Charcoal Garden Paths

Dig out garden pathways and fill them with charcoal instead of woodchips.
Unlike wooodchips ,the charcoal won't decay.
This lowers maintenance, but also means we lose a source of compost.
The charcoal is still a reservoir for water and a a place for microbes to live.



I am inspired to do this because  of a few reasons.
First, the ideal application of biochar is not clear.
Percentage by soil volume recommendations exist, but they vary from study to study and from plant to plant.
Even if you know how much you want, digging that much into the soil is complicated and disruptive.
This way it gets to exist in the landscape and be available to nearby plants without being too much.
It's self serve biochar if you will.
The second reason is capturing surface runoff water, which I have a surprising amount of.
Even if its saturated from previous rains, charcoal is still an agragate,  so it could facilitate infiltration.
Each stretch of pathway would be an infiltration basin.
Vertical mulching on a large scale is another way to look at it.
Third is the pathways.
An  aggragate pathway is nice.
Not having to pay for the aggregate is very good.
The nutrient sucking aspect is not a bug, it's a feature, since we are trying to keep the infiltration going,  we don't want things growing in the path.

Tell me what you think about charcoal footpaths.?

Hi William,
I think it is an interesting idea, but I do have two small concerns.

First, is the mess. We have used ashes (which included chunks of charcoal) from our woodstove, to spread on an icy driveway in the winter. There was a big mess that was tracked in on the bottom of boots. I can only imagine the mess from pure charcoal.

Second, is that I think you would need to add to it frequently. While it seems like you are talking about fairly small pieces, charcoal by nature is very breakable, and I suspect it will finish grinding into powder as you walk on it, and need to be topped off frequently.

What Matt said. ^

It is an interesting idea though, especially if you put your path where a future growing area will be.

William Bronson wrote: The second reason is capturing surface runoff water, which I have a surprising amount of.
Even if its saturated from previous rains, charcoal is still an agragate,  so it could facilitate infiltration.
Each stretch of pathway would be an infiltration basin.

My first thought was, "too messy" - however, my second thought was that so long as you have "landing pads" for that mess, such as grass you're walking across, or even a little boot washing station, there might be ways to contain that mess.

However, yes, biochar holds moisture, but when it dries out it can blow away, particularly if it's been crushed to powder as Matt suggests might happen.

However, what if you tried several experiments and compared? (and reported back!)
1. a wood chip path
2. a biochar path
3. a biochar path covered in wood chips - this might hold water better than either 1 or 2, but I'm just guessing...
4. just for completeness, a wood chip path with biochar on top - as the biochar is crushed, the little bits would fall down between the wood chips and thus would be less likely to either be blown or washed away.

So much depends on the exact ecosystem!  You'd need to observe multiple seasons over several years likely to get a final outcome, or you may figure it out fast if one or two options just aren't workable.

My neighbor always quotes an old mentor, "you have to bump your head to get ahead", which roughly translates to, if you're afraid to make a "mistake", you may never learn something cool and effective. I have to admit, I would hesitate to do this experiment on four 100 foot paths, but four 5 foot paths - why not try it?

I agree about the tracking of charcoal dust/powder to places you would rather not have it... house, auto, nearby pavement to be picked up by others who thought they were avoiding the mess...
I like the wood chip topping idea, sure it will break down, but that retains your source of compost, now with inoculated biochar! While also keeping your shoes clean.
I'm still amazed at how well our deep woodchip paths work for us by not being muddy, dew-ey, not tracked around by shoes, easy to follow in the moonlight, easy to weed/lack of seed bank to germinate in the first place...

I'm pretty sure Ben Law used charcoal finings for path surfaces in his woodland. As others have said I'd be slightly worried about dirt tracking on boots, but a top dressing of wood chip would fix that.

Hey thanks for all the great feedback!
I think I will follow down this path if for no other reason so I have a place to stash the charcoal. This would be over at my second property so there's plenty of places to clean one's feet off before you get home to the house.
Keeping the particles damp and protected is more of an issue to me.
Do you think the charcoal could act as a bed for setting stepping stones into or is that just crazy?
I frequently lay leafy branches down where I want walkways.
The branches get stepped on a lot and broken down the leaves ground up and decayed, and the path stays navigable.
Eventually,  I remove anything that is in the way or I add a layer of soil to cover it.
This makes for a spongy absorbent pathway.
This might work on top of charcoal paths as well.

