CULTIVATION TIPS DLV PLANT MUSHROOMS Extreme summer weather
By Jan Gielen, DLV Plant Mushrooms Manager / Specialist Climate & Energy
j.gielen@
dlvplant.nl
At the moment of writing, the Netherlands is sweltering under hot, sunny skies, with the hottest 2nd of August ever recorded being noted. The weather stations in the mushroom growing regions showed end of afternoon temperatures of 31.3 to 36 °C with an RH of 52 and 32% respectively. As the total heat and moisture content of air not only depends on the temperature, but also on the RH, the weather in the Kerkdriel region was the most extreme noting 31.3 °C and 52% RH. The outside air there had a heat content of 70 kJ/ kg and a moisture content of 15 g/kg, while for growing 46 kJ/kg and 11 g/kg is mostly needed. Conclusion: the outside air was completely unsuitable and would only introduce too much heat and moisture, stretching the cooling capacity and using a lot of energy. By using less fresh air in such extreme conditions it is easier to maintain the temperature and RH levels in the growing room, and less energy is needed for cooling. In practice however, it is not clear just how high the CO2 can go. What we do know is that this figure is lower in summer than in winter. A research project revealed a correlation between CO2, moisture content and oxygen. As the CO2 and/or moisture content rises, the oxygen content will drop. As decomposition in the compost requires oxygen, this could hamper growing if the situation persists. The table uses an example whereby the maximum CO2 may increase to 1800 ppm with a customary moisture content of 11 g/kg. The oxygen value has then dropped to 20.43 %. To prevent the oxygen value dropping even further, at a moisture content of e.g. 11.9 g/kg the CO2 must not be allowed to exceed more than 1500 ppm. Translated to practice this means: if the moisture content of the growing room air cannot be managed in summer and starts to rise, the CO2 cannot be increased in unlimited volumes as this will have a negative effect on the oxygen content. The latest climate control programs offer a feature for this purpose.
Watering
By Erik Polman, DLV Plant Mushrooms
e.polman@dlvplant.nl
Photos: DLV Plant Mushrooms
The amount of mycelium formed after casing depends on several factors. Firstly, how much water is applied. The more water is given, the less likely the risk of exces- sive mycelium growth. What is more important, however, is the moment of watering and how much is sprayed each cycle. With incubated compost the most water can be absorbed in the first 36 hours after filling, if 2.5-4 l / m2 per cycle is sprayed. This is essential on the compost we are familiar with in the Netherlands, with a moisture content of 62-64 %. As long as the mycelium in the compost has not fully recovered, the compost can absorb water quite easily. With a low moisture content (below 63 %) up to 5 l / m2 can also be given in the compost. The amount of mycelium appearing in the casing soil can be assessed three days after casing. This will depend on the amount of cac-material and the quality, structure and coarseness of the casing soil. From day three onwards spraying should be done with the aim of controlling the amount of mycelium. I.e. 1-3 x 0.5 -1 litres / m2 per day until ruffling starts or the recovery period. If phase II compost is used, be more cautious about giving water for the first two days. The mycelium threads in the compost have not been broken - or only the top layer - and cannot tolerate water so well. V
olumes of 1-1.5 l / m2 per spray cycle are better. Do start in time
though with the first watering cycle if you want to prevent an invasion of mycelium in the casing soil (see photo). This means starting with one to two spraying cycles immediately after casing on the same day. Then spray as the mycelium develops up to a maximum of four times a day. Spraying too much will close the pores on the surface of the casing soil.
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