Midden L’eau Chaude: The Big Build

Load #2 being dumped for a total of about 17 cu yards (13 cu m). Let's do this.

Last summer I built the Methane Midden which was inspired by Jean Pain’s epic work in 1970 France.    It was big, it was a little insane, and ultimately it didn’t work. Don’t get me wrong – it made a syck amount of compost, but it failed to meet my goals of also producing methane and hot water.  Time to do better.  The second Midden will focus on Hot Water (L’eau Chaude) with a dedicated heat exchanger and will be even larger.  Not only that, but I wanted to learn how much material it truly takes to make one of these so I also sourced all the biomass myself from two local farms, dropping literally hundreds of invasive buckthorn and honeysuckles as well as aggressive “weed” trees such as red mulberry and box elder over a week and then renting a 27hp Vermeer chipper to grind them up.  It was awesome!

This post is pretty epic itself – I opted for smaller photos in the post to keep the overall post length a bit shorter – click on them for a 600×800 shot.   This really should have been 2-3 posts, but I spent more time working than writing.  Skim or read it all the way through at your preference.  Total work covered in the build is 3 weeks, with another 1.5 in the biomass acquisition.  These are “puttering” time lengths – I am always working on 4-10 projects at a time :).

With the material on site it was time to get it soaking.  One of the keys to Jean Pain style brushwood composting is to soak the material for 2+ days to ensure that the chips are saturated to supply the pile with enough water to sustain it for months.  One of the problems I ran into early on is that of scale.  I can only soak about 6 yards of material at a time, which limited me to 1.5 batches a week with my days off and the shorter daylight of Fall.  All told it took over 3 weeks just to soak all the material.

Giant 375 gln (1420 l) totes I bought off of craigslist a few years back for $25 each. Why? Why not!

Once the material was soaking it was time to prep the ground.  I spent a day spreading the old Midden around the gardens.  This was unreal – never before have I had 8+ yards of compost to spread all at once.  EVERYTHING got mulched.  Yes, spreading compost by the wheel barrow load (40 of them!) is as fun as it sounds.  I will say it again and again – COMPOST is the true point of the Middens – gathering energy from them is merely function stacking an intrinsically useful activity.

As this pile was going to be 50% larger I had some concerns about it breathing well.  At one point I had myself talked into laying out 4″ perforated drain tile for air circulation, but thought better of it for several reasons.

Cupplant, Sunchoke, and Sunflower stalks forming the passive air circulating foundation to the Midden. After the winter it turns into humus and sequesters carbon. Regenerative waste stream? Check.

First – it added expense and resources.  I like to keep the plastic to a minimum; while not afraid to use energy or resources for the Greater Good, I also like to use natural products whenever its feasible.  Second, Jean Pain never did so I’m not even sure its necessary.  My solution was simple – I cut down a half dozen Cupplants that were nearby in the prairie garden that serves a insectary habitat near my permaculture guilds.  The thought is that these will allow air to come in slowly from the under the pile as they decompose themselves.  Basically the same reason you are often told to put twigs under a normal passive compost pile.

Now, the observant amongst you will notice a piece of .5″ conduit stuck in the ground with a tape measure  in front of it.   Of course there is a very good reason for this.  The Midden LC will have a 3′ (1 M) diameter core of brushwood that will be wrapped with 1″ tubing, but I am getting a bit ahead of myself.    With the base down, it was time to get building.

The Core

The core diameter of 3′ was chosen for the simple reason that hot composting seems to benefit from a minimum dimension of at least a meter.  Build a pile smaller than this, and you won’t get hot enough.   One of the downfalls of the Methane Midden is that the layout forced a width of only 2′ in most cases.  I thought that the straw bales insulation would be enough.  I was wrong.  Back to basics then.  Getting wood chips to form a cylinder can take some doing.  Luckily I had enough 2′ garden fencing in the garage to make a “mold”.  The thought was to cut the fencing to the circumference of a 3′ diameter circle.  Time for fun with math!

4' (1.2 m) tall Core. As I unwrapped the fencing, I would wind 150' (45 m) or so tubing around the chips to keep them in place.

A circle’s circumference is Pi x the Diameter of a circle; 3.14 x 3′ = about 9.5′.  Done.   Now, when you cut the fencing – leave the “nubbins” on the cuts – this works well to fold around once you get the circle made – think giant velcro.  The conduit I stuck in at ground zero and measured 18″ off each side to center the core column.  Then it was simply a matter of schlepping in the soaked chips.  About every 8″ (22 cm) or so I tamped the chips well with a 12# (5kg) sledge hammer.  Once I had 2′ tamped in place, I unhooked the fencing and unwound it.  Thanks to the tamping, the chips stay in place very well.  I then wrapped the fencing on the top of the cylinder with about 2″ (5 cm) of overlap on the bottom.  Then I started wrapping the heat exchanger around.

