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Tuesday, 21 January 2003

The Problems of Urban Composting

Permit me, dear reader, (if I have any), to think aloud for a moment about composting in the city. There are some problems specific to urban composters that suburban dwellers and country folk don't have. One of these is a space limitation. Also, urban people are less likely to have gardenning tools such as pictforks or shovels. Your city resident may only have a containrer garden (if that) and no actual plot of dirt to call her own. Also, urban dwellers are more likely to have a ready supply of "wet" matter (also known as "green") than "dry" matter (also known as "brown"). In short, the urban composter may be an apartment dweller with a small deck, no dirt lot or shovel who only has food wastes to compost.

What the is the ultimate compost bin for such a person? First of all, any compost bin on earth must be free of toxic stuff that will leach into the dirt that's being made. This seems to rule out bins made of pressure treated lumber and some plastics, like PVC. Any bin that contains food wastes, even just carrot tops, must be rodent-proof. An ideal apartment bin would additionally be space efficient and not require a shovel of any kind. The ideal solution seems to then be worm composting. You can feed your worms all sorts of food wastes including cooked foods, afaik, and I've heard of some self-straining models, where removing the compost from the worms involves no more than pulling two pieces apart. Instant dirt. Takes up as little space as you want ti to. the worms are even edible. There are a few (as in one or two) cookbooks for how to eat your worms, should you get to be very hungry or decide you have an excess population. What criteria you would use for that, I don't know.

However, worms die. Lazy people continually have to go get new worms because they dry out or go hungry for a while. I guess you could eat half of your worms before going on vacation, but that seems like an intense dedication to composting would be required. Also, all of the worm bins I've seen have been made of PVC. So then, what would be an ideal solution for a lazy apartment dwelling composter who doesn't want to eat worms before travelling?

Since both space and brown matter are at a permium, the apartment bin should contain some form of brown material storge. Perhaps a hopper could be positioned over the main part of the bin so that brown matter, such as peat could be stored in there and then released into the bin via a lever or something. Also, an ideal bin would have a turning over mechanism built in. I have a PVC bin that's round and on rollers, so that it can be turned over just by rolling it around. It's efficient for space usage and requires no tools, although the plastic is a problem. Using a shovel to turn compost seems to have the side effect of breaking up big pieces of things. Periodically, a grapefruit will sit too long uneaten and be sent whole to the composter. Right now, this has a tendency to attract fruit flies, since the grapefruit does not get broken into little pieces. This design also is a bit hopper unfriendly, since the bin openeing and the hopper would need to be lined up before peat could be added.

Compost bins also need to sit a while before dirt can be removed. It's necessary to have two or three bins, so one can be aging while material is being added to another. So the ideal bin would spin, would have some sort of brown matter storage, would break up big pieces of things, would, perhaps, store aging compost in addition to "active" compost (which is being added to daily) and would take up very little space. Additionally, it would be created out of non-harmful materials that ideally are somehow recycled, recyclable or both.

Ok, so this had me thinking. What if the brown matter was somehow built into the bin. I began picturing a bin made somewhat out of metal, but also out of the kind of compressed peat used for some pots. Then a hopper is no longer needed. So what you have is a big metal box, in which there is a round holder of aging compost. There is an identical round holder above this to hold active compost. It's basically a wire frame with strong pegs sticking out the ends, at the center point, so it can rotate. The frame is light, since it's designed to hold a heavy peat composting container. This container keeps out rodents and provides brown matter. The frame has some long spikes that stick inwards. These are designed to piece the peat. They have a dual function of holding the peat in place and breaking up large objects like whole grade fruit. The frame can split open to completely empty it and to load in a new peat frame. It also has a door on it, which must line up to a door punched in the peat, so that the uer can add new vegetables. Both the top bin and the bottom bin should be spun periodically. The bottom bin is in a box (with no top), to catch the dirt that falls out as the peat completely degrades along with the compost. The whole thing, including the bottom box, the two round frames and the mount above the box (which holds up the top round frame) is made of recycled steel. Except, of course, for the peat pieces.

Maybe it's too big. It's probably too expensive. buying new material every go-round may put-off some users. I'd write more about this endlessly facinating topic, but I must go do something about the dern fruitflies getting into the house again.

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