Chinese scientists hope new technologies can save the country's farmland from widespread soil pollution.

Scientists in south China's Guangdong Province have discovered a chemical derived from a type of clay mineral that can help control heavy metal residues in farm soil to prevent them from entering crops.

The material, called "Mont-SH6," can stabilize heavy metals such as cadmium and copper to reduce their toxicity and activity, explained Liu Wenhua, chief engineer of Guangdong provincial geological experimental test center.

Experiment results suggest that heavy metal levels dropped significantly in the tested rice.

"The level of cadmium content in rice dropped by more than 90 percent," said Liu.

"The technology is suitable for large-scale restoration of farmland because it is relatively cheap and effective," said Zhao Qiuxiang, head of the research team.

Zhao said restoration of each mu (one-fifteenth of a hectare) costs only several hundred yuan, and costs will be cut after large-scale application.

But Liu Wenhua said industrial application of the technology requires time. "At least two years are needed for large field experiments before it enters the market," said Liu.

Chinese authorities have become increasingly concerned about the risk to food posed by widespread contamination of farmland.

Official statistics suggest that more than 3.33 million hectares of China's farmland is too polluted for crops, after decades of extensive development left poisonous metals and discharge to seep into soil and crops.

Heavy metal pollution alone has resulted in the loss of 10 million tonnes of grain and the contamination of another 12 million tonnes annually, incurring 20 billion yuan (3.17 billion U.S. dollars) in direct economic losses each year, according to official estimates.