Out of Phosphorous?

The June 2009 issue of the Scientific American magazine has an interesting article of some relevance to those of us who grow plants. The article by David A. Vaccari explores our present situation regarding this very important mineral and raises the idea that we may face a shortage of phosphorous in the next few decades.
As with many debates of this type --running out of stuff, that is, there are two sides to the story. Whereas Mr. Vaccari contends that the economically extractable phosphorous is running out, others believe that we have plenty.

Phosphorous is the middle of those three numbers on every bag of fertilizer. You've seen it: 5-5-1 or N-P-K (Nitrogen-Phosphorous-Potassium). Commercial growers depend on it to grow the huge amounts of food it takes to feed our ever-growing human population.

Mr. Vaccari explores the various scenarios that contribute to this coming shortage, including how we have disrupted the Phosphorous renewal cycle. What Mr. Vaccari doesn't mention is the effect vegetable gardens may have on the demand for food on commercial growers. What would happen if, for example, 30% of Americans grew their own vegetables on their yards? What would happen if 30% of the world grew their own vegetables using sustainable methods?
By the way, I chose 30% based on the fact that when I drive around my neighborhood, only about two out of every ten houses has vegetables growing in their backyards (where I can see anyway). I figured, hugely un-scientifically, that 20% of my neighbors grow veggies, so I just increased that by 10%. I would be interested to find out how wrong I am.
And what about small farms that can supply food locally?

This article cemented my commitment to growing my own food using sustainable methods. I will continue to explore the possibility to grow vegetables all year round using cold-frames and green houses.

Over and out.