Ontario Diagnostic Day 1: Soybean planting depth and planting date for corn

The annual Ontario field crop diagnostic days held at Ridgetown, Elora, and Winchester are going virtual!

The organizing committees of these three highly successful in-field education and learning events are again partnering with crop researchers and extension, along with support from RealAgriculture and a host of sponsors in 2020.

We would like to thank the following sponsoring organizations: The Grain Farmers of Ontario, Agris Co-operative, BASF, Bayer/Dekalb, Corteva/Pioneer, Great Lakes Grain, The Mosaic Company, RealAgriculture, and Syngenta.

“COVID-19 has created many unique challenges especially when it comes to delivering in-person events and the safety of all those involved in these events is our foremost concern,” says OMAFRA field pathologist Albert Tenuta. “As a result, we have had to make the difficult decision to cancel these in-person events this year.”

The virtual video series gives the OMAFRA field crop team and research colleagues from the University of Guelph an opportunity to deliver diagnostic insights in a new way, sharing what attendees have come to expect from Diagnostic Days at Ridgetown, Elora, and Winchester. As part of the offering, continuing education credits (CEU) will also be available.

Check out the first episode featuring Horst Bohner and Dave Hooker (more about the series after the player and a full summary of the episode is below)

The series will consist of eight, one-hour episodes starting Wednesday, July 15. A new episode will then be published every two weeks, Wednesdays at 9 am Eastern through to October 21, 2020. Each episode will highlight a general field crop agronomic theme and will be available here on RealAgriculture for viewing, as well as the OMAFRA Field Crop News website. All episodes will also be available in our main podcast feed.

Historically, these in-person diagnostic days have provided some of the best opportunities for certified crop advisors (CCAs) to acquire a broad range of CEUs.

Certified crop advisors will be able to collect eight CEUs by registering for the event at: https://bdc.ridgetownc.com/useservices/conferencemanagement/southwest-crop-diagnostic-days/. Registration is required for processing CEU credit requests and can be done up to December 1, 2020. A CEU code will be provided at end of each episode.

The videos are free and registration is not required for Grain Farmers of Ontario members, media, and those not seeking CEU credits.

Registration Fees  — Only required if applying for CEU Credits

·      $100 (includes HST) for eight CEU credits. A receipt/confirmation email will be provided.


  • There’s a saying regarding field tours: “Your mind can only absorb what your feet can endure.” We sincerely hope that by offering these one-hour field tour stops, at home, you can save yourself some sunscreen, bug spray, and tired soles.
  • On this episode, OMAFRA soybean specialist Horst Bohner, tackles planting depth is the first video for Diagnostic Days, Why is it still a debate? In the soybean world, establishing a good even plant stand is a lot tougher than we might think, and a real issue in the SW of Ontario.
  • An inch an a half seems to be the best average depth regardless of planting date. One caveat to this, the soybean must be planted into moisture!
  • Plots: On June 12, at the two and half inch depth, not a good stand, not as advanced, one and a half inch depth, nice stand, second trifoliate, closer to the corn row, still enough down pressure from the seeder to get them in a good seedbed, “need to keep beans close enough to the surface to get them out of the ground.” May 22 planting date, June 9 planting date: 2 and a half inch, 1 and a half inch, 2 and half inches is still too deep
  • Bohner concludes that soybeans shouldn’t be planted deeper than an inch and a half, two inches maximum
  • Is there a change in strategy for small seed size and depth? Inch and a half is the right depth for soybeans across the board.
  • Study out of MI, showed 70 per cent of soybeans drilled were not at their intended depth. Part of this whole conversation is how do we get them at the intended depth? How do we get it more consistent? Get out there and check!

