Julia, Freshly chipped branches (aka ramial mulch) if they are fresh, green branches, will heat up quickly in a compost pile. If that were my situation, I would pile the fresh chips in a pile and allow them to do some decomposition.

Unfinished compost inhibits germination. You could use the chips as a top-dressing if you take care not to till them into the soil. Obviously, their rate of decomposition is related to the chip size. People here have observed that wood chips will break down well if they are used as a mulch, but do not break down well if they get tilled into soil.

Do not use the black walnut leaves and branches. They contain juglone, which is toxic to most plants.

Paul

Wood has no place in a compost pile---it does not break down easily. To test---pick a few minor twigs--1/8" wide....and bury in your compost pile.
They'll still be there next spring.

Whether new produced chips from fresh wood can be used as a mulch...how long must a wood mulch age before it can be used. I suppose new is no different than old.
Wood, next to soil, does remove somewhat the nitrogen from the soil to effect breakdown. Same goes for material in the compost. Grass clippings make a great addition to compost--it heats up fast, and provides nitrogen.

Hardwoods should not be used as mulch. Willow, hickory...et al, take forever to break down and do not make for good mulch.
Black Walnut has in it, pathogens that make it undesirable for use in the garden. There are only a few plants that can be grown in surrounding areas of a black walnut tree.

Putting wood mulch on top of soil can be done immediately. Any pH change and N depletion occur at the thin juncture. In some climes, the resulting attraction to worms and other life forms will compensate for any loss.

My statement is conditional in that environs are not the same elsewhere- I live east of the Mississippi where soils are generally acidic and humidity & water tables are plentiful.

I differ about use of hardwoods, having seen little difference vs. softwoods, though avoiding black walnut is good advice. I'm curious whether that may apply to its close relatives, hickory & pecan. Certain cedars will make for a longer lasting mulch.

My objective with the mulch is to keep weeds down but also see it breakdown over time to amend the soil without digging it in. Instead of buying bags or truckload each year of mulch, I want to start using what we have here already in a large brush pile and any further trees we have to trim or clear (large tooth aspen is out of control in back field) be recycled. The chipper/mulcher we have finely chips everything so there are not these 'nugget size pieces' in the output.

Thanks for the tip on Black Walnut. I'll have to see where I can get more specific information on that one and what plants it would be toxic to.

Julia

Wood chips can definitely be composted and/or used as mulch. The larger the chips, the longer they'll take to break down. But they'll still break down. I sent most of an apple tree through a chipper a couple of years ago and composted it with no problems.

If you compost the black walnut, you won't have to worry about the allelopathic properties. Also, if they're mixed with a lot of other types of wood and make up a small percentage ot the total, the effect will be diluted and may not be as much of an issue.

If someone were to put newspaper, or cardboard, on their soil they would not see Nitrogen depletion so if you put wood chips on your soil, as a mulch, you would not see Nitrogen depletion either. All of the studies I've seen that seem to support the idea that wood chips will cause N depletion have had those wood chips mixed into the soil and any time you put a high carbon source into soil the Soil Food Web will go to work on them utilizing, temporarily, much of the available Nitrogen to digest those wood chips.

Thanks all. I hadn't planned to mix in the soil just use as a topper to keep the weeds down in areas I haven't planted any perennials/annuals in.

If I did mix in any mulch into the soil, I could use a fertilizer/manure to help balance any N taken as well, right?

Julia

"If I did mix in any mulch into the soil, I could use a fertilizer/manure to help balance any N taken as well, right?"

Right.

I've used uncomposted wood chips from many sources, known and unknown, as mulch for the past 10-15 years and have always had excellent results in spite of countless people advising me that this (plant) source or that source has a mysterious chemical that is toxic to plants or soil or will introduce some invasive weed or pest into my garden. I figure, if it rots it will be good for the soil, and everything gets broken down to basic elements eventually.

My neighbors meticulously clean and rake every fallen leaf and twig from underneath their shrubs and put this out with their trash while I bring in truckloads of leaves and wood chips to shovel underneath my shrubs.

The only thing I'm careful about are chips/mulches that are contaminated with plastic or glass or similar materials.