Nitrogen fertilizer producer CVR Partners LP said it would buy Rentech Nitrogen Partners LP for about $533 million, excluding debt, as global fertilizer makers aim to scale up at a time when increased supplies weigh on nitrogen prices.

The deal comes less than a week after CF Industries Holdings Inc said it would buy OCI NV's North American and European plants for $6 billion, making CF the world's largest publicly traded nitrogen company.

Potash Corp of Saskatchewan, the world's second-largest potash miner, has been proposing to acquire German salt and fertilizer company K+S AG.

Rentech Nitrogen shareholders will receive 1.04 units of CVR Partners and $2.57 cash for each unit held.

The deal, which also excludes Rentech Nitrogen's plant in Pasadena, Texas, represents a premium of 33 percent to the company's Friday closing price.

Rentech Nitrogen shares were up about 17 percent in light premarket trading on Monday.

Rentech Nitrogen, a master limited partnership of Rentech Inc, will own 40.5 million units, or 35.6 percent of the combined company.

CVR Partners, owned by Carl Icahn-controlled CVR Energy Inc , will refinance Rentech Nitrogen's net debt of about $307 million.

The deal is expected to close by the end of 2015 and no later than May 2016, the companies said.

Sugar Land, Texas-based CVR Partners said it expects the deal to be double-digit accretive to distributable cash per unit before synergies.

Rentech Nitrogen said it planned to sell the Pasadena facility before the closing of the merger with CVR Partners.

Los Angeles-based Rentech Nitrogen hired Morgan Stanley in February to explore strategic alternatives.

Latham & Watkins was Rentech Nitrogen's legal adviser, while Vinson & Elkins served as legal adviser to CVR Partners.