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How to increase mycorrhizal fungi in soil?

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Increasing mycorrhizal fungi in the soil is a topic of interest for many gardeners. After researching this, I decided to condense my findings into this article.

Tillage damages mycorrhizal fungi by breaking up the hyphae and mycelium, causing them to start over again. Having a diverse selection of plants can be instead looked into rather of moving the soil around, as this will increase the mycorrhizal fungi due to their microbial relationships.

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While the said option is one of the main ways gardeners can look into minimizing and stopping altogether to foster the growth and success of increasing mycorrhizal fungi in the soil, we will be talking about more methods and things you can do to make the process more successful for both the plant and the fungi in the next few sections.

The mycorrhizal fungi

To get started, we need to establish what mycorrhizal fungi are and why they are important.

Mycorrhizas are essentially the associations between helpful fungi and the roots of plants. 


The fungi are essential to wild plants and the soil in general. This is because they work to extend the plant’s root area, helping them to thrive. To aid you in having a deeper understanding of these fungi, you can look into this recent article that I wrote on just what mycorrhizal fungi are, as it covers topics ranging from the benefits of these fungi to their subtypes.

The connection between phosphorus and mycorrhizal fungi

As I touched upon earlier, phosphorus is detrimental to mycorrhizal fungi.

This is because it is the job of the fungi to help plants by gathering phosphorus in the soil, which would be very difficult for plants to do without any help. Phosphorus is naturally occurring in soil but is often in short supply.

Therefore, people use fertilizers to boost the amount of this element. However, this suppresses the mycorrhizas as they cannot carry out the function of gathering it.

Methods that can increase the mycorrhizal fungi in soil


Due to fungi being very efficient at absorbing nutrients and water from the soil and the benefits they provide to plants’ well-being, we must take certain measures to increase their numbers in the soil. Most garden plants use mycorrhizas (except the brassica family). A particular type of fungi called arbuscular mycorrhizal, or AMF is commonly referred to as is hosted inside the plant’s root.

Now that we’ve established the function of these fungi and why it’s important to our garden, let’s look into how we can increase it.

Things we should do to increase mycorrhizal fungi in soilThings we shouldn’t do to increase mycorrhizal fungi in soil-plant a diverse mixturePesticidesKeep soil covered adding phosphorus into the soil develop a longer growing season digging and tillingUse the right mix of media mulchProvide enough air and water.

Mycorrhizal fungi are naturally occurring and have an interdependent relationship with plants. So to put it simply, the best way to increase them is to keep your garden as natural as possible.

If the soil has been dug too frequently, the fungi have likely been destroyed, and therefore the need for it to be replenished will be high.

Adding in phosphorus is an easy fix that is not ideal for helping mycorrhizal fungi grow.

It could be tempting to introduce more phosphorus into the soil as fertilizer. This may solve the short-term problem, but it is much better to help the fungi flourish, as this will create a garden full of healthier plants for years to come.

Why diversity in the garden and soil matters for boosting mycorrhizal fungi

One of the easiest ways to increase mycorrhizal fungi in the soil is by ensuring that you have a diverse selection of plants in your garden.

This benefits the fungi because they love being in the company of other microbes, such as bacteria, which benefits them and the soil.

Mycorrhizal fungi work by extending filaments into the soil and gathering water and nutrients from the plants before transporting them back to the roots. In return, the fungi get food and shelter from the plant, so it makes sense that the more plants there are, the more the fungi will also thrive. 

Look into crop rotation to further boost the increase in mycorrhizal fungi

Picture of vegetables in a field

Crop rotation is an effective way to help the fungi, leaving some wilder areas of your garden where weeds grow. The more variety you see in your garden, the more beneficial it will be to the mycorrhizal fungi in the soil.

Some crops should be avoided as they will discourage mycorrhizal fungi. These include; buckwheat, forage radish, canola, and camelina.

Adding mycorrhizal fungi to soil manually is not very advisable in these situations.

If plants are in your garden, the soil already contains large quantities of mycorrhizae. You may come across manufactured mycorrhizae, which claims to add fungi to your soil.

Adding manufactured mycorrhizal fungi may seem like a quick fix, but it is not worth doing in most cases.

Adding it to your soil is relatively pointless because most manufactured mycorrhizae comprise around three fungi types.

Introducing soil helpers can help with boosting mycorrhizal fungi

Fungi and bacteria are technically decomposers. Fungi love to break down carbon-filled matter, so introducing media into your soil to encourage them can be a good way to increase mycorrhizal fungi’s presence.

It’s always a good idea to keep adding beneficial mulches and media to your garden, so not only will this benefit the mycorrhizal fungi, but all other organisms too.

It’s essential to use many small organic materials if you are layering your soil. It would help if you made sure the mixture had a good ratio of carbon to nitrogen to ensure that the matter could break down easily enough for the fungi and bacteria to break it down.

How to boost mycorrhizal fungi using straw and leaves

For fungi, straws and leaves are good materials to make into mulch. You can cover the soil, and the fungi will grow around the straw.

This effective method doesn’t require you to turn the soil like composting would, which can be detrimental to the fungi.

The great thing about soil helpers is that when springtime comes around, you can remove your mulch, and it will be full of helpful nutrients, fungi, and bacteria, which can then be reintroduced into other parts of the garden, which might require a boost.

Why adding in manufactured mycorrhizal fungi can be useless to your soil

Picture of how mycorrhizal fungi works

There are hundreds, maybe even thousands, of different kinds in your soil, many of which are specifically suited to certain growers and plants.

Adding a few fungi manually will hardly have any effect, so it is better to focus on helping the existing mycorrhizae thrive.

Manufactured mycorrhizae are also sensitive to heat, so there is a high chance the fungi will be killed when it is stored or transported. There is no way of knowing if the fungi are alive, so in most cases, it is better to avoid this kind of product altogether.

What happens when soil lacks mycorrhizal fungi?

When plant root systems lack mycorrhizal fungi, it can cause them to grow poorly and fail to establish themselves properly.

Mycorrhizal fungi are essential to the plant’s overall health and play a crucial role in cycling nutrients, reducing plant stress, and providing adequate protection against pathogens.

Plants will suffer in the absence of mycorrhizal fungi due to their importance in the plant’s ability to overcome transplantation shock. The relationship between plants and fungi is the byproduct of a long evolutionary process, so you can understand why mycorrhizal fungi are so important to their survival and health.

Thankfully, by ensuring that your soil isn’t overly dug and by not introducing phosphorus into it, there’s no reason that the mycorrhizal fungi can’t thrive abundantly and help the other organisms to do the same.


Conclusion on increasing mycorrhizal fungi in soil?

Boosting the mycorrhizal fungi in the soil is as much about avoiding certain practices as it is about taking action. Providing too much phosphorus is almost equally damaging as tillage. The plants attach themselves to the inorganic matter in their formative years.

This results in them never really developing a relationship with the fungi. The same can be said for pesticides. Although mycorrhizal fungi are resilient, most pesticides will wear them down over time, so if possible, you should avoid using them.

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