China banned logging in state-owned forests.
If these bans will do more good than harm is out of the question.
Especially as it was already proven that the unwise implementation has failed to secure forest conservation. Besides, these bans affect workers’ households’ welfare. Meaning they impact low-income families as they depend on forestry. Leading to an increase in low welfare while high welfare decreases.
Also, the logging bans increase solid wood imports from low-income countries. Doing even more damage than good.
Besides these direct impacts on forestry, mushroom farmers are affected too. Since the majority of them rely on sawdust for their substrate.
Hence, alternative substrates are investigated.
One such alternative is corncobs, with a worldwide production of 1.2 billion metric tons in 2021. Out of that, 270 million metric tons were produced in China. But only around 17% were used, while the rest were burned. This burning releases pollutants and causes a waste of biomass resources that could be utilized otherwise.
Thus, today’s research article investigates corncob instead of oak sawdust for cultivating Shiitake.
The primary substrate consists of 78% oak sawdust, 20% wheat bran, and 2% gypsum (see Fig. 1). The author then replaced parts of the oak sawdust with corncobs.
The bags had a total weight of 2.3 kg per bag. All substrates had a moisture content of 55%. The bags were sterilized by autoclaving at 100°C for 16 hours and, after the cool down, inoculated with roughly 1.7%. The incubation parameters were 23°C, 60-70% RH, and no light.
Under these conditions, the mycelium running took 35-40 days.
After the browning, the fruiting conditions were 18±2°C and 85% RH.
Using these parameters, the harvesting period lasted up to 120 days and resulted in three flushes.
What can we expect from replacing parts of oak sawdust with corncobs?
Are we better off?
If we look at the mycelium growth rate, the control formula, which contains 78% of sawdust, leads to an MRR of 2.26 mm per day (see Fig. 2). Replacing the sawdust with corncobs increases the MRR to 2.96 mm per day for the mixture of 28% sawdust and 50% corncobs.
What does this increase in MRR mean?
If, for example, it took 40 days for the mycelium to colonize a bag at a rate of 2.26 mm with the new mixture 28/50, it would only take 30.5 days.
But what about the browning, which is necessary for the pinhead formation?
Do we also see an influence, and if so, to what extent?
On browning, the author rated the control with three points (see Fig. 3). At the same time, all other substrate formulas got a higher rating except for formula 5, which got only two points. The highest rating, with five points, was given to the 28/50 mixture.
With these two data points, can we assume that the highest yield can be expected from the 28/50 mixture?
The yield for the control is 514g (see Fig. 4), leading to a biological efficiency of 57%. Replacing parts of oak sawdust with corncob increases the yield and, thus, the biological efficiency. With the highest yield of 722g and biological efficiency of 80% for, you guessed it right, the 28/50 mixture.
But what about the yield per flush?
Do we see a change with an increasing amount of corncobs?
If we look at the control, the yield is spread over the three flushes 17%, 30%, and 53% (see Fig. 5). Replacing sawdust with corncobs changes this ratio, for example, for the 28/50 mixture to 24%, 49%, and 28%. Indicating that corncobs not only increase yield but also gives us 73% of the yield in the first two flushes. In comparison, we get only 47% if we use only sawdust.
As the time between two flushes increases with each flush, it is a good idea to scrap the bags after the second flush. Especially as the likely hood of contamination increases with each flush.
While the introduced logging bans will impact the mushroom industry, today’s research showed that the industry could adapt to the new situation by utilizing alternative substrate sources.
By doing so, the mushroom industry can increase its yield and biological efficiency.
 📝Hailong Yu, Dan Zhang, Lujun Zhang et al. Corncob as a Substrate for the Cultivation of Lentinula Edodes, 11 March 2021, PREPRINT (Version 1) available at Research Square [https://doi.org/10.21203/rs.3.rs-241916/v1], This work is licensed under a CC BY 4.0 License, https://creativecommons.org/licenses/by/4.0/