Detrended Midwest state yield data from the 1950-2014 yield average.  Yield data detrended to account for technological improvements in crop 
production.  Greens indicate an increase in yield compared to the 2010-2014 5-year average yield, while browns, oranges, and golds indicate a 
reduction from the 5-year average.  Data source: National Agricultural Statistics Service

In the summers after a strong El Niño, there was not a strong impact on crop yields.  The detrended average of these years compared to the 2010-2014 5-year average shows most yield differences for the summers after an El Niño are 5 percent or less, except in Kentucky and Missouri for corn and Indiana for soybeans.  The major drop in yields in 1983 were attributed to a drought across the region.