Five fire departments were dispatched to Klinger Road at about 12:30 Saturday afternoon.
Watertown Chief Gary Quimby says the barn was fully engulfed when they arrived. The barn was full of hay and equipment, but Quimby adds they were able to save some of the farm equipment.
However, the hay continued to smolder now several hours after the fire was out. The cause of the fire is under investigation.
They're working with homeowners to determine the cost of damage.