Compost activity during cultivation depends on various factors the major ones being filling weight cultivation method and additives.
‘Activity’ is the difference between compost and air temperature. The greater the difference the higher the activity Fan position also influences activity Increased air movement also increases activity.
The filling weight has an impact too. The more compost in a bag tray of on the shelves, the higher activity will be. Blocks usually have a standard weight of +18 kg. But remember: the more kilos in a block the easier activity is to maintain. The minimum advisable filling weight converted per square metre is 95 kg with phase II and 80-85 kg/m2 with phase III The more compost the higher activity is.
Then the cultivation methods: if wooden trays are used activity also stays high longer as evaporation along the sides and base of the trays is less. With metal shelving systems there is higher evaporation from below and along the sides. Laying plastic under the compost can help retain higher activity. If activity is too high with bags and blocks use perforated plastic.
With phase II compost is very risky to add supplements at inoculation. This is far easier with already incubated compost. Adding supplements also greatly increases activity.
Mark den Ouden, C point
