There are generally 2 types of fungi we are interested in when working with the soilfood web:

Mycorrhiza (myco = fungi + rhizo = root) fungi form a symbiotic, mutually beneficial relationship with plants through close connections in their roots.
We don’t find them in an active form in our compost, because generally there are no plants living in our composts. They need active, living roots to survive. So they can only be found active and living in substrates with living roots. However, our compost may well contain spores ready to kick into action once they detect a root and form a loving relationship.

Saprophytic fungi (sapro = rotten, phyto = plant) live off dead plant (and animal) material, which is hard to digest for other soil organisms. They use complex enzymes to break down complex carbon structures that simple organisms just can’t do much with.
Amazingly, some can also break up toxic waste materials and neutralise them.
Very occasionally, some of these act as plant pathogens, often depending on the overall conditions.
These are often found in our soils and composts. They turn organic material into a vast communication and logistical food delivery network, if we let it. That means tilling and digging the ground breaks up these structures.

This article from the Swedish University for Agricultural Sciences suggests there is a distinct distribution of where in the soil saphorytic and mycorrhizal fungi are found, and that this may be due to some competitive advantages of each group in particular environments. This was studied in a boreal forest.
The authors note that saprophytes live in the upper layers of the soil, where fresh dead plant matter accumulates, and presents a food source for these fungi: Fallen leaves and branches, for example. Saprophytes get their carbon from decomposing cellulose.
Mycorrhiza, on the other hand, receive the majority of their carbon through plant roots, in exchange they “mine” nutrients for plants, such as phosphorus. As such, they live in the deeper soil horizons – in community with living roots. However, whilst possibly not as effective as saprophytic fungi, they can also break down some carbon materials.

This poses interesting questions: How do we get mycorrhiza back in the soil, and how do the saprophytes facilitate this process?
If we are trying to cultivate saprophytic fungi through fungal-rich composts, it seems logical this would best be applied as a mulch, as the fungi continue to need the dead plant materials as food sources, and would simulate natural systems.
In an agricultural situation, it seems we would need to promote active mycorrhiza to form the relationships with plant roots. This then aligns with the need for keeping living roots in the system all year round, particularly where an ecosystem does not have natural winter-dormancy.

I wonder – in systems with winter dormancy, might there be an exchange between saprophytic and mycorrhizal fungi to even out the different carbon sources (dead plant matter and living roots)? A particularly interesting question in broad-leaf situations.

Useful resources:


All things mycorrhiza, don’t be put-off by the old-fashioned look of the pages!

A list of plants that associate with different types of fungi (or not)

Courses (all things fungi, all rather magic): by Peter McCoy and Team

Mushroom Identification:

Here we have good fungi ID information, photos, including very helpful microscopic spore images.

General info on the marvellous world of fungi (books)

To come! For now, check out PeterMcCoy and Paul Stamets.

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