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.