Nah I can't say I like the idea. I feel like the charcoal will crush into dust and blow away all day long, causing all kinds of mess and a need to place a lot of charcoal to cover even short paths. Also, you know how they say wear a mask when crushing charcoal up for biochar? Although it's probably a miniscule amount you will be breathing in while "slow-crushing" it, it's still a 100% avoidable amount.

I get the idea to save costs but it's gotta be more work to create the char than it is to earn $30 to buy a yard of rock.

I love biochar, I just don't see any upside here. Of course, I have no idea what I am talking about, so prove me wrong!

William, the only way you will know will be to try it. Yes, you're going to have to observe it carefully for things like the wind blowing the small stuff, or you risking your breathing, but there are many ideas that people thought were crazy that have turned out to have potential, even if the first iteration didn't work.

I have to admit that I'm partial to the idea of covering it with something - leaves, weeds you've pulled, grass clippings or even boards harvested from heat treated pallets or the stepping stones you mentioned.

If you start with some smallish areas, I think you will learn as you go, and I'm really hoping you tell us what doesn't work, rather than just what does!

Dan Fish wrote:Nah I can't say I like the idea. I feel like the charcoal will crush into dust and blow away all day long, causing all kinds of mess and a need to place a lot of charcoal to cover even short paths. Also, you know how they say wear a mask when crushing charcoal up for biochar? Although it's probably a miniscule amount you will be breathing in while "slow-crushing" it, it's still a 100% avoidable amount.

I get the idea to save costs but it's gotta be more work to create the char than it is to earn $30 to buy a yard of rock.

I love biochar, I just don't see any upside here. Of course, I have no idea what I am talking about, so prove me wrong!

I work with biochar quite a bit.  I crush mine by bagging it and running over it with my truck during my normal trips.  When I empty it, clouds of dust go everywhere, no matter how careful I am to avoid it.  Even trying to wet it makes dust go billowing out.  

The area I make my charcoal in inevitably has charcoal spilled on the ground.  Stepping on good charcoal crushes it, and again, you get a puff of charcoal dust.  It is a small puff, but it happens nonetheless.  Once charcoal is crushed, it blows away quite easily as Dan said.  I don't even use it in my chicken coops anymore because the chickens walking and pecking on it cause enough dust that there is a thin black layer over everything.

I also find biochar far too time intensive to make, and too valuable to use for paths.  My personal answer to paths is sawdust.  It's a little heavier and doesn't blow around as badly as charcoal dust.  It eventually becomes soil but it takes quite a while.  It's free for me from a factory that makes building trusses.

If you are set on the charcoal idea, I would either cover it as has been suggested, or try to figure out a way to keep it damp.  If you have enough water to keep it damp, feel free to disregard everything I had to say :)

I think this is a great idea.  Most of the concerns were valid, but I'd like to provide some perspective.  Crushing the biochar is work that you have to do anyway, and it makes it better biochar by having more surface area.  I do agree with covering it with wood chips, mulch or soil.    I also wouldn't put it right next to the house, I'd put it out a ways.  That way, your shoes are brushed off a little bit before you go in the house, even if you wear shoes inside.

I think it especially works well if you have completed most of the most crucial biochar areas of your garden area.  Rock won't do for you, half of what biochar will do.  It doesn't sequester carbon, it doesn't provide housing for microbes, and it certainly doesn't absorb water for dry spells when needed.  

I live in the Pacific Northwet, so it might work better in an area with a lot of moisture.  Alternatively, you could of course mix it with compost or soil first, before you add it to the paths.  It will really retain moisture then and be unlikely to dry up and blow away.  Most people inoculate their biochar in one way or another, as it has been advised by the "experts" for some time.

I am looking forward to seeing the results of your experiments, William! The way we learn things is by someone like you coming up with an idea and trying it. Sometimes then adjusting it, or inspiring someone else.

John S
PDX OR

I'll drop my recent experience here for your consideration, William. We've had mind-bending amounts of rain this year and now we're heading into winter, which is our actual wet season plus the time when plant growth and transpiration slow way down. So, that means the places that were already damp are now sodden, and anywhere we walk on a regular basis turns quickly to goo.

