Flowers, trees and crops can certainly be beautiful to look at. But did you know that below the soil’s surface, there’s a whole network of fungi working hard to help keep these plants alive?
Mycorrhizae play a significant role in maintaining healthy ecosystems, including in dense forests, gardens, farms and so on. And as climate change becomes a growing concern, these fungi seem to be more essential than ever.
What is mycorrhizae and why is it important? They’re a type of fungi that decompose plant matter and help bring nutrients to plants’ roots. Even though we usually can’t see them, both because they’re very tiny and living down in the dirt (or soil), plants wouldn’t be able to grow and survive without them.
What Are Mycorrhizae?
Mycorrhizae are types of tiny connected fungi that develop underground around plants. They’re so small that they’re considered microscopic, but sometimes they produce edible mushrooms which pop up out of the soil. In fact, mushrooms that you’re probably familiar with, such as truffles, are produced by mycorrhizae.
Mycorrhizae have interconnected threads called hyphae that together create a mycelium, which is a web-like structure found in healthy soil.
What does mycorrhizae do to the soil? Mycelium help to connect multiple plants together, including those of the same species and of different species. In fact, mycorrhizae can even connect plants that are located many feet apart from one another.
There are two main forms that mycorrhizae take:
- Ectomycorrhizae, which surrounds the outside roots of plants.
- Endomycorrhizae, which grows inside of the plant between cells.
Plants and mycorrhizae have a mutually beneficial relationship: Plants feed mycorrhizae to keep them alive, and mycorrhizae help protect plants and allow them to absorb more nutrients through their roots.
It’s believed that arbuscular mycorrhizal (or AM) fungi are the most important mycorrhizae in agricultural ecosystems where crops are grown.
Plants provide mycorrhizae with benefits including:
- Photosynthesis — plants convert sugars produced in plant leaves through photosynthesis and then send them to the plant’s roots so mycorrhizae can use the nutrients to survive.
- Because mycorrhizae are located underground and aren’t exposed to sunlight, they rely on plants to do this for them.
Benefits of mycorrhizae for plants include:
- Help absorbing more nutrients from the soil — fungal hyphae are very tiny and can spread through soil more easily, absorbing plenty of nutrients (such as minerals including phosphorus, zinc, copper and magnesium) that plants struggle to get on their own. Plant roots are not as long as mycorrhiza’s hyphae (they’re about 1–2 mm long compared to mycorrhiza’s roots which can be 15 mm long).
- Breaking down matter in the soil — this improves soil structure and also creates more absorbable nutrients.
- Increasing plant’s chances of survival — mycorrhizae improve the odds that plants will thrive when the soil is damaged or low in nutrients. They also help protect plants against pathogens, diseases and chemicals. Recent studies show that mycorrhizae can help support ecosystems exposed to droughts and climate change.
- Connecting plants together — because mycorrhizae form networks by connecting nearby plants, they can help plants to share nutrients with one another, contributing to an overall healthier ecosystem.
- Producing higher yields of certain crops.
Which plants benefit from mycorrhizal fungi?
Most wild plants, including shrubs, wildflowers and trees, associate with and benefit from mycorrhizae networks in the soil. These include the following groups of plants:
- All groups of Pteridophyta
- Most groups of Gymnospermae
- Most Angiospermae
- All palms
- All plants in the Bryophyta
- Almost all bulb plants
- Anything related to roses, apples, peaches, pears, strawberries etc.
- Most tropical plants (apart from orchids)
- Most horticultural species
- Almost all crop plants
- All cultivated grasses
- Many shrubs and foliage plants (except for Rhododendron, Azalea and Heath)
- Berries except for blueberries, cranberries and lingonberries
- Nut trees except pecan, hazelnuts and filberts
- Fruit trees including tropical fruits
- Many wetland/aquatic species
- Most in the Cupressaceae, Myrtaceae and Caesalpinoideae families
On the other hand, main non-mycorrhizal plant families are: Brassicaceae, Amaranthaceae, Caryophyllaceae and Chenopodiaceae. These include plants like cruciferous veggies such as broccoli and cabbage.
How to Use & Even Make Mycorrhizae
How do you add mycorrhizae to soil?
At this time, researchers are still discovering more about how exactly native fungal networks in the soil might work and what we can do to support them. As one researcher explained to Science website, “No one really knows how to promote soil fungi diversity.”
We do know that native fungal soil diversity in the wild seems to be key to protecting our ecosystems as the climate warms and changes. We can expect to see more research underway in the next couple decades that focuses on how to use fungi in native soil to help protect plants, trees, forests, rainforests, desserts and more.
You can also buy mycorrhizae at your local garden center. Mycorrhizal products — Plant Success Great White Mycorrhizae and Big Foot Mycorrhizae Granular are two popular brands — are often used by gardeners when planting seeds, transplanting or preparing a bed before the planting. Ideally, the mycorrhizae is worked into the soil, throughout the top 4–6 inches.
How do I make mycorrhizae?
If you’re gardening at home and want to help your plants thrive with help from soil fungi, there are some steps you can take. In fact, farmers often use mycorrhizae to help produce healthier plants and greater yields.
At home, it’s possible to make arbuscular mycorrhizal fungi inoculant, which is also called “rootgrow” that will help your plants develop healthy roots. This takes about three months to do. It’s considered superior to make your own mycorrhizae compared to buying commercial types because it’s more sustainable and may also be more effective.
Here are basic steps for making arbuscular mycorrhizal fungi inoculant:
- You’ll first need to collect soil starter from a “host plant” that has mycorrhiza living in it. You can collect soil from areas where there are thriving perennial grasslands that have not been cultivated recently. Look for starter soil under healthy trees or in fertile grasslands. Clear the plants, then dig down about one 6 inches to one foot (10 to 25 cm) to collect soil and as many fine roots as possible. Most mycorrhizae are found in the top 6 to 12 inches of soil.
- Choose the space where you’ll be growing plants at home in pots. Fill an 8 gallon (30 liter) pot or several smaller pots with the starter soil plus ideally some compost. Make sure to remove any rocks. Then plant a combination of grassy species (like corn, millet, sorghum, oats, wheat) or an allium (onion, leek), with a species of legume (beans, peas, lentils, alfalfa, clover). Plant the seeds close together for the best results.
- These are good plants for collecting mycorrhizal fungus and helping them to thrive. You want the plants to first grow well, but then you’ll intentionally kill them so mycorrhizal fungus take over and multiplies quickly.
- Water the plants regularly for about 10 days, then cut down the plants to their stems and stop watering them so they die. The fungus will start producing spores quickly.
- Wait 10 more days, then pull up the plants’ roots, chop them into small pieces, and plant them back into soil. You’ll now have soil that’s rich in healthy fungi.
- What does mycorrhizal do? Mycorrhizae are networks of fungi that live in the soil. They help plants grow and survive, including in harsh climates.
- These healthy fungi can protect plans against diseases and droughts, improving plants’ ability to absorb nutrients, and help connect plants together so they can share nutrients in the soil.
- Plants also give back to mycorrhizae due to photosynthesis, which supplies them with nutrients.
- Diversity of fungi in the soil out in the wild is thought to be very important for the health of the planet. We’re still learning how to protect and promote this type of diversity.
- At home, you can help plants thrive by creating arbuscular mycorrhiza inoculate, which means soil that’s rich in fungi which can be mixed into growing pots or your garden.