Fire and Emergency NZ shift manager Kaisey Cook said there were three fire appliances and two water tankers on the scene of the 30m by 50m blaze.
Firefighters from Rotorua and Lake Okareka stations were working to put out the fire which was on a farm near Bryce Rd, she said.
Cook said the cause of the fire was unknown and there had been no reports of any risk to any nearby structures.
Meanwhile, firefighters from Maketū and Te Puke stations are working to put out a shelterbelt fire on a farm in Gulliver Rd, Paengaroa near Te Puke Highway, she said.
Cook said the fire service was called at 2.20pm and three fire appliances and two tankers from Maketū and Te Puke were on the scene of the 300m by 30m blaze.
Fire crews spent more than five hours battling the blazes, with crews leaving the scenes of each between 8.10pm and 8.25pm.