Biuletyn Producenta Pieczarek PIECZARKI 1\2016 p.12-18
After presenting in the last two numbers of the Biuletyn the knowledge about the processes of nutrition of mushrooms and ways of controlling it one can present its current use in cultivation. This knowledge is the result of many cultivation tests and observations of the behavior of the mushrooms made in the last two years. The aim of the changes in technology is to obtain stable yields of 40 kg/ m2 in three flushes in each growing cycle. Periodic achieving of such yields does not transfer, so far, on the yield of mushrooms at this level throughout the year. It faces a number of constraints. The first group is the variability of the qualities of raw materials, mainly compost. The second – controlling the evapotranspiration, or evaporation from the surface of the spawn and fruiting bodies, the casing soil and the compost, and also transportation of the water from the compost to fruiting bodies. This is a result both of incomplete knowledge of these processes, and deficiencies in the technical equipment allowing to control the microclimate in the cultivation room, which would be able to ensure the provision of maximum volume weight of fruiting bodies throughout the harvesting season.
Today, we can point to several conditions that must be taken into account for it to be possible to obtain high and stable yields. To most important of them are included in the following statements:
- Potential yield that can be obtained is dependent upon the weight of the spawn and the permanent access to water in the casing soil and the compost throughout the cultivation period. This means it is necessary to collect and supplement them in water, according to the weight of the spawn, and managing water in such way, not to allow its deficit during the whole cultivation period.
- Maintaining gas exchange between the ground and the air in the cultivation room is required through the casing soil for the entire cultivation period.
- Thermal effect has to be controlled (temperature rise above 25°C) after application of the compost and the start of the shock and between the first and the second flush. An excessive increase in temperature normally prevents control of the fruiting bodies due to their excessive transpiration, while too rapid evaporation of the casing soil interrupts water flow from the compost and results in drying. At present it is not fully known how to change relations between evaporation and transpiration with increasing temperature of the compost and, how to influence the transpiration, for it not to be too high, and therefore not to be followed by a significant decrease in the weight of harvested fruiting bodies. All indications point that the correct procedure is to prevent exceeding of the temperature in the ground above 26°C, and not only to control transpiration in this period.
Lack of increase in temperature of the compost between the flushes has also a beneficial effect on controlling the amount of pins in the second flush.
- During the shock the resource of created pins allows to obtain a yield of 172 kg\ m2. This means that each time one has to provide the required number of fruiting bodies necessary to achieve the target level of yield. The number of fruiting bodies and generations depends on the conditions the pins have during cultivation.
Controlling the number of fruiting bodies and generations is based on the release of pins after shock in each flush. The release of pins takes place every second day from the middle of the harvest, and is controlled by maintaining the evaporation levels from the surface of the shelf ensuring their growth.
- The yield depends not only on the number of harvested fruiting bodies, but also on their volume weight during the harvest of all the flushes. The aim should be to ensure that those levels are maximized. But they are not constant. Our observations indicate a decrease in the maximum weight of fruiting bodies with every next flush. In the first flush the weight of the fruiting body of a diameter of 5-5.5 cm and of 60-65 g can be sustained, in the second – 45-50 g, and the third – 40 g. Probable cause of weight loss in the several flushes are initially – insufficient water in the compost and the casing soil, followed by – decrease of nutrients supplied to the fruiting bodies because of the increasing duration of their transport from the spawn in the compost. It is not impossible that in the future one will be able to obtain the same maximum weights volume in each flush.
In order to achieve the maximum weight of the fruiting body, the use of calcium chloride should be considered expedient and controlling the salinity of the casing soil, so that it was not too low. It is important to water the fruiting bodies during harvesting as the loaded compost was very dry.
- Only selective collection can ensure that one can get the maximum weight of each fruiting body.
- The occurrence of diseases and pests may significantly reduce the yield obtained.
The potential level of yield of mushrooms is determined mainly by the characteristics of the compost, casing soil and applied feeding supplements.
