Matt Ridley on an interesting paper from Jesse Ausubel and Iddo Wernick of Rockefeller University, and Paul Waggoner of the Connecticut Agricultural Experiment Station:
Globally, the production of a given quantity of crop requires 65% less land than it did in 1961, thanks to fertilizers, tractors, pesticides, better varieties and other factors. Even corrected for different kinds of crops, the acreage required is falling at 2% a year.
In the U.S., the total corn yield and the total corn acreage tracked each other in lock step between 1870 and 1940-there was no change in average yield per acre. But between 1940 and 2010, corn production almost quintupled, while the acreage devoted to growing corn fell slightly. Similar divergences appeared later in other countries. Indian wheat production increased fivefold after 1970, while wheat acreage crept up by less than 1.5 times. Chinese corn production rose sevenfold over the same period while corn acreage merely doubled.
Yet the amount of farmland in the world was still rising until recently. The reason is that increased farm productivity has been matched by rising demand for food, driven by population growth and swelling affluence. But the effects of these trends are waning.
[. . .]
Even with these cautious assumptions, the researchers find that over the next 50 years people are likely to release from farming a land area “1½ times the size of Egypt, 2½ times the size of France, or 10 Iowas, and possibly multiples of this amount.”
Indeed, the authors find that this retreat from the land would have already begun but for one factor so lunatic that they cannot imagine it will not be reversed soon: biofuels. If the world had not decided to subsidize the growing of energy crops on 3.4% of arable land, then absolute declines in the acreage of arable land “would have begun during the last decade.” The prospect of “the restoration of vast acreages of Nature” is enticing for nature lovers.