POTASH CORP. OF SASKATCHEWAN $37 (www.potashcorp .com) exports potash fertilizer to customers outside North America through Canpotex, a marketing joint venture. Potash Corp., Agrium (see below) and Mosaic Co. (New York symbol MOS) each own a third of Canpotex. A major Indian importer recently agreed to buy potash from Russia at $322 U.S. a tonne, down 25% from a year earlier. That will put pressure on Canpotex to lower its prices. Hold.