- Variability of the ground, which took place in the past year, allows to identify those of them that may impact the process of nutrition. Highlights include:
- Water capacity of the compost. It is the ability to retain water after hypertrophy of mushroom’s spawn. Determining water capacity is simple and can be performed independently. It ranges from 200 to 500 g per 1kg of Phase III compost. This means that the dose of the compost 85 kg/m2 can absorb from 17 to 42,5 l/m2 of water. This also explains why at the same dosage of water to the compost, sometimes it is leaking in large quantities and sometimes there is too little water, and thus the compost does not have the appropriate resource to maintain the expected level of yield and to maintain the cooling effect. Is it possible to stabilize the water capacity of compost? Such capabilities are tested and it seems quite likely that one will be able to correct it by adding crafted hemicellulose.
- Highly diverse activity of the compost as a result of the variable nitrogen content and the degree of controlling it by the spawn. The high nitrogen content in conjunction with additives and feeding supplements induces the thermal effect. Short hypertrophy means reduced movement of nutrients to the spawn thereby reducing the potential yield. It also promotes greater proliferation of thermophilic organisms, as they are less controlled by the mushroom’s spawn.
- The casing soil. It is designed to ensure a good exchange of gas between the compost and the air in the cultivation room and soaking water from the compost. Therefore casing soil with a very good and durable structure and large water capacity is the best. But its behavior in the cultivation room has been significantly affected by its application and treatment after applying, mainly rolling and watering. The casing soil may not have anaerobic zones. Combing is treated as the need to correct its structure (its restoration) after an intensive watering. Watering by the so called tree usually makes it worse when applying high doses of water, watering under shelves allows to maintain the structure without combing at the same high doses of water.
- Feeding supplements. Currently, the basic feeding supplement added to the compost is appropriately chosen, dried and grinded corn seeds. Granulation is their important feature. If the granules are very small a significant temperature rise in the compost can be observed, on the other hand when the granules are too thick it reduces their bioavailability. It is visible when emptying the shelves after end of cultivation. The impact of feeding supplements on the behavior of the spawn is presented on photo. 1 and 2.
Currently existing equipment is used. Evaporation process is more easily controlled if one can maintain the required level of temperature, relative humidity, at the lowest, equal movement of air in the cultivation room. Currently used air conditioners have limited ability to meet this condition. This implies the need of designing the new generation that will be able to fully implement these principles.
- Humidification system should be efficient and operate without condensation of water in the sleeve. Its efficiency can be improved by installing additional humidification systems: through the floor and under the shelves. While increasing humidity they are used in the first place, and only then – for the humidification of air.
- The film under the compost should be perforated, which ensures the flow of excess water without accumulation at the bottom of the shelf.
- Having a strain gauge installed in the casing soil makes it easier to control the flow of water to casing.
- Piche’s evaporometer (Fig. 3) makes it easier to control the actual evaporation, evapotranspiration, although not yet fully able to control the behavior of the fruiting bodies of the assumed size of evaporation.
It is also necessary to have well-functioning controllers of microclimate and knowledge of their functioning. This is due to the fact that the process of evapotranspiration (evaporation from mushrooms and casing soil) is the most easily adjusted when one can separately affect each desired parameter of the microclimate in the cultivation room.
The issue of equipping mushroom growers with devices allowing to control the process of cultivation is becoming an important rooming in the future.
What changes can be proposed to introduce to the current technology?
Below are the changes made on a production scale by the few mushroom growers.
- Feeding supplement’s dose of corn to the compost – 2.5 kg evenly mixed with the compost.
- Dose of feeding supplement added to casing soil – 200-300g /m2 evenly mixed with casing soil with a significant dose reduction of caking.
- Compost evenly overlapped by 1-2 cm lifting in the roller of combine in a dose of 80-85 kg/m2.
- Pouring water into the ground and casing soil.
