From Mother Jones magazine:
Who cares about phosphorus? For starters, every living thing on Earth—including humans—since all the crops we eat depend on it to produce healthy cells. Until the mid-20th century, farmers maintained phosphorus levels in soil by composting plant waste or spreading phosphorus-rich manure. Then new mining and refining techniques gave rise to the modern phosphorus fertilizer industry—and farmers, particularly in the rich temperate zones of Europe and North America, quickly became hooked on quick, cheap, and easy phosphorus. Now the rest of the world is scrambling to catch up, and annual phosphorus demand is rising nearly twice as fast as the population.
Our addiction to cheap P (as it’s known in the periodic table) is risky for two reasons. The first, better-known one is that not all the phosphorus that farmers put on their land is absorbed by crops. A lot leaches into water, ending up in lakes and rivers, where it causes algal blooms—which, as they decompose and suck up oxygen, create dead zones.
But the scarier reason is that, like any mined material, phosphate rock is a finite resource, and there’s fierce debate about just how long our supply can last. “Peak phosphorus” doesn’t get a lot of buzz, but it should. In a recent essay in Nature, Grantham, who also runs an environmental foundation, put the case bluntly: Our P use “must be drastically reduced in the next 20-40 years or we will begin to starve.”