I love this shot. It really shows how stable the chips are with tamping (walking on it at this point). Jean Pain didn't use molds, just slapped it all in place with a pitchfork and walked on it.

This progressed 2 times until the core got about 5′ tall.  At this point I was becoming somewhat concerned that the column could topple, despite how stable it seemed.  Redoing it at this point would SUCK, so I opted to switch gears and work on the outer “donut” of biomass.  The thought here was to again use the 1 meter width of material to maximize the bio-reaction of the thermophilic bacteria.  Having 3′ of material on each side of the exchanger giving the Midden L’eau Chaude a total diameter of a bit over 9′ (2.75 m).  The other important reason to start building out the “donut” was that stacking, and especially tamping, the Core was getting difficult as it was over shoulder height for me at this point.  With a 2′ tall rim around the Core I could bring it up to its goal of 6’+ bringing the total heat exchanger length to over 550′ (168 m).  The heat exchanger needs a bit of explaining since it is critical to the Midden, so here goes.

The Heat Exchanger


550′ (168 m) of 1″ (2.5 cm) polyethylene irrigation tubing. Never one to be modest… this is a work of art.

This is the finished heat exchanger and I won’t even try to be modest.  It’s GORGEOUS!.  The water will come in the bottom, spiral up for 6′ and then take two larger loops back down to exit the pile.  Why this way?  It has a lot to do with temperature gradients.  Heat transfers best the larger the temperature differential (delta T).  The final goal is to that the water entering the pile at about 80 F (26 C) and exiting north of 120 F (49 C).  The bottom of these piles are cooler (heat rises!), but will still be rather warm.  As the water in the exchanger warms it is also climbing up through the pile, which is also getting hotter.  The thought is that there will always be a delta T of 20+ degrees between the pile and the water in the tubing.  Slick, huh?  Now wth is up with the big looping spirals?  The poly tubing kinks somewhat easily, so I chose to take 2 revolutions to expand the diameter of the spirals and slowly increase the degree of bend up to my final exit point. Now some final thoughts on the exchanger.  First, I would shift the hole thing up a foot.  Starting 4″ from ground level like I did will not add much heat to the water, whereas there is over a foot above the top of this column now that I am done.  I had thought that the top would be cooler, but that is not the case – no matter how much I pile on the heat just comes right through it: put your exchanger to within 6″ of the top without fear as long as the pile is hot.  Can you see I am already planning Midden #3?  But for now we need to bury that exchanger. Fleshing out the Midden

 

Taking shape! This is about 12 cu yards ( 8 cu m) with a current height of 5.5′ (1.7 m) and a 9′ (2.7 m) diameter. Awesome.

To keep the pile nice a tidy, and also to ensure that I could still walk around it, I again used a garden fence mold for the 9′ (2.7 m) diameter “donut”.  this time I opted for 3′ tall fencing.  The outer section takes an immense amount of material to fill – it was almost 2 weeks to get it to this point as the pile at this point was over 12 cu yards and weighed over 6 tons due to the sopping wet chips.  Remember that I could only do 5-6 yards at a time as the chips had to soak for several days.

 

I had intended to unwrap and re-wrap the fencing again, but in the end chose to leave it on and switch again to an insulating rim of straw, which I ended up stacking 3 tiers high.  It gets significantly colder here in southern Wisconsin than in Jean Pain Provence with winter lows dropping to -15 (-26) at least once or twice.  Time to break out the dump truck again!  Back to Craigslist and I contacted a farmer about 4 miles away with 70 bales of Oat Straw.  I would need about half that for the Midden, but filled up the truck to mulch the beds as well.

BART holds 48 bales of straw. I am not saying *everyone* needs a dump truck. But in my case I am making a good argument..

With the straw in place around the fencing, I then stacked a third tier of straw to form the mold for the final several yards of material.  In the shot at right the pile is nearing 7′ (2.1 m) tall which was the goal.  At this point I was nearing the end of the biomass and began to focus on rounding out the pile and maintaining the 3′ length from the heat exchanger as much as possible.   Was incredibly pleased with how the Midden was literally shaping up.  Sometimes a project just CLICKS.  This was one of those!

