Cultivating mushrooms and producing soil amendments using underutilized waste materials to increase profitability in an agroforestry system.

Final report for FNC22-1358

Project Type: Farmer/Rancher
Funds awarded in 2022: $15,000.00
Projected End Date: 01/15/2024
Grant Recipient: Zumwalt Acres
Region: North Central
State: Illinois
Project Coordinator:
Alexis Weintraub
Zumwalt Acres
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Project Information

Description of operation:

Zumwalt Acres is a regenerative farm, Jewish- and queer-centered community, and hub of land-based learning in Sheldon, IL. We steward the unceded homelands of Kickapoo, Peoria, Kaskaskia, Potawatomi, Myaamia, and Očhéthi Šakówiŋ peoples. We are working to transition the Zumwalt Family 6th generation farm from industrial to sustainable agriculture. We are implementing farming methods that revitalize soil, mitigate climate change, and produce nutritious food. Our farm hosts an apprenticeship program, supporting up to ten apprentices (ages 18-27) each season (fall, spring, summer) to live communally, farm collaboratively, conduct scientific research, and connect with regional farmers and community members. We teach and empower the next generation of farmers, scientists, and activists to build a better food system and tackle climate change.

We have roughly three acres of agroforestry (growing trees for food and ecosystem services), one acre of horticulture, indoor and outdoor mushroom production, and ongoing climate change and soil health research supported by universities. We work with surrounding farmers to implement carbon-negative practices on their farmland, covering 100s of acres. Our aim is to support the regeneration of the local ecosystem, build climate resilience, provide food for our immediate and local community, and empower young people to implement their vision of a nourishing and hopeful future.


The purpose of this project is to increase capacity for mushroom production as a way to convert underutilized, on-farm resources into a nutritious product, while improving soil health, and increasing profitability in an agroforestry system. Mushroom cultivation can play a key role in our system by providing a consistent weekly marketable yield, with low input costs and next to zero waste. For agroforestry to be financially viable for farmers, there must be streams of revenue during the years before the trees and woody perennials reach maturity. Mushroom cultivation provides a relatively secure path to profit during this vital interim and beyond. The spent mushroom substrate (i.e. the “waste” material that remains after mushroom harvest) will be used in a vermicompost system, supporting the production of worm castings, a high quality soil amendment. This vermicompost can be combined with biochar (which can be produced on-site from agroforestry waste products) to produce a biodiverse soil amendment that can improve soil health and plant yields throughout the agroforestry system. Biochar paired with vermicompost has shown to provide synergistic benefits (Doan et al, 2015). With further development, this amendment can become a marketable product in its own right, supporting horticulture, urban farming, and container gardening. 

As a research component of this project, we compared two methods of straw substrate pasteurization with an unpasteurized control.  The two treatment methods we used were soaking straw 12-24 hours in a solution of hydrated lime (pH 12+) and soaking straw in the squelch water from biochar burns (supplemented with lime when necessary to raise pH to 12+).  Detailed pasteurization protocols are linked in this report.

We experimented with six varieties of commercially available oyster mushrooms.  We found four varieties that worked well for us throughout all seasons, and two that were successful in the warmer seasons.  While two varieties were the most prolific, we found that our customers appreciate variety, and continue to offer 4-6 varieties depending on the season. On land utilized in agroforestry practices, native oyster mushroom strains were found which, with proper inoculation procedures, could increase production rates while reducing input costs.

We also experimented with different methods of utilizing spent substrate, including: building outdoor mushroom beds that incorporated fresh substrate for additional fruiting;  vermicompost; incorporating into garden scrap compost; incorporating into cow manure-based compost.  

The timeline, scale and nature of this project yielded more observational data than statistically significant quantitative data.  

We found that both hydrated lime and biochar squelch water provided the benefits of substrate pasteurization.  To our knowledge, this project was the first to demonstrate that biochar squelch water can be used in this way, and we would recommend the practice to other small-scale operations.

All forms of spent substrate management effectively turned the spent straw into useful products for our soils.  Our vermicompost did not reach a large enough scale to overwinter, so we kept vermicompost in bins in our greenhouse. While we had success establishing outdoor beds with spent substrate, the mushrooms that were produced in these beds tended to be irregular in shape and size and were often covered in straw.  These mushrooms were not market quality though they were excellent for home consumption.

