The World's Ultimate Compost Bin

As a Composting Trainer for the Columbia Public Works Volunteer Program, I am always amused by the modern pursuit of a single device that will work perfectly for everyone, everywhere, under every possible set of conditions. One of my favorite sayings is, "If it says one size fits all, it won't fit anyone." So the world's ultimate compost bin is one that meets the following criteria:

1. A bin that you can afford.
You may not be able to afford a $3,000 solar powered, motor driven composting facility. A simple, cheap, but effective compost bin can be made of newspaper, heavy string, and small sticks. (See the diagram and instructions for how to construct one.) A newspaper bin is especially good for batch composting things like leaves. A farmer can tell you how fast hay rots when the bales are turned on end.

If appearances are not a main concern for you, either because you can screen off the bin or because you have a large enough property to keep the bin out of sight, a free, biodegradable bin is as close as a store that sells appliances. Collecting a shipping box from a washing machine or dishwasher and punching some aeration holes in the bottom and sides gives you an instant compost bin that will eventually turn into compost itself. The shipping box and newspaper bins are both static pile composters which means they are not to be turned or stirred. This results in a slower process but is a perfectly acceptable method of composting.

You can also build a very attractive and highly efficient unit very cheaply out of wooden pallets. (See the diagram and instructions for how to construct one.) Wood is an ideal material for compost bins for several reasons. It is biodegradable, strong, a fairly good insulator, makes an attractive compost bin, and when coupled with screen provides protection from insects and vermin. It also protects the compost from the drying rays of the sun and wind, and it is available everywhere.

Wooden pallets are often discarded after a single use or when broken. You can usually get them for free or very cheap. If you don't know of a source through your employment or friends you can purchase pallets very inexpensively from Civic Recycling on Brown Station Road.

2. A bin that is made out of recycled, biodegradable materials.
One of the main reasons for composting is to lessen the flow of materials into landfills. If bins are made of non-recyclable plastics, for instances, they will wear out and need disposal. In the future landfills could be filling up with old, worn out, plastic compost bins.

3. A design that provides an ideal growth environment for the hundreds of organisms that form a community of waste degraders and that works for your lifestyle.
How well your compost bin controls the environmental parameters of moisture, humidity, aeration, and temperature, determines how fast your wastes will break down.

A commonly suggested design is the woven wire bin. The biggest problem with this design is excessive wetting and drying. This means the bin provides ideal conditions only a small fraction of the time in our Missouri climate. The wastes are held up for the sun and wind to do the maximum drying. Dry wastes do not compost. Then, when it finally does rain the pile either gets too wet or the excessively dry material sheds the rain and stays dry. If it should get too wet, anaerobic digestion takes place which causes foul odors. If it sheds the rain _ have you ever noticed how much harder it is to get a completely dry sponge to soak up a spill_ it stays too dry and nothing happens. These problems can be overcome by wetting the pile as you build it and then covering the pile with white plastic if your compost pile is in the direct sun or black plastic it is in the shade. Be sure to cut some aeration holes in the plastic to allow the pile to breathe. Don't cut the holes in the top because it will allow unwanted water to enter the system. You can use rocks, bricks, soil, or boards around the base of the compost pile to hold the plastic in place. But the pallet bin is really a better option.

There are dozens of designs for compost bins to fit into almost any lifestyle. The first step is to decide what you want the compost bin to do for you. Many people have sedentary jobs and need some physical exercise. Having a composting system that requires regular turning with a shovel can be the best choice. Regular turning also speeds up the composting process. The Columbia Volunteer Program, University Extension, or the public library all have information on compost bin designs. You can also visit the Compost Bin Demonstration Sites at Oakland Middle School and the Community Garden on 9th Street to see a number of different types of bins.

Other people are so busy and overworked they don't have the time or energy to turn the compost pile. Most modern commercial composting companies use a composting system called Aerated Static Piles. Instead of regularly turning the piles to expose all parts of the pile to the fresh air, they run slotted flexible pipe throughout the pile to allow the air to flow through the pile. The same technique can be used in a small scale unit. Slotted flexible pipe is used underground to drain water away from buildings and is available at most building supply stores. Simply cover each end with screen or old pantyhose to prevent vermin from living in the pipe, and bury it in the pile with both ends exposed. If the pile is fairly large, bury one or two pieces of pipe in a U-shape with both ends poking up out of the top of the waste material. See below for suggested use of pipe system.

