Early indications suggested the driver of the car was affected by sun strike, he said.
The police were working with the driver who was believed to be a local man, he said.
Mr Clifford said police would also like to speak to the female driver of a silver car that drove past and stopped shortly after the crash happened.
The road was closed at the crash scene near Ohinepanea Rd for more than two hours while police investigated.
A neighbour and long-time friend of the victim, remembered him as a "very pleasant, very charming and well-liked fellow".
The pair had been neighbours and friends for nearly 40 years and the man was well known in the small farming community, the friend said.
He had been alerted to the crash when the victim's son ran to his house to call emergency services.
He was shocked to lose a friend so close to his home.
Federated Farmers general manager for strategic communications Don Carson said the agricultural industry had been identified as "high risk" but the nature of this particular incident was not common.
Ideally, farmers would have and use culverts under the road to keep themselves and their stock safe but that was often not possible, he said. "In rural areas drivers should be aware stock could be on the roads."
