PotashCorp of Saskatchewan, the world's biggest fertilizer company by capacity, reported better-than-expected quarterly sales as prices bounced back from the lows of the year and on record volumes.

Sales volumes rose 16.3 per cent to 2.5 million tonnes in the third quarter ended Sept. 30, the company said on Thursday.

"Supported by improved market fundamentals, spot prices have increased by approximately 15 per cent from the lows experienced earlier in the year," Chief Executive Jochen Tilk said in a statement.

PotashCorp in September agreed to combine with fellow Canadian fertilizer producer Agrium Inc to navigate a severe industry slump by boosting efficiency and cutting costs.

The world's third-largest potash producer said costs of goods sold fell 11.6 per cent to US$792 million.

The company cut the upper end of its full-year earnings forecast to 45 cents per share from 55 cents. The company retained the lower end at 40 cents.

Net income fell to US$81 million, or 10 cents per share, from US$282 million, or 34 cents per share, a year earlier.

Sales fell 25.7 per cent to US$1.14 billion, but beat analysts' average estimate of US$1.04 billion.

Excluding items, the company earned 11 cents per share, above the 9 cents expected on average by analysts, according to Thomson Reuters.