Cover crops can increase soil organic matter, soil tilth, water infiltration, nutrient capture, weed control and reduce soil erosion. Despite these benefits, farmers face significant challenges with spring termination of cover crops. In 2017, a cold wet spring reduced herbicide efficacy for terminating wheat and rye cover crops resulting in "green planting" of both corn and soybeans as the cover crop was still alive. NRCS Nebraska guidelines indicate that cover crops should be terminated at or prior to planting a cash crop depending on their location within the state. No studies have been conducted to evaluate the risk or benefits of termination timing on insects or weeds relative to soybean planting. This 3-yr project would assess the timing of termination of wheat or rye cover crops relative to soybean planting on farmer fields across eastern and central Nebraska. Sites would consist of an existing rye or wheat cover crop terminated with glyphosate using a backpack sprayer at three different times during the spring prior to and after soybean planting.
Soybean fields will be evaluated twice during the early vegetative stage and once during the reproductive stage for insects, plant damage, and yield will be recorded on plots. Weed suppression potential of cover crop will be evaluated at termination and just prior to soybean canopy closure. Findings will be disseminated through field days, conferences, CropWatch articles, as well as extension and research publications. Results from this study would assist farmers to make an informed decision on timing of termination of cover crops leading to reduced risk, increased yields and adoption of cover crop systems.