U.S. has huge appetite for organic food.

WASHINGTON (Reuters) - U.S. farmers are having a hard time keeping up with Americans' voracious appetite for organic foods, say industry leaders, who want federal officials to boost spending on crop research and market development.

Organic food sales grow by as much as 20 percent a year and were forecast for $16 billion during 2006, or nearly 3 percent of all U.S. food spending, the Organic Trade Association said at a pair of congressional hearings.

"In the United States, the buzz about organic has become a steady hum," said Lynn Clarkson, an organic farmer and member of the OTA board. "Organic foods are increasingly sold in mainstream retail establishments, which together represent roughly 46 percent of sales."

Clarkson told a Senate Agriculture Committee hearing on Tuesday that organic production was climbing "but not at a rate to meet the consumer demand" so imports are rising. Mark Lipson of the Organic Farming Research Foundation presented a similar assessment at the House of Representatives Agriculture subcommittee hearing last week.

According to the U.S. Agriculture Department, there are at least 8,500 organic farmers with more than 4 million acres of crop and pasture land.

A "fair share" of USDA research and outreach spending should be $120 million a year, 10 times current outlays, said Lipson.

Two Iowa counties offer real estate tax breaks to farmers who convert to organic crops. Woodbury County, home to Sioux City, also looks first for locally-grown organic when it buys food for its correctional facilities.

"A major problem has been supply," said Robert Marqusee, the county's rural development chief. He said organic farming keeps young and small farmers in business while fuel ethanol, the Corn Belt darling, puts "industrial farming on steroids."

Organic farming means growing crops and livestock without use of antibiotics, synthetic fertilizers and pesticides or genetically engineered seeds and animals. Fields must be free of chemicals for three years before their crops can be certified as organic.