Granulated cork in soil

I was looking at the stuff and was wondering if it could work as bonsai soil, does it tend to sequester nitrogen?

Since cork expands when sturated with water, I think that it would be in contradiction with a free-draining mix. I would fear the roots might choke and rot.

didn't think about the expansion thing, I also wonder if its really a problem since we wont have the cork in a closed box, I think it would simply move and displace itself if it needs to....

 Maybe I should try to grow a grape bonsai in a cask full of wine bottle corks  

It would probably act like pumice and float up out of the soil.
Iris

i was intending it AS soil, nothing else, maybe some charcoal

Cork floats. What do you think would happen when you water?   Use your corks as spacers for pushing branches apart. If you want to grind them up, put them in your compost heap.
Iris

Use your wine corks as your potting media for your orchids, they work well for Phalaenopsis, Vanda, and Cattleya types.

Iris: i understood what you meant the first time, and using them as soil, not in a mix, i dont figure id be watering the tree and end with the barerooted tree in the pot and all the cork on the ground just because cork floats... it floats if it has a volume of water to float on or it comes on the surface of other soil if there is an heavier component in the mix and room for the heavier to lower and the lighter to raise... i dont water by immersion

Leo: thanks for the reply, yes its granulated cork and my sister uses it exactly for growing the orchids (its insulation stuff originally, wasnt talking seriously about using the whole bottle cork for a grape, although now id be curious about it)... i know most wood products tend to sequester nitrogen until they start decaying, accumulate salts to dangerous levels and need flushing etc etc, and that every kind has its quirks (even different kind of bark act differently) I used to grow african violets in just charcoal and they did extremely well... it works well for tropical trees... but the cork its something i have no experience with, thats why i was asking
I heard Vandas grow even in ground up tires as a medium... wouldnt try a bonsai in that...

i have 5 cubic meters of cork granules at work and considered this a few years ago. luckily before mixing it i observed several of my good trees have very poor years in a 'new' soil blend i made up with light shifting ingredients - a grey fired clay ball (that floated) and bark. The root growth in this medium was shockingly bad as it moved while being watered and there was hardly any roots in the upper layers of the pots. after returning to proper dense and well sieved ingredients the tree vigour, colour and health improved beyond all imagination.....i learnt there and then not to try and reinvent the wheel when it comes to bonsai soil.