Dutch Mushroom Farm

A Trend control system supplied and engineered by Panbo Systems BV has been entrusted with the critical and complex task of providing optimum growing conditions at a recently opened mushroom farm in the Dutch province of Limburg. Based on Trend IQ3 controllers, the system automatically controls and monitors the environment at every stage of the growth cycle, using a sophisticated algorithm to maximise yields and produce mushrooms of consistently high quality.


Located close to the German border, the family run farm of MTS Wilke is designed to operate all year round and is capable of producing some 26t/week of white button mushrooms. It basically comprises nine self-contained, insulated growing rooms, each measuring 43m long x 6.3m wide x 4.8m high. By carefully regulating the rooms’ air conditioning plant and water sprays, the Trend IQs provide close control of temperature, humidity and carbon dioxides levels and loss of moisture from the mushrooms. All of these variables have an influence on growth rates and quality.


In the first phase of the production cycle a bed of mushroom compost is laid down and covered with a ‘casing’ layer of lime and peat. The organism that produces the mushrooms (mycelium) spreads throughout the casing, a process that lasts about ten days. Heat is generated by the growing mycelium and in order to maintain the desired compost temperature of 24oC, the air is controlled to between 16 and 22oC. Initially, humidity is kept high (95 – 99%) and the CO2 level is allowed to build up (to 6000ppm) to encourage vegetative growth. After five to seven days, cool fresh air is introduced and growth changes from vegetative to fruiting. The CO2 concentration is reduced to 2500ppm and evaporation from the compost is increased from 7 to 22 gm/m2/hr.


The next stage of the process – known as ‘pinning’ – is when the first recognizable mushrooms begin to appear. During this phase the temperature is held at 17oC, the CO2 level between 2500 and 1800ppm and evaporation between 22 and 25gm/m2/hr. These conditions ensure the formation of the correct number of ‘pins’ and promote their subsequent development.


Harvesting of the first crop begins about a week later and continues for three to six days. During this period the temperature is kept at 17oC, while the CO2 needs to be 1200 – 1800ppm and evaporation 25 – 35 gm/m2/hr. A further two crops are harvested, in both cases the temperature being controlled to 17.5oC and evaporation to 22 – 30gm/m2/hr. The CO2 level is maintained between 1400 and 800ppm for the second crop and 1000 – 400ppm for the third.


A particular complication from a control point-of-view is that the natural ‘activity’ of the compost varies from batch to batch. Panbo Systems has allowed for this by programming the controllers with a formula that is able to predict mushroom growth under any set of circumstances. This enables the control settings to be customised for each growth cycle. The required control tolerances are +/- 0.1oC, +/- 50ppm CO2 and +/- 5gm/m2/hr for evaporation.


Once harvesting is complete, the temperature in the rooms is gradually raised to 70oC, where it is held for 12 hrs before being allowed to fall to ambient temperature (the maximum heat up and cool down rates are set at 6oC/hr). This procedure ensures that the spent compost is pest and pathogen free prior to its disposal.


Each room has an IQ3xcite (with 128 i/o points) for climate control and an IQ3xact (12pts) to regulate the spray water flow.  An IQ3xcite (with 96pts) controls the water pumps and works in a master/slave arrangement with the IQ3xacts, signaling them when they can start watering (only one room can be watered at a time). A further 128pt IQ3xcite controls the farm’s boilers, chillers and heat recovery system. All the controllers are network-linked.


The control system’s main operator interface is a Trend ‘963’ supervisor, which is used by the grower Sjaak Willems to monitor room conditions and the operation of the plant and if necessary make adjustments to the controls. The supervisor has the facility to send SMS messages and can thus transmit alarms directly to Mr Willems’s mobile phone. Conditions inside the growing rooms can also be monitored via wall-mounted Trend IQView4 touch screen displays; there is one of these outside each room.


This unusual application of Trend building controls illustrates the technology’s considerable adaptability and ease of configuration. Importantly, it offered a lower cost solution than the custom-designed controllers that are generally used in this field.


For more information please contact
Panbo Systems B.V.
Schuurkenspad 7
5968 PD
Tel: +31 (0)773 078 900
Fax: +31 (0)773 074 014