I feel moved to testify!
As far as I know, high-carbon mulches like chipped trees on the soil surface WON'T 'tie up/leach out/steal' or noticeably affect the nitrogen/carbon balance.
Dig 'em in and that's a different matter...

Right, so incorporation vs not, as discussed. Mulches always have their advantages.

I agree, Lloyd, that incorporation of high-C materials does as you describe. In light soils it is best avoided altogether.

Regarding mulching with high-C low-N materials, long term that has its own issues, I find. Namely soil domination by fungi which greatly favors certain weeds, shrubs, and brier over crops. I find it impossible to keep wood chip piles from being over-run by vines and briers, for example.

Absolutely, Lloyd. As I have stated many times before it you incorporate a high carbon material into your soil the soil bacteria will go to work on that, using much of the available nitrogen in the soil, digesting it to the deteriment of any plants growing in tht soil.
However, if that same high carbon material is layed on top of the soil, as a mulch, the soil bacteria will not immediately go to work on it and will not use the available soil Nitrogen to digest it so there will be no Nitrogen deficiency in that soil.
Does not make any differentce if it is shredded leaves, wood chips, or partially finished compost, the result will be the same, incorporate that in your soil and there will be a Nitrogen deficiency, lay it on top of your soil as mulch and there will be no Nitrogen deficiency, from that source.

Then it makes all the sense in the world to use a no-till method of gardening and add amendments as nature has for millions (or thousands, if that happens to be your belief system) of years.

Layer after layer after layer. Hardpan exists, accept it and move on.

There are problems and difficulties associated with little tilling and chronic layers of low-N mulches, as I allude to above. I have been doing that for years, there are big advantages, the biggest one being excellent moisture conservation, but the drawbacks are serious factors also.

..
I know the garden guy on NPR is dead set against wood mulch. I've seen the fungus promotion in my own experience with wood chips in and around the compost bins but I'm not too concerned because it's so dry around here in sunny So Cal. Maybe in the Pacific Northwest, it might not be such a hot idea.

It strikes me that high C mulch is more akin to a forrest floor and I don't believe a forrest floor is a good place to grow crops.

If high C amendments in the soil is so bad, what are all those kugel enthusiasts on about?

to sense
..

The only reason you wouldn't grow crops on a forest floor is that very little sunlight reaches through the canopy, not because of excess carbon.

I know the garden guy on NPR is dead set against wood mulch. I've seen the fungus promotion in my own experience with wood chips in and around the compost bins but I'm not too concerned because it's so dry around here in sunny So Cal. Maybe in the Pacific Northwest, it might not be such a hot idea.

Not at all sure who the garden guy on NPR is but I'd want to know his credentials before I'd consider what he had to say about wood chips had any merit. Too much scientific evidence supporting information to the contrary. Of course it depends a lot on what you are growing - not every gardener that visits this forum is focused entirely on edible cropping - but there is all sorts of documentation to support the value of wood chips in the landscape and in the ornamental garden overall.

btw, I'm not sure what the concern is about the 'fungal' issue with wood chips - fungus is going to be present with any organic mulch or amendment as it decomposes and is usually a benign substance. Any concerns with a pathogenic fungal organism would direct one to composting the wood chips first.

Myth of Wood Chips Part 1

Myth of Wood Chips Part 2

Myth of Wood Chips Part 3

I can report from experience that a heavily fungal dominated environment results in lower yields than one that is more bacterially dominated. The reason that careful tillage and use of well-composted manures was and is standard practice for crop production is because that creates a bacterially dominated soil as well as plenty of organic nutrients and the crops produce more in that situation.

It is when tillage gets too frequent and sloppy and fertility depends on concentrated fertilizers, covers are not maintained and etc, that is destructive. I think there is no reason that heavily layered fungally dominated growing situations can't be utilized, and in fact are more sustainable in every way, but more area and labor is required in the long run.

pnbrown, I am going to mulch my orchard with cardboard, leaves & sawdust. To keep the weeds down, this in paths & between plants, but still put compost around plants.
Llody this makes sense to me, but I have tilled carbon waste in with no sign of a N deficiency. Sometimes I till in the fall & let it set for 3 months, of course there is not deficiency with no plant in the bed. I have got behind on the tilling & tilled 2-10 days before planting with no problem. The only thing I can think of is that my soil is a little high in Nitrogen or the compost that I put down with the carbon off set the deficiency.

