For soybeans, think pods, not height

Short soybeans don’t necessarily mean short yields

Farmers worried that short soybeans may not yield as much as normal may be in for a pleasant surprise. As long as they’re packed with pods, short stature shouldn’t impact yield, says Ryan Van Roekel, a Pioneer field agronomist based in south-central Iowa who discussed the 2020 growing season during a Corteva Agriscience media event this week. 

Earlier this year when soybeans struggled to grow in cold weather in many areas, spaces between internodes were tight – less than 1 inch apart. “This created shorter-than-normal soybeans,” he says. When temperatures warmed in June and July, soybeans rapidly grew and spaces between internodes lengthened. 

“I always like to remind growers you are not trying to grow big, beautiful bushes,” he says. “You’re trying to put more beans into the bin,” says Van Roekel. In some cases, lodging can accompany tall bushy beans.  

“It’s all about the pods,” he says. Short beans can have plenty of pods, which reflect the good growing conditions that occurred in many areas this June and July. However, August drought and heat in areas like western Iowa squelched soybeans, and they put on fewer pods during this time. That’s reflected in fewer pods near the top of soybean plants vs. more pods at the plant’s bottom that were formed earlier in the year. 

“You might have three pods per internode at the top of the plant, and five to six (per internode) at the bottom,” he says. “Additionally, lots of pods look like three-bean pods, but have only two beans inside. We saw a lot of this in drought areas.”

So, there’s been a lot of concern about soybean yields in dry areas. Still, most yields in the area Van Roekel covers are coming in better than expected, although they are off from past years, he says. 

Uneven Maturing

Some fields also have unevenly matured this year, says Van Roekel. In some cases, there is little farmers can do about this. Uneven maturing can occur in fields with variable soils. Soybeans planted on a field’s thinner soils with less water-holding capacity basically give up before soybeans planted on deeper soils with better water-holding capacity do. 

On uniform soils, though, uneven maturing may indicate a malady like soybean cyst nematode (SCN) or charcoal rot. Charcoal rot is a soilborne root-and-stem fungal disease that surfaced in parts of Iowa this year.  

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