AGRONOMIC IMPLICATIONS OF CEREAL RYE COVER CROP IN WISCONSIN SOYBEAN SYSTEMS

Abstract

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 (DAP) 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%), and roller-crimper + clethodim in (2021: <66%; 2022: 99%) and roller-crimper + planting green quizalofop-P-ethyl (2021: <63%). Soybean stand density in planting green clethodim (<27%) and planting green quizalofop-P-ethyl (<18%) treatments were less than pre-plant control when compared in both years. Soybean stand density was not affected by other treatments. In both years, soybean yields were greatest in the pre-plant control treatment (2021: 5,454 kg ha-1; 2022: 3,912 kg ha-1) followed by roller-crimper + planting green glyphosate treatment (5,137 kg ha-1; 2022: 3,541 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.