The Stephensons single-decker was a mile off the local bus route and must have been driven down a farm track, said farmer James Mizen.
Mr Mizen said a bus mechanic knocked at the door of his Thaxted, Essex, farmhouse to tell him a vehicle was stuck on the property.
Stephensons declined to comment on the incident. It is understood the bus did not have passengers at the time.
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Mr Mizen said: "The mechanic said the bus was on our muck heap.
"He must have gone down a no-through road, down a single track road, ignored the 'no unauthorised vehicles' sign and then down our farm track before stopping at the muck heap.
"Apparently there had been a road closure and one of his colleagues told him to take a right, which he did.
"It doesn't seem there was much common sense at play. The further he was getting the more awkward it was going to get for him.
"We don't even like taking our tractor right down to the muck heap, never mind a commercial bus."
Mr Mizen and his brother Chris used a tractor to tow the bus free.
A bus ended up stuck in a manure heap after apparently taking a wrong turn.