This project provided numerous educational opportunities for more than 50 farm apprentices over the two years of the project and other practitioners in our community through multiple field days each season.  During the fall of the second year of the project, we hosted a mushroom cultivation field day where participants engaged in all aspects of the cultivation process and made their own grow bags to take home.

The farm now has an established growing system.  We will continue to grow mushrooms in future seasons, providing learning opportunities for apprentices and community members, as well as providing food and revenue for the farm operation.

Project Objectives:
  1. Build infrastructure to support mushroom cultivation including a transfer space, incubation room, and fruiting room.
  2. Refine and document mushroom cultivation standard operating procedures by end of 2022.
  3. Grow and sell an average of 30 lbs of mushrooms per week for 30 weeks throughout the 2023 growing season.
  4. Develop a healthy compost system to match the scale of mushroom production and utilize compost in farm operations.
  5. Develop teaching tools to support apprenticeship education on mushroom cultivation and vermicompost.
  6. Document and share findings through social media and field days.


Materials and methods:

To begin our experiment with indoor oyster mushroom cultivation, we decided to start at a small scale, utilizing temperature-controlled basement space.  We had initially planned to set up our grow operation in a 40' shipping container.  However, once we delved more deeply into designing the full setup, we realized that a system of that size would require significantly more investment than we could cover at this time.  As we researched growing practices, we learned that establishing a new structure (i.e. shipping container) as a grow space would require substantial energy usage, as mushroom fruiting rooms demand high levels of air exchange, therefore requiring high energy inputs for temperature control.  We decided to focus on maximizing existing indoor spaces, in order to minimize the energy and material inputs that would be required to grow.

We used one room in the basement for incubation and fruiting.  In the winter following the first season of the project, we cleared the entire room, retrofit shelving for incubation, and added an additional fruiting chamber to increase capacity.

Basement temperature varied between 50-75 degrees F over the course of a full year, as determined using a temperature logger.  These temperatures are within the range for successful incubation and fruiting without any additional temperature controls. While this range in temperature is not optimal for mushroom production - these mushroom strains would prefer a warmer incubation space and cooler fruiting space - we decided to work with passive heating/cooling in order to stick to our values of minimizing material inputs and energy costs.  We considered this project an experiment in low-tech growing and could add an HVAC system to our setup in future seasons.

We used Peter McCoy's book "Radical Mycology" as a reference for developing all of our systems and protocols and would highly recommend it to others.

The first controlled-environment fruiting chamber is described below:

We purchased and set up a 25 ft sq grow tent (Gorilla Grow 5'x5'x5') in the basement room.  We used a 6" duct fan with ducting to exhaust the tent to the outside.  The fan is connected to a CO2 controller, which turns the fan on to exhaust the tent when CO2 levels exceed 750ppm and brings levels down to ambient before turning off.  Humidity is provided by a DIY humidifier we constructed using a 9-disc pond fogger, connected to a humidity controller that turns on when humidity drops to 70% when it reaches 95%.  (Humidifier design was adapted from Myers Mushrooms video on YouTube "How to Build an Ultrasonic Humidifier Tote for Mushroom Growing"). The humidifier we constructed could handle significantly higher capacity and brings humidity up to 95% in several minutes.  A 600-lumen light cycles on a timer, 12 hours on/12 hours off.

For the second fruiting chamber we purchased and set up a 4' x 8' x 6' grow tent with lighting on a 12 hour on/off cycle.  For the sake of budget and efficiency, we utilized shared equipment to run the two fruiting chambers simultaneously.  We added ducting to our humidifier so that it output humidity to both tents. We had a single humidity controller in one tent that governed humidity levels.  Because one tent was slightly larger than the other, we used larger diameter ducting in this tent.  Humidity levels in the two tents appeared similar, though we were not able to monitor levels in both tents given our choices of equipment.  We also used a single exhaust fan (402 cfm) to draw air out from both tents.  The two tents each had several feet of 6" ducting exiting the tent that connected to a Y splitter that connected to the exhaust fan. For lighting, we experimented with LED string lights to provide more consistent lighting in all areas of the tent.

In the second season we standardized our cleaning procedures, emptying the tents and wiping down all surfaces with dilute bleach solution each week, wiping down and cleaning all equipment.  We replaced ducting that had become heavily coated in spores.  The 9 disc pond fogger burned out after the first season and was replaced.  The fogger burned out again at the end of the second season and was replaced.  The DIY humidifier allows the replacement of individual components, rather than the whole system. 

