How Compost Bins Work – The Full Guide

All you need to know about how compost bins work is a thorough understanding of some basic principles, and nature does the rest. When making compost bins, you naturally create a suitable condition for the rotting and decay processes of plants and other organic matter.

In this post, we will show you how compost bins work and why composting is important.

The composting processes

According to the United States Department of Agriculture (USDA), composting is a process that speeds up the natural decomposition of organic matter by providing a suitable environment for detritus-eating microbes to thrive. The result of the decomposition process is a fertile soil rich in nutrients that help trees, garden plants and crops to grow.

Microorganisms play a vital role in the decomposition process. The goal in every composting process is to create a suitable environment for the microbes to thrive.

The process of composting refers to the activities of microorganisms on the ground. They break down the organic and carbon-containing kitchen wastes into smaller pieces. This is responsible for the production of humus-rich soil with a high proportion of phosphorus, potassium, nitrogen, and fibre. These microorganisms require enough oxygen to function effectively, which you must provide by turning all the compost material into your compost bin.

To get good and fertile compost, you need to provide the necessary conditions required for efficient decomposition. These include:

Balanced carbon to nitrogen ratio

Carbon to nitrogen ratio plays a key role in composting. To get high-quality compost, you need to calculate the appropriate proportion of carbon and nitrogen, which is usually between 25:1 and 30:1.

  • Microbes feed on both carbon and nitrogen.
  • Nitrogen provides nutrient for growth and reproduction, while carbon gives the microorganisms energy released as heat and carbon dioxide. 

If the amount of carbon present in the compost heap is too much, the decomposition process will occur at a slower rate, and generate less heat. On the other hand, if there is an excess amount of nitrogen in a pile, it will increase the, compost pile’s acidity, which can be toxic to the beneficial microorganisms present.

Adequate oxygen

Oxygen is a key element required by aerobic microorganisms to survive and function effectively. Therefore, to provide balanced conditions for aeration, you need to turn your pile daily, or at least once in three days. This is best achieved using a compost tumbler with a handle.

You must note that without proper aeration, the wastes and organic matter will not break down properly.

Adequate amount of water

You also need an adequate amount of water to get high-quality compost. The level of the moisture of the composting materials determines the quality of the compost itself.

Generally, the heap and composting materials need to be well moist. Water is vital for the effective working of the microorganisms in the compost pile. However, you must be extra careful not to add too much water as the composting material can become slimy and smelly.

Adequate and Balanced amount of soil

Adding soil to the composting material is one of the best ways to providing enough fungi and bacteria for composting. This also guarantees the smooth running of the entire process.

Stages of the composting cycle

There are three key stages in the composting cycle, and each stage requires different types of microorganisms to thrive effectively.

Stage 1

Usually, between the first 2 to 7 days, during which microbes that thrive in temperatures of 20 to 45 Celsius (mesophilic microorganisms) begin to physically break down the biodegradable composting materials into smaller particles. At this initial stage, heat is a natural by-product, and it raises the temperature to about 40 degrees Celsius.

Stage 2

during the second stage, the mesophilic microorganisms are quickly replaced by microbes that thrive at a higher temperature (thermophilic microorganisms).

This process can last from a few weeks to a couple of months. The thermophilic microorganisms work effectively to break down the composting materials into smaller pieces. The higher temperatures are more suitable for the breakdown of complex carbohydrates, fats and proteins.

Consequently, during the second stage, the temperature can keep rising and, if not carefully watched, it will get the compost pile excessively hot and eventually kill the beneficial microbes. At such conditions, techniques such as aeration will help maintain a steady temperature.

Stage 3

The third stage of the composting cycle usually lasts for about five months. It begins when the thermophilic microbes use up the available supply of biodegradable compounds. At this post, the temperature begins to drop drastically to a point where the mesophilic microorganisms can resume control of the compost pile and complete the breakdown process.

Microorganisms that help in the composting process

There are two main classes of microbes that help in the composting cycle, known as aerobes and anaerobes.

The aerobes are mostly microorganisms and bacterial that require oxygen levels of up to 5 per cent to thrive. They are the most efficient and important composting microorganisms needed to produce high-quality compost. The aerobes consume all the organic wastes and chemicals such as magnesium, phosphorus, and nitrogen, which are the essential nutrients needed by plants to survive.

Anaerobic microorganisms are microbes that do not require oxygen for survival. They do not process organic matter as effectively as aerobic microbes. The anaerobes produce chemicals that are toxic to the plants, thereby causing the composting piles to stink due to the release of hydrogen sulphide with a rotten egg smell.

Over 80 per cent of the microorganisms found in compost piles are bacteria. The remaining percentage are species of yeasts, mould and fungi.

In addition to the aerobic and anaerobic microbes found in compost piles, other beneficial creatures such as worms, centipedes and pill bugs will also find their way into the compost pile if the conditions are favourable. They will also assist in breaking down the kitchen waste and other organic materials into nutrient-rich soil.

What to compost

  • Fireplace ashes
  • Hair and fur
  • Dryer and vacuum cleaner lint
  • Cotton and wool rugs
  • Woodchips
  • Sawdust
  • Hay and straw
  • Houseplants
  • Yard trimmings including grass, leaves, branches, and twigs
  • Shredded newspaper, paper and cardboard
  • Nutshells
  • Teabags
  • Coffee grounds and filters
  • Eggshells
  • Fruits and vegetables
  • Garden wastes

What not to compost

  • Dairy products, eggs, meat products and fats
  • Yard trimmings treated with chemical pesticides
  • Pet waste (including dog and cat faeces and used cat litter)
  • Diseased or insect-infested plants
  • Dairy products, eggs, fats and oils, and meat or fish bones and scraps
  • Coal or coal ash
  • Certain types of tree leaves and twigs such as black walnut


Are you still curious about how compost bins work (multi-purpose compost)?

We believe the information we shared in this post has helped address your curiosity. If you still have some unanswered questions, feel free to reach out to us in the comment section, and our team will gladly respond.

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