Termination strategies for high biomass cereal rye cover crop in soybean planting green systems

Weed management programs utilizing high-biomass cereal rye (Secale cereale L.) cover crop in Wisconsin soybean [Glycine max (L.) Merr.] production systems are increasing in popularity. Much of this method's success depends on effective cereal rye termination and environmental conditions in the spring. A randomized complete block design field experiment was conducted in 2021 and 2022 at the University of Wisconsin-Madison Arlington Agricultural Research Station in southern Wisconsin designed to determine the efficacy of chemical (glyphosate, clethodim, and quizalofop-P-ethyl) and mechanical (McFarlane roller-crimper) techniques and combinations thereof for termination of high biomass cereal rye cover crop and their impact on yield in planting green soybean systems. The control treatment was glyphosate applied pre-plant (preplant control). Glyphosate-containing treatments were the most effective in percent control of terminated cereal rye 21 days after soybean planting in both years (2021: >98%, 2022: >99%) compared to roller-crimping (2021: <49%, 2022: >96%), the ACCase inhibitors clethodim and quizalofop-P-ethyl (2021: <29%, 2022: <85%), roller-crimper + clethodim (2021: <66%; 2022: 99%), and roller-crimper + planting green quizalofop-P-ethyl (2021: <63%). Soybean stand densities in planting green clethodim (<27%) and planting green quizalofop-P-ethyl (<18%) treatments were less than the pre-plant control in both years. Soybean stand density was not affected by other treatments. Soybean yields in both years were greater in the pre-plant control treatment (2021: 5454 kg ha⁻¹ and 2022: 3912 kg ha⁻¹) than other treatments except for the roller-crimper + planting green glyphosate treatment (2021: 5137 kg ha⁻¹ and 2022: 3541 kg ha⁻¹). Planting green glyphosate, roller-crimper, and all chemical + mechanical combinations did not differ from each other in yield for 2022. This study found that roller-crimper + planting green glyphosate was equivalent to the pre-plant control, and both were followed by planting green glyphosate as the best termination techniques for controlling a high biomass cereal rye cover crop and protecting yield potential in planting green soybean systems.