Protocols for chopping, pasteurizing, inoculating, incubating, and fruiting are attached:

Oyster Mushroom Protocols Straw Chopping 2022

Oyster Mushroom Straw Pasteurization Protocol

Oyster Mushrooms Inoculation, Incubation, Fruiting Protocol

One of the questions we aim to address in the research component of this project is a comparison of two pasteurization techniques: hydrated lime vs biochar squelch water.

To do this, we have done several trials in which we follow the protocols described above, using one 55-gallon drum for lime pasteurization and another 55-gallon drum for biochar pasteurization.  As our system and techniques have evolved, the trials have not been rigorously replicated.  Over the second year of the project, we dramatically reduced our biochar production for reasons unrelated to this project.  As a result, we were not able to collect enough data to produce quantitative results.  We used biochar squelch water whenever it was available, and had success with it as a pasteurization method.  

Because we constructed our indoor growth chamber in the basement without any temperature control, we selected strains that were appropriate for each season/expected temperature.  We trialed six oyster mushroom strains (PoHu, Grey Dove, Italian, Summer White, Pink and Golden) from Field and Forest Products, our spawn supplier.  The first four strains were able to fruit across the entire range of basement temperatures (~50-75 degrees F).  The pink and golden strains prefer warmer fruiting conditions, so we utilized these strains in the warmer months of summer when grow room temps were above 65 degrees F.

We grew all mushrooms in 5 and 6-gallon buckets and collected harvest yield data from each bucket individually.  We washed buckets by hand using a pressure washer and reused them.  We were interested to see if growing in buckets was feasible financially and at what scale. Buckets were removed from grow tents to make space for new buckets after a maximum of 5 harvests, if oyster strains were visibly outcompeted in the substrate, or if the bucket was not producing large enough quantities of mushrooms.  

Another important aspect of our project is utilizing the spent mushroom substrate (SMS), the myceliated straw that remains in our buckets after we have harvested mushrooms and removed the buckets from the fruiting chamber.  We experimented with a variety of approaches:

  • Leaving buckets outdoors in a shady place protected from wind to allow additional opportunities for fruiting while not occupying valuable space in the fruiting chamber
  • We created new beds using SMS using a variety of techniques:
    • Creating simple mushroom beds under fruit trees: we placed torn cardboard in a donut shape around the base of a fruit tree and then emptied buckets of SMS to create 4-6" layer of SMS; we then applied several inches of straw as a mulch.
    • We adapted techniques suggested by Tradd Cotter in "Organic Mushroom Farming and Remediation" and Peter McCoy in "Radical Mycology" to build outdoor beds, digging 4-6" trenches, and utilizing cardboard, woodchips, gypsum, coffee grounds, and fresh straw to encourage further fruiting of SMS.
  • We used SMS in compost:
    • We incorporated SMS as brown matter in our active farm compost which includes kitchen scraps and garden waste.
    • We established piles at the end of the growing season using cow manure and bedding, biochar, and SMS.
    • We established two 40-gallon vermicompost bins by adding worms, a small amount of sand, and filling the bin 2/3 full with SMS.  The bins are in a shaded shed during the growing season and moved into a greenhouse for warmth during the winter.
Research results and discussion:
  • We developed two fully automated fruiting chambers that maintain target ranges of temperature, humidity, oxygen (fresh air exchange), and light.
  • We established protocols that allow us to produce consistent and predictable yields year-round: oyster mushroom harvest log fall 2022
  • We successfully grew 6 different strains of oyster mushrooms (Grey Dove, Summer White, PoHu, Italian, Golden, Pink).  
  • We established relationships with two new vendors, bringing in prices at a range of $7.50 - $10.50/ lb. This price range makes mushrooms one of our most valuable products.
  • We obtained similar yields using biochar squelch water for pasteurization as compared to hydrated lime.  This allows us to make use of the wastewater byproduct from biochar production and allows us to avoid using lime, one of the few consumables in our process.
  • We established protocols for data collection to analyze yields by strain, season, spawn-to-substrate ratio, and pasteurization method.
  • Our outdoor patches established using SMS yielded mushrooms sporadically.  Nearly all patches fruited at least once, and most fruited several times.  Mushrooms were highly variable in shape and condition.  We generally allocated mushrooms harvested from the outdoor patches for household use.
  • Vermicompost was successful at a small scale.  Worms bins were healthy and produced finished vermicompost that we incorporated into potting mix and garden beds.
  • All other forms of compost produced a viable product for our garden beds.  We did not conduct any analyses to evaluate the quality of the compost, however the material was thoroughly broken down.

