What soil? And feed?

I have a five year old japanese red maple bonsai what soil? I've just left it in the pot with regular potting soil and its time to repot. And also what should I feed it and how often? Does the 90 day feed work?

Please tell us where you live so we can answer correctly.
Iris

I live in west ky about an hour near Paducah kentucky

You'll notice most of us put our location with the avatar. It helps tremendously.
A Japanese maple will take standard bonsai soil, possibly with a little extra organic matter, depending on the size of the pot. If there is a bonsai nursery anywhere within driving distance, get some professional bonsai mix. Shipping is prohibitive. Otherwise you will have to mix your own. A basic mix to start with is one third coarse sand or fine gravel, one third Turface or something similar, and one third chopped bark. Add about one tenth chopped charcoal. All ingredients must be sifted or washed to remove dust.
You can't repot your maple now. Just make sure it is not overwatered. Repot in spring when the buds are swelling.
I am not familiar with a 90 day slow release fertilizer. I use a small amount of Osmocote. I rotate a few different kinds of houseplant food, including fish emulsion once a month. It is important to include trace elements. I try to feed once a week.
I think Randy Davis lives near you.
Iris

Thank you very much I just ordered 5 japanese green maple they sent me six and all are very healthy two year old. So they say.. I potted two in bonsai pots how deep does solid need to be? And what is a good book focusing mainly on acer palmatum? Any one?

Google should be a much faster, cheaper, and easier way to get info.  Especially with a tree that is as commonly used in the hobby as a Japanese Red Maple.  Most of the information you would find in a book will also be online.  My generation is a bit spoiled by having the entirety of human knowledge available within seconds  .

(this forum is also an amazing source of info if you're patient enough to sift through posts using the search tool  )

A fellow named Vertrees has written THE book on Japanese maples, thougfh there's little or nothing in it about bonsai.  

Peter Adams has written (one of) THE book(s) on Japanese Maple Bonsai.  

Google can take it from there.