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

Progress 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 unique product 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. 

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 80 lbs of mushrooms per week for 30 weeks throughout the 2023 growing season.
  4. Develop a healthy vermicompost system to match the scale of mushroom production and harvest vermicompost at the end of each growing season.
  5. Experiment on-farm with vermicompost plus biochar amendments in horticultural practices.
  6. Develop teaching tools to support apprenticeship education on mushroom cultivation and vermicompost.
  7. Document and share findings through social media and conferences.


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 that 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.  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 are using one room in the basement for incubation and fruiting.  Incubation occurs on shelving we constructed in this room.  The controlled-environment fruiting chamber is described below:

We purchased and set up a 25 ft sq grow tent (Gorilla Grow 5x5 )in the basement room.  Basement temperatures vary between 50-75 degrees F over the course of a full year.  These temperatures are within range for successful incubation and fruiting without any additional temperature controls.  We used a 6" duct fan with ducting to exhaust the tent.  The fan is connected to a CO2 meter, which exhausts the tent when CO2 levels reach 750ppm and brings the CO2 back to ambient levels before turning off.  Humidity is provided by a DIY humidifier we constructed using a pond fogger, connected to a humidity controller that oscillates between 70-95% relative humidity.  A 600 lumen light cycles on a timer, 12 hours on/12 hours off.

Over the winter, we are working to prepare additional basement space so that we can install an additional fruiting chamber.  We plan to utilize a similar design for the second fruiting chamber.  This spring, farm apprentices will assist with installation of the new fruiting chamber, and will create a DIY guide which we will share as part of our final project report.

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

Oyster Mushroom Protocls 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 to lime pasteurize and another 55 gallon drum to biochar pasteurize.  As our system and techniques have evolved throughout this first growing season, the trials have not been rigorously replicated.  We feel we have established systems at this point that will allow us to collect higher quality data in the next growing season. 

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 techniquest:
    • 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 that includes kitchen scraps and garden waste
    • We established piles at the end of this growing season using cow manure and bedding, biochar, and SMS which we will analyze next season
    • We established two worm bins by transferring several dozen worms from another worm bin into a 40 gallon plastic bin, adding a small amount of sand, and filling the bin 2/3 full with SMS.  The bins are in a shed during the growing season and moved into a greenhouse for warmth during the winter.




Research results and discussion:
  • We developed a fully automated fruiting chamber that maintains 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 (quantitative results to come).  This allows us to make use of the wastewater byproduct of biochar production, and allows us to avoid using lime, one of the few consumables in our process.
  • We established protocols for data collection, that will allow us to analyze yields by strain, season, 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 appears successful so far, though at a small scale.  Worms are breaking down SMS and populations are growing with a range of observable life stages, suggesting healthy population growth.

As our growing system was in a process of development over the course of the last season, we cannot provide replicated quantitative analysis.  We will provide detailed analysis in our final report.

Oyster Harvest log summer 2022 oyster mushroom harvest log fall 2022


Participation Summary
25 Farmers participating in research

Educational & Outreach Activities

2 Curricula, factsheets or educational tools
20 On-farm demonstrations
10 Tours
1 Webinars / talks / presentations
2 Workshop field days

Participation Summary:

40 Farmers participated
10 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-month period.  All of the apprentices during the 2022 growing season (a total of 25), 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 to experimenting with how to cook and/or preserve the mushrooms we grew.

We hosted several events open to the public over the growing season, including 2 field days and 2 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 gave a talk at a local museum to educate community members about our work.

We have developed written protocols for our production systems which we have used internally.  Next growing season, as we formalize these protocols we will produce materials that we can publish and share.

Learning Outcomes

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

In our first season of commercial indoor oyster mushroom cultivation, we have developed a system for very low-input, nearly zero-waste mushroom production.  We established a controlled environment fruiting chamber with automated humidification, fresh air exchange, and light cycling. We were able to acquire the majority of our equipment secondhand and we retrofitted our basement to set up a grow system that does not require any additional heating/cooling.  We have experimented with oat straw and wheat straw as growth substrates and have success with both types of straw.  We have experimented with using the wastewater from biochar production as a means of pasteurizing straw and have had success with this method.  We have grown 6 varieties of oyster mushrooms with a range of temperature preferences and we are learning to plan our strain varieties in order to fruit with the seasons.  We are learning how to streamline our processes to utilize labor efficiently.

We have been exploring a variety of uses for our spent mushroom substrate (SMS).  We have established outdoor beds using SMS and additional fresh substrate and have produced additional mushroom yields from these beds.  We established some of these beds under fruit trees, giving the added benefit of organic matter addition to the trees.  We established small-scale vermicompost in large plastic bins which we moved into the greenhouse for the winter as we were concerned that the worms would not survive as we did not have a large enough volume of material.  We established experimental  piles of manure/biochar/SMS which we will harvest and test next season.  We used SMS as brown matter in our composting when we were short on this material and have been using this material in our vegetable production.

This project has been an incredible learning opportunity for all of us at the farm and we have shared our learning with many people in our community through events and field days.  All of the farm apprentices learned how to complete all of the steps of the cultivation process, from inoculation to incubation, fruiting, harvest, distribution and composting SMS.  The apprentices were involved in researching and establishing protocols and developing data collection and analysis systems.

We have been selling our mushrooms at a local grocery store and farmers market, and have seen interest from people in our community.  Packaging and marketing our mushrooms is a priority for next season.  This first season helped us predict our supply so that we can commit accurate quantities for sale. 

Moving into next season, we intend to install an additional fruiting chamber, doubling the scale of our production.  This expansion will be efficient in terms of labor and space usage and materials costs.  In order to move the additional quantity of mushrooms, we will need to establish new markets.

One of the challenges in our area is distribution as oyster mushrooms are delicate and have a short shelf-life.  We have not found any stores or restaurants in our area that currently carry gourmet mushrooms, which is both an opportunity and an obstacle.  We will focus this next season on establishing connections with local businesses in order to sell our product.

Establishing an indoor cultivation system has added a year-round product to our farm.  We have been selling mushrooms at a price range of $7.50-10.50/lb, making it one of our most profitable products.  We have also been consuming the mushrooms we grow daily, and this has been a delicious source of nutrition for our on-farm community.

We have experimented with preserving mushrooms, making dried mushroom powders and mushroom jerky.  One possible direction we could go is to sell these products in order to have a more shelf-stable product.

We have found that growing mushrooms is highly adaptable 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.


Project Outcomes

1 Farmers changed or adopted a practice
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.