Sustainable Agriculture Student Research Project

Introduction

• Fungi play an important role in most ecosystems, however in agroecosystems their intentional cultivation is neglected.
• Most mushrooms are grown in highly controlled indoor environments. Industrial animal manure is often used as a substrate, and the spent mushroom compost has limited uses as a soil additive because it is relatively low in nitrogen and high in phosphorous and salts.
• Mushrooms are nutritious and have potential to provide a high-value novelty product for small-scale vegetable growers to sell.
• Fungi do not perform photosynthesis and would not compete with plants for sunlight, making them an ideal candidate for understory intercropping.
• Previous studies have also found increased vegetable yields when intercropped with mushrooms.

Methods

• Used a randomized complete block design with 3 treatments and 4 replicates, in the east field at the KPU farm. The bean variety was ‘Rocdor,’ which is typically grown as a wax bean but was grown to the drying stage for this study. For the mushrooms, Golden Oyster sawdust spawn was ordered from Grow Mushrooms Canada (Yellow Oyster Spawn - Grow Mushrooms Canada).
• Beans were started in soil blocks in the passive solar dome at the KPU farm in June, and then transplanted out about a month later in July.
• Plots were 1.5 x 1.37 metres (2.055 metres squared). Originally they were intended to be 1.5 x 2 metres, however so many bean seedling were lost to fungus gnats that the plot size had to be reduced.
• Beans were planted in three rows spaced 50 cm apart, with seedlings spaced about 25 cm apart. Two driplines were buried on either side of the middle row of beans, 20 cm from the outer rows.
• Organic oat straw and mushroom spawn were added to the appropriate plots after weeding all plots as the beans were flowering. All plots were then watered with a hose shower every day or every other day (weather dependant) for two weeks straight. Watering was then reduced to about once a week until the weather began to cool off.
• Mushrooms were harvested whenever they fruited, which turned out to be only once, August 28th. The yield of each plot was weighed and measured in grams.
• Beans were harvested after the plants were mostly dry. Only the inner square metre of each plot was harvested to avoid any edge effect. Beans from one plot were weighed, shelled and the seeds weighed; the subsequent ratio was used to calculate the yield for the rest of the plots.
• Bean yield data was analyzed on jamovi using ANOVA
• Potential mushroom income was calculated by finding the price of oyster mushrooms per gram at T&T and then multiplying by the mushroom weight per plot in grams. (Shop Online or In-store | Asian Grocery Store | T&T Supermarket).
   

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Results

• There was no significant difference between yields for the different treatments, although there was a significant block effect.
• The average income generated by mushroom harvest was calculated at $0.29 per plot.
• As there were no significant differences in bean yields between treatments, bean incomes were not calculated.
   

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Discussion

• The results of this experiment do not indicate that there would be any benefit to farmers in the region attempting this intercrop, on the contrary, the mushrooms do not even pay for their own spawn, let alone the extra labour.
• Intercropping with mushrooms is not necessarily out of the question, however. The spawn was added during the hottest, driest time of year and often appeared to have dried out between waterings. It is recommended that future research experiment with mushroom intercropping in the cooler, wetter shoulder seasons.
• As well, the spawn for this experiment was ordered more than a month before being applied with the expectation that it would take a few weeks to arrive. It arrived much sooner than expected and sat in refrigeration for the next month or so, possibly reducing the spawn’s vigour. Future students should optimize spawn freshness when experimenting with mushroom cultivation.
   

Conclusion

• Understory golden oyster mushrooms in straw do not increase rocdor bean yields, straw mulch does not increase mushroom bean yields, and summertime understory mushroom cultivation does not produce a marketable crop in this region. 

Acknowledgements

• Thank you to Mike Bomford, Sahar Zandieh, Ben Alles, and the rest of the Sustainable Agriculture faculty and farm staff for your help and support.
   

Raw Data