The government subsidies on corn pushes Iowa farmers to produce more than normal (depleting the soil faster) and sell their corn regardless of the market price. This is mostly done at the behest of other industries and huge food corporation lobbyists. It's a perverse economic incentive to say the least. I don't disagree with your conclusion, but I also don't think there's a bright line between corn subsidies and Iowa somehow playing kingmaker in the caucuses.