The top executive at Agrium Inc. (AGU) said Tuesday he expected the board of takeover target CF Industries Holdings Inc. (CF) to engage in talks after CF shareholders tendered 62% of their holdings in support of Agrium's $3.89 billion offer.

The four-month battle among three North American fertilizer makers showed no signs of weakening, however, as CF maintained its shareholders do not back the price of an offer from Agrium it claims may be blocked by regulators.

Agrium Chief Executive Mike Wilson said that "there were no material impediments" to U.S. antitrust approval and called on CF to engage in talks.

"I can't believe they are going to ignore their shareholders' wishes," he told Dow Jones Newswires after the tender offer result was announced.

Wilson said Agrium would refile its Hart-Scott-Rodino request for antitrust clearance "shortly," having withdrawn it in late May.

CF maintains regulatory hurdles remain a key barrier to engaging in talks with Agrium, as CF continues its own pursuit of Terra Industries Inc. (TRA), a smaller U.S. fertilizer maker that has so far resisted CF's approach.

CF maintained the 62% tender offer result did not constitute majority backing for Agrium's cash-and-stock offer.

Agrium had threatened to walk away if it didn't win enough backing in the tender offer, while CF has maintained Agrium was trying to break up its pursuit of Terra.

The often testy three-way contest comes against the background of weak conditions in the fertilizer market despite crop prices that remain well above their five-year average.

Agrium's Wilson insists his company remains committed to acquiring CF, a move that would add CF's wholesale distribution strength and expand Agrium's own presence in nitrogen and phosphate-based products.

Share prices in all three companies have fallen in recent weeks, and Wilson said market conditions remained "fairly tough," with no recovery expected before the fourth quarter.

CF Chairman and Chief Executive Stephen Wilson said in a statement that the tender results "do not change the facts that Agrium's offer substantially undervalues CF Industries, our shareholders do not support the price in the offer and the offer has significant regulatory issues."

On Friday, CF extended its $2.93 billion tender offer for Terra to July 10.

Shares of all three companies were higher Tuesday. Agrium shares were up 1.8% at $39.60, Terra stock was up 2.8% at $25.46, and CF was 3.3% higher at $71.63.

Agrium's latest bid is $40 and one share of its stock for each share of CF. That values CF at $79.23 share, a 14% premium to Monday's closing price of $69.32.

-By Doug Cameron, Dow Jones Newswires; 312-750-4135; doug.cameron@dowjones.com

(Tess Stynes contributed to this article.)