8 year horse manure any good?

I have read that manure will leach nutrients over time and eventually it becomes useless in a garden. Is this true?

We have a HUGE pile of horse manure that has been sitting since we sold our horses 8 years ago. Would it be any good in our garden?

While it has probably lost almost all of its nitrogen, it is still organic matter.
Something in your soil will want to eat it, and it will help your soil to hold water.

It should also be totally safe to use as mulch on young seedlings.

Thanks John, that's an excellent point. I was thinking of turning it into a new garden this Spring to help things along.

I agree with John Polk.
I've used several year old horse manure without a problem.

While loss of N and leaching of nutrients is likely to have occurred, the material would still contain a good deal of hummus. It should make an excellent soil conditioner.

That's excellent to hear! I'm excited to start putting it to use