As more farmers look to integrate cover crops into their systems, getting the timing right is becoming just as important as choosing the right species. A current Illinois Soybean Checkoff-funded study is helping farmers dial in the details by comparing how planting dates and seeding rates impact cereal rye before soybeans, and clover species planted after soybeans and before corn. 

Led by University of Illinois Extension educator Nathan Johanning, the research is focused on building practical, field-tested recommendations that can improve cover crop performance and reduce risks when planting soybeans and corn. 

Back in December, the research team evaluated fall growth across all treatments. They also shared results from past years with farmers to help inform decisions for this spring. Next up is collecting biomass samples this spring, terminating the cover crops, and moving forward with planting soybeans and corn. 

Johanning notes that one of the biggest takeaways so far involves how much cereal rye biomass is too much—especially under wet spring conditions. 

“When cereal rye gets really vigorous, it can be tough to get a good soybean stand if planter settings aren’t just right,” says Johanning. “It can still be done, but it takes attention to detail.” 

Johanning suggests that if your cereal rye is growing fast and the field has a lot of residual nitrogen, it may be worth terminating early, at boot stage or before, to prevent excessive growth that could interfere with planting. 

Looking ahead, the research is also keeping tabs on vole activity, which can be a challenge in certain cover crop systems. Researchers are adjusting their approach to discourage vole pressure as much as possible while also being mindful of cover crop termination timing heading into the 2025 growing season. 

To follow this study and other checkoff-funded agronomic research, visit the Field Advisor Research Hub.