Grow Your Own Soil: Compost Crops

Readers will note that I am HUGE on living soils.  We moved into a dead, denuded landscape and have spent the past 5 years dutifully rebuilding them.  The single most important thing in healing soils is to add organic matter – essentially getting carbon back into the soil.  Why?  Carbon is the primary building block of all life and it is the fuel of the soil food web -from the zillions of bacteria and miles of fungal hyphae to the worms that feed on them.  We’ve been trucking in organic matter for years now – mostly wood chips, but also straw and manures; by the ton.  In fact, over the past five years I would estimate that we’ve surpassed 20 tons of raw material that we’ve either added directly to our soils (manures), or mulched (wood chips and straw).  That may sound like alot, but at least half of the carbon is lost to the air as part of the decomposition process (no fears for global warming as the carbon in wood chips and manure was atmospheric carbon just a year or so ago before it was sequestered by the plants), plus to add an inch to a 1/4 acre (11,000 sq ft) which is my yard (minus house and driveway)  you need to have about 9 tons of compost.  That’s 34 yards of finished compost, or over 100 cu yards of raw material.  Helping others get to this point is why I own a dump truck.

The result is that our soil is teeming with life and the gardens are really starting to “pop” this year with trees adding multiple feet of growth, 5+ cuttings of the Russian Comfrey, and sunflowers over 8′ tall.  We will continue to “uppen” our soils with compost and mulches for decades to come.  But I am trying to do this on as low of inputs as possible.  In the last 5 years we have built our garden soils up and the lawn is getting healthier every year.  It is time to try to see how sustainable I can make this system.  It is time to start growing my own soil.

To grow your own soil you need plants that pull carbon out of the atmosphere, which of course all plants do, but some do it really damn well.  I must tip my hat strongly to John Jeavons and his work on sustainable gardening here, but for annuals the choices are not too hard – what gets really damn big, with a thick stalk?  Think sunflowers, sorghum, corn, quinoa, amaranth, etc.  Add in all the small grains if left to dry out into straw and you get the idea.  Perennial crops are also money as well.  There are a wealth of BIG plants in the tall grass prairie – my favorites are cupplant, giant Joe Pye weed, sunchokes, and the myriad perennial sunflowers like maximillian and ox eye.  The true Big Guns in this area are rapid growth trees, often referred to as weeds, harvested as coppice such as willows, box elder, black locust, and even chestnut and ash.  Other “weeds” like lambsquarter, ragweed, and buttonweed get 6’+ tall , and even invasives like buckthorn coppice well.

Today I spent an hour touring the back yard with my Big Az 10 cu ft mulch wheel barrow, my sickle, and my new brush axe pulling weeds, hacking down old raspberry canes from last year, cutting back insurgent sunchokes, and taking the 4th cutting off the 60 or so russian comfrey I have around the gardens.  That produced an immense amount of green material – piling it into my utility trailer I easily had 80 cu ft.  That is far too much nitrogen for a pile so then I got out my loppers and a pruning saw and took some prunings from the buckthorn out back and two of our willow shrubs.  It wasn’t enough, but in a few years the 2 dozen box elders and  willows I have planted will be on line.  Here are the results.

about 100#'s of material, but dang is it bulky. Brush Axe is leaning on the trailer.

That is from one lap of the backyard – I can do this about 3-4 times a year at present.  In years past I just threw all the weeds into the compost bins, but it doesn’t work too well as the stalky stuff takes too long and the full size leaves mat up.  Now with the Bio-80 shredder it makes marvelous weed puree.

Entropy ala weeds. At least half that pile is/was comfrey so the compost will be awesome. The recycling bin is the chipped tree prunings - not enough to offset the greens, but its a start..

Now the Bio-80 is powered by gasoline, and I am likely to catch flak in the comments for burning dead dinosaurs to save the world.  I agree- its not ideal.  But I am building a transitional system and am not afraid to break some eggs to make an omelet.  The chipper is only 5hp and ran for about 20 minutes using less than a cup of fuel.  In future years I hope to find a way to power the chipper on methane from the ‘Midden or ethanol from a local co-op.  But for now I’m in bed with BP on this one.  One very cool option would be to use a chicken “shredder” to break down the green material – 4 layers in a confined pen would make short work of this over a week or so of adding an inch or two a day for the girls to scratch in.  Of course that is illegal here.  Working on that too…

This bin is 40" cubed and is about 66% full. This will settle almost 30% in the coming days. Making soil takes ALOT of plant material. Plant more trees!

Finally, it takes ALOT of plants to make a yard of compost.  A yard of finished compost weighs about 550#’s.  So the 100-150#’s of material that I put in, most of which was water that will evaporate out, is just a start. But every journey begins with a step.

