charred logs/ biochar?

I have begun a hugelbeet and am about to add to it. I have access to a generous supply of charred logs from the local land trust's bonfire to "get rid of" a lot of wood from the past season's storms.

What role could charred logs play in hugelkultur? Is it biochar? Would it be beneficial to stick the logs in there like biochar or would it be too strongly alkaline like ash?

We put some in the bed that we built already, so time will tell, but I am wondering if we should use them again for the next segment. We could use a little, a lot, or none.

Has anyone done anything like this before?

I, too, am eyeing some charred logs that I hope to "offer" to remove for free.

Awaiting your advice as well.

Jo

We frequently use charred logs in our new garden beds. Generally they are mixed with other, non-char logs, but I can see only benefit for their inclusion. Is it bio-char? Not exactly, but I believe it performs a similar function ... prolonged carbon sequestration (charred logs last longer than non-charred) and the increased habitat for micro-organisms. Close enough for me to call it bio-char-like even if portions of the charred log remain unburned.

Species? We've used charred red pine, maple, scotch pine, white pine, ironwood, basswood, white ash, beech and poplar. All seem to be OK.

We also set out to produce classic bio-char from low-oxygen burns. There is a clear difference between initial bed performance when some kind of bio-char component is included in the mix. From a rough visual estimate, I'd guess there is about a 25% enhanced performance in terms of resulting plant mass and vigor. Beds last longer when some significant portion of the wood involved is charred..

Thanks Jay, that is exactly the kind of answer I was hoping for! In the part of the bed that we have already built, we put down the rotty wood first and then the charred logs on top of that with brush and leaf mould all in between.

In the continuationj of the bed, do you think it would make more sense to put the charred logs on the bottom and the rotty ones on top? once we had finished the bed I began to think this would have been better. It seems as the logs rot the plants above will be able to use the more soil-like rotten wood more easily than the slow rotting charred logs.

Or, as in most things permaculture, I suppose mixing rotty and charred all in, without distinct layers, would be best. Would that be more "edge" inside the bed?

Really it seems that just piling up a bunch of compostable stuff will make a fine bed eventually. It is nice to hear from people who have experience with this.

Matu Collins wrote:I have begun a hugelbeet and am about to add to it. I have access to a generous supply of charred logs from the local land trust's bonfire to "get rid of" a lot of wood from the past season's storms.

What role could charred logs play in hugelkultur? Is it biochar? Would it be beneficial to stick the logs in there like biochar or would it be too strongly alkaline like ash?

We put some in the bed that we built already, so time will tell, but I am wondering if we should use them again for the next segment. We could use a little, a lot, or none.

Has anyone done anything like this before?

watch out.. i was reading a paper. It says when bio char isnt done right it can repel water.

Oh dear, I don't know how to "watch out"! We will see with the bed that is already built. I guess the charred logs on the bottom or the mixed up method would be better, then, in case the logs at the top are repelling water. I suppose that is a reason that they last so much longer.

Matu Collins wrote:Thanks Jay, that is exactly the kind of answer I was hoping for! In the part of the bed that we have already built, we put down the rotty wood first and then the charred logs on top of that with brush and leaf mould all in between.

In the continuationj of the bed, do you think it would make more sense to put the charred logs on the bottom and the rotty ones on top? once we had finished the bed I began to think this would have been better. It seems as the logs rot the plants above will be able to use the more soil-like rotten wood more easily than the slow rotting charred logs.

Or, as in most things permaculture, I suppose mixing rotty and charred all in, without distinct layers, would be best. Would that be more "edge" inside the bed?

Really it seems that just piling up a bunch of compostable stuff will make a fine bed eventually. It is nice to hear from people who have experience with this.

MATU ... I think your last statement may be closest to the truth. I don't think it matters very much WHERE in the pile differing kinds of carbon materials actually go. More important to us is the shear handling required to build over-built beds ... by hand mostly.

To my eye, Nature tends to way over-build and create unlimited contingencies...if one thing doesn't work perfectly, another will. So we concentrate more on getting the under-lay material in place in such a way that will facilitate topping off with large amounts of compost in the top outer layer. Lots of air spaces in the process. To start out then, we are engaging only that top compost layer in the beginning while the under-bed materials settle a bit, soak up water and nutrients and settle into place for the longer run.

Takes a lot of compost, by the way.

We end up building beds in LOTS of differing layers and sequences of materials, and to tell the truth, I can't defend one mix over any other. I suppose I wish it were more scientific and formulaic than that, but it just doesn't seem to make all that much difference.

We seem to have an almost endless supply and variety of materials that can be used in the buried portion of our beds which all end up looking trapezoidal in profile ... some slope to the sides in 4-5 foot wide beds that end up being about 2-3 feet tall in the middle, "mesa" portion of the bed. Charred and "rotten" make up maybe half of the buried stock and a third of the entire bed mass at the onset of use.

We are busy building new beds almost everyday during this fine spring season. I'm an older guy and aim for a finished bed of 100-200 square feet of new garden space per day of what I consider to be fairly light work ... although it can sure hurt like heck at the end of the day, all the same.

