Does Mushroom Compost Serve the Same Function as Mycorrhizae

by Maireid
(Melbourne Australia)

Hello, and thank you for this wonderful resource.

We are organic backyard growers in NE Melbourne, Australia.
I googled "mycorrhiza and mushroom compost" and found your website.
I love the details you have provided.

We've been using organic mushroom compost and compost worms in our raised beds (wicking worm beds) and I was wondering whether mushroom compost serves the function of mycorrhiza.
Can you let me know your thoughts?

Thank you!
Maireid

The Short Answer is No

Mushroom compost definitely doesn't substitute for mycorrhizal fungi.

The type of mycorrhizal fungi that work with most of the veggies and fruits you are likely growing in your garden only reproduce when they are in a partnership with the roots of a live host plant. They do not live or reproduce in compost of any kind though a few might survive the composting process.

These are called endomycorrhizal fungi or arbuscular mycorrhizal fungi - sometimes referred to as VAM or AM for short.

A well established garden that has been managed with few chemicals might already have the mycorrhizal fungi. However, for a bunch of reasons lots of gardens are missing this member of the soil food web. Our plant fungi partnership page goes into a lot of depth about the benefits of mycorrhizal fungi.

As you can see the benefits are considerable so you do want to ensure your garden has this link in its food chain.

In your case I assume you filled your wicking beds with some sort of mix of soil. In the process of transferring the soil you had to at the very least dig it up. And, once in the bed you likely stirred the compost into the soil. This kind of disturbance likely reduced or eliminated any of the fungi you had naturally.

By the way, I'm not criticizing the wicking bed. I plan to put in a couple of those myself this year.

What to Do…

I think it would be well worth the small investment needed to make sure those fungi are in your growing beds. I found an Australian supplier, of a line of products called MycoApply. I reviewed their website and I think they know what they are doing, what they are selling and how and why to use their products.

Their MycoApply Endo would likely do the job you need - filling that gap in the soil food web. A 250 gram package is only $16. You can then apply it to your seeds before sowing them or dust the roots of your transplants when you set them out. Here's a link to the MAI Australia website. They have an online store.

A Few Last Bits of Advice…

Certain popular veggies don't form mycorrhizae. These include members of both the cabbage and beet families. So don't bother to use the product with these crops.

Secondly, in order to keep the mycorrhizae happy in your garden, plant a few perennial host plants every so often. Then,when you harvest your garden there will still be a place for these important members of the soil food web to call home.

I'd love to hear more about your wicking beds if you'd care to share. Good luck with the fungi.

Leslie