Cargill Inc said on Thursday that quarterly earnings fell 82 percent, the giant U.S. agribusiness firm's worst quarter in more than 20 years, with profit margins weak in its oilseed and beef processing operations.

Full year profits were also disappointing as both sales and profits from the company's global food supply businesses were squeezed by soft economies and volatile commodity markets.

"Cargill's earnings performance was not up to our expectations, though with notable exceptions," Cargill Chief Executive Greg Page said in a statement. "We did not trade as well in this year's markets, which were driven as much by the economic and political environment as by the fundamentals."

Minneapolis-based Cargill, one of the world's largest privately held corporations, reported $73 million in earnings from continuing operations for the fiscal fourth quarter ended May 31, down from $404 million a year earlier.

It was Cargill's worst quarter since the second quarter of fiscal 1991 when Cargill earned $71 million, a company spokeswoman said.

Cargill's full-year fiscal 2012 earnings fell 56 percent to $1.17 billion from a record $2.69 billion in the prior year, and were well below expectations, the company said.

Fourth-quarter revenues were $34 billion, a 2 percent drop from a year ago. Cash flow from operations for the full fiscal year was $3.51 billion, compared with last year's $4.55 billion.

Cargill, a leading food processor, grain and meat exporter, and ethanol producer, is a top trader in dozens of commodity markets around the world. But it is subject to risks from weather-related supply problems, including the current ruinous drought in the United States.

Grain prices have soared to records this summer and those effects are likely to show up in fiscal first quarter earnings for June-August. Cargill did not cite any drought effects in its earnings analysis.

Page appeared on television last week to voice support for an easing of the U.S. government's mandate to produce rising amounts of ethanol, saying the squeeze on corn supplies has added unnecessary volatility to soaring corn prices and squeezed livestock producers - like Cargill, a major beef producer.

Among the five main businesses, Cargill said its food ingredients segment was the largest positive contributor to company results in both the fourth quarter and full year.

Ingredients posted record earnings for the full year, with performance particularly strong in sweeteners, starches, specialty oils and cocoa worldwide, and in staple foods in several emerging markets.

Meat businesses were well below last year's record level due to the cyclical downturn in North American beef. The U.S.-based meat units were short of last year's results, while results in Central America were up strongly for the year, Cargill said.

Commodity trading and processing results "were down significantly from last year's exceptional performance, due in part to losses in cotton and sugar," Cargill said. The business also had lower earnings among the grain and oilseed processing businesses, though with positive exceptions in the Americas.

Cargill was jolted last week by the wholesale departure of a team of staff from its Singapore-based vegetable oils trading desk, which handles marketing of production from its Indonesia oil palm plantations and coordinates supplying key regional customers like India and China.

Cargill issued a terse statement saying the departures would not affect any of its commitments or contracts, but gave no explanation for the departures. Grain trade sources have said the team, led by Paul Hickman, had been hired by a Cargill competitor. But few details have been forthcoming and it was not clear the incident affected earnings in any way.

Cargill said its agriculture services segment posted improved results in the fourth quarter, boosted by the growth in Cargill's global animal feed business. North American farm services were on par with the prior year's fourth quarter. But for the full year, the segment was down moderately from fiscal 2011.

Cargill said its big risk management and financial segment posted "mixed" results.

"The financial services and energy businesses outperformed the prior year on a combined basis, but the asset management subsidiaries lagged fiscal 2011's performance. As a whole, the segment was well below the prior year," it said.

Cargill's industrial business results "were held below the year-ago level by the mild North American winter, which negatively impacted demand for de-icing salt products."