Paul Wheaton on the problems with importing wood chips to your land

I have seen some folks that have brought in huge mountains of wood chips to their land and done some great things to improve their overall soil.  I have talked to dozens of people that have imported ten to 500 dump truck loads of wood chips.  Usually the upsides outweigh the downsides. 

They are adding gobs of organic matter.  And when done correctly, this can transform dirt into soil.

When done correctly.

I want to start this thread to help folks become aware of the downsides.  I think a lot of permies are familiar with the upsides.  And I would guess that 90% of those folks are not aware of even one of the downsides. 

I feel like the negative nelly of permaculture.  But it isn't that I am against permaculture or these techniques, but I want to have systems that are even better than the default.  Adding woodchips to improve organic matter seems like eco level 3 or 4.  Adding the right kind of wood bumps you up one more level.  Using full chunks of wood and not wood chips adds another level.  Not importing adds another level. 

Here are a few things off of the top of my head:

1)  Most urban wood will contain persistent herbicides (half life of 7 to 11 years; clopyralid, aminopyralid, picloram, etc).  It will probably be so little that it won't kill your plants, but it will stunt their growth.  Plus, that stuff could end up in your food!

2)  All that carbon will tie up the nitrogen in your soil - just be prepared to mitigate that.

(what else?)

I've been wondering if wood chips might attract termites.

We live in the AZ desert and our soil is very low in organic material. I would like to get wood chips from a local landscaper to use in garden paths and at the base of the compost heap. My thinking was that if I use wood chips instead of gravel as path material, it would reflect less heat and add organic material to the soil, even if it wasn't in planting areas. I am hoping to eventually have a yard that would support a nice earthworm population. The reason I hesitate is that termites are a big problem in this area and I don't want to draw them to our yard, causing major problems down the road.

Local trimmings usually include trees such as palo verde, acacia, mesquite, sissoo, sumac, etc. Pine and walnut trees would not be included in the chips.

Can anyone address this issue?

We have loads of termites in our yard, so far none in the house because there is plenty of wood in the yard and in the soil.

They've been swarming in our area lately and I'm feeling just a little paranoid about them!

I like to believe the termites will stay in the yard if there's enough nice tasty wood for them out there!  But I don't know for a fact they will! 

I've heard rumors of rumors about people bringing in diseases with fresh woodchips.  I've never heard of a documented case myself though.  Again in the rumor category: after Katrina there were warnings not to buy bagged woodchips because they contained termites.  This one I doubt because it is unlikely you'd get a queen that would start a colony, but who knows.  I'm sure you could bring in bugs and other pests, but if you get the chips locally, you'll probably just bring in stuff that would have found its way anyhow.  And I hope nobody here is using chips shipped to the big-box stores.

If you're using them as mulch, they shouldn't tie up much N.  Just don't till them under.

The local recycling center sells woodchips.  They are made from pallets that are beyond repaid and other industrial packing.  For a slightly higher price, you can have them heat-treated.  This helps sterilize them and it also vaporizes some of the resins that lower the pH.

thankfully all of my wood chips are from a very rural area. and are only the tree branches that grow along the road and endanger the power lines. also the guy i know who brings them knows i only want the high quality chips.

the chips only tie up nitrogen for a certain period of time. after that the soil benefits greatly from the addition of the wood chips. the ramial chipped wood information online shows this. i have done many tests as well that show great benefits( not having to water until july for one), usually i amend them in the fall and wont use it for 5-6 months later. this problem can also be avoided by just leaving the chips to age for a season before use. once you see the fungal mycelium on the wood its garden safe as far as the nitrogen cycle goes.

since this thread is about the possible problems with wood chips.

one person i know got chips that included some bamboo in it. the bamboo sprouted, took hold and was quite a battle to get rid of. this comes back to know your source.

I don't find N 'tie-up' an issue or have any trouble using conifers, but I  second Hubert's comment about introducing something by mistake.
I always check mulched areas repeatedly to make sure no ivy bits are growing.

Regarding termites; I feel like I live in the termite capital here.

I have noticed that wood, if it can be broken down very quickly with a lot of green slimy stuff is fine. 

But if the wood is left to break down very slowly, such as in top (decorative) mulch, planters, or borders for raised beds it becomes a magnet for termites.  I currently have a wooden raised bed that needs to be replaced due to termites.  My guess is that this is because it is a 'dead zone'.

My new(ish) hugelkultur bed is not a magnet for termites - I can only guess that it is because there is a lot of green stuff in there; lots of stuff rotting, lots of bugs and worms and bacteria competing for nutrients.  This is not a dead zone – it is very much alive and my guess is that it is too competitive an environment for termites.
That is my very unscientific take on it.

