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Research Highlights
Establishing Thin Rye Stand Key to Green Seeding Soybeans

Planting a rye cover crop with a thin stand can provide some level of weed suppression without impacting soybean yield in northwestern Minnesota.

By Barb Baylor Anderson

“Green seeding” soybeans into an existing rye cover crop can be a successful, sustainable practice for farmers in northwestern Minnesota, as long as the delicate balance between the ideal rye stand and the timing of soybean planting is achieved. 

Research funded by the Minnesota Soybean Research and Promotion Council and Minnesota Wheat Council and led by principal investigator Melissa Carlson utilizing the Minnesota Wheat On-Farm Research Network, investigated the logistical and economical practicality of green seeding soybeans into cereal rye in a wheat–soybean rotation in the state’s upper corner.

“Seeding soybeans directly into living rye that was established the previous fall, which is known as green seeding, is one method of incorporating cover crops into a soybean rotation. We worked with farmers to establish rye in a replicated strip trial following wheat harvest, and then seeded soybeans into the living rye the following spring to evaluate the practice,” says Carlson. 

Objectives included evaluating the growth of the rye and its effects on the environment and planting conditions, as well as evaluating the effect of green seeding soybeans into rye on soybean establishment, yield and overall field management. Data collected included soybean stand and height, iron deficiency chlorosis (IDC) score, soil moisture, temperature and nitrates, weed population density and biomass, and total cover crop biomass. 

“We learned a very thin stand of rye can provide some level of weed suppression without impacting soybean yield even when terminated after the rye has headed four weeks after planting,” she says. “Soybeans planted into very thick stands of rye not terminated until rye has headed will be stunted and have reduced yields due to moisture competition with the rye.” 

Carlson says green seeding can be a viable practice for soybean farmers when done on time. “Waiting three to four weeks after planting until the first regular pass of soybean herbicides at the second to third trifoliate will likely decrease yield,” she confirms. “The next step is on-farm testing of various rye termination timings and measuring effects on yield. This will help farmers be prepared to terminate a rye cover crop at the appropriate time to avoid a yield penalty.” 

This project was funded by the soybean checkoff. To find research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.