The partner of a New South Wales farmer who was found dead on his property earlier this year has been charged with his murder.

Grazier Mathew Dunbar died on his farm at Walcha in northern New South Wales in August.

A funeral announcement for the 42-year-old called for donations to mental health organisation, the Black Dog Institute, but police set up a strike force to investigate the death and treated it as suspicious.

Mr Dunbar's partner Natasha Beth Darcy was arrested on Saturday morning at the Walcha property where she lived with Mr Dunbar and was taken to Tamworth police station.

New South Wales Police say she was questioned on Saturday afternoon before being charged with murder.

The 42-year-old remains behind bars after appearing at Tamworth Local Court on Sunday.

Ms Darcy will front Tamworth Local Court again tomorrow.

Mr Dunbar owned a sheep grazing company in Walcha and was remembered by friends as a "thoughtful, kind man" who was involved in the community.