The mycelial mat (if you a lucky enough to have one) is a tangled web of filaments that mycorrhizae weave beneath undisturbed soil. This mycelial mat is a staple feature of Permaculture gardens. These mycorrhizal fungi colonize the roots of over 90% of plant species. In a previous post we pointed out that this mat figures out what nutrients are needed where, and distributes them accordingly.
Leslie Roberts, the editor of our Ecology Action newsletter, has written a wonderful article on how essential the mycorrhizae are to plant health. She first raises the question, “how do wild plants and flowers reach maturity without someone to fertilize, till, or water them?” Recent research indicates that the mycorrhizae (fungus) and their mycelial mat are essentially involved. All this happens in what is called the rhizosphere—the narrow region of soil that is directly influenced by root secretions and associated soil microorganisms. This rhizosphere is where plants draw most of their nutrients.
The filaments that the fungi extrude are small, thin hollow tubes, so I like to think of this process as intelligent piping. Somewhere, somehow, these fungi demonstrate intelligence and discernment in the distribution of garden resources through the rhizosphere.
Leslie explains it well, “Mycorrhizal fungi can free up insoluble nutrients by secreting powerful organic acids that lower the soil pH, making it more acidic, which helps to make bound nutrients soluble. The fungi then transfer these nutrients to the associated host plants, helping them compensate for low nutrient availability, poor soil structure, and low water-holding capacity. In turn, these fungi receive carbon from the plant host, which is used for fungal growth.” On the other hand, nycorrhizae also use their ability to alter pH to sequester undesirable (usually heavy) metals from plants.
Leslie concludes, “Healthy soil is dependent on soil microorganisms. Develop vital soil that supports these microbes by improving soil organic matter and minimizing tillage unless the soil needs added air. Reintroducing mycorrhizal fungi into our soil can be an important step in the process of healing damaged, depleted, and contaminated soil. Even in garden soil that’s already productive, adding mycorrhizal fungi dramatically improves the health and productivity of plants.”
It is worth checking out Leslie’s article: http://www.growbiointensive.org/Enewsletter/SpringSummer2015/SecretSoil.html