How early should growers in SK & AB start seedbed prep for soybeans?

For Soybean Growers, Timing is Everything

Why? Because soybeans need warm soil and water in order to establish successfully.ⁱⁱⁱ

According to Dave Chappellaz, Thunder Seed Canada’s Provincial Agronomist for Manitoba, soil temperature can mean the difference between a thriving crop and a struggling one. “In order to germinate, soybean seeds take in almost their weight in water during the springtime,” says Chappellaz. “But if that water is cold, you can have issues with vigor and cold stress. That’s why it’s crucial for them to have warm water and soil from the start.”

Due to warmth considerations, certain regions of Saskatchewan and Alberta aren’t suitable for soybean growth. Erin Matlock, Thunder Seed Canada’s Sales Agronomist for Saskatchewan and Alberta, says this includes the Southwest corner and Meadow Lake area of Sask., and anywhere near the mountains or North of Edmonton in Alberta. However, this may not always be the case:

“The prime area for Alberta is in the Lethbridge irrigation region. For Sask., the Southeast part of the province has more options in terms of varieties, and they carry less risk,” says Matlock. “However, with the new varieties and genetics becoming available, these non-suitable areas are shrinking.”

Although most agronomists recommend planting in mid- to late May, when soils reach the ideal temperature,^iv soybean growers will want to get their seedbeds prepped much sooner.

Seedbed Prep: What Soybean Growers Need to Know

To cut down on the time it takes to bring soil temperatures into the right range for planting, it’s best to start seedbed prep sooner rather than later. That’s because soybeans grow best in warm, dark soil with a smooth finish. Excessive trash can make soil warming and crop establishment difficult, so many growers rely on tillage, either in the fall or spring, to darken soil and hurry the process along.ⁱⁱ

“To speed up the seeding time, fall tillage will be beneficial since the blackened soil warms up faster come springtime,” says Matlock.

Because growers in Saskatchewan and Alberta are still relatively new to the crop, Matlock adds that most are still doing spring tillage. And as long as adequate soil moisture isn’t a concern, she notes this is still an effective way of prepping the ground for seeding.

That being said, growers who decide to till in the spring should to begin seedbed prep as soon as conditions allow it. Typically, you can begin once the ground isn’t too cold or wet, but that depends somewhat on your equipment. For instance, growers who can afford to run a cultivator or another piece of machinery over their field to speed up the warming process can actually start when the soil is still wet and cold. But for others, it may be best to hold off and wait for Mother Nature to cooperate.

In addition to tillage, growers should leave time for any necessary pre-seed applications. Since soybean seedlings from emergence to stage V3 aren’t very competitive, it’s imperative that you keep your fields as weed-free as possible before planting.i For this reason, Matlock suggests including a pre-seed herbicide application to your seedbed prep checklist. Additionally, first-time growers may want to double inoculate their soybeans with a seed treatment and in furrow application of rhizobium bacteria. Because soybeans aren’t native to the Canadian Prairies, our soils lack this helpful bacteria necessary for successful soybean growth.i

When Seeding Soybeans, Patience Pays Off

Agronomists unanimously recommend that soil be at least 8-10ºC at time of planting in order for seeds to germinate successfully.^v In the Prairies, this often occurs in mid-May, which can feel very late, especially for a long-season crop susceptible to frost. So once the ground is prepped, some growers may be tempted to start seeding as soon as their soil hits 8 degrees.

While well-intentioned, this strategy can actually end up hurting your soybeans. Because seeds take in so much water during their first 24 hours in the ground, Matlock suggests you first make sure the weather will stay warm for several days before, during, and after planting. “At seeding time, the soil temperature needs to be at 10ºC with no hard frost in 48 hours,” she says. So if temperatures are expected to drop in the next day or two, you’ll want to wait longer before planting.

Though this may make growers concerned with early fall frosts uneasy, experts say there’s nothing to worry about. Later-seeded soybeans are quick to catch up to their more punctual counterparts — every week later that they’re seeded only adds about two to three days to their maturity. ^vi

Slow and Steady Wins the Race

Because of their need for warmth and relatively long growing season, growing soybeans in the Canadian Prairies can feel like a race against time. While it’s a good idea to get the ground prepped as early as possible, it’s imperative to be patient and wait for a string of warm days to start seeding.

Now that you’ve gotten your timing down pat, it’s time to get your field ready for the 2018 growing season. For a quick refresher on all the factors that go into seedbed prep, download our Seedbed Prep Checklist here.

i. Risula, Dale. “Preparing for Soybeans in 2018.” Saskatchewan.ca. Online. Accessed 22 February 2018.

ii. King, Carolyn. “Irrigated Soybeans a Possibility for Alberta.” Top Crop Manager. Online. Accessed 22 February 2018. 

iii. Topham, Gary. “Pulse and Special Crop Production: Q&A with Crop Production Services.” Grainews. Online. Accessed 8 February 2018. 

iv. “Soybean Production in Saskatchewan.” Saskatchewan.ca. Online. Accessed 22 February 2018. 

v. Eggum, Brad. “5 Tips for Growing Soybeans in a Cool Climate.” Grainews. Online. Accessed 12 February 2018.