Corn cannot be broadcast planted successfully. It's very labor intensive after planting and unless you do a lot of cultivating you'll end up with two feet tall stalks that don't bear anything. Soybeans can be broadcast and deer eat them throughout their life cycle from the moment they come up until they bear. The biggest problem I have had with soybeans is that the deer tend to eat them down while they're young and they don't get a chance to seed out. Larger plots will help prevent this.