It seems like it's important to what is decided to plant in the wood chip area. I have neighbors who have nothing but wood chips - they add tonnes year after year and that's all their garden consists of. And they grow the tallest corn, the largest squashes and the best sunflowers around. All are heavy feeders. I notice they don't grow beans or other low nutrient crops. Sepp talks about this in his latest book. The reason he likes fresh trees as the basis of his raised beds is that they break down slowly. And the reason that my neighbors like wood chips is that they break down quickly.

Just negatives or can we espouse some positives if we identify them?


Negatives (most may be repeated):

Weed seeds - from minor to frightfully invasive

Fungal/bacterial tree-killing diseases - chipped trees from your local chipper can be sick or dying

Pests - pests and their eggs may survive the process

Poisons - sudden tree death can be caused by stealth poisoning from who knows what

Allelopathic - chip looks like chip, certain species can be hard to identify if no smell or obvious timber

Lasts longer - compared to straw, for example

Rubbish - a lot goes through a chipper

Urine - that's where the go when they have to get out of public eye

Faeces - I've seen it done

Dead Animals - seen it done

Humans - Fargo

Termites - potential house killers

Carbon footprint - fuel usage, steel, oil, chainsaws etc.


Positives:

Cheap/Free in some cases

Quality Control is possible

Greater water-holding capacity in lower layers of wood mulch - minor hugelkulture waters surface roots

Greater insulatory effect of sun/heat through thickness and density of chunks - thinner still works to a point

Lasts longer

Termites



I use chip mulch (or forest mulch) because I can get it for free, and I can choose what I receive, either hardwood, greens, pioneer species, or mixed.  I have dumped it on one particular area for 7 years now, and the soil is just as good as it needs to be.  Black, friable and wormy.

I have stored it on my property for over a year.  I have come across piles that are several years old.  I have planted trees into rotted-out stumps which are perfect for rainforest species in areas where they don't naturally exist (Ficus in particular).  It always ends up looking the same, no matter whether it was a chunk of Australian hardwood or a pile of chip (time is the difference).

Termites rate a mention in both columns because they have advantages and disadvantages.  Certain Australian hardwood can be good for decades in the open.  Termites will greatly accelerate hardwood decomposition, allowing it to be returned to the soil, sooner than later.

It has its place.  Trees, yes.  Annual beds, not so much. Though, composted or very aged wood mulch would be fine as an adjunct to annuals.


If anyone is interested, I could probably take a photo of a handful of mulch that has broken down in a steel cupboard, away from all the elements. A box was open on our truck, partially filled with mulch and closed again (it held a ladder).  I've reached in and it's coming along nicely and still holding moisture even though it shouldn't be getting wet from rain.  I could also show a handful of soil from deep inside a Eucalypt stump which I discovered recently in a heavily urbanised area and I snuck a Ficus into it.

I've had really good success with all the wood chips that I've imported. Even the conifer. A number of years ago, I had access to a vacant piece of land on the outskirts of town and asked all the local tree trimmers to dump their chips there. Within the first season, there was about 120 yards of chips from many different species of tree. I only hauled a couple yards home at a time so before long most of the chips were 2-3 years old. When I dug into these older chips, they were full of worms, worm castings and some were so thick with fungal strands, it looked like wooden tempeh. The trimmings from spring that have a lot of leaves in the chips have enough nitrogen to get pretty hot, even the conifer. 

in our area there are wood borers called the emerald ash borer that are getting transported from area to area by wood products..

a few years ago our area was clean..now it is infested and I have 100 year old trees dying.

I'm not sure if they came in on firewood or wood chips or some other way, however, they are here

they say they have to be BROUGHT in as they can only fly a couple hundred feet.

we had a huge population of ash trees on our property, and now many of them are infested, very expensive to treat your trees so we are hoping for some natural defenses such as the huge population of woodpeckers and birds..but we are likely going to lose a few trees..which we'll cut up for firewood..we may lose a thousand trees or more..but right now only a few are showing signs of decline

same problem out in the west with the pine borers

What if the wood chips/mulch is left in piles to decompose and break down. Would some of these problems be solved. If big truckloads are coming in then big piles can be made, and high compost temps could be reached.

Paul, I think wood chips are one of those things that just have a lot more positives than negatives. A little bit of alleopathicity or acidity isn't really that bad, the pesticides and poisons get eaten by the mushrooms pretty quickly, pee, poop and dead animals are just more bio matter, and duh, don't use a lot of it for annuals. All you have to do is set it in a pile for a year and the carbon is broken down enough where it doesn't deplete nitrogen.

