ZHENGXIN, China - Half a century after Mao Zedong's "Great Leap Forward" brought irrigation to the arid grasslands in this remote corner of northwest China, the government is giving up on its attempt to make a breadbasket out of what has increasingly become a stretch of scrub and sand dunes.

In a problem that's pervasive in much of China, over-farming has drawn down the water table so low that desert is overtaking farmland. Authorities have ordered farmers here in Gansu province to vacate their properties over the next 3 1/2 years, and will replace 20 villages with newly planted grass in a final effort to halt the advance of the Tengger and Badain Jaran deserts.

"I don't want to move," said Chen Ying, 58, sitting in a sparsely furnished bedroom dominated by a red, wall-sized poster of Mao, the communist founding father who sought to catapult Chinese farming and industry into modernity with the so-called Great Leap Forward.

"But if we keep using the groundwater, it will decline," said Chen. "We have to think about the next generation."

It's not just Chen's home region that's at risk.

The relocation program is part of a larger plan to rein in China's expanding deserts, which now cover one-third of the country and continue to grow because of overgrazing, deforestation, urban sprawl and droughts.

The shifting sands have swallowed thousands of Chinese villages along the fabled Silk Road and sparked a sharp increase in sandstorms; dust from China clouds the skies of

South Korea and has been linked to respiratory problems in California.

Since 2001, China has spent nearly $9 billion planting billions of trees, converting marginal farmland to forest and grasslands and enforcing logging and grazing bans.

The policy is driven in part by concerns over food, as farmland yields not only to the deserts but also to pollution and economic development. China has less than 7 percent of the world's arable land with which to feed 1.3 billion people - more than 20 percent of the world's population. By comparison, the United States has 20 percent of the world's arable land to feed 5 percent of the population.

But the initiative is also a tacit admission by the government that the effort to feed the country at all costs may have backfired.

Chen was just a child when the government turned the rugged grasslands on the edge of the Tengger into an oasis.

In the 1950s, as part of Mao's scheme to boost food production, the government built the Hongyashan Reservoir in Gansu province witsoil to become contaminated with salt.

Worried the desert could reach the city of Minqin, 35 miles away, authorities decided to return the land to its natural state.

"If the government does nothing, it is scared that the entire area will become a desert," said Sun Qing-Wei, a desertification expert with the Chinese Academy of Sciences. "There are alternative solutions like introducing new plant species or conserving water. But this is the quickest solution. The government can show the people they are doing something."

Chen, a grizzled farmer who sports a Mao cap, blue coat and baggy, mud-spattered pants, has planted dozens of trees outside his home to prevent the desert dunes from overrunning his property. He also switched from wheat to less thirsty cotton and fennel.

But he appears to have met his match in the government, which already banned the use of well water for irrigation and threatened to cut the electricity ahead of the scheduled move of his village later this year to a new location about 12 miles away.

Talk of the impending moves dominates the conversations of villagers, gathered around their coal-fired stoves to ward off the springtime chill. Most are reluctant to leave. Authorities are offering up to $784 per family to move 10,500 residents from Gansu Province, but the villagers don't trust the government to compensate them fairly.

Their ancestors are buried on their land, and their crops continue to earn a tidy income, they say - even though the canals that once transported water to the area are bone-dry, and the wheat that thrived here is a distant memory.

"The government is taking this action against desertification, but we are the ones being forced to pay for this policy," said Li Jianzhu, a father of three in the village of Waixi, whose population has dropped nearly two-thirds to 60 residents.

Throughout the province, treeless, wind-swept plains stretch for miles in all directions. Gone are the knee-high grasses and the Qingtu Lake, replaced by sands from the expanding Tengger and nearby Badain Jaran deserts and with soil scarred white from salt.

The only signs of civilization in many areas are the herds of sheep munching on thorn bushes, the clusters of mud and straw homes and the burial mounds. Billboards promoting the country's one-child policy compete with those pushing slogans like "No Reclamation, No Overcultivation."

Many communities have been emptied altogether, leaving behind crumbling homes and empty courtyards.

The battle against deserts is playing out across much of western China. Desertification has caused as much as $7 billion in annual economic losses, the China Daily reported.

Over the past decade, Chinese deserts expanded at a rate of 950 square miles a year, according to Wang Tao of the Chinese Academy of Sciences in Lanzhou.

"There are quite a few countries with this problem but none on the scale of China because it is so big," said Lester Brown, president of Earth Policy Institute. "You only have to go to northwest China and see that the numbers and size of dust storms are increasing."

Expanding deserts have contributed to a nearly six-fold increase in sandstorms in the past 50 years to two dozen annually, Wang said.

Global warming will worsen the problem, as rising temperatures lead to widespread drought and melt most glaciers on the Tibetan Plateau, depriving lakes and rivers of a crucial water source, according to the U.N.-funded Intergovernmental Panel on Climate Change.

Hotter, drier land is more vulnerable to soil erosion, Wang said. "This is the same problem the United States faced in the 1930s with the dust bowl."

Global warming also threatens to make a huge dent in grain production, which Brown said has already slipped from 432 million tons in 1998 to 422 million tons in 2006 because of desertification. At the same time, grain consumption has risen about 4.4 million tons a year to 418 million tons, in part because of rising demand for beef, chicken and pork.

The production declines have forced China to draw down its grain stocks, and eventually it will need to buy a massive 30-50 million tons a year on the world market, Brown said.

"It's not that they are likely to face famine in the next few years. But what they may face is rising food prices, and that can create political instability," he said.

In Dongyun village, Wei Quangcai and his deaf wife may offer a glimpse of that future. Once part of a thriving village of 200 people in Gansu province, they are the only ones left after neighbors fled two years ago.

Walking past the empty homes, Wei, 58, recalls the days when his village hummed with farmers chatting over a game of cards and the school was packed with children. Now, the only sounds are the wind whipping through the empty doorways. His son has left for a job in Beijing over his objections.

"We're the last people," Wei said. "It is lonely. It would be better if my son lived with us. But if he did, he wouldn't be able to find a wife."