Shares of Potash Corp
hit a record high on Thursday as its chief executive gave a rosy outlook for the world's largest fertilizer company to a Merrill Lynch conference.

Record grain prices have spurred demand and prices for fertilizer, sending the Toronto-listed shares of Potash up more than 175 percent in the past year, reaching a record C$221.75 on Thursday.

Bill Doyle said the company is prepared to mine 50 percent more potash fertilizer annually in coming years, at prices that are poised to rise further still.

Yet many investors seem more concerned about what's in the rear-view mirror and whether they missed the ride, with the result that our forward multiples ... are the lowest I can remember, Doyle said.

We encourage our shareholders to keep their eyes on the road ahead because our earnings potential is far greater than where we've ever been before, he said.

Potash shares were up 4 percent or C$8.40 at C$220.90 in Toronto late on Thursday.

Doyle said surging world demand for food will mean farmers need to continue to produce record crops, and said he does not believe crop prices will turn lower any time soon.

Potash producers have not been able to produce as much fertilizer as customers want to buy for almost a year, and Doyle said he expected the shortage would last into 2009.

We're very excited because we know for sure between now and June of 2013, there's no new greenfield mine coming on anywhere in the world, Doyle said.

There has been a flurry of interest in exploration in potash belts in Russia and Canada, but Doyle cautioned it takes five to seven years and at least $2.8 billion to build a new potash mine, plus infrastructure costs.

Anyone looking at greenfield (projects) must justify their project on pricing in years eight and beyond, and that's a very big bet to make, he said.

Agrium Inc , another key producer in Canada's potash belt in the western province of Saskatchewan, is examining whether to build a new mine.

Last month, BHP Billiton Ltd bought out a Canadian junior potash mining partner.

BHP has said it will decide whether to move forward on potash plans in 2010, Doyle said, meaning the mining major would produce potash in 2017, at the earliest.

We'll wait and see what happens there, but it's not immediate. There's no quick fix here, Doyle said. (Reporting by Roberta Rampton; editing by Rob Wilson)

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