What will the 10 year history of corn yields look like if we have a 165 or 170 yield in 2014? We will need to take out the 2004 yield and start with 2005 though 2014 to get a 10 year history. If you believe in peak corn and are currently marketing your crop believing in peak corn I think you need to make a chart for the years 2005 though 2014 and see if 10 years is enough history to actually predict a yield trend. I am not a believer in peak corn so I am not going to spend any time making a graph or chart to show those years but I do have to question it.

I'm sure you can pick a set of crop seasons to generate just about whatever line you want to.  Remember USDA doing just that by throwing out the "anomaly" 2011 crop so they could draw their line pointing to a record 166 in 2012?   How do you account for going from 81 million planted acres for the 2004 crop to 91-97 million recently?   I will submit that there are simply too many problems with generating trendlines.  Rolling ten-year averages are a much more sensible approach.

recently did some math AVERAGING, contrasting & comparing for yields over last 20 yrs

then, i broke last 10 in 2 halves.

results = avg yield over last 10 = about 150.9. ... '94-'03 avg = 132+
** '04-'08 yield avg slightly higher than last 5, so trend last 10 is flat to down, before 2014 yield. anything above 160 this yr will bump 10 yr trend ever so slightly up.

for those who don't think 30, 40 or 50 yrs is enough data for a trend, here is 147 yrs courtesy of NASS:

http://quickstats.nass.usda.gov/data/printable/E593C02F-7AB7-346B-B986-A4D3C0CA163B 

There has been a poster on this site that has stated for a couple of years that we have reached peak corn and the yield will not be going any higher. He seems to have a lot of people that believe him. He is only using the last 10 years of yields to try to prove his claim of peak corn.

He came out with peak yield first and then changed it to peak production after that.