Soil mycorrhizae. What is it? If you’ve seen any of the “Avatar” movies, you would know that James Cameron probably has a good grasp of the subject…and you would have a basic understanding of what we are going to talk about today. Without mycorrhizal activity, there would be very little gardening. To return to the “Avatar” comparison, you know how in those movies, if anyone fell ill or was near death or they needed to call in the National Guard, they could stick a tree root in their ear and they’d get healthy or victorious, and then the movie could have a happy ending? To quote the “Avatar” Wiki: In Avatar, tree roots are critical, bioluminescent conduits for Eywa, Pandora's neural network, allowing Na'vi to connect to their deity and ancestors. Key structures include the Tree of Souls and Tree of Voices, featuring complex, willow-like root systems that facilitate tsaheylu (the bond) for communication and data transfer. Can you see mycorrhizae activity? Yes! If you have a microscope: (p.s. “Arbuscular”: Arbuscular mycorrhizal fungi (AMF) are soil fungi (subphylum Glomeromycotina) that form symbiotic relationships with roughly 80% of terrestrial plant species. They colonize plant roots, forming tree-like structures called "arbuscules" inside root cells that act as exchange sites. AMF improve plant uptake of phosphorus, nitrogen, and water, in exchange for plant carbon, increasing plant biomass and stress tolerance.) Aren’t you glad you asked? What about if you turn over the mulch that’s beneath your persimmon tree. Is that white stuff on the bottom of the mulch that’s in contact with the soil…is that mycorrhizae? Short answer: No. Long answer: That white stuff on the bottom of mulch is a decomposing fungi, saprophytic fungi. Saprophytes act as decomposers breaking down dead organic matter, while mycorrhizal fungi form symbiotic partnerships with living plant roots. Falling asleep yet? Here’s Ben Faber, a soil, water, and subtropical crops advisor for the Ventura/Santa Barbara UC Cooperative Extension, with his more astute look at mycorrhizae. This is from his newsletter, “Topics in Subtropics”: Mycorrhizae means fungus (myco) root (rhizae). These root-associated fungi predate the evolution of terrestrial plants, and the partnership with mycorrhizal fungi facilitated the establishment of plants on earth. Mycorrhizae form symbiotic associations with more than 70% of land plants across a broad range of terrestrial ecosystems. Plants supplies mycorrhizae with photo-assimilated carbon in exchange for nutrients and water. This is the definition of a perfect relationship whereby the two sides support each other and have a personal interest at maintaining their counterpart well-being for survival. Once mycorrhizae colonize the host plant, its mycelium can grow over large distances to neighboring plants connecting them together by a common network. This extension of the root network allows plants to acquire water and nutrients (especially nitrogen and phosphorus) far beyond its root zone, rendering plants more resilient to drought and nutrient deficiency. The ability of mycorrhizae to form this underground web also enables the connected plant to communicate with each other through chemical signals and exchange water and nutrients. For example, in forest ecosystems, saplings rely on nutrients and carbon supply from older trees sent through the mycorrhizal network. This underground mycorrhizal web has also great physical properties because they improve the soil structure by forming stable soil aggregates thereby limiting erosion and leaching of nutrients. Today’s podcast features two interviews. The first is with Sacramento County Master Gardener Pat Rosales. We discuss the chances of you buying living mycorrhizae that might be an alleged part of that bag of potting soil you’re coveting. Or even more doubtful, an ingredient in the fertilizer you’re reaching for. Science says: doubtful. Science also says: “You’ve got to be kidding me!” We do discuss ways to create your own soil mycorrhizae, as well as how to keep what mycorrhizae you already have in top shape. The second part of today’s podcast features Alaskan garden writer Jeff Lowenfels, author of the “Teaming with…” series of books about what’s in the soil below your feet, including microbes, fungi, bacteria, and nutrients. Lowenfels, besides talking about fungi, is a fun guy. He talks about his previous career (he’s a self-described “recovering lawyer”), and his short stint as a Congressional candidate, campaigning on the platform of, “don’t rake your leaves!” Joining us in the conversation is America’s Favorite Retired College Horticultural Professor, Debbie Flower, who thoroughly enjoyed geeking out with Jeff. Warning: this podcast runs nearly 90 minutes. You may want to change drivers frequently if you’re listening to it on a car trip, so no one will doze off at the wheel. On the