wood chips on root zone?


New Member

I'm putting 4" of cedar chips around a western red cedar.
Radial trenching with the air spade is done. I've read some
about wood chips tying up nitrogen in the topsoil.

My question is, would adding a layer of compost under the wood chips be beneficial?

Anyone have an opinion or good alternative?



Well-Known Member
The fresher the chips, the more N they will tie up during decomposition. Try to use some well composted chips that are already partially broken down, and they should already contain sufficient compost.



Well-Known Member
need more info on soil quality and tree condition etc.

generally the N tie-up story is exaggerated and the compost plus broadcast N should allay concerns.


New Member
Dave, if you are top dressing after filling the trenches with soil or compost, you should be fine. Wood chips placed on top, and I emphasize ON TOP, of the soil will not significantly tie up N.

However, if they are incorporated into the soil at all, they will tie up N in that layer.

If you are concerned at all, a thin layer of humus is not remiss; but I would substitute the same amount of wood chips so you don't end up with too much depth too soon.

The actual breaking down or decomposition of the litter layer (in this case your wood chips) is really important for feeding the microbial life in the soil, which in turn serves the tree. This is why allowing the natural process to take place is so much more important than augmenting artificially whenever possible.



New Member
Some good info here concerning wood chip mulches. According to Dr Linda Chaulker-Scott, they don't tie up N at all. Looks like she's done a bit of research on this.


Well-Known Member
Great work by Dr. Linda; the Watson paper was huge at the time.

Unsure what any of this has to do with deadwood removal; that horse is buried and decomposed so it will not be rebeaten and tie up any Nitrogen, or other resources. ;)


New Member
Sorry, I shouldn't have brought that conversation to this thread. Believe me, I'm as sick of it as you are. I even asked Tom to archive it.


I heard Nelda Matheny speak on the topic of wood chips/N.

N is tied up only at the interface of soil and woodchips...a big reason why woodchip mulch can helps to suppress weeds...like Sylvia said, as long as the chips are topdressed, not incorporated.


Tom Dunlap

Here from the beginning
gilman sia that he has found that putting chips on the root ball of new transplants has little effect on new root growth...if I understood him correctly.

I don't think that there is any reason NOT to mulch the root ball though...just shift expectations. Mulch has many other benefits of course.