BEIJING/SHANGHAI (Reuters) - China has shut more than 1,300 heavy metal enterprises since 2016 as part of a long-term plan to curb widespread chronic soil pollution, an environment ministry official said on Friday.

FILE PHOTO: A villager and a boy ride on an electric tricycle past the Guantao Chemical Industry Park outside the village of East Luzhuang, Hebei province, China February 23, 2017. REUTERS/Thomas Peter

Soil pollution is one of China’s biggest and most expensive environmental challenges. The last nationwide survey in 2014 showed that around 16% of its land - an area the size of Mongolia - was contaminated to varying degrees by fertilizers and pesticides, heavy metals, plastic and other chemicals.

But Su Kejing, director in charge of soil pollution at the environment ministry, told a Friday briefing he was confident China could meet a target to make around 90% of contaminated farmland safe for agriculture by the end of next year.

The cost of remediating contaminated soil ranges from 500 yuan ($71) to as much as 2,000 yuan per mu (1 mu = 0.67 square metres), putting China’s total bill in the trillions of yuan. Su said the focus, though, would be on tackling risks, rather than cleaning up every single site.

“It is one-sided to think soil pollution prevention and treatment are expensive,” he said. “The priority is preventing the pollution and controlling risks from pollution. Only a small amount of land will really need to be remediated.”

As well as shutting 1,300 firms involved in producing and processing heavy metal, China has also “rectified” nearly 700 enterprises working with cadmium, a major source of pollution in rice, Su said. He also said that converting arable land to less pollution-sensitive crops would also help mitigate risks.

Tackling soil and water pollution is a major part of China’s efforts to boost agricultural productivity. China is trying to squeeze more food out of its farming belts, especially as its urban populations soar.

A 2015 government study estimated that heavy metals had contaminated at least 10 million hectares (25 million acres) of farmland, reducing annual grain production by 10 billion kg (22 billion pounds) a year.

Beijing published a plan in 2016 that set a target of bringing soil pollution under “preliminary control” by 2020 and starting to cut contamination levels by 2030, but financing has been a major challenge.

Although Beijing has set up a fund to help pay for its clean-up projects, with 28 billion yuan made available over the last three years, it has struggled to create incentives and financing mechanisms, especially in old industrial or rural regions where property values are too low to make remediation worthwhile.

“In the next stage we will work with other departments to encourage private capital and enterprises to inject funds into soil remediation,” Su said.