Re: nitrogen deficiency vs. phytotoxicity - peas/beans are nitrogen fixers if they are inoculated with rhizobium. Perhaps they would be immune from nitrogen deficiency issues if planted into a soil that had leaves tilled into it.

I happen to have a garden bed with a two-year old layer of chipped leaf mulch. Would that qualify as a reasonable test? I can plant some inoculated peas in that currently unused bed, and also plant peas in an adjacent, grass-mulched bed as a control. I'll have to give myself a reminder to buy more peas and rhizobia. I can also plant something sensitive like carrots alongside the peas.

If the peas sprout and grow somewhat similarly in both beds, but the carrots fail to grow in the leafy bed, that would suggest that phytotoxicity is not the reason for stunted growth. It would show that nitrogen deficiency is the reason.

I also have a 'leaf mold' pile that I can pilfer some aged oak leave from. Run them through the hammermill shredder, mix them into another bit of garden bed, and that might be another test bed.

I'm sure a person could use all sorts of high carbon feedstocks (saw dust, wood chips, wood shavings, straw, shredded straw, etc) in various quantities (X# of pounds per square foot) in various soils to see what does and doesn't work. But unless all variables are controlled, it might be interesting but it might not mean much in the end. As an example, something as simple as a thunderstorm could completely change the outcome.

Personally, I'm content with the amount of information from relatively respectful sources already out there.

Lloyd

Agreed, there is so much variation in soil types and climates that the anecdotal experiences are primarily only useful in a specific context.

The garden guy on NPR is called You Bet Your Garden and I think he is an idiot. I use woody mulches and put woody browns in compost and I never had any problems. He is a big time believing in enough peat moss to drain all the blogs in Canada. Some of you anti peat moss people should call his show and get on his case. What a complete ass he is. He has to use peat moss since he won't use any wood.

@tropical_thought i wish there were a "like" button on gardenweb!

..
But I digress
..
The garden guy on NPR is Mike McGrath on You Bet Your Garden. I don't know why I can't remember his name or the name of the show very well. He comes on the air locally 5 in the morning on Saturdays. I'm not a morning person and I'm not a regular listener. He hails from back east and maybe his experiences there color his recommendations. He is a compost booster among other things.

http://www.whyy.org/91FM/ybyg/

WRT the myths. The links gardengal48 provided didn't work for me but a little tweaking on the URL put me at Washington State University Puyallup Research & Extension Center. A search on "Myth of Wood Chips" returned 174 finds. Reading one, The Myth of Allelopathic Wood, by Lynda Chalker-Scott, Ph.D., was a brief, interesting piece focusing on wood chips from cedars. Good to know but I noticed it was carefully qualified throughout. Though addressed in passing in the same article, I'd like to see more information regarding eucalyptus wood. I avoid composting eucalyptus litter - leaves, sticks & acorns - and I've noticed not much grows around stands of eucalyptus so it strikes me that eucalyptus wood chips and saw dust would not be allelopathic as counterintuitive. I'd also like to see the specific articles gardengal48 was pointing to. I can only guess which ones she intended from what I've found.

Thanks
to sense
..

He has a website that you can find when you google you bet your garden. I just did not want to promote him. He could be correct about some things, but not about wood. He acts like one piece of wood in your garden and all your plants will shrivel up and die. He tells people to never use woody mulches so often the bots (who are brainwashed) can repeat it like a mantra on cue, when he tells them to say it.

Here is a link that might be useful: you bet your garden

Nutrition wise, wood chips (not including RCW) really don't do much for compost. Most reputable composters mainly use them to increase porosity and screen them out for re-use.

Lloyd

Lloyd, that's very interesting, re-using the wood chips. I suppose they are using a large sized chip. (My little chipper has a screen on it that determines what size particle gets ejected.)

There is simply no doubt that an environment covered with wood chips and little or no other inputs is quite different from one that is tilled and has more plant-available nutrients regularly incorporated.

On any given soil/climate paradigm. Comparing between paradigms means very little. Like the wood-chip gardener in the PNW on a particular soil, growing vegetables under wood-chips in some other soil and climate won't get the same results.

Why all the fuss over N deficiency?
If it happens why not just add more N fertilizer?

