Fungi are a fascinating and often under-appreciated part of our ecosystem.
Neither plant nor animal, they are the foundation for life as we know it on land. Fungi break down old plant debris, and form relationships with live plants. Fungi support plants, and deliver nutrients and water to them. Fungi are even able to protect plants from threats like pest and disease!
On top of all that, fungi play a critical role in the carbon cycle. Fungi currently store up to 36% of our yearly carbon emissions in the soil. They are a nature-based solution to climate change.
Both our gardens and our planet benefit from mycorrhizal fungi. As gardeners and environmentalists, we should nurture mycorrhizae in our garden.
One way to encourage and maintain mycorrhizal fungi is through regenerative gardening practices.
In this article, you’ll learn:
details on the symbiotic relationships between plants and mycorrhizae
how fungi sequester carbon, in simple terms
how to encourage mycorrhizae in your garden
how to practice regenerative gardening to further support mycorrhizae on your land
What are Mycorrhizal Fungi?
Mycorrhizae are a type of fungi (myco) that is connected to the roots (rhizal) of plants.
Mycorrhizal fungi can have two main structures to them:
All mycorrhizae have “roots.” These “roots” the mycelium. Mycelium forms threadlike structures that extend outwards from plants. These threads are called hyphae.
A small percentage of mycorrhizae produce an above ground mushroom. This is sometimes referred to as the mycorrhizal fruiting body. Some common mycorrhizae that form a mushroom are boletes, chanterelles, and morels
Toby Kiers and Merlin Sheldrake, two expert mycologists, explain how fungi are essential to all life. 500 million years ago, fungal mycelium became a stand-in for plant roots on land. This relationship continued for a Period. Eventually, it was possible for plants to form their own roots. From there, the relationship evolved to how it is today.
During this time on earth, atmospheric carbon levels were extremely high. As fungi and plants worked together, though, they lowered carbon levels by 90%.
This allowed life to form as we know it, and make the planet habitable for humans. Thanks, fungi!
What benefits do plants and fungi provide for each other?
mycorrhizal fungi + plants
Fungi help plants in a plethora of ways:
surface area: Fungi provide an extension of the plant roots. This allows plants to get nutrients from a wider soil area
phosphorus: Fungi deliver up to 80% of a plant’s phosphorus intake
nitrogen: Fungi provide up to 20% of a plant’s nitrogen
other nutrients: Fungi also support plants with essential zinc, manganese, and copper
water: Fungi bring water to plants, which provides them with drought resistance
protection: Since fungi are in a network together, they can communicate with each other. If one plant is attacked by a pathogen, fungi can set up a defense to protect other plants from harm.
yield: Fungi deliver nutrients to plants that help them to flower. In turn, they can provide higher crop and seed production
soil health: Fungi help create soil tilth and optimal soil structure
food: Plants absorb carbon from the atmosphere during photosynthesis. Carbon just so happens to be the preferred food of fungi. Without carbon, fungal networks cannot grow. Around 5 billion tons of carbon are provided to fungi in this way!
According to OSU, there are two groups of mycorrhizae:
Endomycorrhizae are fungal networks that exist INSIDE of plant root structures. They mostly form relationships with herbaceous annuals. Corn, cucumbers, marigolds, tomatoes, basil, onions, garlic, and peas are just a few examples of plants that have a mutual relationship with endomycorrhizae.
Ectomycorrhizae are fungal networks that connect to the OUTSIDE of plant root structures. They mostly form relationships with woody perennials and trees. Chestnut, linden, walnut, hazelnut, and pecans are some examples of plants that have a mutual relationship with ectomycorrhizae.
Carbon Sequestration and Mycorrhizal Fungi
fungi and carbon sequestration from the carbon cycle
“Mycorrhizal networks are a major global carbon sink: ecosystemss with plants that feed carbon to underground networks store an estimated 8 times more carbon compared to ecosystems with non-mycorrhizal vegetation” - SPUN
On their own, plants sequester carbon. However, when mycorrhizae get involved, more carbon is extracted from the atmosphere.
SPUN, the Society for the Protection of Underground Networks, explains that fungi use the energy from sequestered carbon in three ways:
Network growth: Carbon helps fungi to grow and develop its mycelial networks
Exudates: Carbon helps fungi develop exudates. Exudates stablize carbon in the soil and help to decrease erosion
Necromass: Carbon remains in fungal networks even after fungi has died. This is called fungal necromass, and forms up to 50% of soil organic matter
This fungal carbon sequestration happens without any fancy technology.
As Professor Katie Field, who co-authored the study says, “…the numbers we’ve uncovered are jaw-dropping, and when we’re thinking about solutions for climate we should also be thinking about what we can harness that exists already.”
Destructive practices eradicate mycorrhizal fungi
tillage and synthetic inputs deteriorate mycelial networks
Mycorrhizal fungi helps plants to be more resilient. But that doesn’t mean that the fungal networks themselves are indestructible.
Many practices that already damage the environment cause further harm by also disrupting mycorrhizae.
Agricultural practices that damage mycorrhizae:
tilling/digging/ploughing: Tillage is harmful to the environment because it churns up carbon that is stored in the soil. The carbon is emitted into the atmosphere.
On a fungal level, tillage essentially cuts the mycelial plant extensions to shreds. This destruction prevents further carbon from being stored (Kiers + Sheldrake).
synthetic fertilizer: Synthetic fertilizer takes a lot of energy to manufacture. Synthetic nitrogen contributes to nitrates that are released in the atmosphere. Nitrates are a greenhouse gas that is xxx times more harmful than carbon.
