Oyster mushroom cultivation using spent coffee grounds and hardwood sawdust

View the project final report

Commodities

• Miscellaneous: mushrooms

Practices

• Education and Training: on-farm/ranch research, workshop
• Natural Resources/Environment: carbon sequestration
• Production Systems: organic agriculture
• Sustainable Communities: quality of life

The major benefit of using spent coffee grounds and northern hardwood sawdust in mushroom production is
to provide a locally-sourced food while reducing garbage that ends up in landfills. Locally-produced oyster
mushrooms are superior in quality and taste to mushrooms that have traveled more than three days to market
due to their short shelf freshness. Additionally, many oyster mushroom varieties travel poorly, breaking and
splitting during conventional transportation handling. Small scale production of oyster mushrooms can be a
viable part of a CSA farmer’s income. Use of locally-sourced growing medium as well as selling locally
reduces the carbon footprint and coffee is a greater source of population than oak sawdust. [1] Growing
oyster mushrooms on recycled medium is an indoor process that can provide northern farmers with
additional CSA offerings and revenue throughout the cooler months. It is also readily scalable thus
providing farmers the potential to increase production during peak demand times of the year. Finally, spent
mycelium can be composted and used as a soil amendment in crop production, returning carbon to the soil,
enriching the soil, and providing soil organism diversity for plants.

There is little information on the use of spent coffee grounds as a growth medium for oyster mushrooms.
What exists is predominately for countertop production. With the addition of northern hardwood sawdust,
mushroom growing becomes more reliable. This research is aimed at determining the optimal mixture for
highest yield of spent coffee grounds to sawdust based on percent by volume of the two.

The goal is to find an optimal mixture of spent coffee grounds to hardwood sawdust that yields the greatest
amount by weight of oyster mushrooms to make this crop profitable. Additionally, using amendments to
these mixtures to improve yield and quality will be studied. Cultivators will be created by obtaining 15 liter
plastic buckets from local grocery stores, drilling holes for air exchange, sterilizing and filling them with
inoculated medium, and ultimately observing their yield. Weekly observations during the spawn run will
note if contamination from Trichoderma is occurring. Trichoderma is a genus of fungi that competes with
the mushrooms for resources thus reducing yield. Contaminated cultivators will be culled to prevent
spreading of contamination. The amount of culled buckets will be logged and taken into account when
determining profitability. Insect control is critical to reduce the spread of contamination. Sticky traps made
from Tanglefoot insect barrier will be used along with window and door screens to help reduce insects.
Trials will be conducted using varying rates of spent coffee grounds to hardwood sawdust as well as trials
using the optimal coffee ground to oak sawdust ratio determined above with additions of gypsum or sodium
bicarbonate.