A man was taken to Whangarei Hospital after the tractor he was driving on State Highway 1 near Waipu crashed through the roadside barrier and dropped about 5m on to a cattle race.
Northland Police who attended the scene said the driver had serious but not life-threatening injuries.
The serious crash unit was investigating the incident that occurred only metres from the Ahuroa River bridge just after 10.30am today. It was unlikely the highway would be blocked during the tractor's retrieval, as it could be transported across the farmland, police said.