Phosphate shortage

Lately, I have been following the very interesting “Blogging the Periodic Table” by Sam Kean, the author of the forthcoming book The Disappearing Spoon.  Today (entry 7) he has written an interesting piece on the phosphorus shortage:

Some agricultural scientists today fret that we’re eating our way into another fertilizer shortage—and with an element we can’t conjure out of thin air, phosphorus. They call the threat “peak phosphorus.”  (It’s a play on “peak oil).  Plants need phosphorus in a form called phosphate.  Living creatures use phosphates as the structural girder for DNA and in a molecule called ATP which provides the power to run cells. Human beings are 1 percent phosphorus by weight and scientists have long known how important an element it is for health. Even with all the other problems of the Great Depression going on, FDR gave a speech warning America about the diminishing phosphorus in our food. Ninety percent of the phosphorus mined today (it’s abundant in China, Morocco, Idaho, and Florida) ends up in fertilizer bags.  Unfortunately, erosion and runoff waste half of that phosphorus, as the phosphates end up scattered deep underground or chemically changed. So even though the phosphorus atoms never disappear, they’re not available as fertilizer. The world has between 4 billion and 8 billion tons of phosphate reserves, and we extract one-eighth of a billion tons per year; simple arithmetic says we could “run out” of phosphorus in about 30 years. The end could come even sooner if we ramp up biofuel production, since switchgrass, corn, and other biofuel crops will require loads of phosphorus-rich fertilizer. And unlike nitrogen, there’s no other ready source than mining.