The Green Revolution increased crop yields by a factor of 3 for soybeans and between 4 and 5 for corn (maize), wheat, rice and some other crops. Using data for corn (maize) in the U.S., yields increased about 1.7 bushels per acre from the early 1940s until the first decade of the 21st century when concern was being expressed about reaching limits of photosynthesis. Because of the constant nature of the yield increase, the annual percentage increase has declined from over 5% in the 1940s to 1% today, so while yields for a while outpaced population growth, yield growth now lags population growth.