Salamander wrote:
Paul, I think wood chips are one of those things that just have a lot more positives than negatives. A little bit of alleopathicity or acidity isn't really that bad, the pesticides and poisons get eaten by the mushrooms pretty quickly, pee, poop and dead animals are just more bio matter, and duh, don't use a lot of it for annuals. All you have to do is set it in a pile for a year and the carbon is broken down enough where it doesn't deplete nitrogen.

Hi salamander, why would one not use wood chips for annuals? Just curious. 

I have been told that green waste/mulch/wood chips turns organic if you let it sit and compost for 2 years. Do I believe it? I don't know. It seems the compost will sort of balance itself out.

oracle wrote:
Hi salamander, why would one not use wood chips for annuals? Just curious. 

I have been told that green waste/mulch/wood chips turns organic if you let it sit and compost for 2 years. Do I believe it? I don't know. It seems the compost will sort of balance itself out.

Wood chips are mostly carbon, so they would rob the annuals of the nitrogen they need (and most need a lot.) I would use either wood chips that have sat for a year or a small amount of wood chips along with green manure for annuals. Wood chips also provide the perfect habitat for fungi, but not so much for bacteria. Woody plants tend to also like fungi rich soil more than bacteria rich soil, and annuals tend to like bacteria rich soil more than fungi rich soil. If you think about forest succession it makes sense.

enjoyed reading this tread. I have wondered about this too. We have a saw mill down the road from us and they have piles of saw dust. I know that there was a discussion above about wood chunks, wood chips and saw dust. This particular mill and most around here are cutting oak and maples our predominite trees. I wondered if the oak was a problem?
And I was thinking of using it for deep bedding under the cows and chickens this winter before composting it next spring.
kent

Dude. Humanure toilet.

machinemaker wrote:
enjoyed reading this tread. I have wondered about this too. We have a saw mill down the road from us and they have piles of saw dust.

salamander, saw in your profile you are in Pa too. we just moved to crawford county. If i remember correctly the author of the humanure book is here in crawford county.
kent

Yeah he is! You're also pretty close to Darrel Frey's Three Sister's Bioshelter. He just wrote a new book.  http://www.bioshelter.com/Contact.html

I'm in Beaver county, so a little further SW.

Salamander wrote:
Wood chips are mostly carbon, so they would rob the annuals of the nitrogen they need (and most need a lot.) I would use either wood chips that have sat for a year or a small amount of wood chips along with green manure for annuals. Wood chips also provide the perfect habitat for fungi, but not so much for bacteria. Woody plants tend to also like fungi rich soil more than bacteria rich soil, and annuals tend to like bacteria rich soil more than fungi rich soil. If you think about forest succession it makes sense.

Thank you! 

Salamander, thanks for the link to three sisters. I want to visit sometime.
kent

machinemaker wrote:
And I was thinking of using it for deep bedding under the cows and chickens this winter before composting it next spring.
kent

My neighbor is an obsessive woodworker and generates bags and bags of cypress shavings.  I have been using them as bedding for my birds for 5 or 6 years now.  After I take them out of the chicken run and house they mulch my plants and trees.

I have noticed that I need to layer in green stuff (kitchen waste, green plant material) because if I don't the shavings/sawdust will just sit there for a while - even with chicken poo in it.  Now if you are using it for cows it might break down faster due to the higher volume of cow poo.

I believe that wood chips will rob the soil of nitrogen the first year they are down, and then become a plus as they decompose. The more chips that are added, year after year, the more nitrogen and OM that builds up in the soil.

Regarding termites, they are present throughout the eastern US and especially in the South. They move randomly (or so it appears to us humans) through the soil and concentrate when they find a rich food source. New Orleans is home to the imported Formosan Termite. It has colonies at least 4 times the size of our native species and is vastly more aggressive about eating wood. A native species of termites could chew on a home for 10 years before significant structural damage occurred. Formosan termites can destroy a home in 4 years or less. There is/was a moratorium on moving wood products from New Orleans and most of Louisianna.

      Cedar, Cyprus, Redwood, Sequoia and black walnut are a few species whose chips are likely to prevent certain plants from germinating. Young cedars grow well under a cedar tree but many other plants can't survive the chemical onslaught which the parent tree delivers. And some of these woods decay very slowly. I prefer hardwood chips from Maple and alder which decompose quickly especially when they are covered with chicken manure.

what about Juniper chippings?  I've been slowly clearing the bottom branches of the Junipers around our property.  The previous owners did a similar thing, btu they were cutting fence posts.