Gap left for the pump installation. You can FEEL the heat coming from the pile, the core of which is 150+ (66 C) at this point. Dang sucka.

Jean with one of his piles. As you can see his heat exchanger loops would have gone around the OUTSIDE of mine. Then again his piles crested 80 tons - 10x as big as mine. Jean was a visionary, and I am honored to be able to promote his work for a new generation.

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Methane Midden – La Fin

 

The Methane Midden got a ton of press for its attempt to produce energy from brush.  And in a suburban backyard no less.  But as I spent the day Tuesday finishing its tear down I was struck by the need to set something straight.  While the goal of the experiment was to try to produce methane (and hot water in the new Midden), the goal of the system is, and will always be, to make an insane amount of compost.  I routinely trailer in over 10 tons of organic matter, mostly woodchips, each year to my .5 acre ( .2 HA) lot and my soils are still far from done.   Our urban soils are incredibly denuded in most cases, and until the organic matter content gets up to 5%+ in the top 6″ of soil we have a ton of work to do.  And in this region, topsoils used to be 6-10 FEET thick (2-3 m).  To add 1″ of compost on even .1 acre you need 13 yards of compost.  It is mind numbing to think about how much compost and mulch we need to heal the soil of our cities.  Luckily all the carbon we need is unhappily sitting above us in the atmosphere.  Hence my desire to cut down coppice and compost it.  Putting our tea bags in a bin won’t cut it.  The fact that I am working to get energy out of the piles is a fringe benifit.  A really, really cool one. 🙂

The break down of the midden was not sexy, but it was awesome none the less – 8 yards of compost, all at once, is simply staggering in what you can do with it.  The “compost” was really only about 75% done due to the amount of pine needles, it was really a well cooked mulch – very similar to the “duff” layer in a forest.

Rather than bury you with text I will tell it in pictures.  Enjoy:

Cut away of the Finished Methane Midden. The layers of heat exchanger settled over 50%, with the bottom two resting on the ground. Not good - time for a redesign.

What a mess. And you missed all the swearing to get it to this point! Anyone need any yellow garden hose?

Then I started spreading the mulch.  The plan was to use the finished compost to start my willow/poplar coppice that I will plant in Spring 2011.  It is sized for about 80 trees and will have an understory of Russian Comfrey.  Will likely also put in some False Indigo and everbearing raspberries, but I get ahead of myself!

The coppice will be around 3 sides of our kids playground and will have a total row length of about 125' (22 m). This side is close to our fence and is only 2' wide -enough for 1 row of trees..

Good shot of how thick I laid the mulch down here - easily 4-5" (10-12 cm). This is the main width - about 4' (1.5 m) for a double row of willow. Thanks again to author Michael Perry for his help with this during his visit!

The final leg of the coppice to be. Yes, I have 2 wheel barrows... I also have 5 pitchforks - and each has a specific use! So much mulch, and I hadn't even used half the pile yet...

This post may get long, but I really want to pound home the shear amount of Good Work that can be done with one of these Middens – I was beyond giddy driving my barrows around the yard flinging compost at anything that grew! Plus it is a compost eyes view of much of my permaculture beds.  I have been asked if I used more energy than I created with the Midden.  Yes, I did.  But show me an oil rig that can do all this:

'Barrow load under my sole bamboo - a clumper. This will be its first winter -fingers crossed!

 

Mulch spread in my Asian Pear tree guild - I forked it around the perennials so as to not bury the groundcovers

Wheel barrow load of mulch for my sole apple tree. It speaks volumes that I spread most of this compost "by the wheelbarrow load" rather than the forkful. AWESOME! This still needs to be spread away from the trunk.

7-8 barrow loads went on my Sunchoke plantings. Sunchokes are not my favorite food, but this reliably cranks out 50#’s of food for no effort.

Here is the raspberry patch. It was rather overgrown so I hacked it to the ground and refreshed the soil with 8 barrow loads of Midden Mulch. Still not even 75% done with the pile!

Into the Guilds! Mulch under my heirloom Pear - a White Doyne which I have never seen in a catalog, but got from a nurseryman friend.

The other portion of the Pear Tree Guild. This shows one of my Paw Paw's, some hazelnuts, another pear, and a hardy kiwi on the fence. 3-4 more barrows here.

I had so much mulch I decided to start a new guild. This is a pine I bought the year we moved in and is just no starting to grow. In went an elderberry, some thyme, a service berry, and several dozen strawberries. And yes, I just had these lying around...

Mulching under one of my front yard "pretty" guilds, both Peach Tree guilds.

