$1:
U.S. laws that mandate a certain percentage of the corn crop go into ethanol fuel for the transportation industry had lit a fire under corn prices even before the drought. The size of the continent's corn crop has been rising for a decade, before falling precipitously this year.
One of the dumbest things I've seen the US FedGov do yet for the following reasons:
1) Driving up the cost of corn and makes less available for food and feed.
2) Ethanol blended gas negatively impacts fuel milage.
3) Ethanol blened gas destroys small engines. I've seen the effects first hand on outboard marine engines, lawnmowers, etc.