I got free chipped twigs, leaves and small / medium branches from a tree service working across the street. About 6 yards. How long should it cook before it can be used to mulch fruit trees and cane berries? The pile temperature is about 140 F 8" from the surface. Should I wait for it to cool or just some # of weeks?

White "dust" is released when I move a shovel full and the exposed material has a white dusting / coating-- fungi?

Should the pile it be watered to keep up moisture levels? Turned every few weeks? Is thee a prefered pile cross section to mimimize the time needed before use ( 3" deep, 3' deep, 3 yards deep)?

Rufus.

Rufus

Wood chips will be decomposed by fungi.
Leaves and green stuff by bacteria.
The white powder is probably fungal spores.
You have options and these you mention. I am personally a little lazy and do not like to turn piles. If you have available 2 to 4 inch diameter plastic pipe, drill holes in them and insert them into the pile, vertically and/or horizontally. This will allow oxygen in and you can run water through these pipes for moisture without turning anything.

Since the pile is cooking, let it cook until it cools. Then spread under fruit trees, they require fungi food provided by the wood chips. You will read that without proper decompostion nitrogen will be taken from the soil by the decomposers. this is valid in the short term. Long term, nitorgen will increase in your soil as the decompers are recycled.

As long as your trees are showin adequte growth and good leaf color, I would not be concerned.

Free Chips are Nice

Ted