It was so incredibly liberating to be able to spread compost where ever I wanted to – flinging forkfuls into the rain gardens, into the prairie, on the lawn – without have to choose which plants to favor and which had to go without.  Also notice that my annual vegetable gardens didn’t get any mulch.  This was intentional – this mulch is very carbon intensive at this point, and will be heavily skewed to fungal decomposers which my perennials prefer.  The veg garden would have been fine, but the fruiting shrubs and trees would really benefit.  Plus I have another 5 yards of compost in my regular bin for the veggies.

The Methane Midden was lined with over 20 bales of straw. These were a wretched mess... perfect for a winter mulch for the veggie gardens!

Now the Methane Midden has passed, but OMG will it live on.  I covered everything in this post, plus 3 other guilds, 2 rain gardens, and even some into my mini prairies.  Imagine what your gardens will look like if you built 2-3 of these Middens a year?  I can’t wait to find out!

Energy is fantastic and very useful up here where it gets to -15 F (-26 C) in the winter, but being able to make this much compost, from invasive species and “weed” trees is where the true beauty is.

Over 8 yards of compost from one pile in the burbs?  Epic Shit indeed!

And I can’t wait to do it again – only BIGGER.

Be the Change!

-Rob

Methane Midden – Learnings

June 2010

The Methane Midden was my first attempt to recreate, on a significantly smaller scale, Jean Pain’s Epic Compost piles that he used to heat everything from his house, to greenhouses, to sheds, and he even buried methane digesters in them.  He worked on these projects for over a decade and did some truly Epic Shit.  The dude was a bad ass and a Bioneer extraordinaire – and he did all of it 40 years ago.   My Methane Midden didn’t produce any capture-able methane.  Why?  I screwed up the PH, screwed up the solids:liquid ratio, and was doing 4 other projects at the time and didn’t focus on it as I should so missed both of the above, or at least failed to address them.  But that is ok, because when you screw up, you reap a boat load of learnings. So it was with me.

Learnings:

  • Spend more than 30 minutes planning a project. A full third of the issues below were foreseeable and I could have caught them.  But that material was decomposing with every minute I delayed, and/or some other guy could have grabbed it.  I struck when the iron was hot.
  • Rubber is a crappy heat exchanger. Duh.
  • Looping hose through a pile haphazardly doesn’t work real well as an efficient heat exchanger.
  • Digging out said looped hose sucks.  Jean Pain figured this out early on, and switched to an elegant solution.  So will I…
  • 540′ (164 m )of garden hose only holds like 40 gallons of water (151 l) , which at 6 glns/min (15 l /min) only keeps the water in the pile for like 7 min. In rubberized tubing.  Yeah, THAT is going to heat up…
  • Rectangles are stupid. The bio-chemical reaction that happens in composting works as a sphere.  Rectangular piles waste 20%+ of the composting material as it never hits prime temp.  ALL of Jean’s piles were cylindrical (ish).  Rectangles… easy to build, crappy in use.
  • Putting large tanks in the middle of the pile screws up the reaction.  Again, the reaction in a compost pile needs about 3′ (1 m) of width (in all directions) to achieve critical mass.  The 2 digesters in the middle of the Methane Midden meant I only had 2′ (60 cm) of compost materials on each side of the digesters.  I thought the straw bales would provide enough insulation to overcome this.  I was wrong.  Jean Pain’s piles were HUGE and over came his buried tanks with shear volume – he had 9′ (3m) of material on each side of the tank – more than enough apparently.
  • Hot Water or Methane.  Choose One… At the size I was building, I would either keep the methane digesters at 100 degrees (38 C) or heat the water to 120.  I couldn’t do both without separate heat exchanging systems.  Jean Pain had 400 meters of  2″ hose (1200′) so his first 100m (300′) went around the digesters to cool them, and then he had 300m  (900′) of exchanger left to heat up.  I can get an exchanger that big in my piles, but not with a digester in the middle.  Hence the L’eau Chaude pile
  • Pine Needles don’t really work. The Methane Midden came into being because some local guy limbed up a huge amount of pine trees – there was no other time I had seen so much “green” brush all at once.  Pine needles have nitrogen, so the pile heated up, but they also have alot of resin in them which ultimately blocks decomposition.   This meant the pile died after 2 months, where I suspect a deciduous based feedstock would have gone for twice that long.   The compost didn’t really finish, ending up as a humusy mulch, for this reason.  I worked with what I had and learned a ton – like I need to source my own material, and also what happens when you pile up 10,000 #’s (4500 kg) of chipped white pine limbs (140 degrees for 2 months, then 100 degrees for another 1, then ambient)
  • Jean Pain style Brush Composting Works. While dismantling the Methane Midden this week I didn’t come across any anaerobic sections, and the pile was still damp.  After 5 months.  Soaking the material for 2+ days adds enough water to sustain the reaction, and the large particle size of the brush provides enough bridging to let air in.  On paper / first glance composting this way is insane.  But IT WORKS.  I still need to figure out the proper C:N ratio – higher on the Carbon side than a traditional hot compost pile to sustain it, but more Nitrogen than the Methane Midden had to keep it going longer.  I ran several smaller experiments over the summer and they tell me that .5-1″ (1-2 cm) trunks of brush with full leaf should be ideal: thicker trunks, say 2″, and the pile die quickly, to thin or brushy (mature lambsquarter) and the pile goes into runaway mode – hitting 178 F (81 C).
  • Green wood is important. It is precharged with moisture, and the sap is sugary.  Bacteria like sugar…  Mixing a pile with dry, dead chips and leaves and you would need far more water –if you can even get enough into the chips- and alot more leaves, leading to matting.  Luckily the vigorous willow strains such as salix dasyclados will put up .75-.875″ rods in one year of coppice growth.  Just sayin.
  • 8 Cu yards of nearly done compost will turn you into a glutton Will explain tomorrow, suffice it to say virtually EVERYTHING in my yard got a 1-2″ (2-5 cm) layer of humus rich mulch!

