A year ago, this lush coastal field near Rome was filled with orderly rows of delicate dur

um wheat, used to make high quality Italian pasta. Today it overflows with rapeseed, a tall, gnarled weedlike plant bursting with coarse yellow flowers that has become a new manna for European farmers: rapeseed can be turned into biofuel.

Lured by generous new subsidies to develop alternative energy sources - and a measure of concern about the future of the planet - European farmers are plunging into growing crops that can be turned into fuels meant to produce fewer emissions than gas or oil when burned. They are chasing after their counterparts in the Americas who have been cropping for biofuel for more than five years.

"This is a much-needed boost to our economy, our farms," said Marcello Pini, a farmer, standing in front of the sea of waving yellow flowers he planted for the first time this year. "Of course we hope it helps the environment, too."

In March, the European Commission, disappointed by the slow growth of thebiofuels industry in Europe, approved a directive that included a "binding target" requiring member states to use 10 percent biofuel for transport by 2020 - the most ambitious and specific goal in the world.

Most EU states are currently far from achieving the target, and are introducing new incentives and subsidies to boost production.

As a result, bioenergy crops have now replaced food as the most profitable crop in a number European countries. In this part of Italy, for example, the government guarantees the purchase of biofuel crops at €22 per 100 kilograms, or $13.42 per 100 pounds - nearly twice the €11-to-€12 rate per 100 kilograms of wheat on the open market last year. Better still, European farmers are allowed to plant biofuel crops on "set-aside" fields, land that EU agriculture policy would otherwise require them to leave fallow to prevent an oversupply of food.

But an expert panel convened by the UN Food and Agriculture Organization this month pointed out that the biofuels boom produces both benefits as well as tradeoff and risks - including higher and wildly fluctuating global food prices. In some markets grain prices have nearly doubled because farmers are planting for biofuels,

"At a time when agricultural prices are low, in comes biofuel and improves the lot of farmers and injects life into rural areas," said Gustavo Best, an expert at the United Nations Food and Agriculture Organization in Rome. "But as the scale grows and the demand for biofuel crops seems to be infinite, we&39;re seeing some negative effects and we need to hold up a yellow light."

Josette Sheeran, the new head of the UN World Food program, which fed nearly 90 million people in 2006, said that biofuels created new dilemmas for her agency. "An increase in grain prices impacts us because we are a major procurer of grain for food. So biofuels are both a challenge and an opportunity." In Europe, the rapid conversion of fields that once grew wheat or barley to biofuel oils like rapeseed is already leading to shortages of ingredients for making pasta and brewing beer, suppliers say. That could translate into higher prices in supermarkets.

"New and increasing demand for bioenergy production has put high pressure on the whole world grain market," said Claudia Conti, a spokeswoman for Barilla, one of the largest Italian pasta makers. "Not only German beer producers, but Mexican tortilla makers have see the cost of their main raw material growing quickly to quickly to historical highs."

For some experts, more worrisome is the potential impact to low-income consumers from the displacement of food crops by bioenergy plantings. In the developing world, the shift from growing food to growing more lucrative biofuel crops destined for richer countries could create serious hunger and damage the environment in places where wild land is converted to biofuel cultivation, the FAO expert panel concluded.

But officials at the European Commission say they are pursuing a measured course that will prevent the worst price and supply problems that have plagued American markets.

"We see in the United States farmers going crazy growing corn for biofuels, but also producing shortages of food and feed," said Michael Mann, a commission spokesman. "So we see biofuel as a good opportunity - but it shouldn&39;t be the be-all and end-all for agriculture."

In a recent speech, Mariann Fischer Boel, the EU agriculture and rural development commissioner, said that the 10 percent EU target was "not a shot in the dark," but rather carefully chosen to encourage a level of biofuel industry growth that would not produce undue hardship for the Continent&39;s poor. Over the next 14 years, she calculated, it would push up would raw material prices for cereal by 3 percent to 6 percent by 2020, while prices for oilseed may rise between 5 percent and 18 percent. But food prices on the shelves would barely change, she said.