NEXT UP: Dave Hooker, associate professor at the University of Guelph-Ridgetown, on corn planting date

  • What are the factors that might be responsible for a lower yield in corn as compared to optimal? 98 per cent of maximum yield
  • When should our first field be planted? What’s the yield potential of the last field planted? Don’t worry about losing yield from the first field planted!
  • Optimum yields planting date: April 24 and May 15 for most of Ont., year to year differences are very real, want to take advantage of a situation or condition from one year to the next, maybe an earlier planting opportunity
  • Risk management decisions: early planting corn risk is into cold soils, cold imbibition injury, when the seed begins to bring in its first water, crosses the membranes, cold water can damage the membranes, physical process, membranes can repair themselves, but the damage can last for a long time
  • Plots: July 2, field was planted on April 7, planted into soil when the next 7 days where daytime high never got above 10, cold nighttime temps, inch of rain on the evening that it was planted. Perfect conditions to test out the theory: soil temp situation, 30 to 31,000 plants per acre, target was 37,000. Not a bad final stand, missing plants in the row, not as uniform
  • April 7 field, corn stand was pretty good, little bit of luck involved perhaps, that same situation might not be replicable in other fields, but maybe the risk was managed associated with early planting
  • Plant when the soil is as warm as possible, residue can be moved, optimum depth of 2 to 2-1/2 inches, soil temp fluctuations aren’t as great at that depth, talk to your seed dealer about corn hybrids that are more tolerant to cold, seed lots of one hybrid might have lower vigour than another
  • New hybrids: how do they impact the decision on what day to plant? not much difference in terms of tolerance to imbibitional injury, but are differences for tolerance to insects and diseases
  • How early can you plant those short season hybrids? grow the full season or extra long season hybrid, if the objective was to take the corn off early, then the early hybrid is the good fit.
  • If only we could plant alll our corn on the ideal date! But, we have to expand our thinking to planting in a range of dates for that optimum yield
  • If the soil’s fit, and we have the time, should we go harder and get that corn seed in the ground? Yes, especially if you’re a bigger grower and can manage a higher level of risk. Those fields that are planted early, a little bit riskier, those fields are closer to the maximum yield potential.
  • Heavier clay? That field might be at a higher risk for late planting, especially in wet weather, might not dry up until June

More Q&A

  • When is it too cold to plant soybeans? Cold spring, ground conditions were coming along well, but lots of hesitation, hoping the temperature isn’t such a big deal for fear of being rained out and not being able to get into fields
    April 22, -3 at night, 3 during the day, snowed a couple times on these soybeans. That’s the last thing you’d want! But actually ended up with a pretty reasonable stand. We’ve progressed in our opinions of temp as long as conditions are fit.
    April planting date, couple of days later, 13 degrees C, stayed warm for a few days, they do look a little better, plant stand is essentially the same, little more vigorous
  • Plot planted just before a cold rain, April 27th, at the end of the day it stayed cold for a whole week. No difference in plant stand, soybeans look just as vigorous as the others.
  • In conclusion: soil temperature is just not that big of a deal, as long as the soil is fit and the calendar date is appropriate. Good quality seed, seedbed is good, not heavy cold rain after. Good shape.
    Only time there were statistically more plants per acre was at June 10 planting date
    SOIL TEMP NOT A BIG DEAL! Breaking old rules
  • Caveat: use common sense, the seed will now have to be in the ground for a long time, opening it up for disease and insect damage
  • What role does tillage play? More minimal tillage is Bohner’s thinking, tired of issues in no-till, so easily solved with just a bit of blackening, one pass can improve the plant stand, not every field, but a lot of Ont, will do well with a minimum amount of tillage.
  • It’s about the quality of light, light is much more powerful in July than it is in August, solar radiation drops significantly in August.
  • Soybeans can still be OK after multiple nights below zero. But, if you’re going to plant early and take advantage of the full season, you’ll need to plant a long season variety.
  • Should it be corn before the soybean, or soybean before the corn? Chicken or the egg type of situation. Soybeans are a bit tougher than corn in some ways, but where they live (Ontario), long season hybrids yield more and corn needs to dry down more in the fall, but from a strict yield perspective, soybeans should be planted first
  • Not being irresponsible here, we still care about the soil health and preventing soil erosion. The key is “in the row,” don’t need to till across the whole field, strip-till is a great compromise.

The next Diagnostic Day tackles insect and disease management, and will be published July 29, 2020.

Wake up with RealAgriculture

Subscribe to our daily newsletters to keep you up-to-date with our latest coverage every morning.

Wake up with RealAgriculture