When our systems were functioning properly, we were able to produce roughly 3 pounds of mushrooms per 6-gallon bucket of the high-productivity strains, with an average of 1.5-2lbs in the first flush.  The second flush produced 0.5-1lb/bucket several weeks later.  Subsequent flushes were unpredictable.

Given our tent capacity, this produced an average of 20 pounds of mushrooms per week when all systems were functioning properly.  We had a host of troubleshooting technical issues and addressing contamination, so our actual yield throughout the season was closer to half of that, averaging 10 pounds per week. These obstacles bolstered our operating procedures for future performance. 

We allowed buckets to fruit 2-5 times, meaning we left them in the tent following the harvest of the first flush.  Our system would produce greater yields if we inoculated a larger number of buckets each week and removed buckets after the first flush to make room for new buckets.  For this initial experiment, we wanted to minimize the labor and inputs required for production, so we let the buckets remain in the tent for longer than most commercial operations would.  

We also experimented with bringing our buckets outside and placing them in shady, wind-protected areas in order to obtain additional flushes.  We had mixed success with this approach.  We intend to build a low-tech fruiting chamber for this purpose outside.

Our most consistent buyers paid $7.50/lb for oyster mushrooms in our area. We wanted to provide reasonably priced mushrooms to people in our area, and a price point higher than $7.50/lb wholesale for the local grocery store, for example, would not make our product accessible.  We sold some mushrooms direct-to-consumers in Chicago for $12/lb.

After paying input costs for all parts of the process, our earnings from sales yielded about $10/hour of labor.  Thus, while this system did provide some income to the farm, it would not be cost-effective for us to scale our efforts using the current system.

Handwashing buckets took significant time and effort and the labor was not cost effective.  We chose to grow in buckets to avoid using disposable plastic materials. Although the labor for bucket washing is sustainable at this scale, we would consider alternatives if we were to scale up our system.  Compostable grow bags are now available.  From our evaluation of labor costs, switching to these grow bags would be a cost-effective transition in the long run.  We are interested in understanding the environmental impacts of making this change.

Overall, our system is effective at growing mushrooms, generates almost no waste, uses minimal energy inputs, and provides a small revenue stream. It also provides the people living on the farm with a nutritious, protein-dense, and abundant food source.

This funding provided us with the support we needed to establish a functional, small-scale growing system that is integrated into the larger system of our farm, and to teach numerous apprentices, community members, and local farmers about the basics of mushroom growing.  We have learned a tremendous amount in the process and will definitely continue to produce mushrooms at or beyond the current scale.  Our Mushroom Field Day generated interest in our grow bags, and we intend to offer those at farmer's markets in future seasons.

We struggled to find a suitable market in the immediate area that could handle any increase in our production volume.  Distributing outside of our immediate area would only make sense if we scaled up production, as the current scale is too small to compensate for transportation costs.  This project afforded us incredibly valuable experience with the technical aspects of growing and a much better sense of the economics of scale.

A flyer for a Mushroom Workshop hosted by Zumwalt Acres
A flyer for a Mushroom Workshop hosted by Zumwalt Acres
An Instagram post of a time lapse without sound of a Zumwalt Acres apprentice conducting an oyster inoculation, with a description of the importance of the inoculation process.
An Instagram post of a time-lapse without sound of a Zumwalt Acres apprentice conducting an oyster inoculation, with a description of the importance of the inoculation process.
Two Zumwalt Acres apprentices are inoculating straw for oyster mushroom production.
Two Zumwalt Acres apprentices are inoculating straw for oyster mushroom production.

Participation Summary
50 Farmers participating in research

Educational & Outreach Activities

2 Consultations
6 Curricula, factsheets or educational tools
30 On-farm demonstrations
2 Published press articles, newsletters
15 Tours
6 Webinars / talks / presentations
5 Workshop field days

Participation Summary:

50 Farmers participated
15 Ag professionals participated
Education/outreach description:

Zumwalt Acres hosts an apprenticeship program, in which 6-12 young farmers train at the farm for a 3-6 month period.  All of the 50+ apprentices during the 2022 and 2023 growing seasons participated in all aspects of mushroom cultivation.  They helped to design and build the controlled environment fruiting chamber, helped to research and establish protocols for production, and designed data collection systems.  They also contributed to systems for utilizing the spent mushroom substrate and experimenting with how to cook and preserve the mushrooms we grew. Mentors and educators gave presentations on mushroom biology and ecology, and trainings on all aspects of the growing process to each new cohort of apprentices throughout both growing seasons.  

