Unless you are one of the few who remember their high school science classes, the term aerobic composting can be pretty confusing. We’ll explain the term in detail and offer some tips on improving your aerobic composting experience.
Aerobic composting: The bacteria that break down the organic waste in your compost bin need oxygen to survive. Oxygen, combined with heat and water, creates the ideal conditions for aerobic composting.
What is aerobic composting?
Aerobic is basically another word for air. In this case, aerobic composting means breaking down organic waste by exposing it to air.
While some bacteria don’t need air to survive, others do. Aerobic composting relies on those bacteria that need oxygen, which is how the process got its name.
How is aerobic composting done?
In order for aerobic composting to be successful, a few key requirements are needed.
Oxygen
As we’ve now established, aerobic composting only works if the organic matter is exposed to oxygen. Many compost bins may look like piles so for the best results, this pile needs to be regularly turned.
When you put green and brown organic matter into your bin, there will naturally be pockets of oxygen between the layers. However, as this matter breaks down, those pockets of oxygen become compressed.
For a successful process, you should regularly turn your compost. This mixes everything in your bin up and adds oxygen back into the layers. It also helps create a consistent cycle of waste breaking down.
Moisture
Inside compost are thousands of beneficial bacteria which work to break down your organic waste. This bacteria thrives in moist environments and will die if the pile becomes too dry.
A mixture of green and brown organic waste is needed to create a moist environment. You may also want to add a bit of water if you notice the mixture becoming too dry.
However, if the pile is soaking wet, it can actually cut off the oxygen supply to the bacteria, leaving you with a soggy, smelly mess.
Nutrients
One of the first things you will learn when diving into composting is that a mixture of green and brown materials is needed for success. Greens include vegetable scraps and cut grass while browns include dried leaves and old plant matter.
Stored inside green materials is nitrogen while inside brown materials is carbon. Both are necessary if you want a healthy abundance of bacteria and other microorganisms to break down your waste.
If you’re unsure of the correct ratio, simply try to alternate what you put in your compost bin. This can be hard, however, as you will naturally produce more green organic waste in the summer and more brown organic waste in the fall.
If you have enough space, you can create a second pile of fallen leaves and add them to your compost bin throughout the year to offset all the green organic waste. You can also add newspapers in the summer.
Heat
If you take the lid off your compost bin or turn your pile in the fall, you may see steam issuing from it. While the outer layers of your compost will probably be cool, inside that pile should be warm.
The layers of compost will naturally insulate your compost which is essential in helping bacteria grow so it can break down your organic matter. Most compost bins are made from black plastic to help increase the heat factor.
Don’t worry if your compost pile is not warm enough in the winter. Even the most insulated bin won’t be able to protect your compost from freezing temperatures.
Just don’t expect your compost to break down during the winter. The microorganisms will become dormant during this period and once the weather warms up and you add more waste to your compost bin, the process will begin again.
Benefits of aerobic composting
Better soil
The reason composting is so popular and is talked about so often is that it is one of the best ways to add natural fertilizer to your soil. You can basically complete the cycle of turning organic waste into soil that then creates more plants, that will eventually end up in your compost bin.
There’s less waste, and less room taken up in a landfill, and your garden will be happier for it.
Better environment
The byproduct of anaerobic composting is methane, which is incredibly harmful to the environment. Even though aerobic composting produces carbon dioxide (CO2), methane is far worse at trapping heat in the atmosphere.
Furthermore, the warm temperature of aerobic compost kills off bad bacteria. This process makes it safe to add the compost to your garden right away.
Disadvantages of aerobic composting
Time
If done correctly, aerobic composting can have a useful result in just a matter of weeks. However, most home gardeners are not as diligent and it can take months for your compost to be ready to use.
Need for green and brown waste
When you think about it, most of what goes into your compost in the summer will be fruit and vegetable scraps while most of your fall contributions will be leaves and plant matter. In the course of a year, this will even out but will not be useful for your compost in the short term.
It can be hard to evenly mix in brown and green organic waste and you may end up agonizing over the right ratios.
More work
Any time you want to speed up the aerobic composting process, the answer will be more effort. The smaller the pieces that go in a compost bin, both green and brown waste, the faster the process will be.
You may find yourself obsessively cutting up vegetable scraps or shredding leaves to improve the speed. The larger the surface area of your compost items, the more surface area those important microorganisms have to work on.
Anaerobic vs Aerobic Composting: Difference
Oxygen
While both systems rely on microorganisms, anaerobic microorganisms do not need oxygen to survive. In fact, if you let in too much oxygen to the process, you can kill off the bacteria that are trying to work.
As a result, the containers you use for each system will be vastly different. Aerobic composting usually involves a large bin that has air vents. It also has a large opening so you can remove the lid to turn it.
Sometimes, especially on farms, aerobic composting is simply a giant pile.
Anaerobic composting is more contained. For home use, you often have an airtight container that is only opened quickly to add your organic waste.
Smell
When microorganisms break down waste in an aerobic composting environment, they produce CO2. However, anaerobic compost produces methane.
CO2 does not have a strong smell. In contrast, methane is very stinky.
Decomposition
Due to the higher temperatures needed for anaerobic composting, organic matter breaks down more efficiently. As a result, plant pathogens, weeds, and even seeds decompose thoroughly.
Thanks to this, you can add compost directly into your garden, even if you are planting vegetables.
Anaerobic composting on its own won’t produce the high temperatures to kill these pathogens. While some more industrial methods will add heat, many home-use containers don’t.
If you are worried about what is still in your anaerobic compost, it is better to add it to your regular compost to help it break down further. You can still use it in your garden but it’s better to stay clear of areas with root vegetables.
How to increase the speed of aerobic composting
Manual aerators
Many compost bins are sold with an aerator. This is a large metal stick that has a pointy end at the bottom.
To use an aerator, stick it in your compost bin, move it around, and then pull it up. The aerator will shift items from the bottom up to the top and in the process, add oxygen to the pile.
For larger piles of compost, this can take a bit of effort. Furthermore, you need to be in the habit of turning your pile every day for the best benefits.
Compost tumblers
If you know ahead of time that you are physically unable or unwilling to aerate your compost pile every day, you can purchase a special bin called a tumbler.
These bins are designed so the bin rests on a metal frame. Then, you can turn the bin easily so the content inside naturally shifts.
Underground
Heat is a major contributor to the readiness of your compost. If you can bury your bin in the ground, you will better insulate your compost and make it ready faster.
Other insulation tips include using straw or manure around the pile. You can also dig out a hole in the middle of your compost and place new materials inside to help feed the microbes.
Conclusion
Even though it has a fancy name, aerobic composting just means breaking down organic waste by exposing it to air. Be sure to regularly turn your compost pile and keep it warm so that good bacteria thrive and continue to break down your organic waste and create a nutrient-rich substance.
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