Mushroom farming without single-use plastic: A simple, low-tech method for family farmers

View the project final report

Commodities

• Miscellaneous: mushrooms

Practices

• Farm Business Management: feasibility study

1. Growing mushrooms commercially without a lot of energy, infrastructure, and single-use plastic is very challenging. Mushroom growers rely on autoclavable polypropylene bags to contain spawn (e.g grain) and bulk substrate (e.g. sawdust) during sterilization. Once the mushrooms are harvested from the bags, the plastic is sent to the landfill. Additionally, the sterilization process is cumbersome and energy-intensive requiring high heat and vessels that can withstand 15 pounds of pressure for a substantial amount of time. A company in North Carolina, Mycovations, developed a technique to eliminate one of these unsustainable barriers for small-scale mushroom farmers: they found that vinegar can be used to pasteurize hardwood fuel pellets, eliminating the on-farm need for sustained heat and pressure in growing popular culinary mushrooms like Oyster and Lion's Mane. However, their method still relies on the use of new plastic bags.
2. I will explore the feasibility of replacing single-use bags with reusable buckets using Mycovation's vinegar pasteurization technique. All spent substrate will be composted on-site and used to grow secondary-decomposer mushrooms and enhance soil health. The goal is to make mushroom growing as regenerative and accessible to local farmers as possible while reducing the amount of single-use plastic used in production. The Mycovation's technique works because the pasteurized substrate is packed into plastic bags that have been perforated at precise intervals to allow the mycelium to "run" very quickly (due to adequate access to oxygen) while limiting the risk of contamination. I will research the feasibility of simply replacing the plastic bags with gallon-sized buckets that have been similarly perforated and then measuring the yield against input factors, specifically the time spent perforating buckets and cleaning them for re-use.
3. This experiment was concluded in the early summer of 2022 when three factors indicated its unfeasibility for commercial growers:
   
   1. Yield: consistently less than desired (average biological efficiency was 50%, or 1 pound of mushrooms harvested from 2 pounds of substrate) 
   2. Time: Far too much time required for making the hole-punched buckets and cleaning them for re-use, specifically because the small holes get clogged with hardened mycelium and are very difficult to clean effectively. 
   3. Seasonal contamination: Higher temperatures encouraged more contamination in the pasteurized substrate, so much so that the method became impossible without climate control once summer arrived. 

1. Develop a technique for bucket/jar growing that produces reliable and consistent results. Buckets will be used for pasteurized bulk substrate and glass jars will be used for grain spawn made on-site. 
2. Research the time, cost, and yield comparison for Oyster and Lion's Mane mushrooms grown in single-use plastic versus reusable plastic buckets.
3. Share the process with area farmers who may wish to add mushrooms to their operation through field days, social media, and info sheets.