There is no doubt that mycorrhizae fungi play an important role in plant growth. They help aggregate the soil which in turn provides plant roots with better access to water and oxygen. Their symbiotic relationship with plants helps them access water and nutrients. It is only natural that companies want to sell these fungi to you. Don’t fall for it.
Mycorrhizae Fungi
Mycorrhizal fungi (mycorrhiza) are found in all soil where plants grow. They form large networks of fine filamentous growth throughout the soil. They associate with plant roots; some even burrow into the roots to create an even greater association with plants. About 80% of all plant species form some type of association with these fungi.
Think of mycorrhizal fungi as a vast network of very fine plant roots. They are not plant roots, but they behave in similar ways to plant roots. They burrow into nooks and crannies in the soil and collect water and nutrients for the plants. In return the leaves of plants send sugars to the fungi as food. Given this important association it is natural for one to think that it would be beneficial to add more mycorrhizal fungi to the soil. For a more detailed description of mycorrhizal fungi see Microbe Science for Gardeners.
Arbuscular Mycorrhizal Fungi
There are two basic types: EM and AM.
EM fungi (ectomycorrhiza) form associations with only about 2% of plants, mostly the woody plants like trees and shrubs. Since woody plants make up a large portion of the plant community, they are important to natural ecosystems but they are not usually found in commercial products for the garden.
AM fungi, called arbuscular mycorrhizae (a type of endomycorrhiza), make up the largest group and form bonds with the majority of plants. They provide mostly phosphorus to the plant. These are obligate symbiotic fungi, which means they can not survive for long without a host, although they can produce spores (a types of seed) that can survive until a host root shows up. This is the type found in commercial products.
The fact that they can survive as spores is important because it makes it easier to produce them. Commercial products contain a combination of spores, small fragments of mycelium and small pieces of roots that contain bits of fungi. Together these are called arbuscular fungi propagules and the number is listed on some commercial packaging. For example one product claims to have “60,000 propagules per lb”.
Facts About Mycorrhizae
- Garden soil already contains vast quantities of mycorrhizae, or at least it does if any kind of plants grow in it. Adding more is a waste of money, since they are already in your soil.
- Manufactured mycorrhizae consists of 2 or 3 types of fungi. It turns out that there are hundreds if not thousands of different kinds in your soil and some of these are very specific to certain types of plants. How do you know your plants will benefit from the 2 or 3 types you buy?
- Manufactured mycorrhizae are heat sensitive. If the container is left in a greenhouse, or a transport truck too long, the heat kills the fungi. There is no way for you to know that the product you buy contains active fungi – they could all be dead.
- Manufactured mycorrhizae are of a specific species, almost certainly from an area that is foreign to your soil. It is possible that these foreign species inhibit the growth of your native species. You have no way of knowing but it is never a good idea to import foreign species of any kind into your garden.
There is just no good reason to buy mycorrhizal fungi for your garden.
Special cases
There are some special cases that might warrant the addition of mycorrhizal fungi.
Bare Soil:
Soil that has no plant growth probably has few natural fungi. It would seem that this would be a good case for adding them. The problem is that if the soil is not suitable for plant growth, it is probably not suitable for the growth of mycorrhizae. Adding them will simply result in them dying. If you want to grow plants in this soil you first need to solve the problem in the soil. As plants start to grow, native mycorrhizal fungi will also show up, naturally.
Sterile potting soil:
Sterile potting soil used in containers has no natural fungi. Studies have shown that adding mycorrhizal fungi to this type of environment can have some positive results. Keep in mind that the main value of the fungi is to provide the plants with water and nutrients. In a potted situation, many gardeners over water and over fertilize, negating the benefit of the fungi. If you water and feed your plants regularly, there is little benefit to adding mycorrhizal fungi.
Commercial Inoculants vs Compost
Most commercial products have a dozen or fewer species in the product. Some don’t even list the species. A recent analysis of a compost sample showed that it contains 305 fungal species and 360 bacterial specials.
In a recent review I checked with 5 commercial product manufacturer and asked them for proof that their product worked. You can read about the results in Mycorrhizal Inoculant Investigation – Do They Work?.
The Latest Science About These Fungi
The latest news investigates how tilling affects fungi in soil, and how effective commercial products have been in agriculture. Read all about it in Mycorrhizal Fungi – The Latest Scientific News.
The latest data clearly shows that claims such as “In soil that has recently been tilled/worked, mycorrhizae will be lacking” are not true.
Better Ways to Build Soil Health.
10 Easy Soil Testing Methods For Measuring Soil Health
Preventing a Nitrogen Deficiency in Soil – How to Manage Nitrogen Levels
Soil Bacteria – The Myth of Identification & Management
10 Fertilizer Myths That Will Save You Money
So many of the allotment gardens I watch on YouTube use m fungi that I thought I was missing a trick. Now holding fire!
