(Adds prices, sales volumes, background and estimates)
May 7 (Reuters) - U.S. fertilizer maker Mosaic Co reported a smaller-than-expected quarterly profit on Monday as its phosphate and potash sales volumes fell due to delayed spring and transportation bottlenecks in Canada.
Canada, where Mosaic operates potash mines, is facing a shortage of rail capacity, as Alberta oil producers are competing for limited space on trains to take their crude to U.S. Gulf of Mexico refineries.
However, the company raised its 2018 adjusted earnings forecast to between $1.20 and $1.60 per share, from its earlier expectation of between $1.00 and $1.50 per share.
Sales volumes of diammonium phosphate fell 17 percent to 1.9 million tonnes in the first quarter ended March 31, at an average price of $431 per tonne, from $369 per tonne a year earlier.
The company reported net earnings attributable to Mosaic of $42 million, or 11 cents per share, compared with a net loss attributable of $900,000, a year earlier.
The reported quarter included $49.9 million in income tax benefit.
Sales rose to $1.93 billion from $1.58 billion.
Excluding items, the company earned 20 cents per share, missing analysts' average estimate of 28 cents, according to Thomson Reuters I/B/E/S. (Reporting by Karan Nagarkatti in Bengaluru; Editing by Sriraj Kalluvila)