(Corrects analyst estimate in paragraph 13 to 37 cents per share from $37)
Oct 29 (Reuters) - Potash Corp of Saskatchewan on Thursday cut its full-year earnings forecast and said it expects to sell less potash in the year than expected due to weak demand and prices.
The world's biggest fertilizer company by market capitalization reported an 11 percent drop in quarterly profit, also hurt by weak nitrogen prices and increased phosphate costs.
The company lowered its full-year profit forecast to $1.55-$1.65 per share from $1.75-$1.95. Analysts on average had estimated $1.74 per share, according to Thomson Reuters I/B/E/S.
Potash prices have sunk some 20 percent year-over-year in the U.S. Cornbelt, according to Mosaic Co data, as demand weakened due to excessive production and soft crop prices.
Demand has also been stifled in key export markets by a new Chinese tax that makes potash more expensive in the country, as well as by the strong U.S. dollar and dry crop conditions in India.
Potash Corp, the second-biggest potash producer by output after Russia's Uralkali OAO, said it expects to sell 9.0-9.2 million tonnes of potash in the current year.
The company, which also makes phosphate and nitrogen fertilizers, had earlier forecast sales of 9.3-9.6 million tonnes.
Potash Corp's average realized potash price fell 11 percent to $250 per tonne in the third quarter ended Sept. 30, while nitrogen prices fell 10.4 percent to $319 per tonne.
Cost of phosphate sold rose 9 percent to $475 per tonne.
The company's net income fell to $282 million, or 34 cents per share, from $317 million, or 38 cents per share.
Excluding non-cash charges, mainly in phosphate, it earned 37 cents per share.
Revenue fell 6.8 percent to $1.53 billion.
Analysts on average were expecting a profit of 37 cents per share on revenue of $1.45 billion.
Potash Corp shares closed at C$28.15 on Wednesday on the Toronto Stock Exchange, down nearly a third this year. (Reporting by Rod Nickel and Shubhankar Chakravorty; Editing by Savio D'Souza)