I can attest to the benefits of Mycorrhizal Fungi in the root zone of my plants. I brought in wood chips. It takes roughly 18 months to decompose enough in which to plant. Oh my, the Mycorrhizal Fungi was everywhere. I forgot to fertilize the one watermelon that I planted, but got 4 melons. The one barrel gourd seed has developed well over a doze and I can see a dozen more baby gourds sprouting. I credit the microbes. You can buy it in powdered form or even tablets. But, they do help your plants by growing more roots.
