Production of food crops to make biofuels will also tend to favor growers with plenty of capital and large land holdings, they say, rather than small-scale, impoverished farmers lacking modern grain storage facilities in poor countries. “The policies put in place are going to be crucial to whether the small producer and the people who live where hunger is concentrated can benefit,” Mr. Senauer said.

But for now food aid is suffering, as are poor people in poor countries, economists say. And their situation may get even tougher next year, relief agencies warn. The United Nations Food and Agriculture Organization is projecting that low-income countries reliant on food imports, including most of sub-Saharan Africa, will see the amount they pay to import cereals rise 14 percent.

The world’s ability to absorb fresh price shocks has shrunk along with food stocks. “We’re very worried,” said Henri Josserand, who heads the organization’s global information and early warning system. “World food stocks are much smaller than they used to be.”

The food aid declines may also continue. Catholic Relief Services, a major distributor of American food aid, has projected substantial increases in what the federal government pays for food aid next year, based on an analysis of the futures market for the wheat, corn and soybean products that are mainstays of aid. “It’s bad news and it’s not just going to affect U.S. food aid, but food aid from every source,” said Frank Orzechowski, a retired commodity trader who now advises Catholic Relief Services.

This year’s decline in food aid follows a period when the sharply escalating costs of shipping American-grown food aid to Africa and Asia already reduced the tonnage supplied. The United States Government Accountability Officementnd this year that the number of people being fed by American food aid had declined to 70 million in 2006 from 105 million in 2002, mainly because of rising transportation and logistical costs.

Now food prices are also playing a role. New data from the Department of Agriculture show that the cost of food for the federal government’s main food aid program, Food for Peace, rose 35 percent over the past two years.

The amount of food bought for American food aid programs has fallen to 2.4 million metric tons this year from 4 million metric tons in 2005 and 5.3 million metric tons in 2000. Thomas Melito, who supervised the Government Accountability Office’s food aid investigation this year, called the escalating costs of food aid “frightening.”