I gave the willow a good trim over the weekend and with the help of a friends shredder reduced the massive volume of cuttings into big bags of willow chippings. I know willow burns well when dried, so it can start the drying process in the chicken pen. Their scratching and digging through it should also help the drying process.
I've filled their run up to about six inches deep with the stuff and clearly they are enjoying every minute of it. With a summer like we are having the majority of the green stuff should be dried off within weeks.
This is a small scale experiment, but on a larger scale I would hope to be able to fill the run every month in summer and rotate the chicken 'dried' stuff into a green house or similar hot place for further drying. Not sure how or if this is going to work, but it's worth a try especially as willow is so cheap and grows so fast.