So, the new Midden is underway.  It will be hot water only, and it will be cylindrical.  It will be made with primarily made from deciduous plants.  There will be no tanks, and I am upping the tubing to 1″ ID.  There will hopefully be as much as 900′ (300 m) of it if I can find some more compost material.  That should increase the volume of water in the pile by a factor of 10.  Also may purchase a new pump that will drop flow rates to under 2gpm, potentially keeping the water in pile for over 2 hours rather than 8 minutes.

Work is happening faster than I can type up posts, though expect a flurry in the coming weeks.  If you want to keep more up to date, I will be updating Facebook more frequently with mini reports.  This is going to be awesome!

Be the Change!

-Rob

Pimp My Garden: Fall Season Prep

‘Tis fall, the Season of the Soil!  With the shorter days, and frosts in Wisconsin Nature is dropping its leaves to blanket the soil and begin to build the humus necessary to protect the future of it’s ecosystems.  Mom Nature really knows her shit, and we should listen; if Mom is covering her soil, we prolly should too.   Several billion years of evolution are talkin ya know?  This will detail how I am prepping the beds in our annual gardens this year.  These are the beds I built in June and the majority of the soil was trucked in – it needs some healing.  And you know my answer for healing the soil: compost and organic matter.

First up is to strip the organic matter off the top, shred it, and compost it.

In future  years I may skip the composting, but we still had a bunch of weeds so off to the Hot Composting it goes.  Once the beds were clear it was time to add some medicine – comfrey!  I have about 6 dozen Russian comfrey plants on property cloned off 2 plants I bought 4 years ago.  Comfrey is a wonder plant, full on minerals and excellent food for soil microbes.  Here is a shot of my a bit of my comfrey “coppice”, a double row along a 80′ fence line.

The comfrey is hacked done with a sickle and laid out on the beds.  Comfrey is a wonder plant, but it can also resprout occasionally.  To prevent this do two things – compost when you cut it when its flowering (if you have viable seed like me), and also when using it as mulch, don’t cut the fronds too close to the ground to prevent any chance of re-rooting from any root chunks.  Still, you will likely get some volunteers over the years.  In the permie beds I encourage this.  In the veg garden, not so much.   That imposed order is not natural, but its there.  Smother any that come up with a mini sheet mulch.

A layer twice this thick could also be used, but much thicker than that and I would be concerned with  it going anaerobic under the mulch.  Next up I spread nearly finished compost.  Actually this is as finished as most of my compost gets unless I am making potting mix; I prefer to leave some un-decomposed organic matter for the microbes to breed on in place.  Look at the color difference!  In very general terms, the darker the soil the higher the organic matter content.  Humus is black.

This is what about .5" of compost (on average) looks like.

I had about 1/2 of a yard of compost left for the three beds I was prepping.  Dividing it out works to about .6 inches on average.  I would prefer more, but with the mulch breaking down all Fall/Winter/Spring I will add another .5″ over time.  Final step is to “tuck them in” as Nature intended.  In this case its a 4″ (once settled) of well rotted straw that served all summer as the walls of the Methane Midden.

