The carbon / nitrogen ratio of the compost.

      We must consider five factors for making a good compost. You must respect  the C / N or carbon / nitrogen, temperature, moisture, pH and oxygenation of composted materials. Each compostable material  has a C / N ratio, The straw for exemple is richer in carbon, but it contains less nitrogen. The grass clippings from mowing the lawn are richer in nitrogen and less in carbon.
The bacteria  will be the first organisms to colonize the compost. They need carbon for energy source. The optimum ratio is about 30. However, it is possible to compost with a ratio between 20 and 40 and get a good results. A lack of nitrogen limit bacterial activity and causes an excess of ammonia. Ammonia is the source of odors.

The temperature of a compost.

      Initially, the temperature of the compost is about 40 °C. Thereafter, it will rise to about 60 °C. After a few weeks, the compost will cool to room temperature.

The optimum moisture content of compost.

      The moisture promoting good composting should be around 60 %. Too dry, the compost limits bacterial activity and too much water causes a lack of oxygen for aerobic bacteria.

Changing the pH of a compost.

      Initially, the pH of the compost will become acid. Subsequently, the pH rises and it  becomes alkaline. Finally, when the compost has cooled its pH stabilizes and approximates a neutral pH (pH 7).

Oxygenation of compost.

      We want the aerobic bacteria to colonize the compost. To do this, it is important that the walls of the composter allow the air to pass. The alternation of a layer of dry carbon-rich material such as leaves of trees with a layer of wet material such as remaining vegetables helps maintain the oxygen level and C / N.