Nitrogen Cycling with Oilseed Radish Cover Crop in Midwestern Crop Rotations.

Cover crop interest among Midwestern farmers has greatly increased over the past few years, with a focus on cover crops that can be successfully integrated into corn-soybean rotations. Oilseed radish (OSR) is receiving attention due to its large fleshy taproot that winter-kills and is excellent at scavenging nitrogen (N) and penetrating deep into the subsoil. Although OSR can scavenge large quantities of N in the fall, its rapid decomposition in spring may release N too early for the benefit of subsequent cash crops, thereby allowing N to leach out of the root zone. It is hypothesized that planting OSR in combination with a higher C: N ratio cereal will tie up N longer in the spring and reduce premature N release. Although OSR is excellent at penetrating soil, there is less documentation of its effects on other soil physical properties. Cover crop treatments including OSR, OSR+oat, OSR+cereal rye, and a control, were established at two locations near West Lafayette, IN. Bulk soil samples were obtained in the fall and detailed sampling with depth and distance from the radish was performed in the spring, to observe the timing and pathways of N release. Above- and below-ground biomass was sampled in the fall to observe N uptake. Infiltration, penetration resistance, and soil temperature were measured in the spring to determine the effects of the cover crop treatments on soil physical properties. This research is part of the USDA-NIFA, “Cropping Systems Coordinated Agricultural Project. Climate Change, Mitigation, and Adaption in Corn-based Cropping Systems.”