That's only an issue if you assume that farm land is a limited resource but that not really the problem in practice.

There are no fuel shortages just because you have cars that use ethanol.

I'm not a huge fan of ethanol specially not how it was handled in the political process (farm subsides) but using it in general is not a bad idea if it can compete.

No, that's not the problem. The problem is that driving tractors and producing fertilizer requires a lot of fossil fuels.

You can run the tractors on ethanol also, though?