Research Highlights

Research Highlights
Successfully Double-Cropping Soybeans After Small Grains

Soybeans following barley harvest. Photo: Laura Lindsey

Double-crop soybean management differs from full-season soybean management. To be profitable in Ohio, farmers need adequate time to produce the soybeans and adequate water to produce both the soybean and small grain crops with stored soil moisture, rainfall or irrigation. 

Laura Lindsey, Ohio State University Extension soybean specialist, evaluated double-crop soybean practices as principle investigator on a research project funded by the Ohio Soybean Council. She studied double-crop planting date, relative maturity, row spacing and seeding rate.

“Planting date has more effect on soybean grain yield than any other production practice. Early planting of double-crop soybeans is essential for success,” says Lindsey.

She recommends farmers:

  • Harvest wheat at 18-20% moisture. Grain can be dried with air and supplemental heat. Wheat harvested at higher moisture usually has greater yield and quality, while grain re-wet in the field may sprout with lower yield and test weight. Vomitoxin levels may rise.
  • Plant double-crop soybeans after winter barley. Winter barley is harvested approximately two weeks earlier than winter wheat, allowing for an earlier soybean planting date.

“Relative maturity (RM) has little effect on yield when soybeans are planted during the first three weeks of May, but the effect of RM can be greater for late planting,” she says. “Farmers should then choose the latest-maturing variety that will reach physiological maturity before the first killing frost. This allows soybean vegetation to grow as long as possible and produce nodes where pods can form before vegetative growth slows from flowering and pod formation.”

When it comes to row spacing, Lindsey advises narrow, 7.5- to 15-inch, rows. The later in the season soybeans are planted, the greater the yield increase with narrow rows. That is because narrow rows capture more sunlight energy to drive photosynthesis and produce more grain. 

Harvest population for mid- to late-June plantings should be 130,000 to 150,000 plants per acre, while population for early July plantings should be more than 180,000 plants per acre.

“Harvest plant population is a function of seeding rate, quality of the planter operation and seed germination percentage,” says Lindsey. “Harvest plant population also depends on such things as soil moisture conditions, seed-to-soil contact and disease pressure.”

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Published: Oct 12, 2020