NSW farmer's 'shocking' comments

NSW farmer Ian Turnbull was overheard saying on a two-way radio that he'd "just pumped a couple of shots" at Glen Turner the day it's alleged he murdered the environmental compliance officer, a court has heard.

A farmhand who was working at one of the Turnbull family's properties on the day in July 2014 when Mr Turner was shot has told Turnbull's trial it was hard to discern emotion from the 81-year-old's voice over the radio.

"I thought he was joking. I was shocked and confused," Robert Maas told the NSW Supreme Court on Wednesday.

"... That's totally against Ian's nature."

Turnbull admits fatally shooting Mr Turner at Croppa Creek near Moree in the state's north but has pleaded not guilty to murder.

His defence counsel has suggested the elderly farmer snapped under immense pressure from ongoing court proceedings.

Mr Maas, an employee of 17 years, told the court Turnbull had a good reputation in the district and he'd never seen him behave violently.

However in the two years leading to the shooting, Mr Maas' employer had appeared "a bit incoherent" due to stress regarding the issues with cleaning up his property and being "harassed", in Turnbull's words, by the environment department.

"I really think he started to look really old and tired," Mr Maas said.

The trial continues.