UPDATE 1-Agrium fires back at shareholder aiming to split company

* Share buyback, dividend boost unrelated to Jana - Agrium

* Agrium to give more retail disclosure; wary of rivals

Jan 28 (Reuters) - Canadian fertilizer company Agrium Inc will not split its wholesale and retail divisions as its biggest shareholder, Jana Partners, wants because it would "destroy value" for shareholders, Chief Executive Officer Mike Wilson said on Monday.

Wilson was speaking in New York to Agrium's sell-side analysts in an attempt to blunt Jana's move to replace part of Agrium's board and effect changes it says would increase returns to investors.

Wilson said Jana preferred to talk to Agrium's shareholders and analysts rather than to the company itself, despite an understanding last spring that Agrium and Jana would keep talks on improving the company private.

"They'll say one thing and do the opposite ... They're good at breaking up companies," Wilson said. "They're very good at saying, 'Why not just engage some ideas?' The answer is, if we do, we'll destroy value for our company, and we're not about to do that."

Wilson said a share buyback last year and increases in Agrium's dividend had nothing to do with Jana's pressure.

Jana, a New York based hedge fund that owns 6 percent of Agrium, said last week that it was meeting in Canada with Canadian shareholders, who make up an estimated one-third of Agrium's ownership. Jana said Agrium has refused to openly discuss all ways to improve the company's performance.

Along with splitting the wholesale and retail divisions, Jana has said it wants the company to make better use of capital, control retail and corporate costs better and improve disclosure to shareholders.

Wilson said Agrium would improve disclosure of its retail performance at the New York event, but is also wary of releasing too much detail that its privately held competitors could use.

In November, Jana nominated a slate of five candidates to Agrium's 11-member board to buttress its demand that the company split up its wholesale and retail divisions.

In an Oct. 1 presentation to an investor conference, Jana said Agrium's share price could rise by about $50 if the company took steps to improve its business.

Agrium shares were up 0.3 percent and 0.6 percent in early trading in New York and Toronto respectively.