Scientists have been pointing out the “broken” phosphorus cycle for more than a decade: Humanity has unearthed huge quantities of the element, which winds up in waterways instead of returning to cropland.
The problem comes down to crap. People and livestock eat crops and excrete phosphorus as a result. (A University of Iowa researcher calculated that the state’s livestock produce a load of excrement equivalent to a nation of 168 million people.) But most of it won’t end up feeding plants again. Waste treatment can loop sludge or manure back to being fertilizer, but transporting and treating it is often impractical, so it may sit in → Continue reading at Wired - Science