Firefighters were called to the fire near Rochester at 11.06am to find hundreds of stacked bales alight.
Crews from Rochester, Echuca, Timmering and Tongala attended the scene.
District 20 Commander Mick Lavery said the hay bales were all stacked together and luckily, they were in a cleared area.
“There were no structures or fences surrounding the fire,” Mr Lavery said.
“The farmer did the right thing by placing the hay bales in a clear area that had no fuel around it, so when it did catch fire it wasn’t going to go anywhere.”
The fire was brought under control at 12.08pm and the hay was expected to continue to burn over the next 48 hours.
“Make sure to check the moisture levels when baling hay,” Mr Lavery said.
“We have now had two hay fires in our area in two days with no apparent cause, which has resulted in 870 combined hay bales lost.”