The 2012 corn crop was decimated by drought:
“The searing U.S. drought of 2012 devastated the nation’s corn crop, pushing yields down in some states to their lowest levels in nearly 30 years. According to recently-released numbers from the U.S. Department of Agriculture (USDA), Missouri, Illinois and Indiana were among the hardest hit Corn Belt states, with yields at 28-, 26-, and 22-year lows, respectively.”
“To put the severity and impact of the 2012 U.S. drought in context, the top 10 hardest-hit states for crop damage are illustrated in the interactive graphic above. With several states seeing their lowest corn crops in more than 20 years, along with damaged soybean and sorghum harvests, the interactive shows how 2012 ranks against the past 27 years for all 10 states."
Source: Climate Central