In the guide below, we outline the different types and method of composting.
We discuss aerobic vs anaerobic vs vermi composting, hot vs cold composting, and the different ways/methods to make compost.
We also discuss other relevant aspects of composting, such as different waste types used for composting, and more.
Firstly, What Is Compost, & What Is Composting?
What Is Composting?
Composting is the process of decomposition of organic matter/material
Some describe composting as the ‘recycling of organic matter’
What Is Compost?
Compost is what is left over after the organic material has decomposed (i.e. finished the composting process)
Compost can take several forms though – we list the range of ‘composts’ in the guide below
Different Types Of Composting
Composting can be categorised in several ways, such as:
– Aerobic vs anaerobic vs vermi composting
– Hold (active) vs cold (passive) composting
– And, other categories or types of composting
There’s also different methods of carrying out the different types/categories of composting, in addition to different forms of compost.
Aerobic vs Anaerobic vs Vermi Composting
Aerobic, anaerobic and vermi composting are three of the main types of composting.
– Aerobic Composting
Aerobic composting is the decomposition of organic matter involving microorganisms with the presence of oxygen
It usually takes place in open space and open air
Compared to anaerobic composting, aerobic composting might be a quicker process (could take a few weeks vs months for anaerobic composting), involve higher temperatures/more heat, be turned more frequently, and not produce as odorous gases.
The heat also kills pathogens and weed seeds in the compost pile. According to agric.wa.gov.au, composting that maximises aerobic conditions over anaerobic conditions results in ‘… a stable humus that is weed-free and safe to use for agriculture, landscaping, gardening or other purposes.’
Aerobic composting is sometimes referred to as hot composting because of the heat produced.
Aerobic composting can also be referred to as active composting because of the turning of the compost material involved.
– Anaerobic Composting
Anaerobic composting is the decomposition of organic matter involving microorganisms (microbes like bacteria or fungi) without the presence of oxygen
It usually takes places underground, or in pits or trenches (but also in landfills)
Compared to aerobic composting where majority of the gas emitted is carbon dioxide, majority of the gas emitted during the anaerobic composting process is methane
Anaerobic composting also usually takes longer, and involves lower temperatures
Anaerobic composting is sometimes referred to as cold composting (because of the temperature), or passive composting (because it doesn’t require turning)
– Vermi Composting
The decomposition of organic matter (such as food scraps) using various species of worms, instead of microbes involved in aerobic and anaerobic composting
Vermicomposting can be done in several ways, with worm composting bins and worm farms (also known as vermicomposters) being common for backyards. Worm farms can be bought from shops. Worms and waste are added to the top section of the worm farm, and vermicompost (or worm compost) is produced at the bottom
Soil beds can be used for vermicomposting too
A nutrient rich soil can be the outcome of vermicomposting
* Black Soldier Flies Composting, & Other Microorganisms Used For Composting
Other microorganisms can be used for composting too (although not as commonly as the above types of composting)
Black Soldier Flies for example eat and break down organic waste like food scraps/waste, and produce leachate which seeps out into the surrounding soil ready for your plants and worms to turn it into composted soil
Hot (Active) vs Cold (Passive) Composting
– Hot (Active) Composting
Hot composting involves composting at higher temperatures, and active composting involves turning the composting material periodically during the composting process.
The two are usually part of the same composting process
Active composting requires the right ratios of brown and green materials – because of these things, it requires more knowledge, attention and monitoring than cold composting (hence why it’s described as active)
Turning the organic material creates different conditions for the microorganisms (they produce heat as a result of their biological processes), keeps the organic material ‘running hot’, kills weed seeds and pathogens (as a result of the heat), and overall breaks down into finer nutrient rich organic matter
Is a much faster method than cold/passive composting. It may take a matter of weeks – say 3 to 6 week.
– Cold (Passive) Composting
Cold composting involves composting at lower temperatures, and passive composting involves composting without turning the organic material
The two are usually part of the same composting process
It may take a matter of months – say 3 to 6 months, but may also take longer (a year or more).
Other Types Of Composting
Some other ways to categorise composting might include:
– Home vs Commercial
Home composting can be done at home, in the backyard, or on a private property
Commercial composting is done at commercial composting facilities
– Onsite vs Offsite Composting
Onsite composting is composting that takes place at the site where the organic waste was created e.g. food scraps at home being put into a home composting bin
Offsite composting is composting that takes place at another site or facility separate to where the organic waste was created e.g. at a public composting facility that accepts organic waste from a municipal organic waste stream
Different Composting Methods (Ways To Compost)
In addition to there being different types of composting, there’s different methods that can be used for each.
– Traditional Pile Or Heap
A pile or heap organic waste in an open space
– Trench or Pit
Digging a trench or pit, and burying organic waste underground
– In Vessel Composting
According to epa.gov:
This method involves feeding organic materials into a drum, silo, concrete-lined trench, or similar equipment
This allows good control of the environmental conditions such as temperature, moisture, and airflow.
The material is mechanically turned or mixed to make sure the material is aerated. The size of the vessel can vary in size and capacity
Tumblers can be bought as products from a shop
A composting tumbler could technically be classified as a form of in-vessel composting
It’s a sealed container/barrel that is usually turned or rotated with a handle, that mixes the organic waste inside
Is for food scraps and food waste, such as dairy and meat
Bokashi involves using microorganisms known as ‘Bokashi bran’ to ferment organic food waste
Usually involves putting a Bokashi mix and food scraps/waste into a sealed off bin
Some claim Bokashi is a form of composting, whilst others say it isn’t – the reason for this is that the Bokashi bran pickles or ferments the food via a fermentation process, instead of allowing it to decay
– Green Cone
Green composting cones can be bought as a product from the shop
They are cones attached to a basket that is buried in the ground
These cones use the heat of the sun to digest and break down food scraps
– Sheet Mulching, Or Sheet Composting
Also known as lasagna composting, or composting in place
It involves layering organic waste layers on top of each other in between layers of cardboard or paper (like newspaper)
– Aerated (Turned) Windrow Composting
According to epa.gov: ‘This type of composting involves forming organic waste into rows of long piles called “windrows” and aerating them periodically by either manually or mechanically turning the piles’
It is suitable for large volumes of organic waste
The Different Forms/Types Of Compost
Beyond the types and methods of composting, there are different forms and types of compost, all with their own traits and features
Some of the main types or forms of compost are:
The decomposed compost matter left over after the composting process is complete
It can be a nutrient rich soil for example
– Farmyard Manure
Manure from farmyard animals and livestock, such as cows, horses, etc
Some of these manures can be high in certain nutrients though, such as cow manure and ammonia or soluble nitrogen
Some reports indicate that chicken manure can be a good fertilizer once aged and composted properly
– Green Manure
Also known as ‘cover crops’
They are crops or plants grown specifically to help improve soil quality, texture, nutrients, disease load, or to add organic matter to the soil
Organic matter turned into compost matter by earthworms
Using Different Types Of Waste In Different Types Of Composting
Some types of composting are only suitable for specific types of waste.
Additionally, the right mix and % share of different waste types may need to be used for different types of composting to get a good resulting compost product.
For these reasons, the organic material requirements for a specific type of composting should be checked prior to starting the composting process.
Factors To Manage/Control During Composting
epa.gov lists these 5 main factors as factors that must be controlled or managed during composting:
Feedstock and nutrient balance
There may be more factors than these though for individual composting processes.
Potential Pros & Cons Of Composting