Mosaic ( MOS), with a market value of $37 billion, is the world's No. 1 producer of phosphate, with about a 13% share of global production and the second-largest North American producer of potash. Phosphate and potash are two of the three primary crop nutrients. Mosaic owns phosphate rock mines in Florida and potash mines in Canada, giving it a reliable base of supply for years to come. Analysts said tighter inventories would help producers push through price increases in overseas markets, and that there is a shortage of the stuff setting up as farmers get ready for spring planting season. Morningstar analyst Jeffrey Stafford wrote in a Jan. 19 research note that "crop supply and demand balances point to a robust 2011 for fertilizer pricing and demand. However, the long-term dynamics are not quite as clear. "While the need to feed a growing population will lead to increased demand for crop inputs, fertilizer prices will depend on the amount of additional capacity that is brought on line over the next decade," he said. Mosaic, of Plymouth, Minn., has seen its shares rise to a recent 52-week high in the past few weeks. They're up 11% this year and 45% over the past 12 months. Morningstar says its review of analysts' ratings finds five "buys," one "outperform," 11 "hold" and one "underperform" rating.