There is growing interest in use of cover crops for benefits including reduction of soil erosion, managing soil moisture, weed suppression, and increasing long-term soil productivity. While there is on-going research in the Red River Valley and at the CREC with use of winter rye as a cover crop with soybean, research expanded to south-central ND is useful for this region’s soybean farmers as they consider adapting this management practice. In addition, it would be useful for all ND farmers to use proper seeding rates of rye based on fall establishment dates and impact on soil cover and moisture levels, weed management, and soybean yield. Data from these soybean studies, which are within the scope of ND Soybean Council research priorities – soil and water management, will be shared with ND farmers and crop advisers to improve soil productivity and potentially increase profitably of soybean production.

1. At the CREC Tri-county research site (Wishek area), will examine soybean performance with winter rye as a preplant cover crop compared to conventional production:
1. Main emphasis will be determining normal rye termination time to utilize the benefits of the cover crop while maintaining soybean yield in a normally dry environment.
*Study 2. At the CREC, will use winter rye seeding rates and fall date combinations:
1. Measure rye plant population and ground cover, and weed suppression during the following soybean production period.
2. Measure soybean response to the rye treatments.

The two cover crop studies will aid in updating research-based recommendations on use of winter rye with soybean. Study 1 will help encourage south-central ND farmers to consider using rye as part of their soybean management and aid in the decision when to terminate the cover crop. Study 2 will aid farmers in determining proper rye seeding rates based on their goals with the cover crop while maintaining soybean yield.

Updated November 22, 2021:
Completed work:
• Trial 1: Fourth (and final) year of the study was conducted at the Tri-county off-station research site. Winter rye was seeded on October 21, 2020 and resulted in a mid-May 2021 stand of 262,000 plants/A (6 plants/ft2). Treatments: 1) soybean grown without rye; 2) rye terminated with glyphosate 9 days before soybean planting; and 3) rye terminated with glyphosate 6 days after soybean planting. Soybean were planted on May 13, 2021 and harvested on October 8.

• Trial 2: Third year of the study was conducted at the Carrington Research Extension Center. Treatments: Winter rye was seeded on September 17 and October 8, 2020 at 25, 50 and 75 lb/A (six treatments). Soybean were planted on May 18, 2021, followed by rye termination with glyphosate on May 20, and harvested on September 17.
Preliminary results:
• Trial 1: In 2021, soybean seed yield with the conventional production check was greater than the two treatments with rye. Limited topsoil water due to rye growth resulted in reduced soybean plant production during the first-half of the season. Also, the rye provided minimal suppression of weeds compared to the weed control with a soil-applied herbicide used with the check. About 30 people viewed and heard discussion about the study during the July 1 field tour.

• Trial 2: Rye plant density and ground cover measured the last-half of May 2021 ranged from 29,880 to 448, 210 plants/A and 3 to 23%, respectively, among combinations of rye seeding dates and rates. The greatest rye density and amount of ground cover resulted from planting late at the 75 lb/A seeding rate. Green foxtail suppression (54-67%) was similar among the six rye treatments. Soybean plant density and maturity, and seed yield (trial average = 40.6 bu/A) and quality were similar among rye treatments.
Work to be completed:
• Research reports will be written and shared with audiences using CREC website, ND Soybean Council 2021 annual research report, and other electronic options (e.g. CREC Center Points blog, Facebook).
• Data slides developed and presented for farmers and crop advisers during 2021-22 winter meetings and summer tours.

*Study 1. Results will help south-central ND farmers answer the following question: Can winter rye be used to realize benefits as a cover crop with soybean without reducing seed yield in a normally arid environment?
*Study 2. Results will help farmers answer the following question: What is the best rye seeding rate based on fall seeding dates and following season factors affecting soybean production including ground cover, soil moisture, and weed suppression with rye? The information will help farmers select proper rye seeding rate and fall date based on their cover crop goals and resource management.