this story first appeared on Civil Eats.
Collar City Mushrooms is located in a small building along the waterfront in an old industrial area of Troy, New York. Behind the building, between a shed and a yellow Volkswagen bus, dozens of giant Frosted Mini Wheats are stacked waist-high in the winter sunlight. Each one is about the size of a cinder block. Weathered caps of oyster mushrooms defiantly sprout from different parts of the mountain.
The clumpy blocks are used substrate, the living material left over after growing mushrooms. Spent substrate is a unique type of waste, consisting of sawdust and soy pellets laced with mycelium (the thread-like parts of fungi from which mushrooms germinate). It’s also something that has many potential uses. It can be used as compost, as a means of soil decontamination, as biofuel, and simply to grow more mushrooms. While all of these uses offer revenue potential for mushroom farms, the growing piles of used substrate also pose increasing logistical challenges.
“Right now, we have people picking it up almost as a favor to us. Otherwise, what are we doing with it?” Co-founder of Collar City said Avery Stempel as we looked out at the mountains. Stempel currently takes most of the material to a nearby compost facility, but local farms, gardeners and florists also accept some. So do individuals, whether they are composting in their gardens or simply growing mushrooms at home. “People will come and buy $5 buckets,” Stempel said.
Before you start growing mushrooms, carefully mix and sterilize your substrate to maximize efficiency and prevent competition with fungi. The sawdust and soybean hulls are protected in breathable plastic bags, inoculated with edible mushroom strains, and stacked on racks in a temperature-controlled room. Once the mycelium is ready, cut the bag open and the first “flush” of mushrooms will sprout. To make the most of space, many farms discard the blocks after washing them once, but each block is capable of several mushroom productions. In this sense, the board is not really “used up”.
Used circuit boards waiting to be collected and reused. (Photo courtesy of Central Texas Mycological Society)
Color City is a relatively small operation, producing up to 1,000 pounds of mushrooms per week. His Tivoli mushrooms in Hillsdale, New York, about an hour south, produce about 20,000 pounds per week, but he is currently using only half of the capacity of his new 15,000-square-foot facility. not. Shortly after moving, co-founder Devon Gilroy contacted a nearby organic farm and offered to give away their used substrate as compost for free. It wasn’t a difficult sell. “About two weeks later they showed up with a tractor and a big truck to load it up,” he said. “They insisted that we pay for the board, which was really helpful.”
More mushrooms mean more problems
From a revenue perspective, the highest value of specialty mushroom substrates is currently compost, which sells for about $150 per cubic yard. The low pH level helps the soil to be less acidic and has a carbon to nitrogen ratio of about 40 to 1, which is close to ideal for building healthy soil. Used substrate is also useful to add to your vermicompost. Earthworms love to feed on mycelium, which also breaks down woody debris and supports soil biodiversity. It also has excellent structure and water retention.
But that doesn’t mean it’s easy for every mushroom farm to find a second home for used substrates, and as the specialized mushroom industry grows, the puzzle of how to put the material to use becomes more apparent. It is increasing.
“If you’re going to do it, great, but consider this waste stream you’re creating and how you’re going to remove it from your property.” This is from Amanda Janney, founder of KM Mushrooms in California This is the advice they offer to new farmers. Janie’s farm, run from her home in Santa Rosa, is as modest as they come. As the farm’s production rapidly increased, going from 20 pounds of mushrooms per week to about 300 pounds, leftover ingredients quickly became a logistical problem to solve.
“In the beginning, when we were working with very low volumes, it wasn’t really considered. Just distributing bags of used boards through Craigslist or Facebook Marketplace was enough.” Johnny said. “Then our production increased much faster than I had planned, which is great, but a big part of it was connecting with farmers who were interested in producing.” [taking substrate] And get a workflow to quickly move it off-site. ”
Global mushroom revenue is expected to more than double to more than $110 billion by 2030 in 2022, driven largely by consumer interest in meat alternatives. The nutraceutical market for medicinal mushrooms such as reishi, lion’s mane, and cordyceps is likely to follow. Following a similar trajectory, one forecast suggests the market could triple to $62 billion by 2032.
The majority (95 percent) of mushroom production in the United States is Agaricus: common cremini, peonies, or portobello (all the same species). All other varieties, whether shiitake or oysters, fall into the specialty mushroom category.
