Gypsum, or calcium sulfate dihydrate (CaSO₄·2H₂O), is commonly used in mushroom cultivation for several reasons:
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Improving the structure of the substrate: Gypsum helps improve the physical structure of the growing medium. It prevents compaction of the substrate, which allows better aeration and water circulation. This is crucial for the development of mushroom mycelia.
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Regulation of pH: Gypsum helps stabilize the pH of the substrate: it can be used to basify a substrate that is too acidic and to acidify a substrate that is too basic. A stable pH is important for optimal mushroom growth. Although gypsum is not a strong buffer, it can help keep the pH within an acceptable range for fungus growth.
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Source of calcium and sulfur: Gypsum provides essential nutrients, such as calcium and sulfur. Calcium is important for cell development and cell wall structure, while sulfur is essential for amino acid and protein synthesis.
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Reduction of unwanted growth: Gypsum can help inhibit the growth of certain unwanted organisms in the substrate. By improving the structure and condition of the substrate, it can make the environment less favorable for contaminants.
Practical use of gypsum in mushroom cultivation
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Substrate preparation: Gypsum is often added to the growing medium before sterilization or pasteurization. It is mixed evenly with other substrate components, such as straw, compost, sawdust, etc.
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Dosage: The quantity of gypsum to use may vary depending on the type of substrate and the mushrooms grown. A common recommendation is to add approximately 2-5% gypsum by dry weight of the substrate.
Gypsum is authorized in organic farming.
Food quality (E516 code)