On a fungal level, synthetic fertilizer delivers nutrients directly to the plants. On the surface, this seems like a great thing. However, it bypasses the plant-fungal relationship of nutrient exchange. The plant does not need the fungi, and so the fungi are no longer fed carbon by the plant. This discourages further mycorrhizal formation (Lowenfels).
logging + deforestation: Less trees means less carbon sequestration. Logging also disrupts ecosystems. Even when land is replanted, the original biodiversity of the landscape takes decades to redevelop.
This loss of plant and tree biodiversity can decrease mycorrhizal populations down to 5% of their original mass. Moreover, 75% of fungal diversity can be lost (Kiers + Sheldrake).
copper application: While allowed in organic farming, copper pesticide has harmful effects on soil health. Animals and humans also suffer the consequences due to copper use in agriculture.
As a fungicide, it makes sense that copper can harm the beneficial fungi that support plants and sequester carbon. A recent study published in Rhizosphere Journal found a linear correlation between copper application amounts and mycorrhizal loss in grape orchards.
Yet, farmers have noted the impact of copper on tree health for decades. In the 50’s, the correlation between copper applications and a decrease in plant vigor was noted in citrus orchards.
In the 80’s, Graham et al found the root cause (pun intended) to be the decrease of mycorrhizal networks where copper had been applied. In turn, this decreased the amounts of phosphorus and nitrogen that could be delivered to the trees through their fungal relationships (Hartnett).
Strategies to promote Mycorrhizal Fungi in Gardens
this hairy vetch cover crop supports life both above and below ground
“Keeping this fungal network protected is paramount as we face climate change.” - Dr. Toby Kiers, NYT
It is actually really easy to encourage mycorrhizal establishment with regenerative gardening principles.
No-till gardens: No-till, or no-dig gardening avoids soil disturbance whenever possible. In this way, the networks of mycelium can stay intact.
One study from France studied winter wheat crops and tillage. They found that no-till farming had more mycorrhizae when compared to tillage practices. The no-till farm needed less nitrogen fertilizer as well.
Another study from the UK showed that no-dig farms increased fungal populations in the soil. This helped reduce soil erosion. The soil also sequestered more carbon due to the exudates created by the mycorrhizae.
Keep roots in ground when possible: This technique does not work with root crops. But in other cases, gardeners can cut the plant back to the soil and let the roots decompose in place. This builds organic matter in the soil and the roots will continue to feed soil microbes.
Cover crops:A study from South Dakota State University found that fall cover crops increased mycorrhizal fungi. What is impressive is that the increase was up to threefold in the garden! This is one of many studies that have shown cover crops to support fungal soil life.
A cover crop is sown in the off-season once the main crops have been harvested. During this time, the soil would otherwise be bare. The addition of a cover crop keeps the soil planted. Planted soil allows for plant-mycorrhizal relationships to form.
It’s important to note that some mustard family/brassica crops do not form relationships with mycorrhizae. South Dakota State University recommends a cover crop mix to so a diverse fungal population will develop.
Compost: Anytime you add compost to your soil, organic matter and microbes increase. This creates a more hospitable environment for mycorrhizae to thrive.
Perennial crops: Soil with perennial plantings have higher populations of mycorrhizal fungi.
A study from Applied Soil Ecology explains this is because the perennials live longer than annuals. The longevity of perennials provides them with more opportunities to form relationships with soil microbes.
Organic + beyond organic practices: Synthetic fertilizers and pesticides harm mycorrhizae. Organic fertilizers feed mycorrhizae (Teaming with Fungi).
Some organic pesticides, like copper, also harm mycorrhizal networks.
Work with organic fertilizers, homemade garden amendments, compost, and diverse plantings to attract beneficial insects to help your garden thrive.
Benefits of Mycorrhizal Fungi in Regenerative Gardening
mushrooms are fascinating and are probably found in your garden already
“It is important to note that mycorrhizae can be found in most soils naturally, so it might not be necessary to purchase mycorrhizae. Most soilless media does not contain mycorrhizae, so they could be incorporated if growing in containers.” -Bruce Dunn,Richard Leckie & Hardeep Singh, of Oklahoma State University
There are a handful of mycorrhizal inoculants out there.
Inoculants can be beneficial especially if your garden is on the newer side. It's also helpful if you garden in containers. You may also wish to add mycorrhizae into your soil if it has been tilled recently. Past applications of synthetic fertilizers or pesticides may also give cause for inoculation.
If legumes were never in a location before, a legume-specific inoculant can help. Legumes are known as “nitrogen fixers." In reality, it is their relationship with the mycorrhizae that supply legumes with the nitrogen they need.
This year I purchased mycorrhizal inoculant for the first time. I tested the inoculant on my greenhouse tomato plants at transplanting time. I bought a small bag, and gave a generous amount to the first 2 plants and a scant amount to the remaining plants. The two plants that got more inoculant had the most growth. Some of the tomatoes produced were significantly larger than my other plants!
JADAM, a branch of Korean Natural Farming, has a process of gathering indigenous microorganisms. The organisms are grown in a local forest, and then you can apply it to your garden. You can watch a video on how to do that here.
Mycorrhizal Fungi: for plant health and planetary health
Regenerative gardening grows healthier plants, enhances soil health, and contributes to carbon sequestration.
Mycorrhizal fungi are our key allies in this endeavor. As they establish symbiotic relationships with plants, they provide a range of benefits. Mycorrhizae improve nutrient uptake, increase water absorption, disease protection, and soil improvement.
However, it is important to be mindful of practices that can harm these fungi. Tillage, synthetic fertilizers, logging, and copper application should be avoided.
When gardeners support the natural processes of mycorrhizal fungi, gardens will thrive. Additionally, more carbon can be captured in the soil this way.
I encourage you to try regenerative practices in your own garden. You can create sustainable ecosystems to benefit both your garden and the planet as a whole.
