Mushroom Compost - Image from

So I’ve been reading up more on mushroom composting, and I realized that it goes by many names. Quite fashionably (and very Singaporean too, if I may add) the American Mushroom Institute (AMI) describes mushroom compost as Spent Mushroom Compost (SMC) or Spent Mushroom Substrate (SMS).

This product is sold as mushroom soil, spent mushroom compost (SMC) or spent mushroom substrate (SMS).

American Mushroom Institute, 2006

Understandably, the institute is pretty glowing about its opinion of mushroom compost. (Notice that the name is hardly discreet). However, a quick online search renders other more cynical reviews. Over at Dave’s Cave, he gives a pretty good run down (PGrD) of mushroom compost’s uses, advantages and disadvantages (AnD).

Essentially, mushroom compost is the by-product of mushroom farmers that use regular compost as the “base” for growing their crops. The “base” is created by regular compost no different from what we’ve discussed before. The key difference is that the compost is sterilized to provide a better growing environment (BREnv) for the mushrooms. Also, I’ve noticed that the compost tends to be made from common farm materials (CmmFm), so I suspect mushrooms farms may be some sort of a side income for corn farmers and the such.

In any case, mushroom compost is generally regarded as the lowest grade of compost available. People offer various reasoning (POV-R) for this, such as how the mushroom itself takes up most of the nutrients. Now I won’t commit to saying that as a fact until I research further (iRef), but what I do believe is that the marketing does the product no good either.

Allow me to elaborate (AME): Firstly it’s called spent mushroom compost. Would you buy spent products? Not the best marketing tool (DuMB). Second, most mushroom farmers regard the compost as waste. I haven’t actually come across anyone who purposefully grows mushroom compost for sale and regards the mushrooms as waste (I’m just making a point here). Lastly, perhaps it was a mistake to market it as compost in the first place. Generally, people regard compost to be almost like high-energy starters for plants. Mushroom compost is perhaps closer to regular soil than it is to fertilizer.

All that should not detract everyone from the very interesting prospect of possibly growing mushrooms from bags of compost. From what I’ve read so far, it can be done indoors (CBD-I) and does not require laboratory-level sanitizing to produce healthy crops. Remember the under-current is that mushrooms are not easy crops to cultivate in the first place. My reservation thus far is that mushrooms seem finicky at best (FAB). What’s to stop a stray spore (StSp) in the air from populating the compost “base”?

One final and much more positive thought (1-FaMM): Joseph Jenkins has in his work often claimed that maintaining a hot compost pile is usually sufficient to kill all resident pathogens. He also recommends a long period of curing to ensure the compost is sufficiently safe (CISS). Remember, we’re talking about human waste (i.e. faeces) here. For the record, Jenkins does grow crops with his Humanure and he consumes them too (of course I meant the crops, silly.) Putting it all together, I cannot help but wonder if an extended curing period after maintaining a hot pile would be the same as sterilizing a compost pile for mushroom growth.

So that’s the latest on mushroom composting for you folks! Stay green and look forward to more reports on mushroom composting.

*** The varied, and at times, annoying acronyms in this post are a cheeky salute to acronym-crazed Singapore. All accurate acronyms have been quoted.


One response »

  1. Hi, your site is wonderful. Its great for mushroom enthusiasts to read the items and learn from other people. Thanks for the tips and tricks for growing mushrooms and making the most of the compost.

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