What is compost?

Compost is decayed organic matter. It is natures way of fertilizing and conditioning the soil. It helps the soil retain moisture; provides food for earthworms and other beneficial insects; reduces erosion; and helps to maintain the soil temperature.

Compost is the end result of a complex feeding cycle involving hundreds of different organisms, including bacteria, fungi, worms and insects. Composting organisms require four equally important things to work effectively:

1. Carbon for energy.  High carbon materials tend to be brown and dry. It is the microbial oxidation of carbon that produces the heat in the composting process.

2. Nitrogen to grow and produce more organisms to oxidize the carbon. High nitrogen materials tend to be green (or colorful, like fruits and vegetables) and wet.

3. Oxygen for oxidizing the carbon and fueling the decomposition process. This is why it is important to turn your COMPOSTA regularly

4. Water in the right amounts to maintain activity without causing anaerobic conditions. The ideal moisture content is about 60%: moist to the touch but not dripping wet - like a wrung-out sponge.


The correct ratios of these elements will provide the bacteria with the nutrients they need to work at a rate that will heat up the pile. In that process water will be released as vapor and the oxygen will be quickly depleted. The hotter the pile gets, the more often air and water is needed to maintain the bacteria. But, too much air or water can slow down the process, as does too much carbon or too little nitrogen.

The most efficient composting occurs with a carbon/nitrogen (C:N) mix of about 30 to 1. All organics have both carbon and nitrogen in them, but the amounts vary widely. Fresh grass clippings have an average ratio of about 15 to 1 and dry autumn leaves about 50 to 1 depending on species. So, mixing equal parts by volume approximates the ideal C:N range. It is unlikely that an ideal mix of materials will be availible at any point in time and this is fine - perfect is great, but close still works.

A good guideline to remember is: ‘two thirds brown and one third green’. Brown is carbon rich material like dried leaves, bark, twigs, straw and sawdust. Greens are nitrogen rich material like fresh garden clippings, kitchen scraps and grass clippings.

Shredding of garden waste will also speed up the composting process as it provides a larger exposed surface area for the bacteria to survive. It also helps to produces compost with a finer texture.