Friday, August 31, 2012

Our Compost System

     When I see people throwing food or other compost able items in the trash, it makes me a little nauseous.  One of our most important limited resources carelessly tossed in a bin.  Carted off to be contaminated with unspeakable toxins and locked away forever in a huge rubber suit known as a modern landfill.  Treating our organic materials as trash is a preposterously stupid waste of time, energy, and threatens our future food security.


     We have kept a compost bin, even as apartment dwellers, for some years now.  Lately I have grown more and more conscientious about saving materials.  After trying several different systems, I have sort of settled on the following methods.

     For bins I use 4 wooden pallets with 1 piece of baling wire connecting each of the 4 top corners.  Gravity does the rest as far as keeping things together.  This gives me a roughly 4' square cube which is the ideal size.  Anything less that 3' doesn't have enough mass to really heat up and pasteurize the material.  Anything more than 4' has trouble getting moisture and oxygen inside and gets an anaerobic dead zone in the middle.  They are quick and easy to setup, and when one is full I can wire on 3 more pallets to make the next bin with a shared wall between them.  It is also convenient for unloading as any wall can be removed and the contents shoveled out.


     One very important consideration is shaping the top as it is filled.  If you continuously add materials to the center of the bin, as most of us will tend to do naturally, a water shedding dome will form.  The layers of woven fiber will shed water as effectively as a thatched roof throughout the pile never allowing adequate moisture to the center.  Instead, new materials should be added around the walls of the pile first, so that the top always looks like a bowl instead of a dome.  This will allow the pile to collect moisture and is critical if you want good quality compost without a lot of turning and watering.

     We have a bin up near the house where all of our kitchen scraps go, along with yard waste that is collected nearby.  We started with a 3' ring of 3' tall wire fencing, which worked very well.  We never flipped it or really did anything until it was completely full which took about two years.  Once in a while I would chop at the top with a shovel, but mostly we just kept adding and it kept settling.  On the occasions when too much wet kitchen waste builds up and starts to smell, I simply add some carbon.  Dried leaves, wood chips, straw, and shredded paper work great.  When we did finally remove the wire and empty it, we revealed some of the most beautiful black humus I have ever seen.  We switched to a pallet bin for that pile after a neighbor's dog started digging for goodies, and the pallets did effectively discourage her.  I am guessing that it will be several years before we empty that one.

     In the back yard is our larger composting operation that, so far, is working really well.  We compost all of our yard and garden waste with the exception of diseased or thorny material.  I am also actively searching for biomass on a regular basis for all the crazy ideas that I want to try.  Some of it goes directly into lasagna or hugelkultur beds, but most of it is composted here first.  Sometimes I will go out and find a truckload of manure someplace.  Fortunately, a family friend in the tree removal business brings us dump truck loads of wood chips periodically.  I also collect all of the used grounds from a local coffee house.  I provide them with 5 gallon buckets with lids and pick them up every couple of days.  On occasion I will get a pickup load of menure somewhere as well.


     The two primary ingredients we are generally concerned with in making compost are Carbon and Nitrogen.  The best proportions of those is the subject of much debate, and varies depending on the  application.  So I guess, and do the best I can with the things available for free.  My daily routine involves picking up a bucket or two of used coffee grounds (high in nitrogen), and adding them to the pile.  Then I cover them with wood chips (high in carbon) and a couple scoops of finished compost (activator), always taking care to maintain the bowl shaped top for water retention.

     Using my trusty compost thermometer, I have recorded temperatures as high as 165F using this construcion without any turning or additional watering.  Getting the pile to heat up is important to sterilize weed seeds and pathogens in the soil.   After a year or so I empty the bins, either turning them into a new bin, or using the material on the gardens.  Material being used is generally cleaned using a sift box I made out of some 2x4s and some 1/2" hardware cloth.  It is sized to sit nicely on the wheelbarrow.  The larger pieces go back into whatever bin I am currently filling, and what's left in the wheelbarrow is a wonderful mixture of humus and small bits of leaf mould and such.  The non broken down things around the perimeter and in the corners of the bin get mixed into a new bin as an activator.

     I used to do quite a bit of turning, but that's a lot of work.  I figure you can reduce the year or so it takes a pile to break down by half every time you turn it.  The minimum time seems to be about two weeks, but that's for finely shredded material in ideal conditions that is turned almost daily.  Who needs compost that fast anyway?  As long as I can get it to heat up good at least once, I find I am content to wait.  These days I am much more focused on gathering biomass anyway.  I keep a trash can with a secure lid and a couple of bricks under the bag just behind the pile.  The bricks keep it from blowing away and it is really handy to have nearby for the odd bits of plastic and such that always seem to get into the compost.

     So that's it.  I get some excercise without it being a huge chore, and I don't have to worry about where I am going to get Good clean compost for the next new garden.


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