Phase I, the production of fresh compost

Depending on the raw materials this phase will last minimally 3 to even 18 days. The most important goals in this phase are:

• The mixing of straw or horse manure (horse manure can replace straw for a larger part), chicken manure, gypsum and water, so the compost becomes homogenous;
• The opening of the straw, so the straw will absorb water and the mould of the mushroom, the mycelium, can grow in the straw.

After this phase, the compost is called “phase I-compost” or “fresh compost” (in earlier days also “green compost”).

Phase II, the pasteurization and conditioning of the compost

The compost is deposited in an enclosed area. This enclosed area consists of a roster floor on which the compost lies. Conditioned air is blown through this floor. The area where the compost is deposited is called a tunnel. The first part consists of the pasteurization of the compost; this is making the compost disease-free. During the second process in this phase II the compost is conditioned, at which the ammonia in the compost is converted. After this phase, the compost is called “phase II-compost” or “spawnable compost”.

Phase III, mycelium growth in the compost

After phase II, the compost is removed from the tunnel and is mixed with ‘spawn ’. ‘Spawn ’ consists of special prepared grains of wheat that continue to grow with the mushroom mycelium. From the ‘spawn ’ the mycelium continues to grow through the compost. This process takes a minimum of 14 to 18 days. At the end of this phase the compost is called “phase III-compost” or “full-grown compost”. This phase occurs both at the tunnel companies where phase II is carried out as well, as well as at the production farm . In the Netherlands and in the more developed mushroom countries, this phase occurs at the compost company.