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Mycelium growth in casing soil (back to basics)
We are observing that the amount of mycelium in the casing soil often leaves much to be desired. Ideally, thick mycelium strands should grow from the bottom to the top of the casing soil, while leaving enough casing soil not yet overgrown with mycelium. This remaining casing soil serves as a water buffer for the compost and mushrooms.
It's crucial to remember that this water buffer also determines how long and how much you can evaporate in the growing room before the casing soil dries out. If the casing soil dries out, you will need to water, even if it's not ideal for the mushroom quality. Therefore, it is important to pay close attention to the mycelium growth in the casing soil.
If there is structurally too much mycelium in the casing soil, a few adjustments can improve the situation. One option is to start ventilating earlier, although this means the mycelium may not reach the surface as much as usual. You can also adjust the watering schedule.
Once the mycelium starts growing from the top layer of compost and the casing material, it is essential to keep the casing soil well-moisturized. Each watering essentially stops the mycelium; weak mycelium struggles with this and can barely continue developing, whereas strong mycelium has fewer issues and continues to grow. In this way, you encourage more strong mycelium and reduce the amount of mycelium in the casing soil.
Our mushroom strains tend to form pins quite spontaneously, so many growers are ventilating extremely slowly. While this isn't necessarily a problem, it's important to realize that as long as the compost temperature is above 23°C, the mycelium will keep growing in the casing soil. Therefore, you should start ventilating earlier or increase circulation to bring the compost temperature below 23°C quickly. Once the compost temperature reaches 23°C, you can reduce circulation and control the number of pins by adjusting the air temperature.
I believe that with this method, you can control the amount of mycelium to some extent without leading to too many pins or a lack of distribution in the first flush. You might also consider using slightly heavier casing soil.
Slightly drier casing soil offers more certainty in terms of mycelium growth. Also, pay attention to covering. Avoid running the pinning axis and leveler too quickly to prevent structural damage. The mixing of the casing should be adequate, but more speed is unnecessary for the pinning axis.
Written by: Jeroen van Lier | Total Mushroom Service
Cook-out
One of the most effective ways to avoid diseases in the mushroom industry is a cook-out at the end (or beginning) of each cycle.
To reduce the chance that some spores of diseases or insects will survive in the growing rooms after the last day of harvest, it is vital to thoroughly cook out the growing rooms. To ensure that all diseases and pests are killed, it is necessary to heat the entire growing area to 70 ° C for 8 to 12 hours using steam. The entire growing area means that the compost also reaches this temperature for 8-12 hours. Why do I say 8 to 12 hours? In highly effective farms the whole room will be on the same temperature (compost, floors, corners) and 8 hours will be enough, in other farms where you are less effective, meaning the entire room will not be at the same temperature, it would be better to extend the cook-out time to 12 hours.
Often, for reasons of cost or time savings, it is decided to shorten the time or keep the temperature lower, which has the risk that virus can survive. However, to be on the safe side, 70 °C for 8-12 hours is the benchmark, especially if there are diseases or pests on your farm. Some farms decide to cook-out on lower temperatures, especially phase 3 compost farms, to just eliminate the spores for bubbles and cobweb and those are eliminated on lower temperatures. With the high energy prices, a very understandable approach. If there is no virus or Trichoderma on the farm it is probably enough to cook-out on only 60 °C.
After the cook-out, the new growing cycle begins, so it is important that from this moment on no traces of mushrooms, germs or insects end up in the growing area. This is often neglected during emptying, which means that the usefulness of the (expensive!!!) cook-out has been for nothing.
Be aware of that, you invest a lot in cook-out.
Some farms in several countries have not the possibility to cook-out because they have no boiler present on the farm. That means your hygiene has to be excellent, but some farms manage that well. I know farms where they have no boiler and keep the infection very well under control. On the other hand, there are farms that don’t trust their first cook-out and decide to cook the rooms out after emptying and cleaning again before they fill the new compost. Empty rooms are easier and more efficient to cook out.
Of course, you need time in your cycle as well to cook-out. Including the warmup and cooldown period you will need around 24 hours to finish a full cycle. Warming up and especially cooling down needs to be done with a slope up and down in temperature to avoid negative affects to your building.
There are different cooking methods used worldwide. Choose what works best for your farm. If you're building a new farm, consider adding a boiler. Regular cookouts can help prevent problems and keep infections low. This is an effective way to maintain cleanliness and bio security on your farm.
