THE NETHERLANDS


On the last two picking days, the air tempera- ture is increased by 1°C/day to 17°C to stimulate evaporation and compost activity. The first flush is picked over five to six days. This strategy of low air temperatures, the spread created during cool down and graze picking with self-propelled picking trolleys ensures that the peak in the first flush does not exceed 5-6 kg/m2 third day of harvest.


/day on the


Moisture balance Moisture management is a very important item in mushroom cultivation. Sjaak has measured and registered evaporation levels in the growing room and the moisture balance during cultivation for a long time.


After filling he registers parameters such as the number of square metres filled, how many tons of compost were filled and the moisture content of the compost in the climate control computer. He also enters the required moisture content of the compost, which is 70% on average. The computer then calculates how many litres of water should be sprayed per m2 and after each session displays the remaining volume of water still to be sprayed. As a rule of thumb, every 2.5 l/m2 sprayed increases the moisture content of the compost by 1%. Based on Sjaak’s calculati- ons, with a compost moisture content of 62% in this case a spraying session of 8 x 2.5 l/m2


is 20


litres per square metre is necessary. Until the first flush, control is based on RH, and on evaporation in g/m2/hour for the later flushes.


Sjaak near the climate computer per growing with display on 22” screen.


The climate system displays evaporation in litres from the start of cultivation and from the last spraying session. After watering the first flush, Sjaak knows from experience that the beds will be nicely dried when 1 l/m2 rated. With evaporation of 50 g/m2


/hour, this Farm details Wilke B.V.


Product: white mushrooms Number of growing rooms: 9 Surface area of growing rooms: 535 m2 Size of the farm: 4,815 m2 Cropping cycle: 6 weeks, in practice average 5.8. Number of flushes: 3 Filling: on average 1.5 growing rooms per week Compost: Walkro phase III Compost filling weight: 90 kg/m2 Supplement (3 Walkro suppliers): 14 kg/ton Casing soil: Euroveen carbo 8.5 Quantity casing soil: 4.2 m3/100m2 Spawn variety: Sylvan A15 Shelving: two rows of shelving, seven high Climate control system: standard overpressure using fresh outside air Cooling system growing rooms: freon cold water cooling Climate control computer: Panbo systems Production: 32.5 kg/m2 Production performance: 1st flush 16 kg/m2 3rd flush 6 kg/m2


; 2nd flush 10.5 kg/m2 .


Production per week: 26 tons on average. Grades: fine 30- 35%, medium 60- 65%, giants 5%, II+ III 5% Picking performance: 30 kg/hour Number of pickers: 20 Markets: 50% Banken Champignons, 50% own sales to hospitality and retail.


;


takes 20 hours. Since Sjaak started relying on these figures, he has never experienced any more problems with bacterial blotch in the second flush. Controlling evaporation in the first flush is more difficult than in the second and third flushes, because the peak in the compost temperature during the first flight is much higher and stimulates extra moisture transport to the mushrooms.


After the first flush, recovering the same good moisture level in the casing and compost as during pinhead formation in the first flush is no longer possible. If you calculate the volume of evaporation up to the end of the first flush plus the weight of the mushrooms, you soon arrive at 30 litres/m2 litres per m2


and after the first flush 14 to 16 is sprayed. After the first flush,


the compost is normally drier and more densely colonised by mushroom mycelium so absorbing water is more difficult. If too much water is applied at this stage, it will leak from the beds, or if plastic has been placed underneath the beds the moisture will accumulate and make the lower layer of compost too wet.


Linking data


“Controlling the mushroom growing process from entirely behind a computer display is not about to happen yet. You still need to visual checks. However, more measurement data can


30 MUSHROOM BUSINESS


has evapo-


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