How Does Composting Work?

Have you ever asked yourself, or your friends, the following question..."How does composting work?" If so, we've got your answer. If not, then it's time you learned (and reconsidered the conversations you've been having with your friends)!

Did you know that compost is being made naturally in forests and grasslands all over the world, all the time? It is. You may not think of this as compost in the traditional sense of the word, but when it comes down to it, the compost process is a completely natural one that all plant matter goes through.

Let's use a leaf from a maple tree as an example (You can tell we're Canadian, eh?).

Every Fall, in forests around the world, maple trees shed their colored leaves, revealing their mighty structures. After a peacefully descent to the forest floor, each leaf is met with a frenzy of hungry critters that are anxiously waiting to tear it to shreds. Gruesome, isn't it? Nonetheless, as these critters devour the leaf, they begin it's natural decomposition and transformation back into soil.

So...how does composting work?

In parallel to the natural decomposition of the above leaf, when we compost on a small scale (e.g. backyards, indoors, farms, etc.), we are using the same processes that are present in nature, however, we speed them up.

Meet Your Compost Work-Force

Just like in a forest, in a compost system, the majority of the decomposition of compost ingredients can be credited to a variety of microorganisms. These include fungi, bacteria, and actinomycetes. Other compost bugs (i.e. invertebrates) are present, but they don't tend to play as big a role in dynamic composting systems due to their aversion to the high temperatures that the materials reach as they compost.

In answering the question "how does composting work?"

Here is a flow chart that highlights the basic breakdown process and the various microorganisms that are present during each phase. We have also color coded the stages - red indicates hot temperatures (approx. 140-160 degrees Fahrenheit) and white indicates cooler temperatures (less than 60 degrees Fahrenheit). Visit our compost thermometer page to learn why your compost pile heats up as it breaks down.

how does composting work


Note - The microbe descriptions on the above chart apply to compost that is actively managed (i.e. turned at specific intervals based on temperature and oxygen levels). In compost that contains a lot of woody material and doesn't get turned often, there will be a much higher level of fungi and actinomycetes in comparison to those indicated on the chart above. Why? Because every time you turn your compost pile, you're slicing and dicing the fungi. Now you have a couple hints about how you can produce a fungal-dominated compost.

In Summary...

How does composting work? Composting works because of the microbes present in your compost pile. These microbes vary depending on the original materials used as well as the specific composting technique.

Your ingredients go through various stages of decomposition during the compost process (learn more about those stages here). During the thermophilic stage (heating stage), specific microbes transform the original substances into various lignins, sugars, amino acids, waxes, and gums. Then during the mesophilic stage (cooling/curing stage) different microbes convert the above substances into stable humus compounds.

High-quality finished compost is rich in nutrients; loaded with microbes; pH neutral; dark brown in color; and has a high nutrient- and water-holding capacity. It's no wonder plants love this stuff so much.

If you liked this page, you may also enjoy the following...

What are your Ideal Composting Ingredients.

How to make the Composting Carbon Nitrogen Ratio work for you.

Composting Basics Free e-booklet

Five Free e-booklets

Interested in learning more about compost?

If so, you'll love the five free e-booklets we're giving away to all our visitors. The books are short, but they're loaded with great information that you can start using immediately.

All you have to do is click on the Composting 101 booklet to the right and read our Free Goodies page.