Many people have tried to analyze what the future holds for continued increases in crop yields. After studying time series of average U.S. yields for 19 crops, Lin and Seaver [6] concluded that 12 crops including corn, cotton, and wheat have reached yield plateau, and the seven remaining crops including hay and soybeans yields have had a slowdown in their rate of growth. On the other hand, after presenting some of the possible new technologies or changes in existing technologies that could boast yields, Wittwer [15] concluded that it is reasonable to expect possible large increases in yields. Wittwer's list of possible technologies included: changes in the plants' ability to withstand environmental stress; changes in the plants' ability to utilize fertilizer including the possibility of more plants with nitrogen fixation capabilities; increases in the plants' photosynthetic efficiency; and increases in the use of chemical growth regulators. Heady [5], after reviewing a host of other studies, observed that probably the best that can be hoped for in the future is the continuation of the current absolute increases in yields.