By the tens of thousands, peasants in Mexico are abandoning the small plots they considered their birthright.

In recent weeks, thousands of other peasants have taken their struggles to the streets, even to the nation's capital, pushing parts of the agricultural industry to the brink of civil unrest.

The small farmers, typically with plots of a few acres, are being battered by a combination of forces, from the explosion of trade under the North American Free Trade Agreement to plummeting market prices and cuts in government support. Rice, corn and coffee farmers are all being hurt.

Just as U.S. growers complain that NAFTA has forced hundreds of farms out of business because of an increase in imports from Mexico, Mexico's farmers feel similarly overwhelmed.

They complain that they, too, are drowning in a flood of imports from the United States and that the treaty has not given them the access to U.S. markets they were promised.

For Mexican President Vicente Fox, who inherited a crisis rooted in decades of paternalism and corruption in the long-ruling Institutional Revolutionary Party, reforming the agricultural industry and finding alternative employment for millions of subsistence farmers may prove his most important domestic challenge.

This month, 5,000 sugar-cane farmers marched on the capital and blocked access to government offices, demanding $420 million from the nation's 60 sugar mills.

Tens of thousands of other farmers have held their own protests, causing one state governor to declare an emergency. Several other governors acknowledge being worried that the protests could cause smoldering uprisings to ignite.

"The entire Mexican countryside is a disaster," said Carmelo Balderas, hoeing weeds around the young sugar plants in his 2-acre field near the San Miguelito mill in Amatlan in the state of Veracruz. "There is almost no place left in the country where a small farmer can make a good living."

Balderas said two of his four sons had migrated to the United States. Asked why, he pointed in the direction of the San Miguelito sugar mill. The mill's owners still owed Balderas $3,000 for sugar cane he produced last season. His sons, like many other young men in the village, had tired of relying on declining and unreliable incomes.

Some of the most intense protests began early this month in the northeastern state of Sinaloa. Corn farmers blocked access to gas depots to demand that the government impose higher tariffs on corn imported from the United States. In all, there are 3.5 million corn growers across the country, and they are uniformly overwhelmed by a 45 percent drop in corn prices over three years.

Farmers in Sinaloa contend that importing corn from the United States has left them with 2.4 million tons of unsold corn. Imports have increased by 14 percent a year or more since NAFTA took effect in 1994.

After two days of protests, the governor of Sinaloa, Juan S. Millan, declared a state of emergency when panicked motorists began hoarding gasoline and the state's most important businesses, particularly hotels in the resort city of Mazatlan, had to close or greatly reduce their services.

The governors, including those from Veracruz, Oaxaca and Nayarit, pointed out that the crises in their states had generated new waves of migrants to the United States. And using the experience of his own state as a warning, the governor of Chiapas, Pablo Salazar, said the areas most affected were those most prone to armed uprisings.

Mexico's sugar industry offers a window on problems as complex and entangled as the web of shafts and conveyer belts inside the sugar mill in Amatlan.

The San Miguelito refinery has contracts with 4,500 growers, said Ramon Martinez Amaya, the refinery's controller. Unions, once a part of the Institutional Revolutionary Party's authoritarian political machine, determine the size of the refinery's bloated work force. At the start of the harvest last December, tens of thousands of mill workers called a national strike to demand a 25 percent wage increase and improved retirement benefits.

And under the law governing the sugar industry, the government sets the prices that mills pay cane farmers and requires that the mills make most of those payments before the end of the harvest in May.

Even after it sold the mills to private investors in the late 1980s, the government, controlled by the long-ruling Institutional Revolutionary Party, continued to set prices and to force mills to adhere to union demands.

For Fox, lifting Mexico's rural communities -- which make up about 28 percent of the population -- out of poverty is a daunting challenge. The son of ranchers, he has promised to help subsistence farmers find new markets, organize themselves into farming cooperatives, and find financing to modernize operations. In recent weeks, his administration has negotiated agreements with corn farmers in Sinaloa and cane growers in Veracruz that essentially secured the payments they are owed.

But Fox, a former corporate executive, is also committed to free trade. And members of his administration have said that in Fox's modern-day revolution, small farmers are facing a harsh reality: Not all will survive.

But at least one family in Amatlan has decided to break with generations of tradition. Tired of depending on mill officials to pay for the sugar cane they produced, Mari Cruz Hernandez and her husband, Daniel Beristain, decided to grow fruit and flowers on the acre they inherited from her mother. On a recent day, they began planting lychee plants on half an acre. On the other half they plan to plant gladiolas.

The gladiolas, Cruz hopes, will bloom every four months and support her, her husband and her elderly mother for the three years that it will take the fruit plants to begin to yield.

"I got tired of working all year, and then in the end the mill wouldn't pay," she said. "They made us into working beggars. And so we decided, no more."

Many young men, she said, seemed to be making similar decisions. Increasingly, she said, many young men have hopped the evening train heading north.

Going north has crossed her mind, Cruz, 28, acknowledged. She compared the migrants to pioneers, and said that each time the migrant train passed, she whispered a prayer for God's protection. But her goals are still centered on home.

Asked about the risks of abandoning a crop that supported her family over three generations, Cruz said she considered herself a different kind of pioneer.

"Sometimes you have to risk everything if you are going to get ahead," she said. "If the migrants risk everything to leave, then we can take risks to stay."