As a biology teacher I remember trying to change pupil’s perceptions of long held, erroneous beliefs. I used to quote the example in the book Moby Dick. A scientific type was discussing with whale hunters whether whales were fish or mammals. He pointed out they were warm blooded, breathed air, had hair, no scales and their fins are set at 90⁰ compared to fish. At the end of the conversation he asked them if whales were fish or mammals.
They all said FISH!
I believe we are all guilty about some things.
I like your gentle style of persuasion.
I love this post. No one is reading the full article. I think people are looking at the wrong point. We all know fungi and bacteria can help plants, but how do you know it can be successfully harvested and sold to you and still be alive for use? You can’t. But we do know in almost all living/garden soil, the spores for a huge multitude are present. It is probably better and a hell of a lot cheaper to create an environment these things can thrive in with things like leaf litter and wood chips. They will most likely start to naturally propagate in your garden.
Robert,
Thank you for thoughtful discussion on these garden myths. I hold a PhD in analytical chemistry, but I must admit that I have fallen for many of these myths and have gleefully sprinkled “biotone” and similar fertilizers/inoculants around my garden for longer than I’d like to admit. I suppose I need to brush up on my biology….
It is also refreshing to hear another person discuss the identical chemical properties nutrients released by synthetic and organic fertilizers. Nitrate is nitrate. It reminds me of a discussion I had with my dad who had fallen for the myth that “Himalayan pink salt” was somehow better for his hypertension than table salt.
I have mixed reviews on your stand about mycorrhizal innoculants being completely unnecessary for home gardening. True, it’s not for everyone. It would seem there’s agreement on the fungus’s nature and role, and on view of the ridiculous marketing of it. -Saddly, there seems to be as many people trying to make a fast buck off the organic hype as there are ones with a notion that if it’s ‘natural’ you can/have to use lots of it.
Reading article and comments I came across numerous mentions of control elements in various experiments but none on the most basic of control elements. Water. Chlorinated tap water is most readily available to the average home gardener. It’s massively different than well water, or say, that siphoned off of a stream or a fishpond. Tap water is as detrimental to the fungus as tilling of the earth.
Hence, the use of an innoculant. You’d be just wasting your time and money if you not willing to take care of it. Gotta be willing to go chemical-free. It’s not a magic pill. It’s to help reestablish the colony torn to bits by the tiller. As each innocculated plant grows so does the fungus colony. Kinda like rebuilding a village after a hurricane. The longer it remains undisturbed the larger it can grow, and it can’t grow if you you use chemicals. It’s as susceptible to chemicals as a honeybee.
Living soil is a term frequently used to describe or in reference to inoculated earth. Mainly, shifting considerations from the plants in the soil to the soil itself. Treating it something more akin to a pet or creature than to just something you grow your plants in. Get it growing and then keeping your colony happy and healthy. You feed the soil, the soil feeds the plants, the plants feed you. Circle of life type thing.
Longevity of innoculant? Depends on type you have, and on how it’s stored. Some can be viable years after you get it, others have a rather short shelf life.( Price does not nessecceraly dictate which is which.)
-Sorry. Back to water…..
Repeatedly you’ve requested scientific proof of other people’s comments. Don’t have any for you. I’m suggesting you research the most basic control parameter of the experiments and studies upon which you based your options. Something as simple as source of water is very relevant. As is soil. Whether or not chemicals (fertilizer, or otherwise) were introduced during the grow. etc., etc..
Not trying to promote organic purity and whatnot. I’m saying results of experiments would have to be considered inconclusive if standard tap water was being used.
Not sure I follow the logic.
If the chlorine kills fungi, then watering the garden would have already killed the fungi. Adding more from a jar won’t help since they will be killed next time you water.
If the chlorine does not kill the fungi, then the soil has lots of them, and there is no reason to add more.
The fungi population in soil is at its maximum based on the sum of all environmental conditions – soil type, temperature, water source, food source etc. Adding more won’t change this.
Chlorine can be aerated out with an aquarium air pump & stone…it’s what I do. The tap water in our town has a pH of 6.4, so I bubble out all the chlorine prior to watering plants. Rain water is good, plants really seem to love melted snow water. They thrive on that for some reason.
I found out the hard way that in most communities it’s no longer possible to let chlorine dissipate/aerate out of tap water. It was my standard practice years ago with aquariums. But, it had been years since I’d set one up and my last attempt kept falling over and over again. I was finally informed that in the last decades most municipalities have switched from chlorine to chloramine, which does not dissipate. After telling people for years what a waste it was to use a de-chlorinating products, I finally got some and my aquarium started to thrive.
