Wood chips in the garden

[drew51]

Tatiana,

Well that tells me I've beem lazy, I have to look harder, it's here, i just need to find it!

Drew

[COMPOSTER]

What I am interested in finding out, which I'm not sure is covered in anything I've viewed or read is the difference between hardwoods and softwoods. Is one preferable over the other? Does one create more fertility than the other? Should one be avoided? Or is the forest our best teacher containing many different species?

By the way, It was very interesting to learn in the article "The Myth of Pretty Mulch" that bark mulch actually repels water and tends to stay dry instead of retaining moisture. This goes a long way to explaining the dramatic changes I've seen since I changed from pine bark mulch to arborist wood chip mulch in my perennial border.

Thanks for posting those articles Tatiana! Keep them coming

Glenn!

[Tania]

Glenn, I wish I knew the answer to your question. From what I understand, it does not matter too much, as long as you avoid the wood with allelopathic properties (i.e. black walnut). Some woods also take forever to break down (like cedar), so if you want a fast decomposition, it should also be avoided.

I think the overall guideline is to use what is easily available in your area. Unfortunately here it is conifer-dominant (hemlock, pine, fir, cedar) forest, so 90% of the chips are coming from these trees. We only had 2 truck loads where maple and cottonwood was mixed in. The rest are all conifers, including cedar.

[salix]

I understood that up to about 20% or so of coniferous was OK - unless it was pine or cedar. They have various oils/resins/chemicals that are not so conducive to growing plants - think turpentine etc. That's why the cedars take so long to break down.

[drew51]

Originally Posted by salix

I understood that up to about 20% or so of coniferous was OK - unless it was pine or cedar. They have various oils/resins/chemicals that are not so conducive to growing plants - think turpentine etc. That's why the cedars take so long to break down.

True but water soluable, they don't last long at all. Not a big deal. You could let them sit 6 months and water them, you will leach it all out. I myself would just use them, keep the weeds away.

[Tania]

We are using 90% of cedar/hemlock/pine chips. They are fine!

[COMPOSTER]

Although I'm very new to using the arborist wood chips and am just in the initial stages of researching them I am very enthusiastic about using them. The other topic I am very interested in is the use of rock dust. The two "waste" products have two very compelling similarities for the soil building gardener. First,for a little time and effort both can be had for very little money or even free. Second, If applied in the correct quantities both potentially provide benefits for a number of years from just the initial application. In the case of rock dust, an initial application of 1lb per sq ft should mineralize garden soil for 8- 10 years. In the case of the arborist wood mulch an initial application of 4-6 inches should last 3-5 years. I love the idea of doing something once and reaping the rewards for many years. In the case of the arborist wood mulch they reportedly increase soil organic matter every year,so the rewards are actually compounded. Reportedly resulting in increased plant vigor and increased yields. I'm currently using both products and hope to report very positive results in the years to come.

Glenn

[COMPOSTER]

Originally Posted by Tania

Glenn, I wish I knew the answer to your question. From what I understand, it does not matter too much, as long as you avoid the wood with allelopathic properties (i.e. black walnut). Some woods also take forever to break down (like cedar), so if you want a fast decomposition, it should also be avoided.

I think the overall guideline is to use what is easily available in your area. Unfortunately here it is conifer-dominant (hemlock, pine, fir, cedar) forest, so 90% of the chips are coming from these trees. We only had 2 truck loads where maple and cottonwood was mixed in. The rest are all conifers, including cedar.

Tatiana, I believe what I am getting are ramial wood chips consisting of Maple, Oak, Birch and Pine. I did find an article that didn't go into too much detail about which wood would create the most fertility but they did go into detail about the ramial wood chips being the most beneficial in building humus. I'm going to try to find it again and post the link.

Glenn

[drew51]

Well as I stated earlier in practic in a peach orchard, not that much organic matter was created in 7 years. Your plants tend to use it up, so not much if any buildup. I have a hardwood wood pile, and the bark from this hardwood breaks down right on the pile and looks like pure black humus, now that was impressive! I now take the bark off my firewood, let it age, and use it as mulch.
This was stated by Olpea


I remember reading somewhere, something like 25% of the mulch by weight, actually becomes soil. The rest releases carbon back into the air. And since its by weight (and mulch is "fluffier" than soil anyway) it takes a long time to build a lot of soil with mulch. As I recall, an acre foot of topsoil weighs 3 mil. pounds. So to build, say, 6" of topsoil on an acre, it would take 6 million pounds of wood chips (1.5 mil X 4). More mulch than I'd ever want to shovel in my lifetime.

[Worth1]

Get a jump on everyone else and start shoveling now.
Six million pounds.

So all that carbon back into the air.

Just a silly comment due to some things I have heard people say.

Worth

[drew51]

Originally Posted by Worth1

Get a jump on everyone else and start shoveling now.
Six million pounds.

So all that carbon back into the air.

Just a silly comment due to some things I have heard people say.

Worth

I enjoy your comments a lot, don't stop. Reminds of an old Lenny Bruce skit

"Stop, don't...don't stop!"

Well one thing I can say for sure is that the total amount of carbon on the earth is not something that ever changes. It's made when stars super nova.
I would not be concerned about it.
It's well known the more carbon in the air, the faster plants grow. Your trees will use the carbon put off by the mulch, they have to breath afterall!
Another benefit of mulch! And it's right there too! Perfect!