other hand, THIS IS REALLY IMPORTANT STUFF AND IT’S WHY PLANTS GROW. Be advised: this material may appear on the Final. If you’re still reading this, you must be a curious gardener! Free or paid, either is welcome. However, I am praying for the eternal salvation of the souls of the paid subscribers. No pressure. Soil Mycorrhizae TRANSCRIPT Farmer Fred: Today on the Beyond the Garden Basics podcast, we’re talking mycorrhizae. No, don’t go away. Don’t go away. Please. Just listen for a minute or two, would you? Mycorrhizae is the reason you have successful plants. If we didn’t have mycorrhizae, you wouldn’t have a garden. So how can you make more mycorrhizae? Well, you can. You don’t have to buy it. We’ll tell you how. Pat Rosales is with us, Master Gardener in Sacramento County, who wrote an excellent article for the Sacramento Master Gardener newsletter in April, all about packaged mycorrhizae. Now, I think we have to establish something right off the bat. A lot of people think mycorrhizae are critters. But no, Mike and Cora don’t live in your soil. It is a relationship that’s called a mycorrhizal relationship. And it’s because it’s a mycorrhizal relationship is the reason a lot of these fungi, these various funguses, if you will, are called mycorrhizae because they’re involved in a mycorrhizal relationship. It’s basically a two-way street between the roots of your plants and the fungi in your soil taking care of each other, which makes your garden thrive. Farmer Fred: But there are things you could do to it that could destroy it. There are things you may not be even aware of, and you may not even realize you don’t have any mycorrhizae. There are certain conditions where you need to have some mycorrhizal relationships going on where none existed before. And we’ll tell you how. Farmer Fred: It’s mycorrhizae today on the Beyond the Garden Basics podcast. By the way, if you think this is daunting, stick around for part two of today’s podcast, where we talk to Jeff Lowenfels, the author of several books about soil microbes: Teaming with Microbes, Teaming with Fungi, Teaming with Bacteria, Teaming with Nutrients. Well, you get the idea, and Jeff will really give you the lowdown and delve deep into the science of mycorrhizal relationships and why they’re so important in your garden. Pat Rosales, French horn musician and Master Gardener, pleasure to have you with us again to talk mycorrhizae. And a lot of people think that, “okay, I’ve heard about the benefits of mycorrhizal relationships and mycorrhizae now for, oh, most of the 21st century. I guess I’ll go buy me some”. Well, before you do that, let’s talk about exactly what they are and what they do, Pat. What are they? What do they do? Pat Rosales: Well, mycorrhizae are collectively the mycelium of the fungus that lives in our soil. And they develop this, as you said, a very symbiotic relationship with your plants. And so the plants produce a carbohydrate because they photosynthesize from the sun. And they produce this carbohydrate, which they exude at the root tip. The mycorrhizae come along and they live near the root tip. And they use the carbon from the plant as nutrients. In exchange, the mycorrhizae provide nutrients, make nutrients available to the plant that they otherwise wouldn’t be able to use. Farmer Fred: It sounds like a fair exchange to me. One of the big ingredients that the mycorrhizal relationship can provide to the plant is phosphorus. And this is where a lot of gardeners might go askew because if you add your own phosphorus fertilizer, you inhibit the mycorrhizae, the beneficial fungi that are in there. It doesn’t necessarily kill the fungi, but it sidelines it because the plant says, “hey, I’ve got all this fertilizer falling down as a little blue powder. I’ll use that instead. You go play with yourself or something. Just leave us alone.” And the poor mycorrhizae basically just have nothing to do, so they do not thrive. Pat Rosales: And then the plant can’t really use the phosphorus in that form. Farmer Fred: That’s right. Somebody has to change it to something that they can use. Pat Rosales: That’s exactly what the mycorrhizae do. They make the phosphorus available to the plant. Farmer Fred: And that’s soluble phosphorus that we’re talking about. When you apply phosphorus via a fertilizer, that’s usually soluble phosphorus. And that, again, sidelines the mycorrhizae. Mycorrhizae, though, are very good at using insoluble phosphorus and converting that to something that the plant can use. So this is one of the reasons why mycorrhizae are so popular in agriculture. It’s cutting fertilizer costs for agriculture for those who are farming organically or farming sustainably or just want to cut their fertilizer costs by having a thriving soil with mycorrhizal relationships going on. There’s all the phosphorus you need so those ships can just keep circling in the Strait
