The Science Behind Composting: Micro and Macro Decomposers

Although composting may seem like magic, it is actually a controlled form of a natural process called decomposition. Decomposition is carried out by a plethora of organisms referred to as the FBI (fungi, bacteria, and insects). Micro-organisms are those that are too small to see with our eyes, such as bacteria. Alternatively, macro-organisms are those that we can see such as insects and worms. Did you know that a handful of compost contains more decomposer organisms than there are people on the planet? Let’s meet some of the team!

Image of soil microbes

Micro-organisms do most of the decomposition work, these include:

  • Single celled organisms: bacteria, protozoa, and yeasts
  • Multicellular bacteria and fungi: mold and actinomycetes
  • Thermophilic bacteria: heat-loving bacteria
  • Microscopic animals: rotifera and nematodes
Pill bug on leaf

Macro-decomposers usually enter the compost pile from the surrounding landscape in the later stages of decomposition and include:

  • Insects: beetles, ants, earwigs, and flies
  • Arthropods: millipedes, springtails, mites, woodlice, pseudoscorpions
  • Other invertebrates: earthworms, pot worms, slugs, and snails