Centre county Pennsylvania, USA |
Much has been written about national corn yield and yield forecasts, but no actual corn farmer plants the national corn crop in any year. Instead, we each plant the corn crop only in our small part of the nation (our back yard). USDA (NASS QuickStats 2) provides historic corn yield data for every county in every state that produces corn. If we consider our back yard to be the county (or counties) we farm in, then we can mine the USDA data for historic corn yield in our back yard AND the nation.
The attached chart shows results of that data mining for my back yard (Centre county PA) and for the nation. The chart includes 3 panels. Top panel shows linear regression for yield trend at the national level and at the Centre county level. Middle panel shows percent of trend yield at national level and percent of trend yield at Centre county level. Notice they appear to be significantly different. Bottom panel shows that difference, for example, Centre county percent of Centre county trend yield for 2013 was 19% greater than the national percent of national trend yield while for crop year 2011 it was 19% lower. Taken together, those 3 panels clearly show that, as percent of trend yield, corn yield in my back yard has been significantly different than the national corn yield in almost every crop year.
Because we grow and sell corn in our back yard (only), this view of backyarditus may be more informative than historic national corn yield by itself.
 (percent_of_trend_yield.jpg)
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 percent_of_trend_yield.jpg (129KB - 130 downloads)
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historic backyarditus
