Seeding Date
The window to seed soybeans is flexible throughout the month of May in Manitoba. Aim to seed during the second to third weeks of May to maximize soybean yield while reducing the risks associated with cold soil and late spring frost.
From 2017-2019, Kristen MacMillan, UM-MPSG Agronomist-in-Residence evaluated four seeding windows at Arborg, Carman, Dauphin and Melita. Soybean yields did not differ among seeding dates from May 1 to May 24, but yields were reduced by 15%, on average, when seeding was delayed until May 31 – June 4. Very early seeding, during the week of April 28 – May 6 was risky. Late spring frosts occurred in two years and soil temperatures during this window were as low as 0°C, causing plant stand reductions and reducing yield by up to 19% at some sites. Report →
From 2017-2021, Dr. Ramona Mohr, AAFC-Brandon evaluated two seeding date windows, among other factors like residue management at Carberry, Brandon and Indian Head. Seeding dates of May 8 to 14 increased soybean yield by 11%, on average, compared to later dates of May 24 – 30. Click here for a summary of this research →
Seeding Rate and Target Plant Stand
Target a living plant stand of 140 – 160,000 plants/ac to maximize yield. Take into account expected germination and survivability to calculate seeding rate. In on-farm trials, soybean seed survival has been 81% on average (82% with planters and 80% with air seeders).
MPSG’s On-Farm Network has been evaluating different soybean seeding rates on-farm since 2012. There have been 132 trials comparing soybean seeding rates to date and, most of the time (84%), lowering soybean seeding rates by 30,000 seeds/ac from a farmer’s traditional seeding rate has not changed soybean yield. From these trials, seeding above 190,000 seeds/ac has not provided a consistent return on investment. Generally, seeding rates of 150,000 to 190,000 seeds/ac has maintained soybean yield while minimizing seed costs. Dropping below 150,000 seeds/ac is not recommended since it introduces much more risk, especially in terms of weed control. Report →
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