If you have managed you nitrogen, there will be < 1000 ppm in the cornstalks. That is 1000 per 1,000,000 million pounds of cornstalks. A million pounds of cornstalks is equal to 500 tons. With 180 bpa corn, there will be ~ 5 tons of aboveground cornstalks per acre. So you need 100 acres to have a million pounds of cornstalks. So you have < 10 pounds of nitrogen per acre in your cornstalks.

Now, if you will tell me how much organic matter your tillage will oxidize – we can answer your question. Regardless, the answer is the same. You will lose more from tillage than you will add back from cornstalks.

Cornstalks have a very high C:N ratio so microbes don't like themn very much. That is why cornstalks left on the surface are still there the following Spring. So if you incorporate the corstalks into the soil, where do you suppose they get their nitrogen to degrade the cornstalks?