November 29, 1995

Types of composters

There are various different forms of compost sites. Factors like the size of your yard/garden, your neighborhood, the amount of material you want to compost and the usage of the finished compost determine the type of compost site you want to maintain. The time spent caring for it is another consideration when choosing the type of compost site.
If you have doubts that you will have enough material to compost, just consider sharing a compost site with your neighbours as a convenient way to get rid of autumn leaves and grass clippings.
Note that the City of Columbia offers the plastic cylinder composter for free and the Earth Machine composter for a special price of $20 if you take part in a composting free class. See further information section for details.

From left to right: Columbia's compost demonstration site, a compost class, volunteer Larry Hine demonstrating his worm composting bin. Click on the pictures to see full-screen versions of the pictures.

Earthworm composter

Earthworm composting is a highly effective, yet very unknown method of composting your kitchen scraps and food leftovers. The same time you recycle your food scraps in a responsible way, you grow the worms you need for fishing.
All you need it a plastic bin with a solid lid. Its dimensions can be about 3' by 2' by 1' and there should be some small holes in the lid for ventilation. Additional holes in the bottom plate serve as a sewage system. To start, you can add some soil or compost from your yard, some cardboard or paper, leaves and kitchen scraps. Then you add the worms. They are available by mail-order or at hardware stores, sometimes at organic farming sites or fishing gear shops.
There are few things to consider: don't add too much organic material at once, don't let the worms dry out or drown.
Worms eat about 1/2 of their weight a day. The more worms you need, the more space they need. To harvest the finished work compost - a potent fertilizer - needs some special considerations. Furthermore, worms like temperatures between freezing and 30C, so you need to have them in a place like your garage or your basement. For detailed literature about worm composting please see the further information section.

The compost heap

The most simple form of a compost site is a compost heap. You simply place your organic material at some place in your garden and build a heap there. With time, it will turn into compost. Just add new material on top of the heap.
There are some things to consider: First, heaps spread out as they get taller. This can be stopped by installing a frame around it, made out of wooden boards, for example. Then composting on a heap isn't the fastest method because the heap has a big surface where it looses heat and moisture. With rain, minerals in your compost are washed away if you don't cover it. Finally, it may attract rodents as all the ingredients of the heap are freely accessible.

The fenced compost heap

wire fence composter This type of compost site is a simple extention of the compost heap: by providing a fence (like on the picture to the left) or a solid plastic wall with ventilation holes put up as a cylinder or box the compost is kept from spreading out when the compost stacks up. Additionally, it is easier to cover the compost site with a plastic foil, board or cardboard piece to shield it from rain.
The plastic version to the right is available at no cost from the City of Columbia to all its residents. Click on the image to see a photo of the author's compost site using the plastic cylinder.

The compost box

box composter The compost box is similar to the fenced compost heap. But the fence or plastic cylinder is replaced by a solid box made out of wooden bars or plastic.
This type of compost site offers the advantage of increased stabilit compared to the former types. You could use a lid that fits the box' top to protect it from rain. Some other features of this type of composter could be:

an opening at ground-level at one of it's side walls to remove finished compost
'stacking': the compost site is made of elements (or 'rings') of wall material that are stacked on top of each other like Lego blocks. This way you can easily increase the height of your composter as soon as it needs process more organic material (like in autum, when you need to take care of all the leaves). Additionally you could stack up a second composter from the elements when needed.

A very sophisticated version of the compost box is the 3-box-system:
3 box composter

This composter combines several concepts: it integrates three box-composters that are protected from rain by their lids or roofs. Because it has three sections, it is convenient to use it for composting: use one section (for example the left one) to compost, leave the middle section free and use the right section to store excess leaves, grass clippings or other material. The middle section comes into use when you turn your compost over simply by taking it from the left to the middle part (and back, with the next turn). See also adding materials section about turning.

Compost bins

Compost bins are very common. The most simple type of a compost bin is made of old trashcans or barrels. Some holes need to be drilled in the bottom and side walls of the bin to ensure ventilation and ground contact (the latter to get the microorganisms and earthworms into the bin).
Using a lid keeps rodents away. Some versions of commercially available bin composters have doors in their side walls on ground level that make the removal of finished compost very easy (the Earth Machine on the picture to your right is an example).
If you live in a very urban area, neighbours might be concerned about odors or insects that may appear due to the composter. In this case, you can use a closed compost bin with no or only a few ventilation holes. Due to the lack of fresh air, the composting process is slower but doesn't affect your neighbours if they live very close.

Compost tumbler

The compost tumbler is one of the fastest composing devices. It is usually made of a large drum (an old barrel), a frame and some mechanism to turn the drum. There should be a lid to add material and small ventilation holes in the drum's wall.
By simply turning the drum you mix the material in it efficiently. The drum shields rain, rodents and heat. And even the finished compost is easily harvested: it falls through the ventilation holes to the space underneath the drum where you can place a box to catch it when turning the device.
On the other hand, this is the most complex device to build or most expensive one to buy.

Lothar Fritsch, c676037@showme.missouri.edu