Was it farmed though? A lot of people up here us the waste from DeCosta's for their garden, lawns and fields. Who knows what's in the ground if this has been done in the past. Is there water nearby? Anything agricultural besides you and your birds?
I would really lime it heavily or use wood ash if you can get it. This will drive the worms out and let you get a reprieve so you can catch up. From what I've read, cows can pass this on even though they aren't affected by it. I'm in pretty much the same boat here. At the top of the hill I live on, the person renting the land from the town has stock piled chicken manure for years....in the Spring, during the melt, the water runs down the side of the hill and goes through a lot of places on my land. I was doomed before I even started, lol.
Barn lime shouldn't bother as it's much weaker than the 'normal' lawn/garden lime. I wouldn't hesitate to use it at all. I add it to the chicken's dusting box and have even used it in the ducks/goose outside pen without any issues at all. Try it...you'll like it, lol.