Anyway, they tended to deposit all the trimmings in large piles.  Those piles have the thickest grass and plants on our whole property.

So, we trim the trees, and lay the trimmings in windrows on the contours of the hill.  Them seem to help with erosion, and although they take a while to break down, they do provide good habitat for seedlings and animals.

I'm thinking that covering with soil with help with the decomposition, and it will help create some swales down the hill.

I wonder if it is better to bury the trimmings, like hugelkulture, or surfacing mulching chips along swales?

I have often wondered about this.  An 'ideal C:N ratio for compost is stated as 30:1.  Fresh wood chips might be something like 300:1.  In the first year of decomposition, most of the N would be consumed, leaving you with something that might now have a 600:1 ratio.  Further decomposition would become very slow at this point, and probably consume any N within reach of this C rich pile.

Would it not be better to convert your wood chips into bio-char?
A dump truck load of wood chips would create a wonderful pile of bio-char!

Would it not be better to convert your wood chips into bio-char?

the chips do make good biochar. no need to process into smaller pieces. easier to get around and use as well.

A dump truck load of wood chips would create a wonderful pile of bio-char!

a beautiful sight it is, the only thing is the pile shrinks considerably.

imo everyone is overreacting on the chips stealing N. there is such a fine line where the chips are in contact with direct soil, there is not a mass need for the N, there is some yes. its just i think you get the same effect when putting fresh straw or hay as mulch too.

now if you went and tilled in the chips ramial chipped wood style you would have that N effect but only for a certain period of time( usually one-two full seasons from my experiences) and from then on the soil is MUCH better than it was before the addition of the chips.

yeah, biochar would be idea, but there are some issues with that.  One being converting trimmings to chips consumes energy and requires time and equipment.  Then, converting those chips into biochar requires more energy and requires even more time.

When it is a truck load or so, it's not a big deal, but when it is many truckloads, it starts to add up.

I am not worried about the N thing.  I can see the trimmings from past years working just fine, no N added.  So, I don't think you need to worry if you place it on the surface.

The original post was "the problem with importing wood chips", not "making wood chips".
Granted, 'making' wood chips consumes energy, but most people buying, or receiving wood chips are not spending the energy...that has already been expended by the person making the chips.  Tree trimmers use the energy converting the branches into chips to actually save energy and labor.  Any decent chipper will give a 10:1 ratio.  I ran into this when I did tree trimming.  Do I make 10 trips to the land fill with branches (spending gasoline, time, AND tipping fees each load), or do I make one trip?  A decent chipper will pay for itself in one week!

A truck load of chips will break down within a couple of years, whereas a truckload of branches may take a decade or more.  You often need to spend energy to save energy.

If "spending" energy to convert branches into chips is an issue, I could make the same argument against composting.  The spent energy buys time.

John Polk wrote:
The original post was "the problem with importing wood chips", not "making wood chips".
Granted, 'making' wood chips consumes energy, but most people buying, or receiving wood chips are not spending the energy...that has already been expended by the person making the chips.  Tree trimmers use the energy converting the branches into chips to actually save energy and labor.  Any decent chipper will give a 10:1 ratio.  I ran into this when I did tree trimming.  Do I make 10 trips to the land fill with branches (spending gasoline, time, AND tipping fees each load), or do I make one trip?  A decent chipper will pay for itself in one week!

A truck load of chips will break down within a couple of years, whereas a truckload of branches may take a decade or more.  You often need to spend energy to save energy.

If "spending" energy to convert branches into chips is an issue, I could make the same argument against composting.  The spent energy buys time.

Good point! Some energy is going to be spent. I will definitely invest in a chipper of some sort. If there is a reliable source of chips from somewhere else, I would also bring those on as well, but only if they are free

All these replies and no one mentioned wood gasifiers? they can run a wood chipper you know?

My interest was recently peaked seeing a well thought out model. http://woodgasifier.org/

I saw this one at an expo and I guess he has about $1500 into off the shelf parts, I want to see what can be built from salvage.

He says it runs for an hour on 7lbs of woodchips.


If I can get someone to drop off a load of free fuel to me, I will be ok with that!

I wonder how long they would need to dry before burning if they were fresh?

@Casey - how much horsepower for the 7 lbs of woodchips?

Also, consider this: corn stover bales (50 lbs) are available in my area for $1.50 USD. That bale could be worth a good 2-3 gallons of gasoline!

