Creating a Circular Economy with Mushrooms

Palm fronds from my back yard

Modern life poses an increasing number of complex problems, necessitating our coming up with ever better solutions. We know that our typical linear economy, that of manufacture, consumption, and waste, cannot be a long term solution. It is wasteful and inefficient. Mushrooms provide one very simple service that, with a little thought and planning, becomes a very powerful tool. Mushrooms use our waste materials as inputs, giving food and, with a little extra work, soil as an output.

I recently went to a presentation on creating a circular economy, where a city official talked about difficulties with palm fronds in the waste stream. Most green waste gets chipped, shredded, and composted. Palm fronds pose a unique problem, though. They are very fibrous and tough to cut down to a size that can be composted. Since the area in question, Phoenix, Arizona, is subtropical, there are a lot of palm trees around, providing lots of palm fronds to the waste stream. During the presentation, the city official mentioned that they have requested proposals for finding new ways to dispose of the palm debris, without much response.

After the presentation I asked him if anybody had suggested growing mushrooms on the palm debris. No one had. I told him that the palm fronds have a density somewhere between straw and wood and aren't particularly aromatic. They should break down pretty well with the right mushroom. When I got home, I did a little research. Pink oyster mushrooms (Pleurotus djamor) are a tropical mushroom that grows best in warm climates. Like most mushrooms, the pink oyster mushroom has certain preferences on what sorts of organic matter it prefers to grow on. It prefers to grow on tropical woody debris like palm wood and palm debris. Also, being a hot weather mushroom, it grows fast in hot weather. I wasn't able to answer detailed questions, like how long will it take to break down the palm fronds, but I am currently working on an experiment growing pink oysters on some palm fronds from my own back yard.

The whole interaction was actually weird for me. Normally, when I mention that mushrooms might be used to solve a problem, get a LOT of eye-rolling. People hear the word "mushroom" and mentally add the word "psychedelic." I didn't get that in this crowd. The talk was about creating a circular economy. It was a very receptive crowd.

When looking to create a circular economy for most sorts of green waste, mushrooms are a natural fit. In natural systems, the inputs come in the form of good soil, fertilizer (sometimes the soil and the fertilizer are one and the same) and sunlight. Progressing through the system, the plant grows, produces whatever product is desired, then dies. The end result is slightly depleted soils and dead plant matter. In order to create this into a circular economy, all you have to do is find a way to turn the plant waste back into fertile soil. Compost is the simplest way to achieve this, but it is labor intensive and doesn't add any value other than closing the loop to improve the soil. Adding mushrooms to the process helps considerably. By adding the production of another saleable output, the whole process gets improved. It becomes more profitable to close that loop and provides incentive.

Mature garden bed with mushrooms growing between plants

The problem is, this is still short-sighted. There are many more opportunities here. It isn't as simple as "just grow mushrooms on the waste product." Mushroom growing as a business is very equipment intensive, labor intensive, and knowledge intensive. But it doesn't have to be. Just as seed production is a separate business that helps farmers, mushroom spawn production could be centralized. Mushroom production involves several levels of spawn production before the final inoculation to produce the flush of mushrooms. Most mushroom businesses today create their own spawn, but that doesn't have to be the norm. A business could be created that helps farmers set up an outbuilding on their properties for mushroom production. Rather than each farmer creating their own biology lab, they would just buy the final run of spawn and use it to inoculate their waste. That process is pretty simple and easily learned.

But what about yard waste? What about those palm fronds, not to mention the logs, leaves, and other yard debris? Again, a business could be built out of it. They could be local, community centric organizations that somehow collect yard waste and turn it into mushrooms. It could provide for community employment. Again, the spawn production could be done elsewhere and just sold or distributed as needed.

Garden bed pictured above, before planting

Let's look again at that circular economy. What if you could contract that circle a bit, and overlap functions? In my last post I mentioned a different way of gardening. It just so happens that this type of garden allows you to decompose organic matter WHILE growing plants in it. I will get to how all that works soon, but trust me, it can be done. I have been doing just that for a couple of years. Through the addition of mushrooms to the living ecosystem that you are recirculating water through, you can increase the production of the whole system. As the mushrooms decompose the plant matter, they produce quite a bit of carbon dioxide. Might as well put plants right there to gobble it up as a food source, right? As the mushrooms decompose the organic matter, they release nutrients. Might as well sink some plant roots in it to take advantage, right? Mushrooms also function as a really effective water filter. They will help catch even more of the nutrients you are cycling through the system in the water. All of a sudden that little community mushroom growing business is also pumping out fresh produce as well.

So what do we need to get all this going? First of all, we need research. I only know of two experiments that have been done that test plant-mushroom pairings. Certainly some mushrooms are going to be harmful to plants and others will be beneficial. We need to find out which is which. What about climate differences? Paul Stamets, who has done a lot of the mushroom growing research to date, lives in the Pacific Northwest. One of my favorite lines is when he calls king stropharia mushrooms a summer mushroom, preferring to fruit at temperatures up to 90 degrees. Where I live, that is a winter mushroom. But there are others, actual heat loving mushrooms, that would probably thrive here. Pink oysters (Pleurotus djamor), king oysters (Pleurotus eryngii), black poplars (Arocybe aegerita), milkies (Calocybe indica) and paddy straws (Volvariela volvacela) are all native to warmer regions and could do well in southern settings. We just need to work out how best to grow them.

There is one more thing, though. It isn't just the science we need to work on. We need to also work on the marketing side of things. If we all of a sudden start flooding the market with mushrooms, we need to create a market for them. We live in a society that has a lot of phobias around mushrooms. We need to teach people about the new kinds of mushrooms hitting the market. We need to teach them how to cook them. We need to teach them how healthy they are. Most of all, we need to rebrand mushrooms as the food that helps the environment.