(Adds estimates, details)
April 27 (Reuters) - Potash Corp of Saskatchewan 's POT.TO POT.N reported a higher-than-expected rise in quarterly profit as lower costs and increased potash sales volumes more than made up for weak phosphate prices.
Potash prices have rebounded modestly since last year, but still remain low due to bloated capacity and weakening farm incomes.
The company raised its forecast for full-year profit to 45-65 cents per share, from the 35-55 cents it previously forecast.
Potash Corp also raised the lower end of its estimate for 2017 potash sales to 8.9 million tonnes from 8.7 million tonnes, keeping the upper end at 9.4 million tonnes.
"We expect improved consumption trends and nutrient affordability in key markets to support potash demand and our results through the remainder of 2017," Chief Executive Officer Jochen Tilk said in a statement on Thursday.
Potash and rival Agrium Inc AGU.TO announced in September a plan to merge, combining Potash's fertilizer capacity, the world's largest, and Agrium's farm retail network, North America's biggest.
"We continue to work through the regulatory process in key jurisdictions and remain confident the transaction will close mid-2017," Tilk said.
The company's net earnings nearly doubled to $149 million, or 18 cents per share, in the first quarter ended March 31, beating the analysts' average estimate of 11 cents. of goods sold fell 16 percent to $711 million.
However, total revenue fell 8 percent to $1.11 billion, despite a 13.4 percent rise in potash sales.
Analysts on average had expected $1.06 billion, according to Thomson Reuters I/B/E/S.