Gypsum is the common name for calcium sulfate (CaSO4). It is a greyish powder used for making cement and drywall. Gypsum is used in in grain spawn in order to keep kernels from becoming stuck together and as a pH-buffer and lightening agent in bulk substrate and casing material preparation.

Calcium sulfate will slightly acidify a substrate as sulfuric acids evolve.[1]

References[edit | edit source]

  1. Stamets, Growing Gourmet and Medicinal Mushrooms (Third Edition), 2000
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