Every spring and fall, I take an few hours on a nice afternoon and clean out the chicken coop, laying down a fresh batch of wood shavings. It takes 3 or 4 wheel barrow loads to empty out all the nest boxes and the inside of the coop.
I mix everything as evenly as I can and then take it to the garden. That's when the chickens take over...all winter they have been digging in the garden and working the soil. Once the old wood shavings and ~6 months worth of manure are dumped in the garden, the girls go right to work incorporating it into the soil.
They continually work the ground making the soil light and fluffy. It's a win win in my book. They work hard and eat all sorts of grubbies and I get some of the best garden soil I have ever seen.
I've had 6 and 8 foot tall tomato plants with vines heavy with fruit. All I gotta do is keep the girls out of the garden till fall harvest. They love tomatoes too.
I get this chore done by late March / early April, then all is ready a few short weeks later in mid May.
It took 11 days for 4 chickens to incorporate all the chicken litter into the garden.