Erik de Groot
glags.spain@gmail.com
https://www.mushroomsconsultant.com/
Casing soil
Why is casing soil used? There are two main reasons: 1. the Pseudomonas putida bacterium; 2. to regulate evaporation. Mushrooms will not grow without evaporation. The casing soil structure, through the depth of casing and on the surface, is the factor that determines how much water can absorbed and released. This is also known as the water buffer. How can growers influence this effect?
Properties
Casing soil is made up of peat. Peat consist of many small and larger pores which act as communicating structures that affect the flow of water. The very tiny (micro) pores absorb water very slowly, but retain it for a long time. The larger (macro) pores can absorb water faster but release it again very quickly. In good casing soil, both properties are necessary: rapid absorption of water: during mycelium growth and after harvesting, and slow release: during pinhead formation and out grow, and when the mushrooms are harvested.
Air
What is the secret of casing soil? Ensure that the moisture content of the casing soil is good. With “export” casing soil, you have to apply enough water and mix the casing with a loader or bobcat. Ask the supplier for instructions and follow them correctly. This has already been done with casing soil delivered in bulk and ready to use. Casing soil is sensitive to structure loss just before it is applied. If the casing soil is compacted or compressed, the “air” will be squeezed out. This effectively closes off the very crucial micro pores. The casing soil will feel harder. During transport and filling avoid compacting the casing soil too much, for example when using augers, over-filling the hopper on the filler or in front of the levelling axle during filling.
Soft
Casing soil should feel nice and soft. Straight after filling, push your finger into the casing soil. You should be able to plunge your finger in easily and without resistance. Experience will teach you how to feel the difference. A good layer of casing soil after filling is about 6 cm thick. The amount ordered is much less, around 4.5 cm. The rest is air, and these air pockets can largely be filled with the water necessary for the mushrooms to grow!
Mark den Ouden
Mushroom Office
Master class course Mushroom composting and growing is 18 – 23 February, there are still some seats available! Please contact info@mushroomoffice.com ASAP if you want to join! Next course will be 29 April – 4 May.
High, higher, too high?
After the last water during the incubation in the casing soil, the grower wants the mycelium to grow onto the surface. To ensure a good recovery of the mycelium in this period the right settings for the room climate are essential.
An RH at a minimum of 95%. A very slow air speed, if possible zero and an adequate room temperature. That room temperature should be as close to the optimum for vegetative growth as possible. That optimum temperature is 25° C to 26° C.
This means often a room temperature of around 21° as a minimum. Then the mycelium has the right conditions to grow onto the surface.
The next question is: how high do I let it grow ?
Higher means better control of the number of primordia, so no surprises about the number of mushrooms growing out. Higher also means easier picking so a higher pick rate. Another positive experience is that clustering is easier avoided.
But the big dis-advantage of having the mycelium higher on the surface is that the climate conditions have to be perfect. The influence of the climate onto the mycelium and the primordia is bigger. So one moment of for instance too low RH means that you will lose primordia. Deeper mycelium is also easier to stagger the mushrooms so that is an advantage too. Another point is the fact if the grower can stop the mycelium when it grows too high. Overlay as that is called makes the outgrow of primordia more difficult. They come from underneath the blanket of mycelium.
So what determines the choice?
Both ways have their pro’s and con’s.
But for me the crucial point to choose a way is the technical capacity of the farm and the experience of the grower. If you are able to stop the mycelium at all times, still create the stagger and have perfect control of the environmental conditions, grow white.
If you are not sure of all this, grow deeper into the surface of the casing soil. So grow blacker.
Generally blacker is safer.
Mushrooms are not hydroponic
A few years ago, it was standard practice to give a significant amount of water in the first few days after casing. It was common to see people aiming for maximum watering, with 35 liters per square meter being standard and 40 liters considered even better. The goal was to adjust the moisture in the phase 3 compost, with the aim of reaching a moisture level of 72% or more.
Today, clients around the world are seeking better-quality mushrooms. Every grower aspires to cultivate the perfect mushroom.
The Perfect Mushroom
The ideal mushroom looks the same everywhere in the world:
- It has a good color and shape
- It is heavy and dense
- It has a long shelf life
- For us as growers, it must be financially viable, producing a high yield with minimal costs
This type of mushroom grows only when all conditions are in balance:
- The compost contains all essential nutrients that are accessible to the mushrooms.
- The water content in the compost is available to the mushrooms, but not in excess. If the mushrooms have to work a little to access this water, it will produce a stronger mushroom.
- Compost activity should be low during picking. If the compost is too active, water may be forced into the mushroom during picking. This can be managed by adjusting the filling weight or compressing the compost.
