In a bid to preserve the country's remaining 120 million hectares of arable land, the government has called for more bricks to be made from coal dust, cinders and slag, rather than clay.

Speaking at a forum on the sustainable development of brick production in Beijing on Sunday, Liu Renfu, from the Ministry of Land and Resources, said China currently has about 90,000 small and medium-sized brick kilns, which consume more than 1 billion cu m of clay every year.

The forum was held ahead of the 17th National Land Day, which fell yesterday, and had the theme of saving land and safeguarding farming.

Liu was among a group of government officials and experts calling for an end to the production of clay bricks.

Liu said the annual demand for clay was equivalent to the amount of earth that could be excavated from a 3-m-deep hole spanning 30,000 hectares - or about the total area of farmland in a medium-sized county.

As a result, the production of clay bricks poses a serious threat to farming and the land, and more environmentally friendly materials, such as slag, cinders and coal dust, should be used, he said.

Ministry figures show that in recent years, more than 30,000 small-scale brick kilns have been closed down and that bricks made from environmentally friendly materials now account for 10 percent of the total, up from 5 percent in the 1990s. Such measures have helped the country save more than 90,000 hectares of arable land, Liu said.

However, Liu said that bricks made from coal waste would not be well received in rural areas, where the demand for building materials is highest.

"For most rural residents, the new bricks cannot compete with traditional clay ones on either price and quality," he said.

Some 4 million new homes are built in rural areas every year, each of which requires about 100,000 bricks, so the demand is huge, Liu said.