There was an interesting article in the Wall Street Journal last week describing some research on land use and agricultural productivity ( the original research is posted here).
Here are some snippets from the WSJ article:
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.
and
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.
and
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."
in conclusion:
Predictions of peak oil have repeatedly proved wrong. But the factors that made them wrong—productivity and technology—are essentially the ones that make a prediction of peak farmland likely to be right.
I agree - so long as we don't demonize or overly regulate the use of technologies that lead to increased productivity in food. I have faith in our innovative abilities, but I worry about the messages being sent by the foodie cultural elites.