Stuart Pedazzo said:

I have some horse manure that has been sitting in a barn for over a
year. Is it composted enough to add to my garden this year or does it
need to be in contact with soil organisms to compost safely?

If it has been sitting in the barn all this time, it might actually be
sort of mummified rather than aged. What it needs to compost is
moisture and, ideally, air. It might also need some nitrogen as
some of what it had to start with volitilized away.

I actually helped someone clear out a barn full of old, dried out manure
once, and hauled the stuff home (in bags) in my Chevette hatchback!

--
Pat in Plymouth MI ('someplace.net' is comcast)

Any technology distinguishable from magic is insufficiently advanced.
(attributed to Don Marti)