Treatment, which we use, is pouring water into the compost by developed principles. Here is the most commonly used procedure: allow the water to the compost to pour after 24 hours from application, and after reaching the temperature of compost of 23-25°C the spawn’s growth starts. Basic dose, up to 45l/m2, is poured in the course of three days (at the time of the application). The first dose is 12l/m2 on the first day of watering, in the second – 16 l/m2, and in the third – the remaining or lower, if the compost was moist. A single dose of the water of 2 l/m2 poured at intervals of every two hours at lower compost temperatures. With increasing temperature interval are smaller and vary from one to one and a half hours when the temperature of compost is increasing. Water can seep through the compost. The purpose of this treatment is achieved when the compost temperature is stable and equals 23-25°C (up to maximum 27°C) with the air temperature of 18-19°C with moderate air movement on the fifth day from application of casing soil. This allows to start a mild shock. The following correlation is observed: the lower the compost temperature at the start of the shock, the less problems with overheating between the first and the second flush.
In case of a sharp rise in temperatures after the application of the compost and after pouring water, the temperature of the air in the growing room should be increasingly reduced with increasing air movement. In summer, one has to significantly increase the dose of water to stop the rise in temperatures in the compost. Sometimes this can result in the need for additional mixing fans. It is a tried, working procedure, but it requires adaptation to the conditions in the growing room.
- performing shock when applying feeding supplements to casing soil, be aware of the tendency of intensified bonding. This is the result of more spawn in the casing soil and easier growth of pins after completion of shock. A very important procedure is the placement of generations. For this purpose, we traditionally use periodically reducing the temperature difference between the compost and the air. Reducing evaporation until it locks and controlling it using evaporometer, one can also temporarily pause the growth of next generations. Also, periodically raising the level of carbon dioxide to 10,000 p.p.m. may assist in this procedure.
- Controlling the evaporation. The behavior of the mushrooms after getting shocked is dependable of the process of water evaporation from the surface of skin of pins and fruiting bodies. This process is called transpiration. The skin of mushrooms as compared to the plants is not capable of closing stomata, thus self-regulating this process. Transpiration depends mainly on the temperature of the air and ground, air movement and the content of water in it. The case would be simple if one could measure the process of transpiration. Such possibility doesn’t exist yet. So what can we measure? To track changes in potential evapotranspiration, we measure the relative humidity of the air or the water content in the air. Evapotranspiration is transpiration mushrooms, evaporation of water from the casing soil, floor and from any source of water in the room, for example, the one condensed in the sleeve. Relations between transpiration and evaporation of the remaining surfaces where there is water, vary. This explains why, at the same relative humidity and other parameters remaining the same in the microclimate, fruiting bodies behave differently – they are heavier or lighter, round, flat, and white or change color. For example, drying of the casing soil can cause that at the same relative humidity transpiration is greater, that is, there is a greater loss of water from the fruiting bodies that are lighter. We are trying to solve this problem by tracking evapotranspiration based on readings on the scale of Piche’s evaporometer. And then, only indirectly by observing the behavior of pins and fruiting bodies, the conditions are adjusted in the period of typically 12-hour or shorter, by controlling the volume of evaporation of mm of water column in evaporometer. It ranges from zero to several mm of water column. As the evaporation of the accepts standard five mm during 12 hours. In each mushroom farm it must be set individually, tracking the weight and appearance of the fruiting bodies in the period of harvesting and growth of each generation of pins. This method is more useful than the measurement of relative humidity, but it requires experience. Keep in mind that this method requires different approach to the parameters of microclimate. This was described in issue 2/2015 of the Biuletyn. Stabilization and increase of the yields of mushrooms. Cultivation from the end of the shock is carried out with the smallest possible movement of air (remember opening the flaps of fresh air and exhaust flap), a much greater range of carbon dioxide (2-10000 ppm), air temperature from 17-19°C, the activity of 2-3° The relative humidity, needed to maintain the expected evaporation, has got resulting value and can range from 100 to 80%.
- As a rule we set selectively collection, gathering in real time information from the foragers about the weight (what is the current standard fruiting body weight) and the appearance of fruiting bodies (skin adhesion to the glove, shape of the fruiting bodies, do they become flat, and about their color, whether they are white or discolor begins). Depending on the situation, we perform correction of the evaporation – slow it down or accelerate by changes in air movement and relative humidity.
Technology of growth will continue to develop and often there will be reasons to discuss it.