Makin Ruth Stout proud.

Not quite done.  Need to fill the 1′ paths back in with new wood chips.  Why?  Because choosing to use wood chips on the path was brilliant.  It prevents compaction by spreading the load of walking, but it also holds moisture, and breeds soil fungus like crazy, lots of mycelium after only 4 months.  Outstanding!

Notice that none of the beds were turned, nor do I  plan to turn it in the spring either.  Yep – going no till baby!  And from a guy with a $4000 rototiller that is saying a lot!  A surface hoeing with a 7″ scuffle hoe was done to clear the debris.  Once the debris was clear I could see dozens of holes from the deep tilling earthworms.  The straw and compost layers mimic natural soil strata: topsoil-> humus -> duff-> mulch.

No till it is.

2011 is going to be awesome!

-Rob

Be the Change.

Bio-Char Composting

So I’ve written about Bio-Char before – its the essentially pure carbon that is left over from burning wood in the absence of oxygen.  We make some while running our gasifiers and its a prime component in Terra Preta – the incredibly fertile soils found in bits of the Amazon.  It has also been in the eco-news a ton lately as a means of carbon sequestration.  There have even been some low tech trials (low tech are my favorite!) using it as a soil amendment.  What those trials have found is what I had suspected: that while long term fertility potential is increased due to the addition of carbon to the soil, all those free ionic bonds “fix” nitrogen out from the soil and initial fertility is lessened for a year or more.  The trail found that by saturating the bio-char first (in this case with human urine) the results on harvest were substantial.  I have dreamed of using bio-char from our gasifiers as a final filter in a aquaponics system – not only to clean the water, but as importantly to “pre-charge” the bio-char with nutrients for its use as a fertilizer.  Since I don’t have my aquaponic greenhouse yet, and my suburbanite neighbors wouldn’t take to kindly to me pissing in a bucket each morning in the backyard, I decided to use my compost bins as the nutrient source.

Compost bins leach out a significant amount of nutrients -either through runoff, or through ammonia gas.  My thought is that by mixing biochar into a pile, I would precharge the char, and the end result would be an even better soil amendment.  So, putting action to thought as is my wont – here is what I did this afternoon:

35#'s of hardwood charcoal from Whole Foods. $28 and likely a better use than grilling steaks.

We don’t have access to our own charcoal yet (next year I may make my own charcoal maker), so Whole Foods helped me out with an end of season sale.

Next I needed some material.  As I wrote about yesterday – that is no problem anymore.  400# of willow coming right up!

2 days old and free. The things people throw away these days!

Finally, I ran the willow and the charcoal through the chipper.  The thought was to make the char into itty bitty bits to increase surface area.  I figured dust would be an issue, but DAMN is dust an issue!  Carbon dust is quite dangerous – rather explosive and wicked rough on your lungs.  I had a dust mask on, and mixing the charcoal in with the leafy fronds helped, but soaking the char first might be better.  Its an issue, and you’ve been warned.  Here is the results:

Always amazing how much it reduces in volume once its chipped. Plan on soaking this a lot - that char is DRY.

The plan for this bin is to fill a raised bed for a side by side run next year.  My hypothesis is that the compost char will increase the fertility potential of the soil by preventing leaching and raising the overall carbon content of the soil significantly.  Bacteria LOVE to live on the incredibly rich surface structures of char particles, so soil life should explode.  This will hopefully be a major component of my pushing for 10# ‘ sq ft in some raised beds next year.

It will be interesting to see if the added char will affect the composting process at all.  It may inhibit it due to the char sucking up nutrients.  I have a good idea of the process with 4 brush piles in the works, so it should be readily apparent if more nitrogen is needed in a charified pile.

Much more to come!

-Rob

Brush Composting – 5 wks to Humus

So this summer I went Compost Crazy.  First with the Midden and its ongoing Epic Insanity, and then once I saw the power of shredded brush composting, I starting going ape shit with my chipper.  Over the past 1.5 months I have cut or scrounged over 5000#’s of brush, run it through my chipper / shredder and all but filled my Compost Bin of Dreams.  In fact, I am one trip away from it being maxed out which is about 5.5 yards of compost.  Dang sucka.  Of note, I have yet to start my third gallon of  gas.  The Bio-80’s 5hp Briggs is frugal.

