip tillage is the most interesting so far, Lawley says. Strip tillage leaves residue between rows but tills intensively in a narrow band in the row. The strip tillage treatments saw high daily temperatures and the lowest night-time temperatures.
Lawley explains the soil was black and shaped into a berm in the strip tillage treatments. That caused it to heat up during the day. But with no residue to insulate it at night, it also cooled off the most, she said.
Lawley thinks farmers might reap benefits from strip till later in the season.
“Roots can get too hot. So having that residue in between the rows can keep roots cooler in the heat of the summer and they can also keep moisture in the ground when it gets dry.” This could be helpful when soybeans demand water late in the summer.
