As we produce and harvest mushrooms, we inadvertently create a byproduct that we love to share with local farms and gardeners - our spent mushroom substrate compost! In an effort to continuously mitigate our waste in meaningful and helpful ways, we are now offering local pickup of our spent mushroom substrate.
This exhausted substrate consists of oak sawdust, soybean hulls, wheat bran, organic prosso millet, and a mix of coffee chaff and cacao parchment (both the byproduct of bean roasting, either for coffee or local bean-to-bar chocolate production).
What is the NPK of spent mushroom compost? NPK is the proportion of three plant nutrients in order: (N)itrogen, (P)hosphorus and Potassium (K).
Typically, spent mushroom compost has a 1:1:1 N-P-K ratio. The composting process metabolizes and stabilizes these nutrients so they are converted into a slow release form. As is the case for all soil applications, if applied above the recommended rates, nutrients can exceed desired levels.
We break each block down by hand and we are able to pack it in a woven poly bag, and are labeled for easy pickup out back at our HQ. Known uses are traditional composting techniques, myco-remediation projects, passive outdoor mushroom farming (you'll have PLENTY of volunteer mushrooms popping up under the right conditions), integrating into feed for goats and chickens or vermicompost. It has been used as an aid to cover newly seeded grass, to protect from birds and to retain moisture while the seeds germinate. *Not recommended for supplementing certain berries such as, blueberries, cranberries, gooseberries and raspberries.
Our bags typically weigh 35 lbs and self-serve pickup is $10 per bag. Please reach out if you desire larger quantities.
more resources are readily available at: https://www.americanmushroom.org/consumers/compost/