Using Bicultures to Improve Soil Conservation and Phosphorus Cycling in Oilseed Radish Cover Crops.

The use of oilseed radish (OSR) as a cover crop has been increasing throughout the U.S. Corn Belt due to recent studies that have shown its multiple benefits. Containing a large, fleshy taproot, OSR has the ability to biologically till the soil and store large amounts of phosphorus (P) in its tissue. Also characterized by rapid decomposition in the spring, it is hypothesized that OSR may release available P before the subsequent crop is able to recover it and can leave the field susceptible to runoff and sediment loss. Planting OSR simultaneously (biculture) with a crop containing a higher C:N ratio may allow for slower decomposition of the cover crop, better ability to hold bio-tilled soil and accumulated P in place, and improved ability to cycle P back to subsequent crops. Treatments consisting of OSR, OSR + oats, OSR + cereal rye, and no cover crop were established at two locations near West Lafayette, IN to determine if bicultures improve OSR’s ability to conserve soil and cycle P back to subsequent crops. Soil samples were obtained during fall and spring from various soil depths and row orientations, in order to observe the accumulation of P in the soil. Samples of living above- and below- ground biomass were obtained in the fall, and dead above-ground biomass was obtained in the spring in order to observe the accumulation of P in the cover crops. Rainfall simulations were conducted in the spring to observe the amount of soil sediment and P lost through runoff. This research is part of the USDA-NIFA, “Cropping Systems Coordinated Agricultural Project:  Climate Change, Mitigation, and Adaption in Corn-based Cropping Systems.”