There are many advantages to including forage legumes in the crop rotation, including potential to increase soybean and corn yields and more options for reducing agronomic inputs without sacrificing corn yield. Research update, 2011. (378 K PDF)
Planting corn after alfalfa is an effective way to greatly reduce the corn nitrogen requirement and increase corn yield potential, but successful termination of the alfalfa stand is essential in order to fully realize these benefits. Crop News, 2010.
Growing corn following corn is not a bad agronomic practice, but you should expect a lower yield from growing corn following corn due to the rotation effect. 2007.
When are populations of volunteer corn high enough to warrant control? Crop News, 2012.