* S&P affirms 'A' rating, with negative outlook
* GrainCorp deal could bring earnings growth in years ahead
By Tom Polansek
CHICAGO, May 3 (Reuters) - Standard & Poor's Ratings Services said on Friday that Archer Daniels Midland Co's planned A$3.0 billion ($3.1 billion) acquisition of Australia's GrainCorp Ltd should yield benefits for the U.S. agribusiness company in the coming years.
S&P removed ADM, one of the world's top grain traders, from its watch list for a potential ratings cut and affirmed an 'A' corporate credit rating.
The agency said it still has a negative outlook for ADM, "reflecting our expectations for continued weaker credit measures once the transaction is complete" and uncertainty about the size of the U.S. harvest later this year.
S&P first put ADM on the watchlist in October when ADM made an initial bid for GrainCorp.
The GrainCorp acquisition is expected to pay off in the longer run because it will expand ADM's global footprint and give it an important foothold in the rapidly-growing Asian market, according to S&P.
"Although ADM participates in a challenging industry characterized by volatile commodity prices, we believe management's ongoing capital investments in its core business lines will generate meaningful earnings growth over the next several years and increase geographic diversity, which should help offset inherent earnings volatility," the agency said in a report.
ADM, which on Wednesday reported lower-than-expected earnings for the quarter ended March 31, has declined to comment about ratings reports.
Moody's Investors Service on Tuesday placed ADM under review for a ratings downgrade because of the proposed deal. High crop prices and capital spending mean ADM's "ability to generate free cash flow is less certain," Moody's said.
ADM is one of the four so-called "ABCD" players that dominate the flow of agricultural goods around the world, along with Bunge Ltd, Cargill Inc and Louis Dreyfus Corp.
ADM Chief Executive Patricia Woertz said on Wednesday the company could "easily finance" its sweetened A$13.20 a share offer for GrainCorp that includes A$1.00 a share in dividends.
ADM included an extra dividend of 3.5 cents per share a month from October if regulatory approvals lagged beyond the start of that month.
S&P predicted the deal will be completed in early 2014.
The takeover, which needs regulatory approval, is the latest move in the consolidation of the global grains sector amid competition to feed fast-developing countries like China.