CULTIVATIONTIPS DLV PLANT MUSHROOMS Filling tunnels
Compost plants generally assess the phase II and III processes by analysing graphs. Providing no deviations are apparent in the lower and upper temperature, and if the compost sensors are mutually positioned in close proximity, the compost is assumed to be homogenous and will emerge as homogenous compost after the phase concerned is complete.
However, a number of causes can lead to deviations in the process. This may be caused by diff erent compost temperatures when the phase II tunnels are fi lled and variations in the leveling time.
By Erik Polman, DLV Plant Mushrooms
e.polman@dlvplant.nl
Another cause is often human error – namely not fi lling the tunnel correctly. If, during these phases, the usual open grating fl oors are used, it is vital to fi ll consistently to achieve a homogenous process. Crucial in this respect is to fi ll in three layers (see photo) whereby the fi rst layer occupies approximately half the ultimately desired total fi lling depth. It is also impor- tant to fi ll the front and rear ends and corners (edges) of the tunnel suffi ciently well so that later on the air can fl ow evenly through the mass in the tunnel. Instructing the fi lling cassette operator is important for a uniform process. To simplify his task, the fi lling-related activities should be well-organised. This means having enough supplies of compost to ensure a complete tunnel can be fi lled in a single operation, without having to stop fi lling. A regular fl ow of compost also makes it easier to fi ll the tunnel evenly. The distance between the conveyor and the pile of compost must always be the same to ensure an even density of compost layers. These measures will result in a consistent process in the entire tunnel, resulting in a product with the greatest possible homogeneity for the grower.
High tech – low tech
By Jan Gielen, DLV Plant Mushrooms Specialist Climate & Energy
j.gielen@
dlvplant.nl
Photos: DLV Plant Mushrooms
Modern mushroom farms these days use high tech climate installations to keep a wide range of climate parameters at the desired values. But there are still enough low tech mushroom farms that achieve good production and quality without them. It is impor- tant that these growers have a good understanding of the physics involved in climate control, and how the evaporation process can be steered using limited means. See also the previous two articles about the Mollier diagram. They explain that the temperature and RH in the growing room - and outside - can be measured using dry and wet bulb sensors. Another basic requirement is a fan for air movement and fresh air. To check whether the outside air is suitable for the mushrooms, you shouldn’t use the ordinary outside temperature (dry bulb), but rather compare the wet bulb in the growing room with the wet bulb outside. As long as the wet bulb outside gives a lower reading than the one inside the growing room, the outside air can be used as required. If the wet bulb outside gives a higher reading, minimise the use of outside air. Heating is also required to heat the air, and cooling to cool and possibly dry the air. To dry air, the air temperature must be brought below the dew point and then re-heated again. Finally, humidifi cation is needed to humidify the air if necessary.
Many farms still use open water to help achieve the desired climate condition. Water can obviously be used to humidify air. Water humidifi cation will also cool the air. This principle is often applied when supplying fresh inlet air in countries with a very warm and dry climate (desert cooling). Another common method is regularly wetting the fl oors (see picture), and sometimes the walls, of the rooms. As the water evaporates it cools and humidifi es the air. Open water can also even be used to dry the air! In this case, cold water must continuously fl ow over the fl oor. The fl ow of cold, running water has no chance to evaporate so acts as a cooling surface. The air is cooled and dried, as the moisture in the air condenses onto the cold surface of the water. So, to a certain extent, water can be used to cool, humidify and even dry air. This property makes water the magic ingredient in low tech mushroom growing.
38 MUSHROOM BUSINESS
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