Because the calculation uses the weight of dry substrate, it is possible- and actually quite common – to achieve a biological efficiencygreater than 100%.
The calculation uses the weight of all mushrooms harvested from a substrate over multiple flushes.
The fact that the calculation uses the dry weight of the substrate throws many growers off, since much of the weight of a fruiting block or straw log will be water.
Usually it easier to weigh your fruiting containerafterit has been inoculated and compare that number to weight of fresh mushrooms harvested.
Although this is not technically “biological efficiency”, using the “wet-weight” it is still a useful measure for mushroom growers to quantify the efficiency of their grows.
An Example of Calculating Biological Efficieny
Let’s say that you are able to harvest2lbsof King Oyster mushrooms from a 5lb supplemented sawdust fruiting block.
Each fruiting block contains1.4 liters of water, which weighs about3.1 lbs.
Therefore, the total dry weight of the substrate is1.9lbs.
In this case the BE would be 105% (2lbs/1.9lbs), and the wet-weight efficiency is 40% (2lbs/4lbs). These numbers are vastly different in magnitude, but are representing essentially the same thing.
One reason that true BE is important to understand, however, is because this number is what is commonly reported by spawn producers as a way to grade certain strains of mushrooms.
You can use this number to predict how many mushrooms you can grow for a given weight of bulk substrate.
A nice harvest of King Oyster Mushrooms.
Expected Yields for Different Mushrooms
Different mushrooms, and different strains of the same species, will have a wide range of potential biological efficiencies. Typically, Oyster mushrooms which grow well on straw, such as Pearl Oysters and Blue Oysters have a high BE.
More delicate mushrooms, such as yellow oysters and slower growing mushrooms, such as Reishi, tend to have lower BE values.
Let’s look at some different mushrooms and their BE’s, and expected yields.
BLUE OYSTER
B.E.:100-200%
Yield: 6-12 lbs from a 25 lb straw log, up to 3 lbs from a 5 lb supplemented sawdust fruiting block.
KING OYSTER
B.E.:100-150%
Yield: 6 – 8 lbs from a 25 lb straw log, up to 2.5 lbs from a supplemented sawdust fruiting block.
PINK OYSTER
B.E.:100-170%
Yield: 6-10 lbs from a 25 lb straw log, 2.5 lbs from a supplemented sawdust fruiting block.
LIONS MANE
B.E.:90-140%
Yield:Up to 2.5 lbs from supplemented sawdust fruiting blocks.
REISHI
B.E.:80-120%
Yield:1.5-2 lbs on a supplemented sawdust fruiting block.
YELLOW OYSTER
B.E.:50-90%
Yield: 4-8 lbs from a 25 lbs fruiting block, up to 1.5 lbs from a supplemented sawdust fruiting block.
SHIITAKE
B.E.:100-200%
Yield:1.5-2.5 lbs on a supplemented sawdust fruiting block.
How to Increase Mushroom Yield
There are a number of different ways to increase your yield and make your mushroom harvest more fruitful, more efficient and more profitable.
1. Choosing a High Performing Strain
The strain you choose for your grow can have a huge impact on yield.
Different strains within the same species of mushrooms can produce vastly different results. Think for a second about the mushroom life-cycle. A mushroom culture starts when the hyphae of two compatible germinating spores mate and start to grow out as mycelium.
This means that when starting a grow from spores, there are untoldgazillionsof different possible combinations or “strains”, all with minute genetic differences that can have an impact on yield.
Luckily, top-performing strains have been carefully developed and optimized over the years to produce good and reliable yields. These strains are preserved as cultures, which are commercially available.
Of all the factors involved in trying to maximize yield, choosing agood producing commercial strainis probably the most important.
Different strains will have different yield characteristics.
2. Supplementation
Supplementation is the process of adding a nitrogen rich nutrient to the mushroom substrate in order to increase the potential yield. This works by providing the mycelium with a larger nutritional base in which to support stronger mycelium and produce larger, healthier fruits.
Supplementation is usually achieved by adding bran to the substrate, typically wheat bran or oat bran.
Adding too much supplementation, however, will actually have detrimental effects. With increased supplementation comes the increased probability of contamination, and thus diminishing returns on your yield.
Use supplementation carefully, starting small and increasing slowly to achieve optimum results.
In a way, increasing your spawn:bulk substrate ratio is a way to increase your nitrogen content, and is a form of supplementation. Again, too much spawn will eventually lead to diminishing returns. You need to find your sweet spot.
King Oyster Mushrooms harvested at different stages of growth.
3. Timing Your Harvest
When you choose to pick your mushrooms obviously has a huge effect on overall yield and biological efficiency.
Picking mushrooms when they are small, such as Agaricus species in the button stage, will decrease your BE. Picking mushrooms late will allow for a larger overall yield, but the quality of the mushrooms may be less due to the fruits being past their prime.
Every cultivator should be able to find the sweet spot for when to harvest their mushrooms in order to achieve the best yield for the desired quality. The right time to harvest mushrooms will depend highly on the species of mushrooms, and the different ways you plan to store your mushrooms before consumption.
Posted by
Tony Shields
Hi' I'm Tony. I've dedicated a ton of time to learn all about the amazing world of mushrooms- and would love to share that information with you! I am particularily passionate about growing mushrooms, and teaching others how to do the same.
