WINNIPEG, Manitoba - Agrium Inc (AGU.TO), a Canadian fertilizer maker and the world's biggest farm retailer, on Thursday forecast a less profitable year than expected and said its quarterly profit plunged.

The Calgary, Alberta-based company said after normal trading hours that it expects to earn $4.50-$6 per share in 2017. The midpoint of $5.25 fell below analysts' average estimate of $5.45, according to Thomson Reuters I/B/E/S.

Sagging U.S. farmer incomes and soft fertilizer prices have pressured crop nutrient producers, even as new capacity for nitrogen and potash comes on stream this year.

The company said it expected farmers to remain cautious in purchasing crop input supplies, and sees U.S. corn acreage falling to between 90 million and 92 million acres this year, from 94 million in 2016. Corn is a fertilizer-intensive crop.

In September, Agrium and Potash Corp of Saskatchewan (POT.TO) agreed to join forces in an all-stock deal.

The tie-up, pending regulator approval, is expected to close in mid-2017.

U.S.-listed shares of Agrium fell slightly in after-hours trading, after closing down 1 percent at $104.02.

Net earnings fell to $67 million, or 49 cents per share, in the fourth quarter from $200 million, or $1.45 per share, a year earlier.

Agrium said revenue fell 5 percent to $2.28 billion, slightly exceeding the average estimate of $2.2 billion, according to Thomson Reuters I/B/E/S.

On an adjusted basis, it earned 60 cents per share, and it recorded a further investment impairment of 8 cents, for earnings per share of 68 cents that Agrium said were relevant to guidance.

Analysts on average expected earnings of 68 cents per share.