Soybeans: How you seed is just as important as what you seed

Written by Walter Ens on Jun 05 2014

Category: Grow Grain

We're on the home stretch for planting soybeans in Canada. If you're seeding in the next week or two, here's what you need to consider.

Soybean seedling

No longer limited to Ontario, soybeans are quickly growing in popularity across Manitoba and further west. Whether you’re growing them for the first time or the fortieth, remember that how you seed is just as important as what you seed. Here’s some advice on choosing the right seeding tools, row spacing and seeding dates.

Choosing a seeding tool

Soybeans can be planted with an air drill or planter. There’s a lot of debate around ideal spacing for soybeans: Is wide row, narrow row or solid seeded best?

Solid and narrow seeding takes advantage of more sun and heat than wide row spacing. But if you have high fertility and plenty of heat, wide rows can pay off in yield. More air movement through the canopy reduces disease pressure. Planting soybeans in rows will crowd the plants, making the soybean plants grow taller and lifting bottom pods off the ground. You may have already experienced that that kind of crop is a breeze to harvest.

The most popular row spacing is between 14 and 20 inches. We can achieve it with an air drill or seeder by plugging every second run, but nothing beats a planter for accuracy of seeding depth. Planters still win out when it comes to rapid emergence and plant spacing.

Setting plant population targets

Soybeans tend to be elastic like canola when it comes to yield. They can usually compensate quite well for thinner stands. Target one of the following plant populations:

  • Solid seeded or air drill:
    Target a population of 200,000 plants per acre, which means seeding at a rate of 220,000 plants per acre to accommodate for about a 10% mortality rate.
  • 14–20 inch rows:
    Target a population of 150,000 to 160,000 plants per acre and seed at a rate of 180,000.
  • Wide rows or planter:
    Target a population of 140,000 plants per acre and seed at a rate of 160,000.

In my experience, we often struggle and see a higher mortality than 10%.

This season, we’re following a few soybean fields in Manitoba and Ontario and Tweeting out photos and insight (designer to insert link to Stalk Option blog post) of the fields as the crops mature. In one of the Manitoba fields we’ll be following, we’ve targeted an average of 175,000 seeds per acre on 22 inch row spacing. We have also included a few strips at 200,000 and 140,000 seeds per acre to see how the plant stand is affected. Follow @StalkOption to see what happens in the trial.

Deciding when to plant:

Soybeans are a long-season crop, so growers usually plant during the second half of May or the first week of June. Soybeans need to absorb 50% of their weight in water before they will germinate. Germination is very sensitive to water temperature. It is recommended that the average daily soil temperature be a minimum of 8-10 degrees Celsius before planting beans. The first eight hours after planting are the most crucial, so aim to plant mid-morning once the soil has had a chance to warm up.

Once it emerges, the seedling’s growing point is above the ground, also making it highly susceptible to spring frost.

Do you plant your soybeans with an air drill or planter? What kind of row spacing works best on your farm? I’d love to hear from you. Contact a Cargill expert today for more information on seeding soybeans, or follow me and my fellow agronomists on Twitter @StalkOption


Tags: Agronomy, Cargill Experts, @StalkOption, Crop Establishment

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