Every time a bunch of investors think they’re smart, the market teaches them a lesson. Fertilizer stocks are the example du jour. Last night, Mosaic (MOS), which is a huge seller of phosphates and potash (more phosphates than potash), released earnings … and they weren’t good. Earnings came in at $2.65 a share, way up from a year ago, but a full 29 cents below estimates. Moreover, management indicated that phosphate prices have begun to flatten out, so much so that the company is cutting production going forward. Now, before the announcement, the stock was already down a whopping...