“most communities it’s no longer possible to let chlorine dissipate” – that is not true. Most communities still use chlorine which dissipates. Some communities now use chloramine which does not.
https://youtu.be/axshg204Ql8
I use mito for germinating seeds and the difference is 10-fold as well I’ve noticed marketable differences in vegetables where I add to the soil and the stuff is fairly cheap. $15 last me several seasons stired correctly. I also add other good things that might already be in the soil as well. just like me. the more good food I get, the better I perform!!
1) Show me some evidence that fungi affects seed germination?
2) With most vegetable seeds you get more than 80% germination rates. How can you claim that fungi gave you a 10-fold increase??? That means you get an 800% germination rate?
You can’t claim what is in your soil or compost, until you put it under a microscope to see for yourself, it’s called blind faith. Proved that with my own farm
You can’t make a claim even after you put it under a microscope
https://www.gardenmyths.com/soil-bacteria-myth-identification-managment/
This almost 7 year old article has been proven false. There are many youtube videos done using control groups and each group containing at least ten plants. Same conditions of every type-light, water, humidity, soil, etc.The mychorriza groups had better yield. Period.
It is as true today as it was when I wrote the article.
Youtube videos are NOT scientific proof – but if the experiments were done correctly they might be of anecdotal value. Could you not find one valid one to link to here?
If experiments are done correctly (controls & replication) & with integrity then then the results are not anecdotes they are are experimental evidence. Science is science – doesn’t matter if it is done by a YouTuber or an Ag extension scientist.
True – but you missed one big step in the scientific process. You have to document your experiment and publish it so others can critique the work. That is the only way we know it was done correctly.
I have never seen a Youtuber present such an experiment.
For those of you wanting more recent information on this subject I recommend you look at the work being done by the University of Colorado. They have scientific proof that fungi increase yields in farm harvests. More specifically, they state that 2 pounds of extract from a fungal focused compost can both replace 200 lbs of fertilizer and increase yield by more than double. It is scalable and proven n the field.
And were is the link to this study? Until it is published it is not valid information.
Robert I think understand your point… they are there already. Just feed the existing population and they will increase, there is no need to add more. Adding more to a population without something to feed on would not work long term anyway. You just saved me money… I’ll get Forrest mulch delivered from the local tree lopping company and let them multiply.
Old conversation but I’m going to hijack it anyway. I live in mesa Arizona and did an experiment with 2 tc banana plants that were 1 foot tall. I planted one on one side of my orange tree and one on the other side. I dug a 1 foot hole and mixed it with cactus soil 50/50 for each and dropped the banana plants in. Both were sticking out of the soil about 6 inches and built a mound with compost. I covered the whole area with well composted kitchen and yard waste. One plant was inoculated with mycos and the other wasn’t. They both get the same amount of sun, shade, water, and being tc bananas they are most likely from the same parent plant.
After 4 months the inoculated banana plant is 3 feet tall stem hight while the other one is only a foot and a half tall. The inoculated one has kept all its leaves even the tiny baby leaves that it came with. The other one has only one nice leaf 2 so so leaves and one that’s yellow and ragged. Also it is December now and the inoculated one is still putting out leaves all be it slow vs the other one thT hasn’t done much in the past 4 months. Don’t know how accurate my experiment was, maybe I needed more plants to test at once, but I was shocked at the results. I have in the meantime inoculated the other banana plant and will see how it does in the spring.
Planted in two different places and only one plant in each spot – not enough plants.
Co9uld be due to different plant condition to start with, amount of light, different root competition, different amounts of water etc.
I do wonder if sandy SW US desert soils may be an exception? These soils have low productivity, are often damaged by decades or even centuries of livestock grazing, and are often dominated by the few plants that don’t have mycorrhizal associations, i.e. Brasssicacea and Amaranthaceae ruderal weeds.
Though I suppose just adding compost to this kind of soil would accomplish the same thing…
What is the problem in these soil? Poor conditions for mycorrhizal fungi, or a complete lack of them? If the former – adding them will not help. If the latter then adding might help – but is there such a location? Mycorrhizal are associated with 80% of plant species.
Found this – seems they are present in desserts. https://www.scienceopen.com/document_file/6bebedee-0c13-49f1-a33e-4e5e02a612af/PubMedCentral/6bebedee-0c13-49f1-a33e-4e5e02a612af.pdf
Can you tell me if adding either leaf litter mold or/and commercial mycorrhizae along with brief sprinkles of water to a pile of small dry tree branches, twigs and brush would make them break down faster?
Leaf mold might help a bit, but I doubt it makes much of a difference. The leaves are already covered with billions of fungi spores.