First we have to fret about peak oil, then peak coal, and now… peak phosphorus? Maybe. Over at Salon, Andrew Leonard reports that the price of both synthetic fertilizer and Monsanto's Roundup, a popular weed-killer, has been spiking in the past year—partly because of rising demand, partly because of rising energy costs. But Leonard also points out that our current reserves of rock phosphate, a key ingredient in both industrial fertilizers and Roundup, could run out within a half-century. Okay, so does that mean we're staring at an organic-farming future?