The New York activist hedge is targeting Frank Proto, Susan Henry, Derek Pannell, Russell Horner and Mayo Schmidt.
Schmidt, the former Viterra CEO, was one of two directors Agrium (TSX:AGU) recently appointed to its 12-member board.
"We believe these five directors embody the lack of relevant distribution experience, passivity in the face of underperformance, lack of shareholder alignment, and entrenchment tactics of Agrium's board that have caused Agrium to underperform," Jana managing partner Barry Rosenstein said in an open letter to shareholders on Thursday.
"Removing them will lift a burden off Agrium, without depriving it of necessary experience or company knowledge."
The letter accompanied a proxy circular filed in preparation for Agrium's April 9 annual general meeting in Calgary.
Proto, who was chairman until last year, has been on the board for two decades, making him the longest-serving member. Henry served on the board for 11 years, Pannell for five and Horner for eight.
Agrium chairman Victor Zaleschuk said in a statement that Jana's efforts are "certain to fail."
"It is unfortunate that Jana has chosen to personally attack directors who have impeccable track records as members of a board that continues to oversee significant value creation and which has been recognized for excellence in corporate governance," he said.
"I am proud of our directors and the role each of them has played in generating a 467 per cent shareholder return over the past eight years."
Agrium says its directors have a total of $23.7 million invested in the company, or an average of $2.6 million each, excluding new additions Schmidt and former John Deere & Co. executive David Everitt.
Jana's slate includes David Bullock, Stephen Clark and Mitchell Jacobson, who had leadership roles at UAP, Brenntag and MSC, respectively. The dissident slate also includes Rosenstein and former Liberal agriculture minister Lyle Vanclief.
The Jana proposal that has garnered the most attention has been to split off Agrium's retail segment, through which seeds and other products are sold to farmers, from its wholesale business.
Agrium says that notion will expose shareholders to too much risk and destroy value. Jana has criticized Agrium for focusing too much on the split idea while not addressing other proposals to cut costs, improve corporate governance and allocate capital more effectively.
In its own proxy circular earlier this week, Agrium likened Jana's slate to a "Trojan Horse" misleading shareholders into breaking up the company.
"Agrium has called our board slate a 'Trojan Horse' even though these nominees would be a minority of the board and could only accomplish change through building consensus," wrote Rosenstein.
"Why is Agrium's board so afraid of a minority of independent board members with relevant experience who can ask the tough questions?"
Agrium's proxy circular also took aim at a so-called "golden-leash" arrangement, whereby Jana would give its nominees special incentive payments to serve on Agrium's board. Agrium said that raises questions about the independence and commitment of Jana's candidates to Agrium's long-term performance.
"Agrium raises this smokescreen now out of desperation. Despite its misleading attacks, this formula is automatic, not discretionary, and based solely on stock performance, and thus fully aligns our nominees' interests with those of all shareholders," wrote Rosenstein.
"While Agrium falsely claims that we are focused on the short term, we would put our nominees' integrity and long-term value creation records against the records of any of Agrium's directors."