The Wonders of Mycorrhizae

Photo from J.R. Leake University of 

Sheffield United Kingdom 2001

Mycorrhizae works tirelessly beneath the soil and is often undervalued in favor of its fruiting body, the mushroom. But what makes mycorrhizae so phenomenal is that it acts as a network of arms (or "hyphae") reaching from the root zone or rhizosphere of a plant and out into the soil. It is my favorite part of the soil ecosystem.

This network of hyphae is reaching for water and nutrients for plants, and in return the mycorrhizae get a constant source of carbohydrates. These carbohydrates, or mucigel, is a gelatinous substance created and excreted by plant roots. This mutualistic form of symbiosis between the roots of the plant and the fungus allows both the plant and the mycorrhizae to get the things they need in a highly efficient manner.

Around the roots of our vegetables, there are areas called Nutrient Depletion Zones that quickly become devoid of nutrients as the vegetable sucks up available water, phosphorus, carbon, nitrogen, and other minerals in the immediate area. Without mycorrhizae to extend the surface area of the root, there would be a lack of nutrients for the plant to absorb. 

One type of mycorrhiza can actually grow on the inside of rocks where it aids in mineral weatherization. The nutrients gathered here would be impossible for a plant to have access to without the help of mycorrhizae. 

Not all vegetables or plants can benefit from mycorrhizae. Here is a list of which plants need it and which ones do not (see Sources below). One other consideration is that there are two types of mycorrhizae. endomycorrhizal and ectomycorrhizal. One indicates a relationship formed outside of the plant's roots (ecto). And one indicates a relationship formed inside the plant's root cells (endo). This is important to note if you decide to inoculate your garden with this valuable fungus. You may need to inoculate for both!

Why you should care for your mycorrhizae and your soil:

- Mycorrhizae are present in all healthy soils, but they can be reduced or entirely absent when soils are over-tilled, allowed to lie fallow, allowed to become overrun with weeds, eroded, or compacted. So it's important to plant a cover crop, to turn your weeds under or pull them out, and to build up your soil over-time instead of tilling.

- Mycorrhizae help reduce your need to water . Because the network of hyphae can extend for miles, it is not necessary to water as frequently if your soil is healthy and full of this beneficial fungus.

- It also cuts down on your need to amend soils with fertilizer. The presence of mycorrhizae will help prospect the soil for nutrients that are normally inaccessible to your plants. This doesn't mean don't build up your soils or amend at all, but it does mean that if you inoculate and care for your soil, you shouldn't need to use as much fertilizer or amendments as you have in the past.