In a surprise move early Monday, Terra Industries Inc. (TRA) announced that it has agreed to be acquired by Norwegian fertilizer company Yara International ASA (YAR.OS) for $41.10 in cash per share, for a total purchase price of $4.1 billion.

On Friday, Sioux City, Iowa-based Terra's shares closed at $33.25, down 2.3% from Thursday's close.

The announcement comes almost exactly a month after CF Industries Inc. (CF) withdrew its contentious offer for Terra. CF had been offering $36.75 and 0.1034 share per Terra share, amounting to about $46.39 a share at CF's closing price before it dropped the bid. CF, which had been in pursuit of Terra since the beginning of 2009, had its three-person slate of directors elected to Terra's board in November, with 45% of shares backing CF.

CF itself has been the subject of a takeover offer by rival Agrium Inc. (AGU) for almost as long, though CF has repeatedly rebuffed Agrium in favor of its now-defunct offer for Terra.

Terra chairman Henry Slack said Monday that Terra's board is "unanimous in its firm belief that this transaction is compelling for our shareholders, customers, and employees." Following the close of the transaction, Terra will become a wholly-owned subsidiary of Yara and will be called Yara North America.

"Yara and Terra are a perfect fit, and the combination will elevate Yara to a truly global leader in the industry," said Jorgen Ole Haslestad, president and chief executive of Yara.

The transaction, which the fertilizer companies expect to close by the end of the second quarter, is subject to approval by Terra's shareholders, approval by Yara's shareholders of its rights offering, as well as antitrust and other regulatory approvals.

Yara plans to fund the acquisition in part through a $2-$2.5 billion rights offering.

-By Tara Zachariah, Dow Jones Newswires; 416-306-2100; tara.zachariah@dowjones.com