by Carl Zulauf and Evan Hertzog, University of Illinois
In a previous article, we compared the trend in U.S. average yield per harvested acre for the 1940-1995 and 1996-2011 periods. The year 1996 was the first year that biotech varieties of crops were commercially adopted in the U.S. The analysis included 14 crops, 3 biotech crops (corn, cotton, and soybeans) and 11 crops for which adoption of biotech varieties is limited. This article specifically examines the deviation of average U.S. yield from its trend-line yield. The objective is to provide information concerning the commonly-expressed argument that biotechnology has reduced yield variability.