You are absolutely correct, all areas are not the same.  That is the reason for the post, just because someone says fertilizer prices are too high to grow corn  doesn't mean that they are too high everywhere. Look at the big four corn growing states, they grow a lot of corn because that is the crop that works best. To abandon the crop that works best in your area because of perceived high input costs is not rational, you need to run the numbers on all potential crops and then decide on what combination is best for you.

Right now there  is a bidding war between corn, soybeans, and wheat for acres.  There are not enough acres to meet the demand of all three crops.   As soon as the intended planting acres report is out the price of all crops will drop with the winning crop dropping dramatically. So once the decision is made enough crop should be locked in to cover your input costs.