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!



17 Responses

  1. Thank you so much for posting, you are a most needed example and inspiration. One thing i felt was lacking in the “Permaculture” community was real, well documented working examples. Your dedication and sharing is paving the way for increasing the number of demonstration model sites… and setting the high standard by which other will be judged.

  2. I agree with Adam the documentation of your process is invaluable, thank you for taking the time to report on this.

  3. Rob,
    Very interesting — you’ve got some beautiful stuff cooking there. I have a couple of questions…

    First) Maybe I read to fast… are you turning your piles, or is having the right ingredients and prep enough to get the results you are seeing?

    Also) Do you worry at all about pesticides when you gather materials from the municipal lot? (I occasionally pick up some grass clippings there but accept that I can’t confidently call my garden “organic” –and worry some about residue in the grass.

    Finally) I’m wondering if you need to be careful about risks of mold disease, blastomycosis and such in working with large volumes of composting material.


    • Yes – I turn the piles religiously and also use thermometers. This is a hand on process for sure! The time spent on material prep is important, and would likely make great compost in a season, but to push the envelope with time, you need to add labor. Such is life. Within a day of building the pile it will hit 160-170 degrees (damn!) and stay there for 1-2 weeks. When it cools to just under 120 degrees I turn it again, and add water as needed. This time it will fire up to 140 again, and cool to 110. Once under 110 I turn it a third time and it will hit 120 if there is any raw material left, and drop quickly to 100. after 2 weeks I turn it the final time and let it mellow until I need it. 50% usually goes into the worm bin. On the final turning, it rarely heats above 100.

      I would worry about pesticides using grass clippings – the people that don’t spray typically understand the importance of the clippings and wouldn’t dump them in the municipal lot. But using brush I think I am fine – not very many people spray their trees.

      The mold is an issue on cold composting brush piles – and when I get my mulch I often wear a mask as the spores can be thick. But in this composting, the temps are far too high for mold to grow so its not an issue.

      But, overall, my general thought is to study some, then leap on my best guess. The shit is hitting the fan faster than I ever imagined, and saving the world is not for the timid. Recklessness is folly, but courageously pushing envelopes will be needed to accomplish what we *must* in the coming decades.

      Be Bold.
      Be Brave.
      Be the Change!

  4. […] 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 […]

  5. Just learning to compost. This information is useful. Buy a composting bin this fall. Will be stopping by here to get more great information

  6. Rob,

    Why not take your shreader with you and cut up the waste there vs take so much bulk home?

    • Yep – that would make a lot of sense from some angles. However, here is my thinking: I can load up the trailer in 10 minutes (timed this one), but the trimming and grinding will take 4x that. This way I can be at home with the kids riding bikes up and down the street, take a break for a beer, or whatever. Plus I only need 2 loads a week and it would take almost as long to load/unload the chipper onto the trailer than it would to load all the wood. If I ever decide to do a Mother Load, say for a Midden if enough material was there – that would make much sense to grind up a full trailer load of chips (4 loads of wood) all at once.

  7. Great composting! My main problem is that we are in year 3 of a drought, so water is in very short supply – barely enough in my dams to get direct-seedings going, so fast, hot, wet composting is a thing of the past, especially as most of the material I can get is woody. Oh well, we live in hope of better rain (we’re – happily- waaay beyond the reach of municipal piped water…)

    One comment on pesticides, etc. in collected materials: With the temps you’re hitting I wouldn’t worry too much – I would guess that those temperatures will mostly break down the relatively complex molecules, rendering them harmless. Certainly I have found this to be the case with stable-sweepings where horses have been dosed with antibiotics, exoparasite sprays, deworming medicines and such.

    Only thing I didn’t understand, though… all this 145 degrees and 178 degrees… what’s that in real temperatures? (Just pulling your leg a bit 😉

    • Sorry about the drought there Mike! I am all about the leg pulling – we Americans need it more than we know. That said, if I started quoting numbers in metric, Celsius, or other “immigrant” numerations there is no telling how much of my audience (suburban Americans) I would lose 😉 !

      Thanks for the prodding – next time my pile hits 81 “degrees” I will let you know!

  8. Really enjoying the comments… beginner and learning..thanks

  9. It would help me a lot too, when metres and Celsius are used (in brackets maybe?) – even an approximation. Thanks!

  10. Ria..
    converting website

    Maybe this can help


  11. I read this post last week, and as I was biking to work along the Military Ridge Trail between Madison and Verona got thinking… There are so many invasive honeysuckles just along that bike trail. What would it take to organize an effort to hack some back, chop them up, and compost?

    I feel like all that biomass is just waiting to be put to good use. Has anyone else tried this? I’m starting to consider guerrilla pruning…

  12. Trying to think of the vine that grows crazy..??? this would be another plant for mass composting

  13. Are you thinking of kudzu?

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