In the United States, Agaricus The mushrooms are produced in large quantities on farms that have been established for generations, most of which are located in Kennett Square, Pennsylvania. Mushrooms grown in a combination of manure and straw produce a unique type of spent substrate that can also be used as compost, but it is a very different material than specialized mushroom substrate and has limited uses. . Growing button mushrooms cost-effectively is very labor- and space-intensive, and small-scale production does not make much economic sense.
By comparison, it’s relatively easy to grow enough oyster mushrooms to sell on the market for more than $10 per pound, compared to about $5 per pound for button mushrooms. It’s also easy to purchase some ready-to-grow kits for home growers. For these and other reasons, most small emerging farms are likely to grow specialty mushrooms. Sales of specialty mushrooms increased by 32% from 2021 to 2022 alone. This means that used substrates are increasing as well, leading to even more questions about what to do with it.
At the extreme end of the substrate spectrum are emerging mycelium materials companies such as MycoWorks and Ecovative. [Disclosure: The author worked for Ecovative in 2022 and 2023.] Ecovative is based on oyster mushroom mycelium, and most of its substrate is shipped as compost, and the company is considering selling some of the vast amount of leftover substrate to farms in Pennsylvania. This includes doing a second mushroom production.
However, there are limits to that market. “Frankly, it is impossible for us to eat enough oyster mushrooms in the United States to use up all the substrate we produce if we reach our goal,” said Ecovative CEO Eben Beyer. “It’s a big opportunity on a spreadsheet, but operationally it’s like, ‘Get me out of here now.'”
Community solution to substrate waste emerges in Texas
The question of what to do with the substrate is primarily answered by local communities of specialized mushroom farms, rather than relying solely on the market. In Austin, for example, the Central Texas Mycological Society (CTMS) has organized a network of about 20 locations to collect used substrates for free. They report that about 9,000 people have signed up since the program began three years ago, with enrollment surging during the pandemic, when interest in homegrown mushrooms increased dramatically.
“Using a used mushroom substrate, we seized this opportunity to keep people connected,” said Angel, lead organizer of CTMS, whose front yard was the first drop-off point for the program. Schatz said. But what people do with that material is their own business. “We know a lot of people grow mushrooms and take second flushes out of bags, but we don’t want to steal from commercial farms in any way, so we start by teaching people how to compost. start. “
Photo courtesy of Central Texas Mycological Society
Until recently, a significant amount of used substrate for CTMS recovery programs was supplied by Smallhold. Smallhold quickly became a prominent specialty mushroom grower over the past five years, before declaring bankruptcy in early February. With facilities in Los Angeles, Austin, and New York, the company’s goal was to grow specialty mushrooms near major cities. Each of the three large-scale farms produces approximately 80 to 100 cubic yards of used substrate per week, and the company has hired a team dedicated to finding productive uses for that material.
“At the end of the day, this is a valuable material,” said Travis Breihan, the company’s impact manager responsible for researching uses for used substrates. “But it’s a new material in the field, and there hasn’t been an established industry for second-flushing blocks, using them as garden amendments, or even using them as large-scale farm amendments. I think we’re still in the early stages of adoption in the world, but all the signs are very strong that it’s a big area of focus for the mushroom industry as a whole.”
CTMS is not concerned about losing Smallhold substrate. “We still work with another farm that produces about 1,900 used substrate blocks a week, but those will likely grow from now on as Smallhold is not here.
Meanwhile, CTMS not only distributes the blocks, but also works with local farms, food producers, and environmental remediation projects that use the materials to clean up contaminated sites such as Circle Acres Nature Preserve on the edge of Austin. We are cooperating.
Given the limitations that scale creates on the transportation and productive use of used substrates, the future market for the material is certainly most likely to be shaped by small-scale operations. Specialty mushrooms lend themselves well to this dynamic. It is not suitable for long-distance transport and can end up in waste streams such as sawdust from nearby industries. They can take on different shapes and, importantly, sizes. As the specialty mushroom industry grows, spent substrates could become a market for secondary mushroom production or soil and waterway construction and restoration. The potential of this material may be best realized in linking mushroom production with other food and soil-based initiatives to support more circular local economies.
“The least we can do is make sure the cycle is complete and put it back in the soil and not in the dump,” Schatz said.