This analysis finds that, while the yield trend increased for all 3 biotech crops after 1996, the yield trend increased for less than half of the crops (4 of 11) for which biotech varieties are of limited importance. This finding does not prove that biotechnology is the reason for the higher yield trend for corn, cotton, and soybeans. It only reveals that the evidence on linear yield trends is not inconsistent with such a conclusion.
Over 10 years, the higher yield trend translates into a harvest yield that is 1.6 bushels, 0.6 bushels, and 69.1 pounds higher for corn, soybeans, and cotton, respectively. This addition to yield is 1.0%, 1.4%, and 7.9% of the highest harvest yield observed for corn, soybeans, and cotton, respectively. Thus, for corn and soybeans, the increase in yield trend since 1995 is not large.
These implications are subject to change with more years of data. Also, the analysis does not address what the yield trend would have been for corn, cotton, and soybeans if biotech varieties had not been introduced.