The man managed to crawl out and walk home to ring for help.
St John district operations manager Stephen Smith said ambulances from Porangahau and Waipukurau were dispatched and the Lowe Corporation Rescue Helicopter put on stand-by.
Mr Smith said the man sustained painful neck injuries and spinal injuries and was flown to Hawke's Bay Hospital for treatment.
He said his condition was considered moderate at the time and last night he was in a stable condition.
Mr Singer said the accident is a timely reminder of the importance of wearing helmets while on quad bikes and other farm vehicles.
"I've been to three fatalities on farms in the past nine months that have involved some kind of farm vehicle. People have got to be so much more careful."
Mr Singer said people need to be aware farm vehicles can be dangerous.
"They need to be treated with respect to prevent any further accidents."