At Iowa’s latitude, trying to produce ethanol isn’t a winning proposition. Unlike in Brazil, on the equator, who produces ethanol using sugarcane, corn can’t yield enough ethanol precursors using current technology.

There was an effort sell “cellulosic” ethanol to help make more ethanol from corn, using more than just the sugar in the seed.

But in this universe you don’t get something for nothing (except may the universe itself but that is off topic.)

The long term erosion and depletion of top soil will eventually be a big problem for the US. Now, some places like most of Iowa and northern Illinois had an amazingly deep topsoil formed over thousands of years of wet grasslands existing there.

But nothing lasts for ever, especially if you use it.