The Liverpool Plains were long considered off-limits to mining, their rich black soils ranking among Australia's best farming land. Until China came to town.

Now a small group of farmers who have refused to sell out to China's Shenhua Watermark Coal are locked in a battle playing out across the nation -- mining boom versus the future of food.

Seventh-generation farmer Michael Clift and neighbour Tim Duddy say coal mining has always been a fact of life in the area -- an ancient coal-burner stove has pride of place in Duddy's kitchen.

But the nature and scale of mining has changed dramatically in the past 10 years, the smaller shaft-style mine replaced by vast open pits which leave craters in the landscape and fill the air with dust and noise.

"A lot of people never thought that there would be mining on this land, ever," said Clift, from his property some 440 kilometres (270 miles) northwest of Sydney.

"This land should be protected for agricultural purposes; it's a sustainable practice that we do, agriculture. Mining is not sustainable, and you don't get land like this again so this has to be protected."

The Liverpool Plains offer some of Australia's best grazing and cropping -- a sweeping silt valley at the foot of the Great Dividing Range with a complex aquifer system which keeps the land fertile all year long.

It is also a rich coal basin, with Duddy estimating there is fuel worth "hundreds and hundreds of millions, probably a couple of billion dollars" under his farm, Rossmar Park, alone.

Mineral resources belong to the state, and surging global demand for commodities has seen Australia's mining industry explode in size, with key market China on a global hunt for firms and projects to secure supply.

Shenhua paid more than Aus$300 million ($320 million) for the licence to mine on Clift and Duddy's doorstep and another $150 million buying out 43 of their neighbours to secure the mine footprint, offering well above market rate.

Project spokesman Joe Clayton said Shenhua had promised from the outset not to mine the black-soil plains in the north of New South Wales state and the closest pit would be at least 150 metres away.

It's cold comfort to Duddy, who fears health impacts similar to those seen near huge mining projects in the neighbouring Hunter Valley.

"In the Hunter I know there were dairy cows that died a bit younger than they thought they should, and when they autopsied them they found big lumps of coal in their guts," Duddy told AFP.

"They had actually formed from the dust (in their food), slowly starving them to death, so imagine what it's doing to people.

"People have so much money tied up in their share portfolio and they love what mining does to it that they don't even think about the rest. They want to believe that it's all fine but the reality is that it isn't."

The Greens party is pushing for tougher regulation of Australia's land ownership laws and wants water resources like aquifers included in environmental protection regulations.

A study commissioned by the party in June showed 83 percent of Australia's mining industry -- key to its economic success -- was foreign-owned, with an estimated Aus$50 billion in profits to flow offshore in the next five years.

Greens Senator Christine Milne believes the conflict between mining and farming is nearing a flashpoint, with the experience of recent decades showing they were "not complementary activities".

"Australia has to make a decision about long-term issues like food security, like where the next generation of farmers are going to come from," she said.

As food shortages grow, Milne said, there was a "real obligation for countries like Australia, which is a net exporter of food, to not only grow as much food as it possibly can but also to export into overseas markets."

A mining veteran with 30 years of experience in countries including Papua New Guinea and Indonesia, Clayton rejects the notion that mining and farming can't co-exist or that mined land can't be rehabilitated for farming again.

Shenhua will have to submit detailed environmental management plans and must also consult with surrounding farms which are considered to be within the dust and noise zone -- an area including Duddy's and Clift's properties.

Whether the farmers come to the table is "their issue," Clayton said.

"If it wasn't us here it would be somebody else here; the issue is the coal belongs to the state, to the people. It's a resource and it will get developed," he said.

Shenhua still needs to win environmental approval for the mine and has to sell the land within 18 months if its proposal is knocked back under foreign ownership laws.

Duddy is hoping for a government intervention on environmental grounds before it's all done and is bracing himself for a High Court challenge.

"We've made the decision that we are here to stay, and we will punch up and fight to the death, so that's that."