In Wisconsin, the time is coming soon (Mid March) to frost seed red clover into winter wheat.
It is a practice that works, and nicely introduces an N fixing legume into rotation.
Corn can be planted into rotated red clover the year following winter wheat and benefit from an 80 lb/ac N credit. The clover works as a cover crop in the late summer and fall after the wheat, providing soil erosion protection, as well as other soil quality and soil health benefits.
The following link will take you to a UW Extension publication by J. Stute and K. Shelly that helps explain the process.
There are a few guys in the Elk Creek Watershed and several more in different areas of the state that tried ‘frost seeding’ rye into what will be 2017 soybeans. Will be interesting to see if we get any growth and whether it protects the soil until the soybean canopy gets more established. Those June rains can be tough on erosion so it will be interesting to see if this helps and what impact there is or isn’t on the soybean crop.