Agriculture and environmental protection authorities in Henan face 30,000 yuan ($4,762) fines if contaminated water is discharged into farmland, according to the China's land watchdog.

The fines will come into force from May 1.

The Ministry of Land and Resources said on its official website on Monday that the Henan provincial government released a regulation to monitor and enhance farmland quality recently. The regulation clarified water used for farming must meet national standards. A failure to meet those standards will result in fines for irrigators and local agriculture and environmental protection authorities.

The regulation required local authorities at county level or higher to establish a farmland quality information portal and conduct regular surveys.

Farmland quality will be linked to assessments of the local authorities, according to the ministry.

Henan is a key grain producing province. About 56.4 billion tons of grain were harvested in 2012, contributing about 10 percent of the national grain production.

Studies by the Chinese Academy of Sciences showed nearly 20 million hectares of arable soil, about 20 percent of the country's total farmland, were contaminated by heavy metals. This is estimated to account for a loss of more than 10 million tons in food supplies every year.