Agriculture Minister Barnaby Joyce has ruled out resigning from the frontbench after lashing out at his own government's conditional approval of a massive coal mine.

Mr Joyce on Wednesday said "the world has gone mad" after Environment Minister Greg Hunt approved the open-cut Shenhua Watermark mine in the Liverpool Plains, a prime farming region in north-west NSW.

Labor's agriculture spokesman Joel Fitzgibbon said the deputy Nationals leader needed to "consider his position on the frontbench" following the outburst.