Anybody know the purpose of the wood ash? I've seen on these forums a lot of people that don't use it
It is super fine particles. Helps dry out/dislodge/smoother bugs. Think about how well wood ash and wood soot/charcoal stains your hands and clothing. That is due to the small particle size. The white ash is also still great for this as well. Also, a significant component of ash is actually the minerals left over from the wood after burning. So that helps as well. They are dusting in a good mineral mix.
"Wood ashes contain all the mineral elements that were in the wood. Potassium, calcium, and magnesium carbonate or oxides are present in comparatively large quantities giving the ashes a strongly alkaline reaction which can neutralize acid soils. ... They also contain 25 to 50 percent calcium compounds."
https://vric.ucdavis.edu/pdf/fertilization_Woodashes.pdf