Soybean School: Fertility and inoculant considerations, from a Prairie perspective

The principles around fertility and nutrient uptake in soybeans are the same, whether you’re farming in Ontario, the U.S., or Western Canada, but there are some unique or special factors to be considered by soybean growers in western and northern growing areas.

Following up on this Soybean School episode from last month with Horst Bohner of OMAFRA discussing fertilizer strategies for soybeans, Jeanette Gaultier adds some Western Canadian perspective heading into the planting season as part of the discussion below.

“It’s interesting that despite how different we are, Horst’s message is really on point for the West as well,” says Gaultier, BASF’s senior technical services specialist, based in Manitoba. “But there are definitely some differences, and a few that pop to mind are iron deficiency chlorosis (IDC), and the way we look at inoculation.”

IDC is seen in the West and not the East due to differences in soil properties — the presence of calcium and magnesium, tying up iron in alkaline soils, she explains.

“There’s been some work done looking at chelated irons, but typically we find that just choosing a soybean variety that has good tolerance to IDC is probably the best way to go,” says Gaultier.

While soybean growers in the East may pick up bags of seed that are already inoculated with rhizobium bacteria, inoculation in Western Canada tends to happen just-in-time when seed is picked up in bulk. “It definitely gives us some flexibility and different options, and that ties in well with equipment differences we have in the West too. Maybe thirty percent of our soybean acres are planted, whereas the rest would be solid-seeded,” she notes.

Heading into the 2022 season, soil moisture extremes, from flooding to drought, must be factored into every inoculant plan. “Too dry is something we hadn’t really considered, but the last few years we’ve actually seen some lines in the field where there’s been single inoculation versus double inoculation,” says Gaultier. On the other end of the spectrum, as is the case with many acres in southern Manitoba this year, standing water will also reduce rhizobium populations as the bacteria requires oxygen to survive.

“We know they’re not native here, and we have a longer crop rotation that other soybean growing areas as well, so I think it will be a unique decision to every farm,” she says.

Check out the video below for more with Jeanette Gaultier on mitigating yield losses due to IDC and how to plan an inoculation strategy before seed goes into the ground: