I make a lot of compost. I would say I make a ton of compost, but in reality I make *several* tons. Every year. At home. In the ‘burbs. If you want to follow the path of Gaia’s Garden – you almost certainly need immense amounts of organic matter. We live in a newer subdivision so without mature trees we have to get creative to get our biomass for composting. In years past I resorted to tapping into local waste streams, namely our local coffee shop to the tune of 30 gallons of grounds and sandwich trimmings every week. That volume eventually inspired me to build my Compost Bin of Dreams to handle it. The gorp from the shop was good, though it was heavy and was difficult to aerate. To our horror that shop closed down this past Spring due to the recession and we lost a significant element in our local community. It was an awful tragedy to the owners, whom we knew. As time went on and the grieving passed, and I realized I needed to find another source for compost material. I had also recently bought a chipper and learned the joys of brush wood composting. Here is my new system which allows me to make up to 15 yards a year:
To compost at this scale – 5-10 yards a year – you need a lot of material. You can count on a 75% reduction in weight due to loss of water and half the carbon in the decomposition process. A yard of compost weighs in at 540#’s or so – so you need literally tons and tons of material. That means you need to get it for free. With my local grounds dried up, I turned to other waste streams, in this case brush and wood chips from our local municipal yard (and local farms when we clean up the hedgerows) as well as weeds from fallow feeds at the farm. Personal favorites from our local / free waste stream:
- Box Elder
- Corn/Sunflower Stalks
- Straw after fall decorations
There is not many food scraps in here, though we continue to add ours and I kick in lawn clippings as needed to fire up a pile. I certainly could be pounding the pavement of the local grocers and restaurants, but have chosen not to. First, that would again lock me into a pickup schedule and I am getting waaaay too busy. Second, the waste streams from those outlets are almost pure nitrogen and if aren’t picked up daily turn into a stinky, anaerobic mess when I get them. I have pushed my neighbors quite a bit this past year, so want to keep this recent uptick in activity pleasant. Sourcing my own brushwood and weeds keeps me in control.
Trailer: To carry all this material you need something rather large, but I not necessarily a truck. I do all of this with my 90hp TDI Golf and a 5×8 trailer from Farm and Fleet I bought 3 years ago for $700. Trailers are useful as they are MUCH lower to the ground to make unloading/unloading easier than a truck, and you only use it when you need it. I get 48 mpg on my Golf without the trailer. With it loaded I take a 20% mileage hit and a bit of wear and tear on the brakes. I also upgraded the suspension with higher spring rates when I needed to replace them, but that is cause I am weird. Even with all of that it still beats the hell out of 15mpg in a 1/2 ton truck.
Chipper- I resisted this for years, but finally caved. My chipper is a Bio – 80 from BCS and I got it used for $550. They are very hard to find and would cost over $1000 new. Alternatives would be a 3″ model from DR or Bearcat, but again – be ready for sticker shock as they are EXPENSIVE. Luckily, they can be found on Ebay, and more rarely on Craiglist. Avoid the “craftsmans” type ones like the plague. They are underpowered, poorly designed, and worse than useless. This is also why you see them on Craiglist by the dozen. This is almost commercial level work, and you need Real Tools. The rub: To compost brush, you need a chipper, and chippers use fuel. Mine is averaging less than a gallon for every 7-8 hours of run time, which is more frugal than a typical gas lawn mower, which I haven’t used for more than 8 years. A larger pto model could work on a tractor running on methane, ethanol, or homemade bio-deisel. This Briggs could run on ethanol as well. Methane too, but it would be a bit harder to put the tank somewhere.
Bins – I wrote this up in detail in my Compost Bin of Dreams. I have a 4 bin system that can handle over 2000#;s of material at a time. It is a flow through system – start on the left and turn each bin to the right. When the 3 turnings are done, most of the compost is ready. When I compost sod, or other marginal material, it usually isn’t done so it goes into my 30 cu ft outdoor vermi-composter for “finishing”.
This is the real beauty of this system. You read any book on composting and they say if you really want an ideal pile you need to gather the materials before hand. But, since that is nearly impossible, they then tell you about how you can compost your lawn clippings (2-3 cu ft at a cutting at my house) kitchen scraps (half a cu ft), soiled napkins etc. Most homeowners will never fill a bin even after a year unless they have mature trees to add the leaves in. Given the amount of organic matter we need to put back into our soils we need to do far better than that.
