Hi there, I may have the answer you've been looking for: I used to run a 50- horse boarding facility in a flood-prone area. In the winter, the horses wood churn up the mud so bad, some would be almost up to their knees in soupy mud. Tried everything, nothing worked. Then an old pro suggested wood pellets (the kind sold for pellet stoves), & to our surprise, this solved the problem completely. Turns out this stuff is the most absorbent, best bedding we've ever found, and it's not even marketed for that! The pellets are sold in 50# bags for about $6-$7 a bag, but you can often find a store that will give you a deal on broken or rained on bags, or even free, (b/c it turns to sawdust when it gets wet & is useless as stove fuel then). 1 bag will easily cover a 12' x 12' area. It will not look like it at 1st, as it takes a few hrs for it to absorb the water & fully expand, but you will be impressed how much mud 1 bag can take on. The wood is compressed so tightly, that when it comes in contact with moisture, it sucks it up & expands about 20X it's original size. Once it fully expands, it becomes a soft, great smelling carpet for your chickens to enjoy. The wood has natural tannins, so it doesn't rot & start to smell bad like straw. It packs down & you can throw their food on it, and once it packs down, it's easy to remove the manure from it by gently raking it up. The wood they make it from is hardwood &v it is very clean- it can't contain any noxious chemicals, b/c people burn it for heat & fumes from chemicals would be dangerous if inhaled as smoke.
I use wood pellets in all my coops now, almost exclusively. Sometimes I mix it in w/some sand. Sometimes I even have to spray water on the pellets to get them to break down, as they use up the surrounding moisture quickly. All of my coops are now mud- free and have a pleasant woody smell as a bonus! I would say it is definitely worth a try, good luck!