[Tania]

Another interesting article about the Living Soil.

http://www.healthy-vegetable-gardeni...livingsoil.pdf

[drew51]

Interesting articles you have posted. I don't agree with all of them though. Well the short one on bark for one. I have found that the water repelling properties of bark extremely useful. One of the major problems with potting soils is the use of peat as a base. I love peat moss, but it is best used in smaller amounts with the main ingredient being pine bark. It drains well, keeps the soil structure a lot longer as it takes longer to break down.
Using it as a mulch it lasts longer, is not a solid body, so if you pour water unto bark, the water is not repelled 10 feet away, the ground becomes very wet. That statement by
Linda Chalker-Scott is nonsense, and no reference to studies of such is given. Green wood chips do not hold water either, and we don't put it on to hold water, but to cover the ground that is holding the water. So both sap wood, and bark work equally well. Pine bark does not rob the soil of nitrogen like sap wood does, as it breaks down a lot slower. Plants grown in pure pine bark thrive, they do not fail. You cannot grow plants in sap wood at all.
Hardwood bark breaks down fairly fast,even faster than hardwood itself and does absorb water like sap wood. It is not a good soil amendment for potted plants. As it behaves too much like sap wood. In my wood pile it's the hardwood bark that creates the humus, not the wood. It breaks down extremely fast.

[COMPOSTER]

Originally Posted by drew51

Interesting articles you have posted. I don't agree with all of them though. Well the short one on bark for one. I have found that the water repelling properties of bark extremely useful. One of the major problems with potting soils is the use of peat as a base. I love peat moss, but it is best used in smaller amounts with the main ingredient being pine bark. It drains well, keeps the soil structure a lot longer as it takes longer to break down.
Using it as a mulch it lasts longer, is not a solid body, so if you pour water unto bark, the water is not repelled 10 feet away, the ground becomes very wet. That statement by
Linda Chalker-Scott is nonsense, and no reference to studies of such is given. Green wood chips do not hold water either, and we don't put it on to hold water, but to cover the ground that is holding the water. So both sap wood, and bark work equally well. Pine bark does not rob the soil of nitrogen like sap wood does, as it breaks down a lot slower. Plants grown in pure pine bark thrive, they do not fail. You cannot grow plants in sap wood at all.
Hardwood bark breaks down fairly fast,even faster than hardwood itself and does absorb water like sap wood. It is not a good soil amendment for potted plants. As it behaves too much like sap wood. In my wood pile it's the hardwood bark that creates the humus, not the wood. It breaks down extremely fast.

Drew, I can only tell you what my experience is with pine or cedar bark mulch vs ramial wood chips. I have used cedar or pine bark mulch in the same area for 7 of the last 8 years. I always wondered why the soil never seemed very moist and there was little evidence that earthworms were interested in inhabiting the area, even after heavy rain. I was adding small amounts of compost (most is dedicated to the vegetable beds) every year and I wasn't making any progress in noticeably improving the soil. No nice crumbly top layer not much in the way of earthworm castings, nothing. Dry dusty soil underneath 2 inches of pine bark mulch. I kind of felt like a failure. Last year I used the ramial wood chips and the soil is much different this year. Nice crumbles on top and lots of evidence of earth worms. I'm not willing to attribute this 100% to the wood chips but I think they have made a substantial difference in the moisture that is retained in the soil over the bark mulch.

Just my experience.

Glenn

[Tania]

Drew, these are great points, and I agree that both ramial wood chips and bark mulch have their pros and cons.

We are not growing anything in wood chips. Everything is growing in the dirt. The wood chips is just mulch. We NEVER mix them with soil. It always stays on top. I think it is very important to state, as some folks may think otherwise. If we need to plant anything, the mulch is moved to the side of the bed. Once plants are established, it is moved back.

I went out to the garden yesterday and moved a 6" layer of wood chips mulch away to reveal the dirt underneath. It was quite interesting to see that the top 1" mulch layer was wet (we had about 30 mm of rain in the last 2 days, very heavy), the next 2" of mulch were totally dry! And the layer in contact with soil was very wet. There were quite a few worms just under the mulch, including baby warms. I counted 8 in 5"x5" area, just on the surface, I did not dig to see if there are more down there.

In our 3 year experiment with our herbal bed, I can certainly say that we see a noticeable increase in organic matter in the bed where we used wood chips. This year we added new layer of wood chips to that bed, as everything broke down 100%. I am so sorry I did not watch that bed over the years, as I was unwell, and neglected this herbs bed, so I cannot say when the wood chips breakdown finished. The soil there is so rich (and no fertilizer or amendment was applied, ever). The original soil was blue clay, the herbs were transplanted there temporarily, as a holding area, but then they got neglected. We could hardly scratch the soil surface to put the transplants in there back in 2010! The chips went there in summer 2011.

Now it is a forest of healthy looking stinging nettles, wormwood, and St. John Wort. Some stray mustard is also growing there happily. I am very happy with the bed and it will certainly stay there. As an experiment, we will continue not adding any amendment or fertilizers into the bed, only wood chips, and see how it goes. I also think that the herbs themselves helped to build the soil, so I am not sure how much of that were wood chips vs. herbs greens. But it is working!

By the way, 'green' wood chips already contain quite a bit of water. They also contain lots of nitrogen, which helps to break down the wood chips without supplementing with nitrogen (although adding more N will certainly help to speed up the process). As the wood chips break down, their water retention capacity increases.

We have a few natural 'hugel' stumps in our back yard, and a few fallen trees that have been these for almost 10 years, they were not buried and hence were exposed to the elements. They are in various stages of decomposition. We examined them carefully and found the rotten logs to be very moist despite very dry spell we had in the last month. They are like a sponge!