I have good reason for my madness.  Shredding weeds and very brushy material makes SYCK compost – and it does so incredibly fast.  The batch of lambsquarter I ran through on July 29?  Yeah – its DONE.  Not “yeah, I can *probably* spread this.” done.  Its DONE.  And its not only the speed on the decomposition end – its on the sourcing end.  One of the problems with home composting is it takes all year to get material to fill a bin, then another 3-4 months to cook it down.  Thats a year or more.  I don’t have time for that given the harvest goals for my place and the resulting soil building needs.  With my Chipper, I now cruise the municipal yard like a crack addict looking for fresh cut shrubs or prunings on an almost weekly basis.   I can take 2 loads from the yard to my house and shred them in less than 3 hours, and 2 loads will get me about 1.75 yards or chips (800#’s) which will cook down to about .8-1 cu yard.  3 hours of work and a fraction of a gallon of fuel for 600#s of humus.  I’ll take it!  Here are some shots of the process in action – the Week 3 shot didn’t turn out, but I will add one tomorrow.

It all starts with shredded material – this is what 350#’s of willow looks like after the Bio-80 has its way:

Small particle size is crucial. LOTS of green material as well. This is soaking in 20 gallons of water overnight to raise water content.

It takes 2 loads of with the trailer to fill a bin, about 8-900#’s of brush.  Here is what it looks like after 2 weeks – remember that this will be 165 degrees with in 24-36 hours and stay over 140 for 14 days.  This system is stunning.

Woody chunks still visible, but greens are all gooey. The woody bits in the middle are well on their way to humus. This will heat again to 150, and fall to 120 over the next 2 weeks. Add water if needed, but if you soaked it well, it should be fine.

Again, Wk 3-4 pic was a flop, but will add one soon.

Here is a shot of the lambsquarter : box elder pile after 5 weeks.  This is the fastest I have ever seen compost created, and on par with the commercial operations with mechanical turners.

Done. The clumping is due to moisture - this pile is sopping wet due to rain. There is virtually no identifiable raw material left other than some box elder twigs. 5 weeks!

Now, the lambsquarter pile is likely going to outperform the other 3 piles in the bins right now due to the fact that it was primarily annuals with much less cellulose and lignin to break down – it also shrank almost 50% for that reason. This pile was also so nitrogen rich that it hit 178 degrees in early August – that is just silly and literally destructive to the microbes in the piles – at that temp you are cooking your hibernating mezophillic bacteria which is NOT a good thing.

I am very curious to see what the pure brush piles look like in 1.5 months, but they aren’t tracking too far behind.  This pile can be recreated with sun choke stalks, cupplant, as well green sweet corn or sunflower stalks – but again – it takes ALOT – 800-1000#’s per pile since green material has so much water in it.

But the results speak for themselves.  With my new setup I can have 2-3 cu yards over winter to be spread in the spring for my early plantings, and start new piles in April.  By June I should be able to spread another 1″ of compost over the beds before the Heavy Feeders go in, and then another 1″ after they come out.  It should be possible to run 3+ batches through the Compost Bins netting up to 15 cu yards of compost – in theory, enough to cover my 1000 sq ft annual bed 5 times to a depth of an inch.  Of course the permaculture beds, insectary plantings  and coppice mini- groves will get their share too.  With this much humus hitting the soils of the system, organic matter will skyrocket along with yields.

And the icing on the cake?  15 cu yards of compost (humus) will sequester about 4 tons of carbon each year as well.  Not bad at all.

Be the Change!

-Rob

Carbon “Fixing” Plants

Most gardeners are aware of “nitrogen fixing” plants; those plants, typically legumes, that have formed symbiotic relationships with soil bacteria to take airborne nitrogen and fix it into water-soluble form.  As far back as the Romans, humans have fostered this natural occurrence to increase yields and increase fertility.  What we hear about much less is carbon “fixing” plants – in Permaculture speak – biomass or mulching plants.  In the past year, as I have learned more and more about soil ecosystems, I have become far more convinced that these “carbon fixers” are even more important in early successions as we heal our suburban ecosystems.

I have developed a mantra over the summer as I have worked to sloganize what it is that we are doing.  The result has been my oft-repeated imperative to: Heal the Soil, Store the Water, & Plant Useful Plants.  In a nutshell it is a roadmap to maximize the potential of any garden space – if the soil is alive it has more nutrients cycling in it, if the soil has sufficient water stored under mulches and in humus then  the potential increases again.  And once these two are in place, one can maximize the solar potential by filling in the canopy.  Of these, I feel the first is the most important as it makes the others possible.  And to heal the soil, you need carbon (organic matter).