1) Gather your materials I ask you to refer again to the picture of the loaded trailer earlier in the post. This pile chipped up to about 37 cu ft of material. That will settle to about a yard, maybe a bit less. What you can’t see in the picture is that it is not ALL brush. The top 3/4 is willow, maple, and pine. This is the carbon for the pile. I try to only use green brush as I want the moisture, sugary sap, and nitrogen from the leaves. Green brush still has all the water soluble nutrients in it – and you want those in your compost to feed the microbes which then feed your plants. Under the compost is about 300#’s of fresh cut, mature (6′-9′ tall) lambsquarter. It is also just getting ready to set seed. Normally adding several million weed seeds to a pile would be asinine, but reference the compost thermometer on the top – these piles get wicked hot and stay over 130 degrees for over 2 weeks solid. They should kill the weed seeds, and lambsquarter when young is a tasty treat whilst weeding and it weeds easily. Brush bulk is deceiving – that huge pile is barley 8 cu ft chipped, so I also added .3 yards of wood chips from the city pile to be shredded to offset the nitrogen of the lambsquarter and help build humus. Remember it is lignin and cellulose that build humus, and for that you need woody material like leaves, straw or twigs.
Entropy Once the materials are on site, limb the larger brush with a loppers or axe to ensure easy chipping. Do this before you fire up the chipper to save on fuel. I typically start with the brush as its close to perfect on the C:N ratio if its real leafy. I chip the trunks until the stem is under 3/4″ and then I shred the rest. As I go I keep an eye on the discharge – if its too brown I add more green material; the mixing starts this early. Once the brush is done I then move to the green weeds. These clog even my chipper very quickly. Luckily my shredder has a removable debris screen. By opening the screen it is able to shoot out the material after beating on it for a bit. I like the lambsquarter as it is long enough that I can hold onto the stalks as I feed it – otherwise the shredding blades can pull it through too fast. If something comes out unprocessed I refeed it later. Every cu ft of material or so, I close the debris screen again and add the wood chips. This clogs the machine every time, so I keep a tamping stick like a 3′ chunk of 2×4 or 4″ limb thats too big for the chipper to encourage the material to enter the shredder. This is the slowest part, but oh so worth it since the shredded wood chips are very fine and decompose very quickly for a carbon. GORGEOUS humus.
Building the Piles.
As the material builds up from the chipping I add it to my 10 cu ft wheel barrow. Half way through I pour in a 5 gallon bucket of rainwater from a rain barrel, and add another when the barrow is full. This is vitally important. As Jean Pain taught us – brush needs A LOT of water to decompose well. Using rainwater is important for two reasons. First, rainwater is free from the chlorine present in municipal water which would inhibit bacterial growth for a day or more. Secondly, rainbarrel water is bacterially active. It is churning with colonies of bacteria and fungal spores and almost certainly helps jumpstart the pile. Each heaping barrow load (13 cu ft) gets 10 gallons of water – so I end up with 30 gallons of water added to each bin. Actually, composting is the prime us of my rainbarrel water, as once the compost is in the soil, I barely need to irrigate! I might try soaking the material as Jean Pain did, but this process goes so fast it doesn’t seem necessary. As I add the material to the barrow I continue to eyeball the mixture and scoop up greener or browner forkfuls as I go to mix it well. The end goal is a perfectly mixed and soaked pile from Day 1. Finished piles should look like this:
Pile the piles as tall as possible as they settle significantly. I lightly tamp the piles with the fork as I fill them, especially around the edges where the friction on the sides resists settling. My bins hold 1.3 yards and I mound them 18″ over the top. If you don’t have enough material it doesn’t seem to matter if you add to it in a week or so, just know that that material will need an additional week to decompose.
A compost thermometer is vital to this process. The piles heat up almost immediately – the temp shot at the beginning I took this morning I the pile I built yesterday – about 15 hours ago. DANG. 160 is the highest you should let the piles get. The first one of these I built hit 173 – that is far too hot and at the point of concern that it may begin spontaneously combusting like a hay barn. To slow it down I have added more carbon to the mix. Watch the pile temp almost daily – as it drops below 125, turn it again, and add more water. This time is may only hit 140, wait a bit until it drops to 115 or so and then turn it a third time. The 3rd turning should be done at about 105 degrees, but at this point you are almost done, and the pile should be left to “mellow”. This can take months, so I typically put some in my vermicomposter and spread the rest as mulch which I top dress with some straw in the veggie garden, or wood chips in the permaculture beds. The microbes will continue munching on it in place.
This system is not for everyone. It takes serious equipment and a serious intent. I have almost $2000 invested: $600 for the chipper, $700 for the trailer, $500 in the bin. And that is using used equipment.
But the results! By spending the extra investment on the front end in material sourcing and prep you are able to take waste brush and turn it into compost in 3-5 weeks. That means at a 4 week average and my 4 bin system I can reasonably do 15 yards of finished compost in a 6 month composting season. In reality some batches will take longer, but I also compost more like 9 months of the year. 15 yards is 4 tons of finished compost and enough to spread 5000 sq ft 1″ thick. To do this I would need a trailer load of material a week for 24 weeks – about 12 tons of raw material. It will take alot of organic matter to rebuild our soils, and the 8000 pounds of compost I could put back into my yard is roughly 4 tons of carbon that isn’t in the atmosphere anymore and will continue to sequester more as it aids the growth of the plants in my gardens.
Hopefully this system will help you in your quest to rebuild your soils and sequester carbon naturally to help heal the planet as we feed our families.
Be the change!