I spread about a 2 cm layer of some chunky biochar on the main pathway across the lowest paddock to the chicken coop and it made an immediate impact. No more squishing, slipping, or sinking in. The char bears up under foot traffic and has a nice feel to it...sort of halfway between a crinkle and a cushion. I think the low density is a real plus, keeping it on the surface and dissipating the force of steps without turning into ball bearings.

The area that I treated already has a fair bit of biochar in the topsoil, so I don't expect to see much impact on the pasture health or soil quality, but the problem I wanted to solve was the walkability and for that I'm giving it two thumbs up.

I'm loving this feedback!
So I will definitely cap this thing.
A soil cap is extra appealing,  because it's right there, but it would also be muddy.

The pathway is right in front of a bed that is primarily dedicated to growing biomass, so tossing down leafy branches is where I'm probably  going with this.
The soil being removed from the trench/pathway such as it is, is going into these beds along with leaves, etc.
The digging is hard work , with little topsoil, and lots of rocks/clay, but I want  soil in that raised and I want a nice path so I'm doing the thing.

I made a stab at it:

So stepping away from biochar, I've had good luck making paths with wood chips, cardboard (free of plastic), rebar, pallet strips, and wire ties.

So basically the pallet strips are ~3" tall, and get used for the borders of the path. I drive 1' of rebar down and wire tie the strips (to keep them in place and vertical) to it. Then I put cardboard down, then dump wood chips on. The cardboard keeps weeds from popping through, the pallet strips keeps the wood chips from spilling out, and the wood chips makes it pretty and easy to walk on.

Just some ideas!

This looks good, Tony, but I don't see why biochar couldn't be incorporated into the mix, preferably below surface level.
John S
PDX OR

John Suavecito wrote:This looks good, Tony, but I don't see why biochar couldn't be incorporated into the mix, preferably below surface level.
John S
PDX OR

Yeah you totally could. My soil is pretty barren, so my biochar is for areas I'm planting. ~10% biochar ratio when you get into fruit trees is a phenomenal amount of material.

I think charcoal (bio char) on foot paths may be a good way to slow the spread of jumping worms. These worms love to live in and eat wood chips, so they lay their cocoons there (each worm lays 60-100 cocoons per year each with 1-2 eggs inside and cocoons is the size of a mustard seed). Then the cocoons attach to our boot soles and we spread them around our land, where they grow into more worms. Biochar can, depending on the size of the granules (I have read) be disruptive for the digestive systems of these worms. I may try this charcoal idea on one of our paths. I understand the problem people here have here with making a mess, but I’m more deeply concerned about the damage to the soil from these worms.

A natural walking path has developed in one of my back gardens and I happened to have a large amount of freshly made char on hand. I have added the char into the pathway on top of woodchip to start delineating the path. The char already seems to be crushing readily so I am wondering how long it will in fact last before melding into the ground.

I'm hoping the raw char will help keep the bath 'clean' of weeds for the time being. I assume it will tie up some nutrients for now.

I have dug in places where I put biochar 3-4 years ago and I couldn't find it. The soil was darker, but there were no chunks of biochar.  I think it becomes incorporated into the soil.  It still does its job, though.  I agree with Tony, though. First priority for me would be around the plants.
JohN S
PDX OR

I excavated  the spot where the charcoal was path was, as a part of a front yard make over.
Much of the char had melded in with soil.
Since the path way area became part of a larger bed, I used the soil and planted it out.
The larger chunks of char that persisted were tossed into a nearby compost pile.
I will certainly do this again, next time it will probably be holes filled with char and topped with a stepping stone.

I spread a few yards as a deep 'mulch' over an area, mainly out of curiosity, a few years ago. Has been walked on a fair bit, but not as heavily as a path would be. It's held up pretty well, not a lot of noticeable pulverizing or dispersal, except when heavy rain creates enough surface flow to wash some of it downslope, since it floats so readily. It's slightly compacted now, but footsteps still feel somewhat "crunchy" - I could imagine a 50/50 mix of char and sawdust (not chips) might be a nicer overall matrix and feel for a durable walking surface.

Also worth keeping in mind that char dust is not something you want to be breathing in, so would be cautious spreading it in high traffic areas that stay dry for long.

I would put some mulch or even dirt over that. It would keep the dust down.  In addition, you want the biochar to be kept moist, so all of the microbes can stay alive in side it.  That's my two cents.
John S
PDX OR