Soybean yield as affected by biomass and nitrogen uptake of cereal rye in winter cover crop rotations

The inclusion of cereal rye (Secale cereale L.) as winter cover crop (WCC) following corn (Zea mays L.) has been suggested as a valuable nutrient management tool in the typical corn-soybean [Glycine max (L.) Merr.] rotation of the U.S. Midwest. However, little information is available on the effects of rye WCC on the soybean crop. The objectives of this study were to quantify biomass and nitrogen (N) uptake of rye WCC and to evaluate the effect of rye WCC on soybean yield. The effects of four rotations (corn/soybean, hairy vetch-corn/ryesoybean, rye-corn/rye-soybean, and hairy vetch + rye biculture-corn/rye-soybean) on soil residual NO3-N content, rye biomass, N content, and C/N ratio, soil residue cover, soybean light interception, and grain yield were investigated at Urbana and Brownstown, IL. Rye N content was highly correlated with soil residual NO3-N content (r = 0.64, p < 0.0001). Rotations that only included hairy vetch (Vicia villosa L.) reached maximum N content at lower corn N rates compared with rotations with rye. Soybean light interception at R1, R4, and R6 growth stages and grain yield were not affected by the treatments. Rye WCC planted after corn appears to take up a significant proportion of residual NO3-N without affecting soybean grain yield, providing an environmental service to the agroecosystem.