Funny, no one I know builds garden bed in this fashion, but it saves us lots of work and turns out to be a much higher degree of productivity in a given garden space than more "conventional" methods of gardening.

We live on a large parcel that is about 80% forested with a variety of forest types, both natural and plantation. Normal forest management supplies more "hugelkultur" materials than we can use, even at a constant building pace. Trying to IMPORT such materials seems almost out of the question. Living in and immediately near forest resources for wood and compost is the only way we could do this.

One suggestion -- break up the charred logs before you add them to the pile. Reason being that the purpose of adding biochar is to provide a home for microbes, and they do better distributed throughout the hugelbed than bunched up in one place. Several ways to do this -- the messiest is to feed the charred logs through a wood chipper. If you have a powerful enough lawn mower, you can run over burned sticks and small pieces of charcoal, making them even smaller, and empty the grass catcher bag on the hugelbed. I have taken to using an immersion blender (one that has been retired from the kitchen) to whiz up biochar with some water in a large plastic cup and use that as a root drench.

The blender idea is funny!

We have no wood chipper and we mostly use a rotary mower, we are trying to get away from fossil fuels here, so we may just have to stomp the logs and bash them with a maul or something like that.

We have the site mapped out now so the hugelbeet will be in the general shape of a spiral built in three stages with three different sets of material. The first is done and planted with various things, the second is partly done, and the third will probably be finished by the end of June.

It will be interesting to see how the different sections fare. The charred logs are in the first bit already, and I think I will use less in the second, but still some. I wonder how the partially charred logs will fare over time versus the thoroughly charred ones.

How is charred wood different in a garden from wood ash? I know they are different but I'm not sure I understand how. Is the charred wood alkaline like ash?

How is charred wood different in a garden from wood ash?

Ash is completely oxidized material; potassium oxide (K2O), calcium oxide (CaO) various phosphorous oxides (mostly P2O5), with no carbon left....as in all the CO2 is gone. Charred wood contains a lot of carbon on the burnt surface, that's the biochar that you want. If you scrape off the friable char, you may be able to get down to wood that is "just scorched" and still chemically resembles wood. The more cooked the wood is, the more ash will have formed, and the more alkaline it will be. This material is still food for various soil fungi, unlike the char which they can't utilize for food.

When I do a biochar burn, I light a stack of wood on fire and let it burn until it collapses and the pieces of wood start to fall apart. Hitting the burning stack with a hoe and pushing the intact pieces onto the top of the flames hastens the process. When all of the wood has fallen apart and has turned into glowing coals, then I quench the fire with the garden hose. At this point, you have turned all the wood to char and further burning will turn the char into ash. After the fire is out, what you have left is char mixed with ash. Leaving the pile sit for a few rains allows the ash to leach out of char and lose its alkalinity. You could add the char to the hugelbeet at this point, but it wouldn't have any microbes living on it. For that you need to inoculate the char.

Char gets inoculated when it is swamped with microbes, either bacteria or fungi, and they have time to move in to all the little microscopic pore spaces left from the wood structure. The way I do this is to brew up a batch of compost tea, add the char/water slurry, and let it aerate a few more hours. When you throw that on your hugel pile, that's when you give the soil food web a big boost.

Wow, excellent info, thanks!

High ALL : I know I'm going to get some negative vibes from this suggestion. But let me get it out and then explain! Yes i can see some good to breaking up the wood
that is going to be placed within the Hugelbed. therefor I am passing on an old camping trick, I have always placed a long piece of fire wood between a rock and a hard
place. or two trees, and just leaned into the wood until it broke at the pivot point ! It takes no time to learn to do this, although it is easier if you are heavy and built
close to the ground, strength has little to do with this.

I can hear here future voices worried about damage to the tree, not so, old time farmers used to go out and switch their Maple trees to loosen the bark and aid maple sap
production ! Other trees like apple were switched to aid in growth. If you are still worried about it don't do it to soft woods or smooth barked hard woods ! Its a lot easier
on the feet too ! Hope this helps !

For the good of the Craft ! Be safe, keep warm! PYRO-Logically Big AL

Your leaning trick might be a good one for me, big Al, I'm rather pregnant (due May 25th) so the simpler the better

The chainsaw does come out on occasion here but we try to use non fossil fuel solutions when possible

we had a need to cool down our wood furnace once this winter and hubby threw some charred logs on the snow ..so I placed them around my peach trees on either end of my hugelbed that I built last year..I'm not sure what benefit they'll have, but they are there..also there were some broken pieces of char that ended up on the bed as it is near the wood furnace shed door..and it got ash and chunks of coals thrown on it in the winter.

right now there isn't a lot planted on the hugelbed as I hope to put some more tender things on it in a few weeks..but it is growing a nice crop of lettuce, spicey spring and spicey italian mix and I just put on some cabbage and broccoli transplants.

alkalinity should work well for all of the above mentioned plants

I dug a six foot ditch and filled with dried and green wood. Lit it up and let it roll until all the wood was sooty and falling in on itself. Then tossed all the dirt back on to smother the flames. After the puffs of smoke died down in a few days I sprinkled with winter rye seeds. They are growing better there than anywhere else. It was such a success that I completed another larger one today and planted kale in it.