BEIJING, June 25 -- The vast swathes of polluted land and contaminated ground water caused by decades of reckless development has left its mark on China: This is a threat that can no longer be ignored.

Officially, 16 percent of China's soil and nearly 20 percent of farmland is polluted, however, ecologists warn, this may just be the tip of the iceberg.

In 2014, the Qingyuan City government, in the southern province of Guangdong, launched a pilot project to treat soil contaminated by heavy metals in Longtang Township, which was a hub for the processing of scrap metal for over 20 years.

Following experiments on farming and construction land "remarkable results" were observed, said Fang Xiaohang, a senior engineer with the South China Institute of Environmental Science, which provides technical support for the project.

Government-backed initiatives, like the one in Longtang, have cropped up across the country, as soil pollution, and contaminated crops, water and air become just too big to ignore.

As National Land Day falls on Thursday, ecologists are calling for clearer rules and supportive measures to ensure the success of land treatment projects: Its time to snow the seeds of change.

CATCH UP

Although many developed countries started to address soil pollution decades ago, China's own drive to clean up its own act is in its infancy.

"The government has spent heavily on research, and technology is developing rapidly," said Song Yun, chief engineer of the Environmental Protection Research Institute of Light Industry.

At the experiment sites in Longtang, chemicals have been used to stabilize heavy metals and reduce their activity on polluted land.

Before the project, samples of the local soil showed it contained worrying amounts of copper and 10 times more lead than the national standard.

Following remediation, Fang said, soil samples from one patch of land showed active heavy metal content was down by more than 50 percent, and rice grown on another plot was safe for consumption.

However, it is too early to celebrate, said Song, since current approaches in China were not developed enough for large-scale application.

"Restoring farmland, with a focus on ensuring the soil is suitable for growing crops, is much more difficult than treating land intended for construction," Fang said.

In addition, the high cost of treating polluted farmland, which can soar into the tens of thousands of U.S. dollars per hectare, is a huge burden for the government, according to Song.

However, money is not a problem for real estate developers, whose top concern is time, Song said.

"A safe and inexpensive method to treat heavy metals on construction sites is to use microorganisms. It's popular abroad, but not in China. Why? Developers don't want to wait the three months to a year needed to see results," he said.

China's ability to treat polluted groundwater lags far behind that of its more developed peers, he said. "Meaning, once treated soil is very likely to be contaminated by polluted groundwater, again."

ABSENT RULES

Compared with the technological challenges, the land treatment industry is struggling to grow due to a lack of rules to regulate the sector.

There are many unanswered questions, said Wang Shuyi, director of the Research Institute of Environmental Law under Wuhuan University.

"Who is responsible for the pollution? Who should pay for the treatment? What technical standards should be followed by treatment firms and how should their work be assessed?"

In China, it is hard to hold someone responsible for soil pollution, due to frequent transfer of company ownership, according to Yang Pingjian, a guest researcher with the Ministry of Environmental Protection.

In sharp contrast to the "polluters pay" principal widely adopted around the world, it is the state and developers that must foot the bill.

However, many are hopeful that a law on soil pollution, which is expected to be rolled out by 2017, could clear up some of these sticking points.

"We advised the drafters that the law should answer the questions I mentioned," said Wang, who also headed the law's advisory panel.

He said that the law may call for the establishment of a soil pollution monitoring system.

Gu Qingbao, a professor with the Chinese Research Academy of Environmental Sciences, called for incentives to attract more investment into land treatment.

The Land and Resources Ministry revealed that that the land treatment industry accounts for less than 1 percent of the total output of the environmental protection sector. In some developed countries, this proportion surpasses 30 percent.

In 2013, there were 500 land treatment firms in China. It is estimated that the market will be worth 40 billion yuan (about 6.4 billion U.S. dollars) in 2015.

"The sad truth is that only around 20 firms have practical experience and less than 10 are really competent. That's why we need clear rules and legal grounding," said Gao Shengda, general secretary of China Environmental Remediation Industry Alliance.