Soil is being washed and blown away not only in remote rural areas, but also near mines, factories and even in cities, the official Xinhua agency cited the country's bio-environment security research team as saying.

Each year, about 4.5 billion tonnes of soil are lost, threatening the country's ability to feed itself.

If the loss continues at this rate, harvests in China's north-eastern breadbasket could fall 40 per cent in 50 years, adding to erosion costs estimated at 200 billion yuan (S$44.8 billion) in this decade alone.

'China has a more dire situation than India, Japan, the United States, Australia and many other countries suffering from soil erosion,' Xinhua quoted the research team as saying.

Beijing has long been worried about the desertification of its northern grasslands, and scaled back logging after rain rushing down denuded mountainsides caused massive flooding along the Yangtze in the late 1990s.

But around 1.6 million sq km of land is still being degraded by water erosion, with almost every river basin affected.

Another 2 million sq km is under attack from wind, the report said.

The survey was the largest on soil conservation since the Communist Party took control of China in 1949.

REUTERS