How composting works

Composting speeds up the natural decay of organic material by providing the ideal conditions for detritus-eating organisms to thrive. The result is nutrient-rich soil that helps plants grow.

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The key to effective composting is creating an ideal environment for micro-organisms to thrive: warm temperatures, nutrients, moisture and plenty of oxygen. There are three main stages in the composting cycle.

The first stage typically lasts only a couple of days. During this time, mesophilic micro-organisms (those that thrive in temperatures of 20°C to 45°C) begin breaking down the biodegradable compounds. Heat is a natural by-product of this initial process, and the temperature rises quickly to more than 40°C.

Mesophilic micro-organisms are replaced by thermophilic microorganisms, which thrive in higher temperatures and break down the organic materials. (Higher temperatures are more conducive to breaking down proteins, fats and complex carbohydrates.)

The temperature continues to rise and, if not closely watched, the compost pile can grow hot enough to eventually kill off the beneficial micro-organisms. Aeration and turning over the pile can help keep the temperature below about 65°C, as well as provide additional oxygen and new sources for the thermophilic micro-organisms to break down.