The company, which reports in U.S. dollars, said it earned slightly more than $2 per share during the last three months of 2012, up from its previously expected range of between $1.50 to $1.90.
Its shares rose more than three per cent, or $3.39, to $114.04 in late-morning trading on the Toronto Stock Exchange on Thursday, topping a 52-week high of $111.48 set Wednesday.
"The increase in our estimated financial results is due to a very strong finish to the fall application season in our North American retail operations, supported by an extended fall season in the U.S. and continued strength in grain and oilseed prices," CEO Mike Wilson said in a release.
"Going forward, continued strength in crop prices and low global grain inventories are anticipated to support a strong spring application season in 2013."
Agrium's revised guidance comes as New York-based investment fund Jana Partners LLC campaigns to win support from other shareholders for major changes at the company.
On Wednesday it said it was meeting with Canadian Agrium investors to detail the concerns it has with the company and how it intends to remedy them.
Jana wants Agrium to concentrate on its wholesale fertilizer business and spin off its retail division, which operates in Canada, the United States, Argentina and Australia.
It has welcomed recent moves by Agrium to buy back $900 million in stock, double its dividend and disclose more information about its retail business, but Jana also wants Agrium to lower costs, allocate capital more effectively and improve corporate governance.
Agrium's management has been resisting the split idea, saying it would expose shareholders to too much risk.
In its updated guidance Thursday, the company said the retail business is expected to generate about $120 million in earnings before interest, taxes, depreciation and amortization in the fourth quarter, resulting in a record $950 million of EBITDA for the division in 2012.
Wholesale EBITDA is expected to exceed $500 million during the fourth quarter and $1.9 billion for the full year — better than expected.
Agrium said its full fourth-quarter financial statements and audited annual financial results, plus a more detailed review of operations and an updated outlook, will be provided on Feb. 22.