Tutorials/Substrate/Manure-Based Substrates

Many cultivated mushrooms are coprophilic: in the wild they grow on dung, mostly from grazing animals. They'll fruit happily on plain CVG, but adding manure gives them the food they evolved on. Growers commonly report heavier, more consistent flushes, at the cost of more prep and more contamination risk.

If you're new, get a couple of grows done on CVG first. Manure is a step up.

Choosing manure

• Horse manure is the standard. Horses digest grass less efficiently than cattle, so their manure keeps more usable fiber. Cow manure also works.
• Aged or composted manure is what you want: dark, crumbly, earthy-smelling, with no ammonia smell. Fresh manure is too hot, too wet, and full of competitors.
• Ask about dewormers. Many growers avoid manure from horses recently treated with dewormers, since the residues pass through into the manure.
• Bagged composted manure from garden centers is convenient. Read the label and skip anything with added fertilizer, wetting agents, or "moisture control" additives.
• Around the Pikes Peak region, stables and horse properties are often happy to give away aged manure. Bring your own bags and pick the oldest pile.

Dry it before storing. Sun-dried manure keeps indefinitely and is much less smelly to handle.

Recipes

Ratios are by volume. All of these take a little gypsum, about 1 cup per 5 gallons of finished mix.

Mix	Manure	Coir	Vermiculite	Notes
50/50	1 part	1 part	–	The most common starting point
Manure CVG	1 part	1 part	1 part	Lighter and airier, holds water well
Manure-heavy	2 parts	1 part	–	Richest. Highest contamination risk.

Break up or sift the dried manure so there are no big chunks, then mix it dry with the other ingredients before adding water.

Pasteurizing

Manure carries far more competitors than coir, so pasteurization matters more. The target is 150–170°F for 1–2 hours. Going much hotter starts to kill off the beneficial microbes too.

Bucket or cooler

The same bucket tek as CVG: dry mix in a cooler, boiling water poured over, lid sealed. Use a thermometer the first few times to confirm it holds temperature; denser manure mixes cool faster than plain coir.

Oven or stovetop

1. Hydrate the mix to field capacity first.
2. Pack it into an oven bag or a covered pot.
3. Hold at 160–170°F for 1–2 hours. Use a probe thermometer in the center of the mass; the oven setting will be higher than the substrate temperature.
4. Let it cool, covered, to room temperature.

Hydration

Manure absorbs water differently than coir. Add water gradually and do the squeeze test as you go. Aim for the same field capacity: a few drops when squeezed hard.

Working with it

• Spawn at 1:1 to 1:2 by volume. A heavier spawn rate helps the mycelium claim the substrate before anything else can.
• Expect a slightly longer colonization than CVG.
• Many growers top manure mixes with a thin casing layer of plain hydrated coir or CVG. It keeps the surface cleaner and holds moisture for pinning.
• It smells. Keep tubs somewhere with good ventilation.

Troubleshooting

• Ammonia smell after pasteurization: the manure wasn't aged enough. Ammonia inhibits mycelium; start over with older manure.
• Green or other colored mold in the first week: pasteurization was too short or too cool. See contamination ID.
• Slow, patchy colonization: too wet, or too little spawn.