Agriculture Minister Barnaby Joyce is facing calls to consider resigning from the frontbench after he castigated the government for approving a massive coal mine in his electorate.

The furore comes as the federal National party pressures NSW Deputy Premier Troy Grant over the potential impact of the mine, which must pass a final Baird government hurdle before proceeding.

Mr Joyce on Wednesday said "the world has gone mad" following Environment Minister Greg Hunt's approval for the deeply divisive open-cut Shenhua Watermark mine in the Liverpool Plains, a prime farming region in north-west NSW.

The Nationals MP withdrew from an expected appearance with Prime Minister Tony Abbott in Grafton on Thursday, but both Mr Abbott and Mr Joyce said it was due to scheduling issues.

However Mr Joyce's split from the Coalition stance follows an apparent pattern of tension between the Liberal Party and Mr Joyce, who is considered a future deputy prime minister.

Mr Abbott instructed him not to appear on this week's episode of the Q&A program after fallout from the appearance of former terror suspect Zaky Mallah.

The ban prevented Mr Joyce from promoting his highly anticipated agriculture white paper and Mr Joyce reportedly said "it would have been good" to have received more notice.

In March, the white paper's release was reportedly delayed after being heavily scrutinised by senior ministers and cabinet. The ABC quoted senior government figures saying it contained "every crackpot idea" from the past 25 years.

Labor's agriculture spokesman Joel Fitzgibbon questioned how Mr Joyce could sit in cabinet while railing against the mine decision, saying "he needs to consider his position" on the frontbench.

Mr Fitzgibbon said the mine approval showed Mr Joyce was either "incompetent and lacks influence in cabinet" or worse, did not seek to properly represent his constituents.

Mr Joyce said "the real lack of competence" lay with disgraced former NSW state Labor minister Ian Macdonald, who approved the Chinese government-owned firm's exploration licence.

Mr Joyce said he sought to influence the approval decision by successfully asking Mr Hunt to establish an independent scientific and environmental review of the mine.

He refused to respond to calls to reconsider his cabinet role.

The approval of the Shenhua project has prompted Tony Windsor, the former independent MP for Mr Joyce's seat of New England, to consider running for the seat again.

Abbott's words 'hollow'

Meanwhile, Federal Nationals senator John Williams has contacted Mr Grant to express concern over the mine, which he fears will damage aquifers and spread coal dust over the region.

The NSW government must grant a mining license to Shenhua before the project can start.

About $1.5 billion in royalties is expected to flow into the NSW government coffers over the life of the project. The state will also receive $200 million when the mining lease is granted.

Mr Grant's office did not comment. A spokesman for NSW Resources Minister Anthony Roberts said Shenhua was yet to apply for a mining lease, but any approval would require the firm to meet environment and planning laws.

Sarah Hubbard, 27, lives on her parents' crop and cattle farm at Spring Ridge, close to the potential mine site.

She said younger farmers fear the project will permanently damage groundwater supplies.

"I want to stay and live and work here. [The mine] creates total uncertainty for us. We don't know what's going to happen."

In 2010 as opposition leader, Mr Abbott visited the New England electorate and spoke of the "threat ... of mining in some of Australia's best agricultural land".

"The message I am getting loud and clear from locals is that they don't want to destroy this agricultural breadbasket with mining," Mr Abbott said, adding mining should be barred in the region until thorough water studies were done and it was "absolutely crystal clear" that agriculture would not be harmed.

NSW Farmers president Fiona Simson said on Thursday Mr Abbott's words were "hollow".

"No decision maker has had the backbone to do what is necessary, and that [is] to simply say no," she said.

"Local communities have raised serious and real issues in relation to impacts on the agricultural groundwater ... once that groundwater [is] affected, there is no going back."

On Thursday Mr Abbott, who has described coal as "good for humanity", said the Shenhua mine would be subject to "very strict environmental standards … put in place by a good government that is determined to strengthen our economy while at the same time protecting our environment".

Asked about Mr Joyce's dissent, Mr Abbott said MPs sometimes had to "give voice to the feelings of your constituents while at the same time being a loyal member of the government".

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