Compost – Part 2

Here is a video tour of my compost bin (I promised a video). The bin is over a year old now, and hasn’t shown any sign of material or design flaws. It may have dry wood termites in it, but there is enough redwood that it might take a decade before they do any harm or spread anywhere else. Otherwise I think its working pretty well.

In compost part 1 I talked about reaching a balance. That balance is as much about adding things to the composter as it is about having the right composter for the household. Bins come in many shapes and sizes, so it is important to think carefully about what is needed before the compost piles up.

I built mine with balance in mind. I wanted something that could take care of all of our food waste, and all of our yard waste, yet wouldn’t take up a ton of space, or time to keep going. Turns out my design was just right, and not only can the composter handle all of our yard and kitchen waste, but it actually needs it to function well. The approximately 40 cubic foot bin was the perfect size to reach a balance for my household. It does take effort, but it isn’t too bad and is comparable to taking out the trash.

I hinted in part 1 at the idea of brown and green compost materials, so let me explain them a little. Green material is a term used to describe organic material that is high in nitrogen. Brown is something with little nitrogen and high carbon content. As you might guess something like fresh grass clippings would be considered green, while fallen leaves, brown. But why is it important?

Nitrogen is what I would call the meat, and carbon the roughage and carbs in a compost diet. Most organisms use nitrogen for the complex molecules needed in energy storage and transfer. Some examples are proteins, chlorophyll, and fats. Consequently, those are the things that microbes, bugs, animals and even us humans like to eat, but without the roughage, none of us biological creatures would be energized. I won’t get into the specifics of biological compositional analysis (not that I have a background in it), but think of how you would feel if meat was the only thing you ate.

The needed ratio of carbon to nitrogen is something like 9 to 1 (Correction: 25 TO 1), but I don’t think its super important as long as you have quite a bit more brown material than green in the composter. If you add kitchen scraps and green grass to your compost heap, and nothing else, you will end up getting a lot of nitrogen-rich molecules floating around. These will take the form of smelly fumes, and will probably spur a lot of unwanted growth like from various slimes, and maggots. In any case, too much nitrogen leads to a lot of foul activity. Sure, the waste will still compost, but you won’t like the experience. Trust me, I know from experience.

So what kinds of compost materials generate a good balance?

My bin takes all the leaves (brown) from the various trees we have, along with our kitchen scraps (very green), and anything else considered a natural waste, like fallen fruit (green), weeds (green and brown), or yard trimmings (very brown). Occasionally, I’ll even throw in shredded bills (very brown). This seems to make for a good balance. You would probably be surprised by what else I throw in there, though (like two dead rats I caught in a trap I set out. Gross and very green, plus nutrient rich.)

What surprises most people is that there really aren’t very many limitations to what will compost. There is a myth that centers on not adding meat or dairy to a compost heap. I challenge that myth. I compost everything from the kitchen except bones (these actually don’t compost well). Meat, dairy, bread, paper, you name it, it all goes in and disappears.

The only thing that didn’t break down well in my hot heap, surprisingly, were the leftover tortillas from my MFA thesis reception. I had bought them from the “regular” supermarket in bulk, for cheap, and as a result were loaded with preservatives. Those things stayed true to form in my heap for weeks, while everything else from the reception like the paper plates, beans and cheese slipped away into soilness.

I think the premiss of the myth revolves around the idea that meat takes a while to break down, and in that time becomes foul, drawing in animals. My experience is that with enough compost going on around it (a foot or two of material on all sides) almost anything will rot away before it becomes a problem. The size of the heap is the key factor. Nothing composts well in anything less than 3 or 4 feet of space, so meat would just magnify the problem of a composter that is too small (which I think is often the case.)

So, after all this what do I get from my composter?

In part 3 I will talk about what comes out of the heap, and what I think is important to know about your nitrogen in the garden. Didn’t I tell you compost was complex and fun?



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