We hosted several events open to the public over the growing season, including 4 field days and 5 community events.  Each event was attended by 20-30 people.  We also hosted several smaller, informal groups of people throughout the season.  During these events, we gave tours of the farm, highlighting our mushroom cultivation as a way of producing high-quality food with little input, as a model of closed-loop production systems.

We also gave a talk at a local museum to educate community members about our work.

A substantial effort went into training and this was a highly successful part of the project.  Most apprentices came in with little to no knowledge and experience with fungi.  Working with oyster mushrooms in a low-tech environment gave apprentices the opportunity to engage with the different stages of the life cycle, and to become familiar with a range of techniques involved in cultivation.  Apprentices took the lead in developing new systems for dealing with spent mushroom substrate and incorporating this material into garden beds, compost, and tree mulch.  The mushroom growing system makes the ecological role of fungi more visible on the farm - we grow and harvest straw, feed this to fungi, continue the decomposition in compost or mulch, and return the transformed straw to our soils.  We used this system as an invitation to learn more about the role of fungi in regenerative agriculture and also introduced apprentices to foraging mushrooms in the wooded areas of the farm. 

Our project culminated with a Mushroom Field Day in the fall of 2023.  Attendees participated in all parts of our cultivation process and made DIY fruiting kits to take home.  We also offered workshops on foraging, mushroom identification, and tincture-making. 

Over the past two years, Zumwalt Acres has continued to develop as an organization.  We have increased our skills and capacities to train young farmers and to share our knowledge and skills with other farmers, researchers, and community members in our region.  This funding supported us in establishing an indoor mushroom cultivation system, which added a new and important layer to our educational offerings.  We are continuing to fine-tune our system and to share our learning and our mushrooms with the people in our community.  

Thank you SARE for the support!

Learning Outcomes

40 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Lessons Learned:

The project provided the basis for solid experience in mushroom cultivation, and gave us the tools to work with fungi in a range of capacities, including increased food production on the farm.  Exposure to inoculating growing substrates with fungi has improved on-farm capacity to inoculate crops with complementary fungal strains to achieve higher crop yields with minimal input costs.

One of the challenges in our area is distribution, as we live in one of the least densely populated areas in the state.  Given our small scale of production, transportation across the large distances of rural IL is energetically inefficient and cost prohibitive.  While we established a relationship at our local grocery store, the market is quite small and was unable to keep up with our modest supply.  The local farmer's market provided an additional opportunity for sales and a slightly higher price point (at $10/lb), however, this market only runs for several months and draws limited attendance.

Before we can expand our production, we need to address the challenges of market opportunities. We have experimented with preserving mushrooms, making dried mushroom powders and mushroom jerky.  Given the lack of proximity to large, urban markets, developing shelf-stable value-added products from our mushrooms could be a way to handle the challenges with distribution. 

We found that growing mushrooms is a highly adaptable process and could fit into almost any farm operation at a small-scale using materials that are readily available.  A number of people who have seen our setup at the farm have expressed interest in establishing their own systems, and we are excited to share our knowledge and help others establish systems that are appropriate for their particular situation.  We would be happy to consult with other farms that are interested in mushroom cultivation (feel free to contact us through the website:

We have also been consuming the mushrooms we grow daily, and this has been a delicious source of nutrition for our on-farm community!  

Project Outcomes

1 Farmers changed or adopted a practice
Success stories:

Young apprentices who practiced growing mushrooms as part of a diversified income stream have decided to continue their education in soil science. One apprentice is currently applying for Environmental Management Masters programs at local universities to study how fungi can be utilized in remediating soil contaminants from industrial practices to support safe agricultural activity in underrepresented communities.  


Research into additional uses of fungi in managing chemical discharge from agricultural effluent in mycoremediation practices would provide a low-cost vector to reduce groundwater degradation. With farmers already utilizing fungi to diversify their income stream before agroforestry practices pay off, utilizing inoculated buffers could come at a lower cost while preventing downstream pollution. Based on whether the research demonstrates an economical advantage to building mycoremediation buffers, grants to implement mycoremediation practices near discharge sites and avoid soil contamination could also provide farmers with the funding necessary to begin building a mushroom production facility.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.