I put in a hugelkultur bed this year and it has been amazing.
I'd never been able to grow squash in my heavy clay soil, this year they are doing great so far and are very green. I did pour a jug of urine into the middle of the pile, it seems to have taken care of any N deficiency problems.

"Why all the fuss over N deficiency?/"

It can result in a loss of vigour and yield potential.

"If it happens why not just add more N fertilizer?"

By the time one realizes it, some damage may have been done already and there may be less opportunity for recovery to full plant potential.

Most everything I've read claims it may be better to avoid problems such as this rather than try to fix them mid-growing season.

Lloyd

gardengal -

For some reason I haven't been able to access you links. Just gives a page not found error. Am I the only one?

Val

Interesting posts in this thread (pnbrown in particular) about fungal vs. bacterial dominated. I've been reading a book on fungus (Mycelium Running: How Mushrooms Can Save the World by Paul Stamets). This guy is a real fungus geek par excellance. He makes a pretty good case for the benefits of fungi. I'm not sophisticated enough to understand this stuff in great detail, but it does seem like we need both in most environments.

How do you tell if your system is fungal vs bacterial dominated?

Then there's Dave who buries massive amounts of wood. You should see the healthy plants that grow in those beds!

Karen

Here is a link that might be useful: hgelkultur

I've seen that before Karen, it looks interesting.

A couple of notes though. Large chunks of wood are not an easily digestible carbon so a lot of nitrogen would not necessarily be tied up in a slow breakdown of the product.

Secondly, he used old and partially rotted wood so the potential for N being tied up is even more reduced.

Last, he put humongous amounts of high N materials onto his beds so there would be an abundance of N available to begin with.

Lloyd

Yeah, Lloyd, I realize that. But still interesting.

Honestly, I've used wood mulch for almost 30 years and have seen nothing but good come of it. I tried pine needle mulch for the first time this year. I already hate the stuff. Next year I'm going back to wood. LOTS of wood.

Karen

I have this huge windrow of shredded trees on the edge of the field. There is some soil mixed in with it and some of the chunks are pretty darn big. I was thinking of spreading it out to about two to three feet thick and covering with grass clippings and straw to see what will happen.

Lloyd

That sounds interesting Lloyd, post the results, but it will take at least a few years and since it gets cold where you are. Did you know I can compost all year? I am in zone 10. I sort of messed up my hands gardening and composting now, so I have to like back off so much soil improvement. So, maybe I try some slower more passives batches.

Hi Dave

The windrow varies in height due to the way it was dumped. In some spots it's 5 feet high, down to 3 or so between dump areas. I was thinking of spreading it out to also level it out and make it easier to work with or on. I'm not sure I will be planting anything on it anyways as available time is an issue for me.

I will also have to see how much material I get this year as I am sheet composting my largest field and will probably need all I can get for that project. If it turns out I get sufficient materials I can always throw some on top of the wood. But for now, the priority is the field.

Lloyd

I ran a highly unscientific experiment last year. Took about 1/3 of my raised rows and mulched around 3 inches thick with wood chips in my veggie garden around the 1st of April. Just placed on top of the rows and did not stir in. Peppers, tomatoes, snap peas and squash.
By the end of May I pulled that mulch back and replaced with grass and straw. All of those plants were dwarfed by rows mulched grass and straw.
My mom tried a similar experiment with okra and green beans. The okra died.
For me trying wood chips as a mulch was big NO GO.

One could add nitrogen at the time the wood clips were added like maybe under the clips mixed in with some compost.

I did not find my soil/compost test, but here is one from the processor who I got the coffee waste from.
Nitrogen 3.46%
Carbon 50.23%
c:n ratio 14.50%
Phosphorus0.135%
Potassium 2.19%
Calcium 0.88%
Magnesium 0.41%
sulfur 0.28%
zinc 20ppm
copper 56ppm
manganese 63ppm
iron 1315ppm
sodium 110ppm
Organic Matter (LOI) 90.40%
Do not exceed one ton per acre

ah, but this is for crops, in which they are harvest able. I am talking about shrubs, landscape plants, it doesn't affect them. You can pull the mulch of wood clips back a bit from the roots and put in some kellogs amend which has bat guano. I never have any problems. In my veggie boxes, I don't mulch them, because the soil is really good and there are no weed seeds in the boxes. I have never seen vegetable rows mulched with wood chips. It would look pretty silly.