Inclusion of a winter legume cover crop into a crop rotation has been suggested as a method to provide a substantial portion of the N requirement of the following crop. While the benefits of winter cover crops such as reduced soil erosion, increased soil organic matter, and increased mulch cover have been well documented, the N contribution to the subsequent crop has shown to be variable. The objective of this study was to determine the N contribution from a red clover (Trifolium pratense L.) cover crop following wheat (Triticum aestivum L.) to a subsequent corn (Zea mays L.) crop. The experiment was conducted at two western Ohio locations over 3 yr. At both locations, red clover was either interseeded into wheat or seeded after harvest, the red clover cover crop was eliminated with tillage or herbicide application, and corn was planted with three N rates (0, 90, and 180 kg N ha(-1)). The data revealed that for three of the four site years (when the cover crop was successfully established) there was no N contribution attributable to the presence of red clover. The one site that did show a N contribution revealed that the amount of N contributed was less than 90 kg N ha(-1). However, even when no N benefit was found, yields were improved by non-N-related rotational effects. Significant reductions in N fertilization rates following a red clover cover crop are likely to result in lost corn yield opportunities in western Ohio.
