Article about peak phosphorous and the future of agriculture by John Michael Greer:

http://www.realitysandwich.com/two_agricultures_not_one

From the text: "Talking about the future after peak oil is a challenging thing. One of the things that makes it most challenging is the extent to which so many people seem unable to imagine any way of doing things that isn't business as usual in some lightly modified form. This odd blinkering of our collective imagination is evident in the current worries in the peak oil blogosphere about "peak phosphorus."

It's true, of course, that the rapid depletion of the world's reserves of rock phosphate, a key ingredient in chemical fertilizers, is a serious short term problem. Today's agricultural systems depend on chemical fertilizers, and there aren't any other abundant and highly concentrated sources of mineral phosphate available to be dumped into the intake hoppers of fertilizer factories. Still, this doesn't mean that we're all going to starve to death; it means that the way we produce food nowadays is not long for the world, and will be replaced by other ways of producing food that don't depend on mass infusions of nonrenewable resources."