The design of a compost bin is limited only by the imagination, but the best bin is one that fits the needs and lifestyle of the composter who uses it.

4. Finally, a compost bin that is legal.
Where you live determines what waste disposal regulations you have to follow. If you live in Columbia, composting is legal unless it becomes a nuisance because of odor or is attracting or providing a breeding site for flies or rats. If one of your neighbors calls in a complaint about your compost pile to the Health Department it will be investigated. If it is determined there is a problem you will be given seven days to fix the problem and you will be referred to the Columbia Volunteer Program for help in solving the problem and maintaining the pile correctly. If you are a renter you will need your landlord's permission to start a compost pile. Even if you own your home, you may be restricted by neighborhood codes.

Many rural people can legally have a simple, open pile in the backyard under the old oak tree. Open piles are cheap, but the drawback is that they are slow, prone to excessive wetting and drying, offer poor insect and vermin control, and can be very unsightly.

Building a Newspaper Compost Bin
Assemble newspaper, heavy string, small, fairly straight sticks and compostable materials (A).

Cut several small matching holes along the edge of several thicknesses of newspaper. If you fold the edge and cut a >, it will form a diamond as pictured (B). Add a few holes scattered throughout the face of the paper to provide aeration. Don't make too many aeration holes.

Lay the newspaper down with ends overlapping and diamond cuts matching. Weave a stick in and out through the diamond cuts to hold the newspaper together (C).

When you have enough sheets to form the diameter you want, overlap the two ends and weave them together. Three sheets should be a manageable size, but it can be bigger if you like. You will wind up with a cylinder of newspaper (D).

Fill the cylinder with compostable materials like leaves and grass clippings. Tie a few bands of stout biodegradable string around the bin during the filling to provide extra support (E).

You will end up with a bale covered on the outside with newspaper. You can even remove the support sticks once the bale is made and use them over and over if you have done a good job of tying the string.

The Baffled Compost Bin
The Baffled Compost BinA moderately priced compost bin that is very efficient A moderately priced compost bin that is very efficient is the baffled bin. It works so well because of moisture, humidity, and air control. Hot dry wind can dry out any material it comes in direct contact with. The baffles (see illustration) prevent hot dry air from coming in direct contact with the composting materials. As the air is drawn into the bin it swirls around and slowly picks up moisture before being drawn into the interior of the pile where composting is taking place. Having moisture laden air drawn into the center of the pile is very beneficial because compost piles dry out from the inside out. The moisture laden air also stimulates many microorganisms because they can draw their moisture from the air. The baffles provide excellent control of large vermin like rats and mice and if screen is used to cover the openings there is excellent insect control. The baffled bin will compost as efficiently as any high priced system and is very attractive if built with quality materials.

Construct five baffled panels for your bin. This will give you four sides and a top. A top is very important on a baffled bin to moderate the air flow. Construction is similar to the pallet bin. In fact, pallets can be turned into baffled panels by nailing boards and spacers onto them. For ease in turning the pile or getting at the finished compost, have one side open out or detach. The top panel can either be hinged so it can be raised or just rest on the top edges of the four sides.

Building A Pallet Bin
Assemble four wooden pallets, six fence posts, some boards, nails, and wire.

Try to get pallets the same size as it will make construction easier, but they don't have to be exactly the same size. You can join the pallets together using six steel fence posts, some 1" x 4" boards, galvanized wire or coated heavy copper wire, or galvanized nails. But be creative. If you have materials at hand like untreated wooden posts or nylon rope instead of wire, use them.

Choose the largest of your pallets to be the roof and measure it's length and width. This will be the maximum outside dimension of the walls of your compost bin. Draw a square or rectangle that size on the ground where you will be placing your bin. Next measure the other three pallets and lay out a C-shaped design smaller than the roof (see top view).

Drive two fence posts for each wall spaced about a foot from each end. Drive them in so the top of the fence post is lower than the top edge of the pallet. This will keep them from sticking up over the top edges of the sides and interfering with the roof. Wire or tie the pallets to the posts.

The pallet you have chosen for the roof needs to be modified for maximum effectiveness. What you want is a roof that doesn't leak too badly. Use the 1" x 4" boards to cover the open spaces between the boards that make up the top surface of the pallet (see the roof).

Then put the roof on and wire it to the pallets used for the walls. Some kind of front door would improve effectiveness, even one as simple as a heavy canvas flap with a board stapled to the bottom. Or purchase five pallets instead of four and wire or tie the fifth to the front as a door.

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