It doesn't rot easily which is the problem with bark as gives off spores as it does so which can harm chickens. I have used it in part of the run to see what difference it makes - answer, quite a bit. Yes it sinks into the ground a bit but it is miles better than just the mud and no sign of it breaking down.
Yes, we used bark for a couple of years in our old hen run and it worked well. We just emptied a new sack over the muddy bits once in a while, and then barrowed the whole lot out and replaced it periodically. Our run was only 4m x 5m though, so we're not talking a huge area.
I also remember reading that the spores were dangerous to hens, but since we'd already been using bark for 18 months without any problems before I found that out, I figured what the hell!
Another alternative I've seen advertised is
rubber chippings. I've never actually spoken to anyone who's used them though, so I don't know how well they work.
Reports from other forums are mixed too:
I used to be a big fan of rubber chippings, installed on top of a permeable membrane and hosed down regularly so the poo dissolved, and then a can of disinfectant on top to keep everything sweet. This used a lot of water, and the earth underneath got saturated and thus drained less well. Nevertheless, they are soft and warm and the hens did like sitting around on them. I thought they would be a permanent solution to the problem of dealing with dirty litter. I was wrong.
After a year, I realised that, although most of the poo does dissolve, there is still a residue composed of little bits of grass stem and other non- soluble components of their diet, and this was accumulating under the chippings and caking up, making the drainage poor and the hosing inefficient. The membrane was effective at keeping the poo separate from the earth underneath, but I had to laboriously rake the chippings to one side of the run, scrape up the caked mess, rake the chippings back, rake the other half over, scrape up after theat part, rake it back.... Very hard work and the chippings were pretty dirty underneath the to layer by then as well. So for a while, I poo picked in the normal way, and when I had a bucket of dirty chippings I spread them out on a garden sieve and hosed them down, using the water as liquid fertiliser on the garden. Good for the garden, but hard and unpleasant work. Also we were by them on a water meter, it used a lot of water hosing them down. I gave up, bagged them up and took them to the dump. I retained the permeable membrane, which is an excellent idea whatever bedding you use as it prevents the hens digging mud up into it, and went over to Aubiose, which is soft, incredibly absorbent, and a doddle to poo pick as it just coats and dehydrates the poos so they are easy to pick up. The hens like digging in it and it doesn't go mouldy if it gets wet.
So, as for the rubber chippings, you can probably infer what my advice would be........
The other concern with them is that they're not biodegradable, so I think getting rid of them eventually could be tricky.
Has anybody else on here used them with more success perhaps?