I am very proud that this bin. When I add another weed lap in September, plus all the corn, cupplant, sunchokes, and sorghum stalks form the yard this fall, this cu yard of finished compost will be 100% homegrown.  As the gardens mature, I will begin getting leaf litter from the trees and willow and box elder coppice to add to it.  My gardens, minus paths, are about 3000 sq ft – that means that 4-5 cu yards could cover it all with .5″ of compost annually, which is alot if you are only maintaining fertility.  I can do that in about 5 years if I add more coppice trees; I am convinced that I can sustain the fertility of my gardens without additional inputs.

We can do this.

Be the change!



27 Responses

  1. I’m really enjoying your blog. It’s extremely informative and very interesting following your adventures.

    I had always assumed that the best you could do was maintain soil fertility if you composted everything possible, including humanure, from a piece of land. I hadn’t considered that plants can draw carbon out of the atmosphere. Well duh!

    I’m off to rethink my own garden now. Thanks for the inspiration!

    • You’re welcome!

      Carbon is the first step – the next will be mining the subsoil for nutrients (Comfrey and other dynamic accumulators) to ensure phosphorus, potassium, and others are maintained. Humanure is a real solution, but we need to get chickens and grey water in the burbs first. Running the humanure through small scale methane digesters would be a positive step too.

      Finally, preventing leaching will be needed through the addition of bio-char to create terra preta. Some friends are working on a rocket stove inspired biochar “machine” to allow us to create bio-char while heating our season’s canning in an outdoor kitchen. HATE heating up the house while putting all the food by!

  2. I’ve been dumpster diving at my local coffee place for grounds – and its something I recommend we all do.

    Even sticking just to the espresso grounds that are pretty much pure grounds (they have a trash can just at that machine, while brew grounds go in the general trash) they are tossing some 15+ gallons a day – and they are a small store, nothing compared to the half dozen or more larger starbucks in town – and we are not a big city at all. While not backyard biomass, this place is only a few blocks away, and these grounds are bound for the landfill otherwise. It really is stunning how much organic matter can be mixed in to poor soil (we are clay here) – my mantra here is “no such thing as too much organic matter”


    • Excellent Preston! That system can work wonders – much of our soil came from our local shop – to the tune of 30 gallons of “gorp” a week for over 4 years, even going so far as to close the loop and sell salad greens and tomatoes back to them – it was a fantastic system. Unfortunately they were unable to weather the recession and have folded. 😦 Most, if not all, Starbucks will gladly give you their ground in their old coffee bags, but I have found the local shops to be more willing to modify their procedures to save their grounds for you – I used 5 gallon buckets w/lids.

  3. It is very inspiring to know that there are still a hard working and dedicated gardener in this world. And this world needs a lot of some like you. Who will till the soil and grow advantageous, nutritious and healthy plants like the ones you are growing. All I can say is I am two thumbs up with you. Good luck and have a nice gardening years ahead of you.

  4. Some shrubs will add nitrogen to the soil as they grow. Eleagnus, for example.

    • Good point. I’ve got half a dozen Goumi (Elaeangus elaeangus) scattered around, but they are not thriving. Trying a different cultivar of Silverberry to see if they do better. So far I have not been able to take prunings from them, but trust they are enriching the soils in place.

  5. …”Some friends are working on a rocket stove inspired biochar “machine” to allow us to create bio-char while heating our season’s canning in an outdoor kitchen.”…

    Now THAT woke me up! Do you have any material posted about the rocket stove biochar outdoor cooker for canning? Not exactly sure what that means, but it sounds like exactly the type of system that I’ve been trying to figure out.

    Thanks for being the change. Great inspiration.

    • Thanks Perry. We don’t have anything up yet on the rocket stoves, but I have “commissioned” one so hopefully soon. We have made small, portable gasifiers about the size of a barbecue grill, and we have made small portable rocket stoves of the same size. Both use steel well casing and chopped up propane tanks to keep the materials local and salvage grade. Our hope is to make one that is a hybrid that can both run very efficiently on “waste” wood *and* produce biochar, or if that is too difficult, be able to switch from rocket stove to gasifier modes with relative ease. We had both on display at the MREA this year, but the hybrid is still in development. I would expect a post before too long, as I am anxious to get at least a rocket stove at home to begin to do our canning outdoors and get the heat out of the house and the fossil fuels out of my salsa, pickles, and marinara!

