University of Kentucky researchers are studying the best way to seed cover crops into double-crop soybeans and determining which cover crop provides the greatest nitrogen benefit to corn planted in the same field the next spring.

The group of researchers led by soil scientist Edwin Ritchey is studying whether making an aerial seeding application of cover crops before soybean leaf drop aids in timely cover crop establishment without interfering with soybean harvest.

“Soybeans, especially double-crop soybeans, are often harvested so late that it’s hard to get a cover crop established if a producer waits until after harvest,” said Ritchey, associate professor in the UK College of Agriculture, Food and Environment. “Another issue is that soybeans leave very little residue in the field, making these fields more prone to erosion. By seeding the cover crop before leaf drop, we hope to reduce erosion and provide a nutrient benefit to the soil for the subsequent crop.”

Ritchey seeded the cover crop into the soybean plants before they dropped their leaves this fall in small plots at the UK Research and Education Center in Princeton. The leaves provide additional protection to the seeds so the cover crop can grow. Ritchey is using a combination of wheat, clover and rapeseed in the UK Grain and Forage Center of Excellence demonstration.

Seeding timing is critical for establishment. If farmers seed a cover crop after soybean leaf drop, it will not have the soil contact it needs to grow. Seeding too late can result in little or no fall growth due to cold growing conditions. If the cover crop goes in too early, excessive cover crop growth may occur in the fall, which could interfere with soybean harvest.

UK researchers are studying which cover crop or cover crop combinations results in a nitrogen benefit for the subsequent corn crop.

“We want to see how these cover crops affect the nitrogen dynamics of corn,” Ritchey said. “Depending on the cover crop, it may provide a nitrogen benefit or result in a loss.”

In addition to the UKREC small-plot research, UK researchers have larger on-farm studies with producers in Hickman, McLean and Trigg counties. UK soil scientists Mark Coyne, Brad Lee and Josh McGrath, agricultural economist Jordan Shockley and weed scientist Erin Haramoto are collaborating with Ritchey on the study.

A U.S. Department of Agriculture Conservation Innovation Grant is funding the projects.