Chickens do not use water to clean themselves. They actually use dust. It sounds counterintuitive but the dust helps them exfoliate, contol their oils and smother unwanted pests.
There are 6 different ingredients to this recipe. They all have important uses for chickens.
Sand and soil
These help to control oil by reducing the amount that can build up on their feathers. Which is good because certain parasites will thrive in the old oils. It also removes dead skin cells which if left harbor parasites as well. Plus is can knock off and smother any parasites they do have.
Wood shavings
The shavings help absorb moisture in the soil, which is good because birds don't honor their bath the way we do and will sometimes poop in it. Due to this, the wood also helps with odor control. The shavings will also absorb excess oils from their skin and feathers. The wood should not be cedar or treated.
Wood ash
Ash is not only anti-parasitic and anti-bacterial but it also provides vitamin K, calcium, and magnesium when they ingest it. (They both poop in and eat their dust bath. To each their own I guess.)
Lavender
There are many different herbs that you can add to a dust bath but my personal favorite is lavender. It is not only a good pest repellent but it relieves stress too. This ability to calm down your layers can actually increase their egg production.
Diatomaceous earth
This is a well-known and very effective ingredient for killing parasites. The only thing you have to be careful about is not breathing it in as it can be bad for your respiratory system.
I like to mark a bucket with the quantities I need so all I have to do later is fill my bucket to that line. (I used gallons of water originally to make my lines.)
Chicken Dust Bath Recipe
2 gallons SAND
1 gallon SOIL
1 gallon WOOD SHAVINGS
½ gallon WOOD ASH
¼ gallon LAVENDAR
¼ gallon DIOTOMACEOUS EARTH
Mix it together well. I used a cement mixer for mine but you could pour from bucket to bucket or dump it in a wheelbarrow and use a shovel to stir it.
It actually feels really good on your skin and it smells so good.