  6. Hi Rob,

    I enjoy reading your blog as well. I would have never thought of doing what you’re doing on such wide a scale. We bought a house 8 months ago and have a 10,000 sq ft backyard that’s wildly overgrown with weeds, and I’m drawing inspiration from what you are doing. Step 1 has been to run a lawnmower (electric powered) over the weeds and collect them all into two cubic yard compost heaps. Step 2…well, we’re still working on that.


    • Have you read Gaia’s Garden yet? It was a huge inspiration to me 5 years ago and I still reference it at least monthly. For me, an overriding focus is to ensure that the areas of the garden are serving multiple purposes since the amount of space is limited – ie the peach tree provides fruit (duh), beauty in the spring, habitat for spring nesting birds, and mulch material for me each year as I prune it. In many instances the plants and features don’t change, just my perception of them has. In others, such as using the heat from my compost bins to start my spring plants, took some thinking. Good luck!


      • I have not read that book, but I will definitely pick it up. Thanks!

        What made you decide to go with the Bio-80 chipper shredder? I feel like we need a leaf/branch shredder and I’m looking at at 14 amp electric one in lieu of a more expensive/noisy gas-powered one.

      • Fred – another great book to read after that one, especially if you are starting from scratch, is David Holmgren’s Permaculture Principles. It is essentially a systems thinking 101 (and 501 if you re-read it and see all the nuances you missed the first time) and really helped me put the need to think DEEP on this stuff – like where our fertility will come from, how to heat my home with compost, and other things that are far beyond the normal thought pathways of landscape design.

        I’ve used alot of 5-10hp chippers an in a word, they all suck donkey turds. They can’t handle real branches and their shredders clog almost immediately. Likely the ones from DR and Bearcat would do the job, but they get pricey. I originally wanted the Bio-80 as it fits my Grillo “tractor”.

        But also there are several significant engineering advantages. First – the flywheel is 18#’s. That is a good weight for such a small machine allowing it to act like it has more horsepower. Second, the shredding knives are sharpened – allowing the shredder to mince wet material like comfrey stalks rather than beat them with hammers and clog. – most “shredders”are really hammer-mills. Finally, the shredder side has a straight shot through for the material and the screen for the shredder comes in various sizes including a wet screen and has a hinge so that it can be removed altogether for REALLY wet stuff (comfrey). The fact that I can get his much work done with an old 5hp Briggs on it is testament to its design. Sorry for the lengthy reply but I am a bonafide tool nerd. I import my spades from Europe for crips sake.

        Speaking of which – Earth Tools BCS has the best tools you can find anywhere. They are pricey, but will last generations. You have to apprentice 7 years to be a craftsman tool maker in Europe. You won’t find these tools at Home Depot!

  7. If the local wood chips aren’t enough to offset the greens, how are you doing so? Do you have some browns stored?

    I’ve read a little about the Indore method and biodynamic composting, and wonder what your thoughts are about using soil to balance out the greens.

  8. Storage is something I am strongly considering. Essentially start a leaf mold pile and pull from it all year long as needed. In my case it would be a corn/cupplant/sunflower/sorghum stalk pile. Problem there is that those are still relatively low in carbon so it will take more than I am growing. In 3 years I will have enough willow and boxelder that it will be moot. In the mean time I will likely coppice woodlots on friends land nearby.

    The biodynamic methods intrigue me, and I have friends that swear by them. I am not a fan of adding that much soil to compost as it makes it too heavy to breathe well and I don’t really have much to spare. I “slow cook” sod in compost heaps and the result is more of a rich topsoil than compost, but it works very well. Turning them is a chore though.

    • Good to know.

      The more-authoritative of the two biodynamic sources that I’m familiar with goes into some detail about the relative depths of soil layer for clay vs. loam vs. sand. It stands to reason that the layer can be very thin if the soil has a lot of capacity to absorb nitrate, and must be very thin if it isn’t very permeable to air; IIRC, you have silty subsoil at home, such that an appropriate layer of it would only be a fraction of an inch.

      I think those methods could be a good starting place in efforts to turn charcoal into terra preta: a light dusting of soil plus a thin layer of coarse-ground charcoal might serve well in the role traditionally played by a dusting of lime and a layer of soil.

      >In my case it would be a corn/cupplant/sunflower/sorghum stalk pile.

      Hm…do you still re-bulid your woodchip paths each year? It might save a little effort if the stalks went in to the bottom of the path trenches whole, and then woodchips were layered on top to fill the gaps & make a smooth surface. The product of digging out your paths sounds like it would resemble leafmold. It might mean re-scheduling the rebuilding job, to happen six or eight feet at a time.

      There are also probably some creeping legumes that would do well in a pile that regularly sees an inch or two of loose browns added to the top, and occasionally is undermined for humus.

