Moisture availability is the key to getting soybeans off to a good start; they need it to germinate properly and emerge.

But how deep should you plant to tap into the moisture the seed needs for strong plant stands and high yields? On this episode of RealAgriculture’s Soybean School, Ontario Ministry of Agriculture, Food and Rural Affairs soybeans specialist Horst Bohner shares what he learned from his 2020 planting depth research trials.

Bohner planted soybeans at four depths (1, 1.5, 2 and 2.5 inches) on three different planting dates (April 22, May 22, and June 10). For the early planting (April 22), Bohner observed the highest plant stands at the 1.0″ and 1.5″ depths. He notes that some growers like to plant deeper than these depths to protect the seed against the impact of fluctuating temperatures, but that’s not a good strategy for soybeans, he says. “We want it to be relatively shallow so they get as much heat from the sun as possible.”

Bohner noted the same trend at the May 22 planting date. Here again the stand count did not drop significantly until seed was planted at 2″ or deeper.

The yield story mirrored the stand count results with the shallower depths — 1.0″ and 1.5″ — showing significant yield advantages, between 3 to 5 bu/ac in no-till soybean planted in 15″ rows at 175,000 seeds/acre. (Story continues after the video.)

Overall, Bohner was surprised at the yield strength of the soybeans planted at the 1″ depth. When moisture is available, the data does support the fact that soybeans can emerge quickly and efficiently at this depth. But Bohner cautions growers that moisture levels at 1″ can dry up quickly in the top layer of soil and they need to be careful.

“When I look at these numbers, I think 1.5″ is a good recommendation, regardless of date,” says Bohner. He plans to replicate the trial again in 2021.

Click here for more Soybean School episodes.

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