Plants are truly the conduits of energy into the earth – by capturing solar energy and turning it into simple sugar they supply the foundation for 99.99% of all life on the planet, whether it is through root exudates in the rhizosphere or nectar through their flowers, plants make life possible.  But life also needs carbon, and most life on the planet gets its carbon from plants in the form of organic matter – the main food source of the bacteria and fungus in the soil.  But some plants do this better than others.

There are the grasses with their dense root systems that build soil visibly every year, and there are trees that cover the ground in a thick blanket of leaves every year.  Finally there are other plants that form stalks and stems that form significant amounts of soil as well – the tall grass prairies, corn/sunflower stalks, and windblown branches from softwoods such as willows, sycamores, and poplar.  What these have in common is tough, long carbon chains in their cell structure that resists decomposition.  This resistance to decomposition -in lignin, cellulose, etc-  is what forms humus.  And it is humus that forms rich soils.   This is something to be very mindful of as we mulch our gardens.

If you were to build a compost pile of nothing but greens, with only the barest amounts of “browns”, the pile would heat up very quickly, but would decompose down to almost nothing – 75-90% of the bulk would be gone.  That is because greens lack cellulose and lignin and are mostly water and nutrients – vital to soil life, but almost completely consumed in the decomposition process.  Compare this to a similar sized pile of shredded leaves.  It will take 4x as long to decompose, but the result will be 400% more humus with only a 25% reduction in size.

In most of my permaculture guilds I have stressed the green mulches of comfrey, sorrels, chives, etc to pull and cycle nutrients, and for several years I have imported my cellulose and lignin in the form of dozens of yards of wood chips.  Now that my gardens are maturing, I am starting to pay more attention to including plants specifically to “fix” carbon to maintain soil humus levels.  In the 6 years I have lived here I have lost about 1-2″ of total height in our 3 oldest perennial beds compared to the sod.  That is because the humus in the perennial beds is degrading over time, while the roots of the fescues in the lawn are forming .25″ of humus a year.  I had not been mulching these beds much as they have almost completely closed “canopies” of thyme ground cover that I didn’t want to smother.  I will try mulching more aggressively this year.

While all my guilds include nitrogen fixers such as leadplant, false indigos, New Jersey Tea, Serviceberry, etc and green “mulch” plants such as Russian Comfrey, I am beginning to either add in “carbon fixers” and am planting guilds specifically to grow brown mulches.  Some of this I am accomplishing by letting box elder seedling mature in my guilds as they sprout in the wood chip mulch.  In one spot, I have planted a 20 tree “short rotation coppice guild” of willows, poplar, and box elders.  In my annual gardens I am taking much inspiration from John Jeavons and planting “stalky” plants such as corn, sorghum, and sunflowers specifically to produce compost carbon in addition to edibles.  Once you change your mindset it isn’t overly hard.  Of course, having a chipper to use can become important as well – though many plants such as sunchokes, and weeping willows produce stalks and “leaf” mulches that are laid down without chipping and fast growing trees such as Empress and Sycamore have HUGE leaves that really add up.

As my gardens have matured, and I seek to support the soils I have built using primarily the inputs of my site, I find myself planting more and more of these carbon trees to grow my soil.  In doing so I help to maximize the potential of my site by using these fast growing plants to sequester carbon to build the soils beneath my edibles, while also pulling carbon from the air to heal our climate.

Prime Short Rotation Coppice Trees:

Willow, Hybrid Poplar, Black Locust, Box Elder, Empress, Sycamore, Ash, Hazelnut, most Standard fruit trees (annually pruned)

Prime “Carbon Fixing” Annuals/perennials:

Sunflower, Corn, Sorghum, Cupplant, Sunchoke, Small Grains, Amaranth, Quinoa, etc.

Many of these trees are useful in many other regards – Black Locust is a nitrogen fixer, provides rot resistant wood, and its flowers are a great early nectar source.  Black Maul willow is one of the most striking plants I have ever seen and the new growth makes incredible baskets.  Hazelnuts and Sunflowers are some of the best ways to grow healthy fats in the northern hemisphere.  Carbon gardening is by no means boring or a wasted effort!

Productive soils need to have all their nutrients cycled, not only the water soluble ones, but also carbon to replenish that which is lost due during the respiration of the soil organisms.  If we are to truly garden in the spirit of nature, we need to make sure that the carbon is replaced with the same diligence that we give nitrogen, phosphorus, potassium, calcium, and the 96 other macro and micro nutrients.

-Rob

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