Soybean School: Data crunch says plant soys before corn


Should you plant soybeans before corn?

The answer is yes if you’re a believer in big data and its ability to help you make better farm management decisions.

Earlier this month at the SouthWest Agricultural Conference at Ridgetown, Ont., University of Wisconsin-Madison soybean extension specialist Shaun Conley made his pitch to have farmers put corn on the back burner and kick off the spring by planting soybeans.

Conley’s assertion is based on analysis of four years of data from 7,000 farm fields and 500,000 acres across the U.S. midwest. On this episode of RealAgriculture’s Soybean School, Conley explains when he looks at data from growing areas with similar weather, soil types, and growing environments as found in Ontario, there’s a clear case for making the switch to planting soys before corn.

According on the data, soybeans lose 0.4 to o.5 bushels of yield per acre for every day planting is delayed past April 20. “So that tells you every 10 days you delay planting you’re losing four to five bushels,” says Conley. “That’s free yield, you’re just giving it away.” The data accumulation and analysis is funded by the North Central Soybean Research Program and is available at

Conley notes that May 1 is generally considered the optimum date for planting corn in these areas. He says if the soil is fit, there’s no reason why farmers couldn’t get at least 30 percent of their soybeans planted before they start rolling with corn. (Story continues after the video.)

Conley points out that many farmers tend to operate with one corn planter, start with corn and then shift to soybeans. He believes that a four- to five-bushel yield bump for early-planted soys could justify investment in a second planter. However, he does recommend that growers test the theory before making the leap. “If you could get one-third of your soy acres planted before you switch to corn — try to take advantage of that early yield potential and that greater yield gain… Just don’t go crazy in the first year,” he advises farmers. “See if it works on your farm and expand over time.”

Conley also shares other big data insight in this interview, including potential advantages for tillage; a 6.5 bu/ac yield advantage for fungicide applied at R3; and yet more proof that soybeans don’t like wet feet.

Click here for more Soybean School episodes.

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