Take the comparison farther.
If we banned the export of wheat, what would happen to our wheat production?
Farmers could not afford to produce more than could be used domestically. They would drastically cut production.
In just a few years, we would be importing wheat as the farmers would need to make sure each year their production stayed under domestic demand.
Maybe. But what would likely happen is livestock feed would switch from corn to wheat, because wheat would then cost less than corn. Wheat and corn have almost the same carbohydrate content, but wheat has a larger protein content, so cattle would get bigger, fatter and leaner, as well as pork and chicken, so prices would fall. Since wheat is used in beer, that price would fall as well, so we would have BBQs and beer fests all over the US!...................