Center for Regenerative Agriculture and Resilient Systems

How the Fungus Might Save Us

by Sheryl Karas, RAI staff

mycorrhizal fungi on small tree roots

When we think about the multiple challenges the world may face due to climate change—chaotic and extreme weather patterns, food and water scarcity, to name just a few—it’s easy to hope that somehow the same scientists that are predicting these catastrophes might be able to invent a safety net to save us all. They’re certainly trying. But interestingly, some scientists say that there already has been a net, of sorts, around various parts of the globe and that it’s not too late to repair and extend it. The really surprising part is that it’s been imbedded in the soil all along, can also be found in the ocean and other waterways, and is made up mostly of microbes— in particular, mycorrhizal fungi.

What are Mycorrhizal Fungi?

Most of us aren’t very aware of this type of fungus and have a tendency to feel squeamish about the word “fungus” in general. After all, an overgrowth of certain kinds can make us sick. But there is a form of mycorrhizal fungi we are all familiar with—mushrooms, the very same item you may have had on a slice of pizza this week!

Mycorrhiza from the ancient Greek word mikes (μύκης) meaning fungus and rhiza (ρίζα) meaning root, are fungi that live in a useful two-way relationship with the vast majority of plants grown in healthy soil. They surround and sometimes penetrate the roots of the plant in order to exchange nourishment. The vegetative part of a fungus (the mycelium) consists of a network of fine white filaments (hyphae) that act to extend the roots system of the plants they work with to draw in water and specific nutrients the plants cannot reach on their own. In fact, it has been estimated that they increase the amount of nutrients a plant’s roots can absorb anywhere from 10 to 1000 times(opens in new window), depending on the plant and related environmental factors. In exchange, the plants provide the fungi with the foods they need, most often in the form of photosynthesized sugars.

Why This is Important

The role mycorrhizal fungi play on the planet cannot be underestimated.

The very oldest plant fossils that have been found show associated fungi. Some scientists think that this symbiotic relationship is what might have enabled plants to emerge from the oceans and survive on land nearly 500 million years ago. The same interrelationships are found everywhere around the world, in all terrestrial, marine and freshwater environments.

Perhaps you have heard of the “wood wide web”? That’s a playful name for the mycorrhizal networks a team of researchers(opens in new window) discovered in 1999 while investigating how the high levels of atmospheric carbon dioxide that is accumulating in our atmosphere might affect trees. Despite attempting to isolate specific trees in a forest for the experiment, researchers discovered that the effects of the experiment extended to all the surrounding trees, including many other species that did not appear to be connected in any way. Through a fair bit of detective work they determined that it was the fungi that connected the trees. Not only were the fungi exchanging nutrients with the trees that hosted them, they delivered these nutrients to all the other trees they connected with in the vicinity.

A number of other studies since then suggest that mycorrhizal networks have a significant role to play in regards to the atmosphere (and, hence, potentially with climate change).

According to scientists at the University of Leeds(opens in new window), the fungi were likely responsible for creating the oxygen-rich atmosphere we live in today and could not live without. The research team conducted experiments with plants and fungi grown in atmospheres that resembled the ancient Earth. They discovered that fungi access the nutrient phosphorus from rocks and transfer it to plants to enable photosynthesis. The fungi in return received the carbon the plants produced from carbon dioxide drawn from the atmosphere.

This had an enormous impact on the creation of the atmosphere and, ultimately, on the climate. And that finding woke a number of scientists up to the idea of exploring soil health and whether the fungi could help with the global climate change crisis we face today!

Could mycorrhizal fungi really help us now?

The answer is potentially yes.

In healthy soil, the fungi not only exchange nutrients with the plants. In conjunction with other microbes, insects, worms, etc., the combined biology of the soil breaks down plant debris such as fallen leaves and creates a more fertile environment for planting. And when allowed to proceed undisturbed, this naturally keeps the carbon drawn down from the atmosphere by plants via photosynthesis in the ground (a process known as carbon sequestration). And that’s exactly what we need.

Unfortunately, due to conventional agricultural practices like the use of tilling, herbicides, fungicides  and insecticides, the biology of the soil has been depleted in many places around the globe and the topsoil itself has been eroding at a frightening rate.

The good news is that regenerative farming practices that avoid tillage and keep the ground covered have been shown to help the soil recover. And if the soil biology is specifically attended to by using multi-species cover crops and adding microbial-rich compost, including the fungi, back in, they multiply incredibly quickly in just a few short years. When they are back in force enough to do their job, the changes that can occur are remarkable. Our own research shows that an increase of fungi in soil test results appears to be associated with increases in soil carbon (an indication of carbon sequestration). Multiple studies are currently underway to try to confirm these results and determine what they mean.