      Sodbusting sounds like hard work. I can understand why people used to build houses from the stuff.

  9. This is a neat post! Thanks for sharing all the info. I am convincing my family to start composting this year and it’s worked out great.

    I also like Preston’s idea of coffee grounds. I will have to stop by our local coffee shop and ask for them now.

  10. I’m currently trying to source as much compostable material as I can to build up our garden beds over the next year, so I really enjoyed this article.

    I’m wondering if an old manual chaff-cutter might be a good way to turn corn and sunflower stalks into readily-compostable mulch without petrol (gasoline). I guess it’d probably be a lot of effort to chop up decent quantities, though.

    • Darren- Chaff cutters or straw bedding blowers would work very well. Also, silage cutters, combined with a pto driven light grade commercial chipper processing short rotation coppice (SRT) would be ideal for sustainable large/mid scale composting operations. The silage cutters are essentially flail mowers with a blower attached and could process the stalks of carbon feedstocks such as sweet sorghum (ethanol), flour corn (people food) or oilseed sunflowers (bio-deisel and engine lubricants). The only difference here is that we would then add carbon materials from the SRT coppice for aerobic decomposition and the creating of humus. I am strongly considering this as an endeavor in the future in combination with Methane Middens. The amount of carbon that we need to pull from the air and get back into the soils is staggering – but absolutely necessary as we can’t survive the climate, nor grow our food, if we don’t. Building small, decentralized systems that use local flora to capture hundreds of tons of carbon, mid scale agricultural equipment to process it into composting material and then use the “Waste” heat from the composting process to produce energy in methane middens and compost heated greenhouses like those from the New Alchemists would help us to offset some of our energy needs while building our soils to produce food while employing hundreds in meaningful work either growing the feedstock, processing it, or on the small sustainable food farms on the “finish” end of the carbon chain.

  11. Hi Rob,
    I just found your blog while searching for an equation to figure out how much oats to grow for the amount of straw I need for the garden, etc. We are on the same page as far as our views go. We bought a farm 3 years ago in the Driftless area of Wisconsin, met Mark Shepard when looking into permaculture practices and are trying to sell our business property in IL so we can move there permanently. Here is a link to a video I made of our Amish neighbors helping us plow swales for hazelnut planting. Thought you might get a kick out of it…

    Keep writing…

  12. You might find this interesting:

  13. Hi Rob:

    Great stuff as always. Your ability to keep beating the drum is amazing. We are doing some experiments with Comfrey as well. Not too sure how many plants we have out there. Focus on tomatoes to see how much better they do versus just compost and bone meal. A fun google is Ragman’s Lane Farm in the UK when you have the time. We envision a similar area of perhaps 1/4 acre of comfrey which we will keep cutting down to help with our soil requirements. Limited succes with elaegnus as well. We planted multifora and it just doesn’t seem to want to do anything. Our best find so far has been the blue honeysuckle or honey berry or haskap. Berries 3 weeks before strawberries, got beat up a little by the heat, but is putting out alot of new growth as things cool. We’ll probably put in another 50-60 this fall. We’ll try a couple of other things, but we’re just about done at this point. Have you ever read any Guy Mcpherson? He’s another on that is doing it, and not just yapping about it.

    Best Hopes

    Lucky Dog Farm

    • Comfrey on the ‘maters should work great – mine got a 6″ layer to start to build up the soil with calcium to fit blossom end rot. Also read a fascinating blurb on their potential as a methane fuel stock. Hmmm.

      1/4 acre should be easy to plant – if you have a tractor out there at Lucky Dog plant a double row length – wise across it and then pull a chisel plow through it – I’ve seen it spread 100 yards that way.

      Thanks again Ed!

  14. Hi Rob:

    Thanks, let us know how the potatoes come out. So often I read all these great theory articles, and the stuff just doesn’t work. No chisel plough, but I’ll make it work with the rotary plough on the BCS. Same way I’ll plant the quamash this fall.
    Overdue thanks on the info about planting potatoes in buckets. I don’t think it was you, but it was linked on your site. We were first at market and could have sold them for any price if we were the least bit greedy. We use the spent compost and vermiculite mix from the micros we grow for the soil. Actually pulled the plant out and picked off the potatoes, stuck it back in and got some more potatoes later on. We have carrots in there now, and will start some potatoes shortly.
    Good luck with the Yardening. If we were closer we would show up. To actually see the right things being done is worth the money.



    Lucky Dog Farm

  15. What are your thoughts on the Japanese fiber banana, or musa basjoo? Too much work to mulch and irrigate?

  16. Think i’ll start composting too. interesting stuff

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