Fungi are very important to the forest ecosystem, especially the mycorrhizae in the soil which helps the tree roots take in water and nutrients as well as communicate with tree seedlings. They are also responsible for the ongoing recycling of nutrients and break down of organic material into usable forms for trees and other plants.
For those who attend the Williams Lake Farmers' Market you may have visited the Mushroom Monarchy display of edible mushrooms grown by Bryden Kohnke. As well as providing a wide variety of tasty mushrooms, the spent growing medium is also a valuable soil amendment.
When we visited the Kohnkes' home and mushroom business to pick up some soil amendment we toured the growing facilities housed in a steel container which has just the right temperature and humidity.
The bundles of fertilizer, about a foot square in plastic bags, are left over after the mushrooms are harvested and are sold for a dollar each. He indicated that he purchases the growing medium from eastern Canada which often consists of white oak sawdust . The spent medium could be best described as coarse sawdust which has the remnants of the mushrooms species that were just harvested. To use as a fertilizer you can just layer it on the area you want to treat or incorporate it into the soil.
I did a little research on making compost for growing mushrooms on a commercial scale and found the following. The medium is often made from a variety of agriculture products like straw and animal manures that are composted and then heated to sterilize so that the desirable edible mushrooms can grow without competition. Making your own compost not only takes a lot of resources but you would probably need to be in a rural area to avoid problems with your neighbours.
Since the Kohnkes have a normal sized lot in the Dog Creek area it is more logical that Bryden uses a consistent medium that has proven successful for his business. It is also convenient for gardeners to pickup the spent growing medium and apply the product to their gardens. According to some other sources the fertilizer contains lots of nutrients and tends to increase the soil pH and would therefore not be good for blueberries but is excellent for tomatoes, zucchinis, pumpkins and carrots. It is also a slow release type of fertilizer so has a longer lasting impact on your plants.
I sent a rough draft of this article to Bryden and he sent me the following comments.
“The pre-made substrate you mention is used in farms that grow button mushrooms (Agaricus bisporus). These mushrooms are called secondary decomposers and are likely what most of your internet research on the topic has regarded. I grow primary decomposing mushrooms (the type that grow on trees in the forest). I do prepare my own substrate with wood shipped from eastern Canada. The company I purchase from specializes in making organic hardwood pellets for the mushroom industry. I mix these pellets with various other nutrient sources such as wheat bran, rice bran, soy bean hulls and whole oats. I then hydrate, pasteurize and inoculate in a laboratory clean room. I also wanted to add that my substrate is not composted in the same way prior to growing as they do in the button mushroom industry. My spent substrate blocks could actually be added to a button mushroom farm's compost to be further broken down and grow Agaricus bisporus mushrooms.”
