soil mix for in ground fig tree :

1) Organic compost
2) 25% peat moss or coconut core
3) vermiculite

accompanied with

1) worm castings
2) kelp meal
3) rock dust or Azomite

maybe throw some horse or cow manure

I heard that some mushroom compost is really good, what was your thoughts on that?

Are you adding this to a tree that is already established or around a tree thats going in? 

PS. I also threw in some lime dust/pellets

what about blood meal and bone meal for nitrogen and phosphorus? Then again the organic compost and manure should have some of that.

Before you add anything to your soil, I would get it tested. In NY, your state extension or Cornell may do it for free. I know Cornell offers the service. If your soil pH is in a good range, lime addition will be harmful. Composting any area you want to plant a tree typically improves soil qualities. Worm castings are a great source of nutrition and beneficial microorganisms. I do not have experience with kelp meal as a fertilizer. It is not clear what soil improvement you hope to achieve with the peat moss or coir or the vermiculite or the rock dust. My initial take is that they are unlikely to cause any meaningful soil improvement. Good luck!

Reads exotic to me

think you could use perlite or something to lighten it up and get more air to the roots

Why just not to use the same soil that you dug out? I would not use more than 5-10% of compost when back filling the hole. You can broadcast some limestone and Osmocote on top and mulch. That is all. Other stuff is not needed. Many times trees (not just figs) die, because they were either planted wrong or lots of composte was added to the hole during the planting, making the bath tub effect. Rotting the roots or root strangling (esp with shade trees).

Navid.