A farmer accused of murdering an environmental officer in north-west New South Wales continued firing as the victim tried to flee, a court has heard.

Ian Robert Turnbull, 79, has been charged with murdering environment officer Glen Turner on July 29 at Croppa Creek, near Moree.

Mr Turner had been in the area to respond to reports of illegal land clearing when he was shot on a dirt road.

The two men had been involved in a long-running dispute over land clearing in the area.

Turnbull appeared in Moree Local Court via video link on Tuesday and applied for bail.

In opposing bail, the prosecution said Turnbull armed himself with a rifle and confronted Mr Turner and his colleague.

He allegedly told Mr Turner he would be leaving the area in a body bag.

The court was told Turnbull fired five shots at Mr Turner and continued shooting when his victim attempted to flee and his colleague tried to give him first aid.

The prosecution said when the accused finished shooting he said to Mr Turner's colleague: "You can go now. I'll be waiting at home for the police."

The court also heard that in a conversation in 2012 the accused told Mr Turner he was an old man and could do anything he wanted.

The magistrate refused bail, saying the money and bail conditions being offered were not adequate to mitigate the unacceptable risk posed by Turnbull.

Sorry, this video has expired Farmer accused of murder continued firing as victim tried to flee, court hears ( Joanna Woodburn )

Turnbull was also charged with two further offences, namely common assault and taking or detaining a person with intent to commit a serious indictable offence.

The matter was adjourned until September 22, when Turnbull is expected to reappear via video link.

NSW Environment Minister Rob Stokes has asked his department to fly flags on its buildings and properties at half-mast this weekend to remember Mr Turner.

Mr Stokes led an emotional tribute in State Parliament.

"Glen's death is a shocking event. He has been taken from his family and friends suddenly and prematurely," he said.

"There can be no justification for acts of violence on public officials simply doing their job.

"It does not matter what the law is, our laws are made by the NSW Parliament, not by the people who are tasked with implementing them, whether they are police officers, council officers or environment officers."