The Agronomists, Ep 99: Managing residue ahead of soybeans with Horst Bohner and Dr. Yvonne Lawley

If soybeans need a cozy warm seedbed to get rolling, tillage is a must, right? Well, no and no.

Emerging research suggests that cool soil isn’t nearly the detriment to soybean growth once thought, which also means working an entire field for spring “warm up” isn’t required either. To dig in to managing residue ahead of soybeans, we go to Horst Bohner, with the Ontario Ministry of Agriculture, Food and Rural Affairs, and Dr. Yvonne Lawley, with the University of Manitoba, to get the answers.

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This episode is brought to you by ADAMA Canada, FMC Pre-school, and the Soybean School!

Summary

• It’s episode 99! The great one? Maybe, we’ll see
• Soybeans can really surprise
• We underestimate new genetics at times, Horst says
• Manitoba had its surprising yields last year, too
• So let’s dig in — do soybeans need “black dirt”?
• Fall field work vs. spring
• In Ontario, nearly want a drought in April
• For Manitoba, fall field work is common, but need enough residue to keep soil in place
• It doesn’t matter where the beans grow, rain during pod fill makes or breaks yield
• Residue holding moisture late in the season is more of a Manitoba issue
• Big question: should beans go in before corn?
• It depends! But there often is an early window that can be the biggest yielder
• What about cold soil?
• Cold soil is not nearly the threat it was thought to be
• A cold rain directly after planting isn’t good, but cool temperatures shouldn’t stop you
• In Manitoba, what about before canola?
• Flea beetle risk might make it more common
• Soy or corn after canola might be delayed early but as soils warm up, they’ll catch up
• A poor-looking soy crop early on isn’t necessarily a bad thing
• Early planting in to dry soil, even if it’s cool, is ok
• Horst is hooking up the tractor next week — and he’s going to plant beans in the first good window (maybe March?)
• Tillage does warm up soil, but how much is enough, too much?
• The sweet spot (of keeping residue on the field and warming up the ground and keeping residue out of the row) of strip till really did what it should
• This was done in the fall, vs spring tillage
• Spring tillage leaves more residue for the fall and spring, but can cause a crunch in the spring
• Plant stands in tilled fields can be stronger/higher, but it doesn’t always translate to yield
• Clip 1 – Soybean School – with Shawn Conley
• Does adding N in the spring speed residue breakdown?
• Does adding N in the spring boost soybean growth?
• Basically, spring applied N OR a tillage pass basically improves yield by 3 ish bushels/ac
• Nitrogen accounting: remember adding N means the bean will fix less, potentially
• Push those beans to make their own!
• Because less nodulation early can hurt late in the year where the plant needs to draw that N, Yvonne says
• Leave tall stubble (of wheat) ahead of beans for excellent results (about 30-40 cm)
• The stubble doesn’t create the mat on the ground and mess up the row
• Residue and trash in the row is a combine problem, too
• But good row/trash cleaners or getting between last year’s corn rows solves many issues and gets those beans rolling, without working the field
• What about low populations?
• Low pops can make plenty of beans per plant, but doesn’t make up for all the lost friends
• And wide rows or low pops can create weed issues
• Fall rye — excellent fleabane control, but can negatively impact soybean establishment and yield if terminated too late
• Stop working residue after harvest! It’s not needed. Get a cover crop on, too please

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