Take a look at the information here, this will give you a guide on the different manures to use:
Animal manures in the garden
Feb 27, 2010
horse manure by: Anonymous
I live near a horse corral that advertises...Free manure help yourself. Is this a good thing to mix into your garden with some potash mixed in?
Aug 04, 2009
Dorothy of Michigan by: bill t
You are a very lucky person Dorothy to have such an abundance of natural manures. Go for it, but may I suggest you add some sulfate of potash for helping the flowering and fruiting stages.Your animal manures are brilliant but lack sufficient quantities of potash. Good luck,and healthy satisfying gardening.
Cheers Bill T. :)