Jan 16 (Reuters) - Mosaic MOS.N on Friday said North American fertilizer demand fell sharply in the fourth quarter, well beyond normal seasonal weakness, pressuring sales volumes and cash flow. The U.S. fertilizer producer said phosphate shipments in North America were down about 20% from a year earlier, while potash demand was only modestly weaker.

(Reporting by Sumit Saha in Bengaluru)

((Sumit.Saha@thomsonreuters.com;))