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Aerating Your Compost

Written by Angus Stewart

One of the secrets to successful composting is to create the right balance between air and water inside the heap to create an environment where beneficial microbes thrive at the expense of the not so desirable ones.

As organic matter breaks down and turns to compost the particle size progressively decreases, meaning that there is less air in the heap and if the moisture content is maintained the heap can become waterlogged and compacted. The denser the compost becomes, the slower it breaks down and can sometimes even become anaerobic.


An anaerobic environment is one without air (and therefore oxygen), and this favours the wrong sorts of microbes that produce substances such as rotten egg gas (hydrogen sulphide) that have strong, unpleasant odours and can produce substances toxic to plants as well as high acidity levels. Biodegradable materials will still break down in this environment, but the end result is undesirable compared to a compost heap rich in organisms that thrive in an oxygen rich situation. 


As well as favouring the right kind of microbes, an oxygen rich environment will also encourage worms, and many other soil dwelling critters responsible for breaking down household organic waste. Naturally these are the ones we want to thrive in  our Tumbleweed composting units. By turning your compost, you dramatically increase the amount of air in the system, which in turn increases the speed of composting. As the compost cools over time, you can introduce composting worms to help finish off the process but this is not essential. 


Keeping your compost unit well aerated doesn’t have to be an arduous, labour intensive task. There are a few ways you can ensure the contents stay nice and oxygen rich and the first is through use of a compost tumbler. Compost tumblers sit on a metal frame and can be easily rotated. By rotating the compost bin, the contents will be nicely aerated and will tend to have a ‘fluffed up’ appearance. All it takes is a few turns every week to keep the conditions ideal inside the unit. 


If you wish to purchase, or already own a composting unit that sits flat on the ground, the way to aerate it is by hand. You can use a garden fork, but the chopping and slicing action from it can not only make the process labour intensive, but also could harm any worms that are present. Pictured below is a handy tool called the “Compost Mate.” This tool is very easy to use. Simply wind it through the contents of the compost bin, give it a jiggle and lift it back out again. Doing this once a week will keep the compost aerated and also mix through the kitchen scraps. The compost mate can also be used to create holes in the heap to enable you to bury these scraps along with a good amount of carbon rich “browns” such as dead leaves. Such new additions to the heap are then able to be mixed in whilst you are also aerating, ensuring they will break down faster as opposed to non-mixed additions. 


Aerating Your Compost


Aerating compost can also help improve conditions within the bin if they become too wet. This can sometimes happen after heavy rainfall. If you take a handful of compost from the heap and you can easily squeeze out drops of water it is generally too wet. Adding a good amount of ripped up cardboard or dead leaves and mixing them in with the compost mate or garden fork can correct this.


As with most things in life and gardening, finding the right balance creates that sweet spot where the good life thrives.


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