Yes and no about that. It takes diesel to grow corn, harvest it, and get it to the plant. Run out of oil and how do you grow corn? Running an engine on pure renewable ethanol, (corn), would cost more than the product you are making would cost. I guess you could plant corn and harvest it using electric vehicles run on batteries that you would plug into a vast solar array. But then, you would not need to grow corn for gasoline anymore. Just grow it for food. It's a merry go round. We have more oil than we know what to do with and are shipping it overseas right now. Maybe we need to think of ways to make our engines more efficient and less polluting than growing corn to subsidize a section of people.
Texas flood: U.S. oil exports pour into markets worldwide | Reuters
In addition to your comment-
Unless you are organic, most of your fertilizers are petroleum based. In the 120 years or so that we have become dependent on petroleum, the world population has climbed from <1 billion to somewhere north of 7.8 billion. Trying to go back to the way things were in 1900 will have disastrous consequences.