Details are not fully known, but two fire engines were dispatched around midday to the accident scene, on Mabel Grove Bush Road in Mabel Bush, about 30km from Invercargill.
NZME reports the man was trapped in the tractor for a time.
St John spokesman Gerard Campbell said a rescue helicopter had been dispatched from Dunedin and that the man, who is in his early 20s, was in a serious condition.
Fire and Emergency NZ shift supervisor Andrew Norris said the man had been “released from the tractor” by fire crews.
One fire engine came from Invercargill and another had been manned by the volunteer fire brigade at Hedgehope.
The accident, the cause of which is not immediately known, happened during harvesting a field of parsnips.
WorkSafe has been notified.
