* Shares up 9.1 percent at $12 after IPO priced at $11
* Expected price range cut to $11-$12 from $13-$15
* Sells 28.6 million shares, raises $314.3 mln
* Soros fund is main Adecoagro shareholder (Updates with details of market conditions, company financials, share price; adds analyst comment, byline)
NEW YORK, Jan 28 (Reuters) - The shares of Adecoagro SA (AGRO.N), a Luxembourg-based agricultural company backed by billionaire investor George Soros, rose 9.1 percent in their stock market debut on Friday.
The shares rose to $12 on the New York Stock Exchange on an overall day of declines, as Adecoagro became a new addition to a hot -- but relatively sparse -- list of agriculture sector plays.
Adecoagro, one of the largest farmland owners in South America, has 38 farms in Argentina, Brazil and Uruguay spanning almost 288,000 acres. It runs rice facilities and dairy operations in Argentina and has two coffee processing plants and two sugar and ethanol mills in Brazil.
With world food inflation on the rise, investors have been clamoring for all things farm-related, especially in heavily agriculture-driven countries such as Argentina.
The shares of Adecoagro's closest analog publicly traded in the United States -- Argentina-based farm operator Cresud (CRESY.O) -- have advanced almost 70 percent in the past eight months on the New York Stock Exchange.
"It has been the only play in the U.S." for equity investors looking to cash in on the booming Latin American agriculture business, said Pedro Herrera, senior vice president of HSBC Global Research, who covers Latin American food, agribusiness and biofuels.
"There are difficulties for investors to play the agriculture sector. There are only a few plays," he said.
In recent years, Adecoagro has also delved into renewable energy, while more than doubling its corn, sugar and ethanol sales in the first nine months of 2010 compared with the same period in 2009, the filing showed. The company now plans to use the proceeds to build a third sugar and ethanol mill in Brazil and buy more farmland.
At the same time, the ethanol expansion has taken its toll on Adecoagro's bottom line, causing the company to record operating losses. The firm reported negative net cash flow of $80.9 million in September 2009 and negative net cash flow of $27.1 million in September 2010.
The company said it acquired a significant amount of land in Bahia, Brazil. The western part of the state has become something of an agricultural frontier in the last decade, with vast flat plains that lend themselves to mechanization, attracting investment in industrial-scale, lower-cost farming.
"The Latin American platform, particularly Brazil, is one of the only places where you can efficiently increase production," said Herrera, who follows Cresud.
Following the IPO, Adecoagro plans to sell shares worth about $78.6 million to Al Gharrafa Investment Co, a wholly owned subsidiary of Qatar Holding LLC, an investment vehicle of the Gulf state's government. The deal would increase Al Gharrafa's stake in the company to 11 percent from 6 percent.
At the same time, Pampas Humedas LLC, an affiliate of Soros Fund Management and Adecoagro's largest shareholder, will reduce its stake to 23 percent from 33 percent.
Pampas, as well as several other Adecoagro's principal shareholders, had planned to sell some shares in the IPO, but scrapped that idea.
A spokesman for Soros, who also owns a 1.2 percent stake in U.S. seed producer Monsanto Co (MON.N), declined to comment on the change.
The company said on Friday it sold 28.6 million shares at $11 each, raising $314.3 million.
In a regulatory filing on Thursday, Adecoagro cut the price range to $11-$12 from $13-$15 as its existing shareholders also reduced the number of stock they planned to sell to only 165,503 shares instead of the originally expected 7.1 million.
Credit Suisse, in which Qatar Investment Authority also owns a 6 percent stake, led underwriters on the offering. Other underwriters included Morgan Stanley and Itau BBA.
The details of Adecoagro's IPO pricing were originally expected to be released on Thursday after the U.S. market close. (Additional reporting by Peter Murphy in Brasilia; editing by Phil Berlowitz, John Wallace and Andre Grenon)