The Compost Conversation – Fungi, the quiet party guest

A fungi hyphae under the microscope x400 total magnification.

By Mikaela Beckley

Neither a plant nor an animal, fungi are unique, often misunderstood, and essential to making a good compost. 

Often the first thing that comes to mind when we think of fungi is mushrooms, but in fact these are just fungi’s fruiting bodies. The actual fungi live under the ground growing in a delicate network of branches called hyphae (hahy-fee). While there are many fascinating types of fungi, in our compost piles we are growing the ones known as decomposers (or saprotrophs) and these fungi have super powers! 

Super power number one: decomposing fungi are uniquely capable of breaking down the very strong substances lignin, cellulose and chitin found in our compost ingredients like wood chips, leaves and straw. 

Super power number two: adding to the small clumps made by the bacteria, fungi further improve the structure of our soils and compost by pushing and gluing together even larger clumps of particles. These particles make it easier for oxygen to get in as well as helping to retain water and nutrients. 

Super power number three: they are very efficient at storing carbon in their cell walls making them total pros at keeping carbon in our soils and out of the atmosphere, yay! 

In many ways, building a compost pile is similar to hosting a party. Like any good host we like to cater for all dietary requirements and keep everyone well hydrated. 

As we discussed last week, our extroverted bacteria friends arrive early and go straight for the junk food (coffee grounds, kitchen scraps and leafy greens) while our fungi friends take a little more time to get their groove on. Luckily for us, they have quite different food preferences to the bacteria; in fact, they will take care of all the leftovers (straw, woodchips, woody garden clippings and dry leaves). So while the bacteria will polish off the pizza as soon as it arrives, late in the night we would not be surprised to see ol’ mate fungi sitting quietly on the couch casually chewing on the pizza box! 

Unlike bacteria, fungi hate to be disturbed. Their delicate disposition does not fare well on a crowded dance floor (read: turning our compost piles). As composters we must always weigh up turning our piles to add oxygen against the need to leave our fungi undisturbed. So, only turn your compost when it’s needed. At YIMBY*, our compost piles are turned twice, relatively early in the process, leaving plenty of time (three to four months) for our fungi to go about the business of curing our compost. 

Next week the party analogy will get even weirder and start to resemble something like The Hunger Games with the arrival of our next guests. We will meet the protozoa and the nematodes and discover their role in nutrient cycling. 

Mikaela Beckley works with Yes In My Back Yard, (YIMBY*), a community-scale composting initiative in Castlemaine and surrounds. Send questions or comments to