Emergency services were called to Church Farm on Philips Lane in Darrington at around 4.20pm last Friday.
A West Yorkshire Police spokeswoman today confirmed the force was leading an investigation into a work-related incident at the farm.
She said: "A 68-year-old man was taken by air ambulance to Leeds General Infirmary with a serious head injury. He sadly passed away from his injuries."
The Health and Safety Executive (HSE) has also been notified.
A spokesman said: "HSE is aware of the incident and is assisting the police who have primacy."