The usefulness of straw in mushroom cultivation

Straw is an important ingredient in compost production for mushroom cultivation.

Why do we need straw?

Straw has three functions:

1. It creates structure in the compost
   Why is the structure important? Mycelium is very similar to ourselves. What do we do 24/7? We breathe, we need oxygen. And that is what mycelium needs too. Just like micro-organisms during composting and – to a lesser extent- during the caramelisation process. The structure of the straw allows air to flow through the compost. This supplies oxygen and extracts CO2.
2. It provides a water buffer
   Straw doesn’t absorb water easily. It is a waste product of weed production. As the weed crop grows, the waxy layer around the straw protects it from being infected by moulds and bacteria. The first, and one of the most important, processes during composting is removing the protective, waxy layer from the straw. Only then is straw able to absorb and release water, so that it functions as a water buffer. I can’t emphasise the importance of water enough.
3. It provides the micro-organism with nutrients
   During composting, the micro-organisms feed on the straw, and later on the mycelium also uses it as a nutrient source.

What is the main treatment of straw?

During the first few days, process water is used to wet the straw. The entire bale, all the separate sprigs and blades, must be wet. The bale then has to be drained properly. If the straw is left wet, it will stay cold and nothing much happens. So the straw should be damp, but not dripping wet. In other words, the excess water must be drained away. The micro-organisms will automatically become active and the temperature in the straw will rise from 50 up to 70°C. This activity of the micro-organisms decomposes the waxy layer. The length of time needed for this process depends on the quality of the straw.

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Mark den Ouden | Mushroom blog