- The climate in the growing room should be natural; this means avoiding extremes in air temperature, CO2 levels, or fan speed.
Compost Filling Weight
Many farms worldwide still prefer to fill a large amount of compost per square meter. It’s often believed that more compost produces more mushrooms, which is true. However, this added compost must also be managed carefully. Typically, if you increase compost volume, you’ll need to employ extreme climate controls to manage compost activity, such as high fan speed or low air temperature. During the first flush, this compost activity often makes it difficult to maintain a gentle climate. A gentle climate in the first flush is crucial for producing high-quality mushrooms. It doesn’t help to have an excellent third flush if the majority of your first-flush mushrooms are damaged due to extreme climate adjustments for compost activity. This increased activity dries out your compost and casing, causing issues for the second and third flushes.
Watering and Compost Activity
After filling phase 3 compost, the mycelium is damaged and needs time to recover. Adding too much water in the first two days after filling halts mycelium growth. The mycelium cannot spread over the compost because water sits on the outside of the compost. In these cases, high compost activity occurs because the mycelium is competing with the water. It is much better to allow the mycelium to regrow (recover) for two days after filling, only adding small amounts of water to keep the casing moist.
Watering on Different Types of Compost
A watering schedule depends on various factors:
- When the compost is not fully colonized with mycelium and remains active, wait before watering to allow mycelium to incubate. Once the mycelium starts growing into the casing, you can gradually increase watering.
- When the compost has a long or coarse structure, you can begin watering earlier. The loose structure allows excess water to drain to the bottom of the compost.
- When you have a short or soft compost, be especially careful with watering during the first two days. This type of compost acts like a sponge, absorbing water in its top layer. This prevents the mycelium from regrowing in the upper layer, creating a weak connection between the compost and casing.
- If you fill with warm or highly active compost, it’s better to minimize watering on the casing, adding just enough to keep it moist. Some growers add large amounts of water to cool down the compost, but this only halts mycelium regrowth and increases activity.
Compost Activity
Mushroom growers worldwide face the same problem: there are times during cultivation when the compost exhibits either more or less activity than desired. This can happen right after filling the compost, during ventilation, or if the compost temperature rises too quickly during the first flush, which can severely impact mushroom quality.
Most farms have this under control, but each grower must find the optimal formula for their own operation. This principle can be compared to a balance: if you change something on one side, you must adjust the other side to maintain equilibrium.
The entire process starts with filling the compost in the room. There are a few important factors to consider at this stage. The moisture content and structure of the compost are crucial for the expected activity right after filling. Dry compost with a lot of structure will show high activity immediately after filling. This compost should always be filled thicker to achieve the desired kilograms per square meter. This extra thickness is mainly filled with air, which acts as a buffer for heat.
Once the compost becomes active, this air warms up and is very difficult to cool down again. Compact it as firmly as possible. For wet compost with little structure, do the opposite: fill it loosely and avoid watering immediately after filling.
Mycelium Growth during incubation
If everything proceeds normally during the growth phase of the compost, the first signs of activity can be seen around day 9 after spawning. This activity increases as the compost continues to grow. By day 15, the compost should be fully colonized, and activity will start to decrease. If, for some reason, the compost needs to be covered or removed from the tunnel earlier, this activity will continue in the growing rooms. At that point, controlling this activity becomes very difficult because the casing soil acts like a blanket, retaining heat in the compost. In such cases, keep the air temperature in the room very low to maintain the compost temperature at 26°C. This will also cool the casing soil, preventing mycelium growth in it.
Supplementing
Supplementing the compost provides extra activity. The level of activity depends on the type and amount of supplement used. Typically, 15 kilograms of supplement per 1,000 kilograms of phase 3 compost yields optimal results. However, this depends greatly on the compost. If the compost has a high nitrogen content, 15 kilograms might be too much. Supplementing is an excellent way to increase both the quantity and quality of mushrooms, but the compost must be free of competitive mold infections. Infected compost can react negatively to supplements because these are also food sources for competitive molds, which can harm the mycelium or mushrooms, negating any benefits of supplementation.
Filling Weight
Filling weight is a crucial factor for compost activity and significantly affects the total mushroom yield. Generally, a 10% increase in compost results in a 10% increase in mushrooms. This is true, but the climate unit must be able to manage the additional compost. Again, it's about balancing the ability to handle increased activity with the potential yield benefits.
As you can see, the desired but sometimes troublesome activity of compost depends on many factors. Literature provides ideal filling weights, but in practice, it varies from farm to farm. Growers must determine the ideal ratios for their specific operations.
Total Mushroom Service
Jeroen van Lier
