The effects of roller crimping direction for termination of fall sown cereal rye (Secale cereale L.)

Consensus around the optimal direction of roller crimping a row-planted cover crop has not been established. Several publications report crimping either parallel or perpendicular to the direction of cover crop planting with little to no justification apart from unpublished observations or hypotheses. This study explicitly compared the effects of roller crimping direction on crimping efficacy, weed suppression, and cash crop yield. At Elora, ON in 2020 and 2021, and Harrow, ON in 2021, a cereal rye (Secale cereale L.) cover crop was planted in three orientations (north-south vs. east-west vs. no rye control) then terminated with a roller crimper parallel or perpendicular to the direction of planting. A sweet corn (Zea mays L.) cash crop was planted either north-south or east-west in the same direction as roller crimping. A split plot treatment of weediness (weedy vs. weed-free) was applied. It was found that roller crimping direction did not have a consistent effect on rye mortality or number of upright tillers, nor did it affect weed control. However, total marketable sweet corn fresh weight decreased in perpendicular crimped rye compared to parallel crimping, despite equivalent cob counts. We did not find evidence in this study to suggest that perpendicular roller crimping improves ground cover and therefore weed suppression, contrary to other unpublished observations. Given the effect on sweet corn yield, roller crimping perpendicular to the direction of cover crop planting may not be a suitable practice. Alternative methods for improving cover crop-based weed control should be investigated.