I have a couple fields that have been corn on corn for 10+ years, and have learned a few things:
Plant into black soil, whether it be disked, strip-tilled, or whatever. Planting in the old root ball is where diseases and bugs live, and I have better results keeping the plant healthy by planting into 'soil'. If you strip-till, going in between the old rows helps immensely, just do your best to plant into dirt.
Liquid N helps break down the old stalks the fastest, dry is next, and NH3 is the slowest, if you need to get the old stalks rotted off. I have had good luck going with liquid N immediately before disking in the spring. How much residue you have to deal with determines what works the best.
Sidedressing about 50# of 32% seems to be the 'magic' number in my soils (and yours may be different). I know it takes more running around with tanks going a higher rate, but for me, the yield response has been worth it. I just adjust my pre-application as needed to sidedress everything at that 50# rate.
Cultivation also helps to loosen the soil, and aid in the breakdown of the old stalks, as well. How much this helps depends on how much you have to deal with. In high-residue BT corn, it almost always helps me. My soils need the 'loosening up' in COC, though.
Set your trash wheels to move as much trash as possible, and to roll the old root balls over, but not to move any more mellow soils than necessary to do this. Finger wheels work very well.
Also, select varieties with strong disease resistance.
Lastly, and this seems odd, but the 2nd year of continuous corn seems to be the hardest. After 3-4 years of COC, for me anyway, things seemed to work better (or I just figured out what worked) and yields came up. I had my continuous corn yield within 2-3 BPA of the guy over the fence, who planted into bean ground on a field that has seen nothing but corn for over 10 years. To be fair, I did have to fertilize more, and do extra tillage to make it work.
