Compost is a natural fertiliser made from biodegradable material. This means that organic matter is always required for the production of the compost. Composting is not complicated, but it requires time and dedication, as well as adequate space and facilities.

The composting process relies on the action of micro-organisms that act on this organic matter. What they do is to transform this element into compost through a process of decomposition. For those who do not know, organic matter is any product or element obtained from the tissues of living beings, generally plants and animals.

Benefits of composting

Compost can be made from any organic material, as long as it is not contaminated. The first materials are usually the ones listed below:

Branches and trunks from pruning that are shredded to prevent them from taking too long to decompose.

Green manure, grass cuttings, all weeds.

Animal waste: Excrement from farm animals such as cows, horses or chickens.

Marine plants.

Algae: Algae have antibacterial and antifungal agents that are ideal for protecting crops and vegetation.

Urban waste: All organic matter from kitchens or domestic use. This is commonly known as the organic fraction and is recycled in the brown bin.

Mineral supplements. Sometimes crushed powdered minerals are added to the compost in order to correct deficiencies in certain soils. Some examples include potassium-rich rocks, calcareous rocks, magnesium rocks, and natural phosphates.

What to avoid throwing into the compost?

For a good composting process, it is necessary to avoid organic material contaminated with non- biodegradable elements. The use of the following is not recommended:

  • Coal ashes.
  • Cigarette filters.
  • Waste from the vacuum.
  • Synthetic fabrics.
  •  Organic waste with a very high heavy metal content.

Factors that can influence the composting process

Some parameters must also be considered in order to make good compost. This is why, in order to have a better control of the process, the compost is made in specific and prepared facilities. The factors involved are:

Microbial population:

Composting being a process of decomposition of organic matter, it needs a wide range of populations of bacteria, fungi and actinomycetes.


It has to increase to a peak around 60-80 °C for sanitisation, then the temperature has to decrease.


The amount of humidity has to reach 40-60%. It also depends on the type of raw materials used.


It is important to keep the pH in a range of 5-8, as this prevents the microorganisms that produce the compost from dying.


This is essential for the composting process, as it is aerobic, i.e. it needs air (oxygen) to function.

Carbon (C) to Nitrogen (N) ratio: in theory the ideal ratio is between 10 and 20. But it can always vary depending on the organic matter used. A bad ratio can affect the biological process of the microorganisms.