Victor Davis Hanson makes an interesting point:

An ironic note: The agricultural revolution that changed America was not entirely a result of efficient machines, chemicals, and new crop species. Much of it was due to the end of devoting millions of acres to pasturage and feed stuffs for millions of horses. My grandfather told me that when he was small half our farm was used to feed the horses that pulled the cultivators for the vineyard and orchard. But apparently here we go again-planting land for transportation. And we should expect everything from ice cream to beef to rise in price as a result.

And Iain Murray adds detail:

Efforts to force-feed the U.S. corn ethanol industry are likely to trigger lots of forest clearing, but U.S forestland is of substantially poorer quality than its corn land. Our corn is grown on our best land, while our forests grow on our worst. Forest land is steeper, dryer, poorly drained, or somehow lacking