From the time US energy policy shifted under EPA mandates, corn increased in price continuously in every year until 2013 except for 2008-2009. Corn [and most other commodities] was flat during that period because of the onset of the recession. There was also a crash in the price of ethanol at that time, because there was substantial drawdown in consumer mileage. For a period of about 5 months, people really weren't going anywhere.
Before the expansion of ethanol, corn had historically traded in the $2.00-$3.50 range. During the years from 2005 - 2013 its price rose dramatically. One consequence of that was the livestock growers switched to other feedstocks; beef steers and dairy beef will east just about any indigestible biomass you put in front of them. That reduced the price of corn, as did the EPA moratorium on increasing the mandate during that time, and other factors like lower international demand [the overall world economy is slowing, regardless of what lies you've been told.]
Considering the consumer price of an agricultural output against agricultural inputs on a spot basis is usually tricky. Commodities markets have to some degree been stabilized by the advent of futures and other smoothing forces, but spikes and crashes still happen all the time and they aren't reflected back into the consumer end of market in realtime. The actual transfer-function depends in very complicated ways on weather, imports, exports, trade agreements, existing stocks, demands in non-consumer markets ... you name it.
The bottom line is that the long term trendline for corn prices have been increasing, and the reason for that is clear. This despite the fact that, as always, US farmers continue to farm more productively than ever.
really helpful. thank you. i need to study your post in detail, but thanks.