Mushrooms on Coffee Waste : effectiveness of incorporating locally available coffee chaff for improving the effectiveness of small-scale oyster mushroom production

• 2016 annual report

Commodities

• Miscellaneous: mushrooms

Practices

• Crop Production: organic fertilizers, application rate management
• Production Systems: transitioning to organic
• Sustainable Communities: new business opportunities, partnerships, urban agriculture

My research topic is to assess the benefit of using coffee chaff as a supplement in commercial oyster mushroom production. Oyster mushroom is a common choice for startup farms (ease and relative inexpense of production, readily available spawn (i.e. seeds) and medium (wheat straw, sawdust) recognizability/marketability, and superiority to bulk produced, freight shipped oyster mushrooms).  Growing oyster mushroom commercially, however, generally requires the addition of a nutrient rich supplement. The purpose of supplementation is to increase the weight yielded (biological efficiency) of the substrate - supplemented substrates produce more wet mass of mushrooms per dry mass of inputs - as well as the quality, flavor and shelf life (and therefore marketability) of the mushrooms produced. By increasing the efficiency of substrate degradation by the mushroom, the farmer is able to reduce labor and material expense while limiting the negative ecological impact due to fossil fuel consumption (for heat treatment of materials) of their farming. Wheat bran is a widely used additive, however the addition of bran drastically increases overhead expense (and fossil fuel use) through the need for expensive pressure sterilization and the need for sterile conditions/ air filtration equipment. Also, some farms may have difficulty obtaining local and organic/non GMO bran. Alfalfa hay is the most common substrate additive reported by oyster mushroom growers. It increases nitrogen content, supplies protein and lipids used by mushroom mycelium, and is often used exclusively by commercial producers as an all-round supplement for oyster cultivation on wheat straw.  Alfalfa hay can be mixed (typically a dry weight of 20%) and pasteurized along with the straw and does not require extensive sterile procedure, i.e. it can be used for open-air grows. Though we have experience with the use, and benefits of alfalfa addition, alfalfa is excluded from this study as we have not finalized a protocol for preparation and use with our method of growing. Coffee chaff (CC) is the papery husk discarded by local coffee roasters. The chaff must be degraded (i.e. by oyster or shiitake mushroom or in compost) before it can be used as a soil amendment. Because of the prevalence of small roasters using exclusively fair trade & organic coffee, high quality chaff can usually be obtained for free.  As an agricultural byproduct, coffee bean chaff is widely used as a substrate for mushroom cultivation, particularly in Asian and South American countries. Percent of CC used in substrates varies widely, as do cultivation techniques, but many sources reference a consistent heat treatment/hydration regimen by boiling chaff, anywhere from 15 - 30 minutes. We have had successful results using CC as an additive of up to 20% while growing in open-air conditions, i.e. without need for extensive sterile procedure.  In the US, use of CC has been documented, but this author is not aware of any published protocol for its use. Spent coffee grounds (CG), which are also readily available in high quality formulations, are easy and inexpensive to use, and though they boost available nitrogen and increase yields, do not provide the same increase in fruit quality that we have observed with CC, wheat bran, or alfalfa hay.  CG are included in this experiment because of their increasingly frequent use in mushroom farms, particularly new startup operations. Thus, it is necessary, when assessing a new substrate additive, to test its compatibility with CG when used simultaneously. The CG will also provide us with additional control data, in order to compare the yield and quality benefits of CC independent of nitrogen content (protein, lipids usable to mycelium).