Two trailers were “deliberately” set alight near Little Orton.
Firefighters were called shortly after 6pm on Sunday to two trailers full of round bales of straw on fire.
Crews from Carlisle East and Carlisle West fire stations found the blaze was positioned under some power lines.
The teams managed to bring the flames under control which allowed the farmer to drag the bales out to burn down naturally.
A statement from Carlisle East Fire Station said: “Sadly, it is believed that the fire was started deliberately.”
