U.S. corn production from 1860 to 2010 increased by a factor of 17. Corn yields in America are now averaging 180 bushels per acre, while worldwide yields are 82 bushels per acre. Increasing yields should continue, since non-irrigated yields of about 300 bushels per acre are already being produced with new varieties.
The story of India is instructive.
- Population = 435 million
- Diet = 2000 calories a day
- Farmland = 398 million acres (slightly more that 2 times the size of Texas), 0.91 acre/capita
- Population = 1.155 billion, increase of 2.66 times
- Diet = 2330 calories a day, or one-sixth more
- Farmland = 420 million acres, or 5.5% more, 0.36 acre/capita
China in the post-Mao period has a similar history. The population doubled, GDP increased 45 times, farmland planted in corn doubled, but corn yield was 4.5 times greater per acre. The corn yield increase kept 297 million acres of land from being used to produce this corn. Chinese forest land increased from 1990 to 2010 by 30%.
Without crop yield increases from 1960 to 2010, about 7.4 billion more acres of farmland would have been needed worldwide. This land area is almost twice that of South America or equal to that of the USA, Canada, and China combined. Fortunately, farmers today are producing almost three times as much food on the amount of land used in 1960 for farming.
Ausubel and colleagues estimate that the world average corn yield in 2060 will be about equal to that of the USA in 2010. General increases in crop yields will release between 360 and 990 acres of farmland by 2060. In addition, about 40% of the world's grain is used for livestock. A biotech company called Modern Meadows wants to use 3D printers and tissue engineering to make meat. If that idea works, less farmland still will be needed. The forests are saved.