Phosphorus and potassium cannot be synthesized—they're found in significant amounts only in a few large deposits scattered across the planet, in the form, respectively, of phosphate rock and potash. After less than a century of industrial ag, we're starting to burn through them. In a column in the November 14 Nature, the legendary investor Jeremy Grantham lays out why that's a problem: These two elements cannot be made, cannot be substituted, are necessary to grow all life forms, and are mined and depleted. It’s a scary set of statements. Former Soviet states and Canada have more than 70% of the potash. Morocco has 85% of all high-grade phosphates. It is the most important quasi-monopoly in economic history.