Mushroom compost is not something related to typical composting, nor does it contain mushrooms. It is a by-product of mushroom farming. The growth medium (soil) in mushroom farming is removed after mushroom harvesting, and it is often used as fertilizer and soil amendment.
Mushroom soil or mushroom compost, like regular compost, is often valued as black gold. It delivers the same value as regular compost.
How do you get Mushroom Compost?
The mushroom substrate is prepared by mixing a variety of natural substances. The composition varies from grower to grower, but common ingredients usually include horse & poultry manure, hay, corn cobs, cottonseed hulls and meal, brewer’s grain, cocoa bean hulls, and gypsum.
It is then prepared for mushroom growth by composting for about 30 days at 160F. This process kills weed seeds, pests, or disease pathogens. The substrate is then steam-pasteurized at 140F. Mushrooms are then planted; it takes 4-5 weeks for mushrooms to grow.
Once the mushrooms are harvested, the substrate loses its ability to sustain another round of mushrooms. The substrate is then removed and packaged to be sold as SMS (Spent Mushroom Substrate) or SMC (Spent Mushroom Compost).
DIY Mushroom Compost: Can you make your own Mushroom Compost?
Yes. You can make mushroom compost at home. However, you can only prepare small batches of mushroom compost at home. Large-scale manufacturing requires specialized instruments. Here’s how you can do it.
- Get some straw from the market or make it at home using a wood chipper.
- Clean the straw by adding it to a large tub or in the sink; rinse with clean water to remove dust and debris.
- Pasteurize the straw by adding it to a large pot of boiling water.
- Bring the heat to around 160°F and let the straw sit for at least an hour or two.
- Drain the straw, place it on a clean surface; let it cool.
- Add the straw to your mushroom spores; mushroom compost will be ready after the mushrooms harvest.
Mushroom Compost – Pros & Cons
- Adds nutrients like nitrogen, potassium, phosphorous, calcium, magnesium, and iron to the soil
- Increases the water-holding capacity of the soil because it is rich in organic matter
- Enhances clay and soil structure which improves drainage
- Good for most edible and ornamental plants
- High calcium concentration is great for plants like tomatoes
- Eco-friendly; doesn’t have any harmful impacts on the environment like commercial fertilizers
- Reduces land waste if used as compost
- Composition varies based on materials added for mushroom harvesting; it cannot be used on all plants without checking
- A high concentration of soluble salts may kill some germinating seeds
- High calcium concentration is not good for all plants
- Can cause fungal infections in plants
Regular Compost vs. Mushroom Compost
Many confuse regular compost with mushroom compost. These two are not interchangeable. Hence it is important to know the key differences between the two for better gardening and farming.
- Mushroom compost contains less nitrogen than regular compost because it has been used for mushroom farming.
- Regular compost suits almost all soil types, but mushroom compost isn’t. It is a good choice for nitrogen-deficient soils; adding regular compost can in nitrogen-rich soil make plant growth stunted.
- Mushroom compost is rich in calcium because chalk is added for mushroom growth. It isn’t a good option for plants like blueberries. Mushroom compost makes soil alkaline, but regular compost doesn’t alter the pH.
Mushroom Compost – Use Guidelines
- Make sure you buy cured mushroom compost; fresh mushroom compost must be cured at least one season before use.
- Aged or cured compost can be applied anytime during spring/summer; apply when the soil is dry to get the best results.
Plants That Like Mushroom Compost
- Vegetable gardens (broccoli, cauliflower, kohlrabi, cabbage, and kale)
- Container plants
- Trees, shrubs, and perennials
Plants That Don’t Like Mushroom Compost