The 'plastic bag' method

Use of plastic rubbish bags is perhaps the simplest way to make compost. The bags are easy to handle, and require minimal maintenance. To make compost using this method, the plastic bags should be alternatively filled with plant wastes, fertilizer and lime. About one tablespoon of a garden fertilizer with a high nitrogen content should be used per bag. Lime (one cup per bag) helps counteract the extra acidity caused by anaerobic composting. After filling, add about 600ml of water. Close tightly. Set aside for six months to a year. Bags can be set in a basement or heated garage for better decomposition during winter months. Using garbage bags requires no turning or additional water after closing. The main advantage of composting in garbage bags is that it requires little maintenance; however, because oxygen is limited, the process is slow.

The '44 gallon drum' method

The barrel or drum composter generates compost is a relatively short period of time and provides an easy mechanism for turning (Figure 1). This method requires a large barrel or drum with a secure lid. Be sure that the barrel was not used to store toxic chemicals. Drill 6-9 rows of 5cm holes over the length of the barrel to allow for air circulation and drainage of excess moisture. Place the barrel upright on blocks to allow bottom air circulation. Fill the barrel ³/4 full with organic waste material and add about ¹/4 cup of high (approximately 30%) nitrogen containing fertilizer. Apply water until compost is moist but not soggy.

Figure 1.

Every few days, turn the drum on its side and roll it around  to mix and aerate the compost. The lid can be removed after turning to allow for air penetration. Ideally, the compost should be ready in two to four months. The barrel composter is an excellent choice for the island dweller with a relatively small garden.

The bin method

For larger quantities of organic waste, bin type structures are the most practical. As an example, a circular bin can be made by using a length of small spaced woven wire fencing and holding it together with chain snaps (Figure 2). The bin should be about three to five feet in diameter and at least four feet high. A stake may be driven in the middle of the bin before adding material to help maintain the shape of the pile and to facilitate adding water. With this design, it is easiest to turn the composting material by simply unsnapping the wire, moving the wire cylinder a few feet, and turning the compost back into it.

Figure 2.

The traditional three bin method

A very efficient and durable structure for fast composting is a three-chambered bin (Figure 3). It holds a considerable amount of compost, and allows good air circulation. The three chambered bin works on an assembly line idea, having three batches of compost in varying stages of decomposition. The compost material is started in the first bin and allowed to heat up for three to five days. Next, it is turned into the middle bin for another 4-7 days, while a new batch of material is started in the first bin. Finally, the material in the middle bin is turned into the last bin as finished or nearly finished compost.

Figure 3.

To make a three-chambered bin, it is best to use rot resistant wood or wood treated with an environmentally safe preservative or a combination of treated wood and metal posts. Unless the wood is treated or rot resistant, it will decompose within a few years. Each bin should be at least three to five feet in each dimension to contain enough volume to compost properly. Using removable slats in the front offers complete access to the contents for turning.

The compost pile should be located close to where it will be used and where it will not interfere with activities in the yard or offend neighbours. From the aesthetic point of view, it is best to compost in a location screened from view of both your property and your neighbour's property. Examples of good locations for the pile include: near the garden or between the garage and house. Do not locate the compost pile near a well or on a slope that drains to surface water such as a stream or a pond. The pile will do best where it is protected from drying winds and in partial sunlight to help heat the pile. The more wind and sun the pile is exposed to, the more water it will need. Locating the pile too close to trees may also create problems as roots may grow into the bottom of the pile and make turning and handling the compost difficult.

Organic wastes, such as leaves, grass, and plant trimmings are put down in a layer eight to ten inches deep. Coarser materials will decompose faster if placed in the bottom layer. This layer should be watered until moist, but not soggy. A nitrogen source should be placed on top of this layer. Use one to two inches of livestock manure, or a nitrogen fertilizer such as ammonium nitrate or ammonium sulphate at a rate of one third of a cup for every twenty five square feet of surface area. If these nitrogen sources are not available, one cup of 10-10-10 fertilizer per 25 square feet of surface area will also suffice. Do not use fertilizer that contains herbicide or pesticide.

Most compost piles should initially be prepared in layers. This will facilitate decomposition by insuring proper mixing. 

To prevent odours and hasten decomposition, the pile must be turned occasionally. Turning also exposes seeds, insect larvae, and pathogens to lethal temperatures inside the pile. 

Reasons for the pile not heating up may be due to: too small a pile, not enough nitrogen, lack of oxygen, too much or not enough moisture. The pile should be turned when the temperature in the center begins to cool. This will introduce oxygen and undecomposed material into the center and subsequently regenerate heating. The composting process is essentially complete when mixing no longer produces heat in the pile.

Generally, a well managed compost pile with shredded material under warm conditions will be ready in about 2-4 months. A pile left unattended and material not shredded may take over a year to decompose.