It could burn lots of things, From the link. - The 5.5 hp Tecumseh engine was chosen because it was a suitable match for the 65 amp automotive alternator and it comes with a starter. This rating is also ideal for safely charging a battery bank that is typically used to power a small solar home or cabin.  Some have asked if they could use a different engine on their system.  While that is entirely possible, you would discover that the gas mixing valve and governor linkages as designed may not match up correctly with the engine you want to use.  Every engine is different and would probably require some modification. However, if you have good mechanical skills you might be able to adapt it your engine. The DVD has a section that explains the concept of what you would need to do to make it work correctly. 

One more negative.

The neighbor of one of my friends had several loads of wood chips dumped on his property to use in pathways and for mulching. Unfortunately, the wood was full of scorpions and the neighborhood that had very few scorpions is now infested. I wouldn't take the material unless I knew exactly where it came from. I had the opportunity to get a bunch of chips from a citrus grove that had been taken out. I refused the wood because I was afraid of all the unknowns that might accompany it into my yard.

I may be paranoid, but I'm going to build up my organic matter more slowly and safely.

What I would be worried about most is contaminated wood in my wood chips. A friend of my who runs a major demolition dump for a major city recycles wood. They do this not to make profit from selling the wood, per se. The make money by diverting it from the landfill. It is profitable to do in some places. This means some wood chips out there could be recycled wood. A major concern for the landfill was unacceptably high arsenic, dioxins, and asbestos levels in their product. They found it was next to impossible to produce quality product that could be used for households. The point is that you should know the source (company and especially product). Additionally, I would avoid recycled and especially recycled and mass produced.

Ok, now I've confirmed lurking invaders from a load of pine and fir chips last year: Morels!!

Several places around the periphery of the chips I spread last summer, I now have morel mushrooms popping out! Free wood chips are like a box of chocolates...

I think one thing that many people don't take into account is the fact that our air is almost 80% N. Yes, if you till a bunch of fresh wood chips into your garden soil those chips will take N from the soil because there's no other source of N. If you have a thin layer of chips - I'd say <6", but that's anecdotal, not scientific - on the surface then the chips will absorb the vast majority of the N from the air around the chips. The contact area between the chips and the soil is minimal, especially when compared with the surface area exposed to air.

That being said, I still don't layer my garden beds with fresh wood chips. Instead, I cover all the walking paths in my garden with a deep layer of fresh chips. This layer keeps the weeds down very well, slows down and helps to retain water in the area, and I'm pretty sure that nutrients begin to leach into the soil as the chips break down. By the end of the year, this layer of chips in the path is usually well populated with various bugs/worms/nematodes as well as a number of mycelial blooms. After protecting any plants that I plan to overwinter I let the chickens run free in the garden for a while, giving them a little protein and nutrient boost while dumping a little more N all around. Everything just sits under the snow over the winter, letting everything settle. Come spring the old chips in the path are worked into the garden soil and new chips are placed in the paths.

Using this method over the past 3 years has allowed me to start building a nice little oasis on a lot whose soil was basically nothing but pulverized andesite. Now that I've been following this site, I'm thinking about first using these aged chips for a layer in hugel beds, then just layering it over a layer of chop and drop vegetation each successive year - no till and much less overall effort I think.

Keep in mind I would never be doing this if it wasn't for the fact that I basically have an unlimited supply of wood chips - I own a tree service and the chips are seen as waste by most people. This means that I'm constantly trying to find creative ways to use wood chips. Once I can get more room I'll be able to do some of the larger projects I have in mind (think Jean Pain). Quite amusing when I get paid to chip good woody debris, haul it off, and then watch the same customer pay $20+ for a bag of commercial compost to use in their garden. Some people refuse to think beyond what the big box stores tell them they should think, regardless of friendly attempts at education.

I think that most of the cons of using wood chips around the homestead can be overcome with a little education, patience and quality control. Usually large mega-grinding operations don't find it profitable to separate construction woody debris (think chemicals) from clean tree and brush waste. Most tree services work with trees only and any arborist worth their certification would refuse to give you known contaminated wood unless they'd discussed how to mitigate that contamination. Don't hesitate to ask the crew why the trees had to be removed or pruned, this will usually give you an indication of what to worry about in the wood chips. One of the best methods to ensure your wood chips are clean is to cover the pile with black plastic with soil piled around all the edges to act as a seal. Allow a few sunny weeks to pass and you will have killed any insect larva (think Emerald Ash Borer or Asian Longhorned Beetle, among many others) and the majority of any pathogens. If you're still worried or know that the wood was really contaminated, allow the chips to compost fully before using.