Soybean School: When should you plant for high yield?

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In recent years, leading U.S. soybean researchers have touted the benefits of early planting to reduce the loss of yield potential as planting stretches into late April and pushes into May.

But does this research give growers clear direction on the best time to plant further north in Ontario? Horst Bohner, Ontario Ministry of Agriculture, Food and Rural Affairs soybean specialist, believes the oilseed planting story is a little different in this province. He contends that growers need to think optimum planting window, rather than fretting about yield loss as early days get crossed off the spring calendar.

Last year on RealAgriculture’s Soybean School, Wisconsin soybean specialist Shawn Conley shared research looking at data from across the north-central U.S. (representing 82 per cent of the country’s soy production) to rank management practices and the impact they can have in farmers’ fields.

Topping the list of the management ranking was sowing or seeding date. Mounting data shows the benefit of planting soybeans early — April 20 in Wisconsin, for example. Based on the data, on average farmers can expect to realize an additional 0.2 to 0.3 bushels per acre, per day when planting starts April 20. “Over ten days that’s three bushels of free yield. That’s big,” says Conley.

Earlier this winter, University of Illinois plant physiology professor, Fred Below, shared a similar story. His trials indicate Illinois growers lose almost half a bushel (0.47 bu/ac) for every day planting is delayed after April 23.

On this episode of Soybean School, Bohner shares the results of planting research he conducted in Ontario in 2020 and 2021. Overall, his recommendation starts with soil conditions. If the soil is fit, he’s comfortable planting soybeans in the province on April 20. If the soil is dry and their are no significant weather events (cold and wet) on the horizon, growers should not hesitate to plant.

“You can plant quite early and get away with it, but we’re also not seeing a yield benefit to super early planting,” says Bohner. (Story continues after the video)

Based on his data, Bohner says there is a spring planting window in Ontario where soybeans have essentially the same yield potential. He notes that weather conditions and soybean variety will influence performance, but overall the research shows that yield for soybeans planted between April 20 and May 15 only varies two to four bushels per acre.

“There’s a pretty big window where we have not seen a very big decline,” says Bohner. “I’m not one who thinks you have to plant by May 1 or you are losing five bushels. The new data doesn’t really support that.”

Click here for more Soybean School videos.

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