Substrate Supplement PRO — 1 L Jar

Substrate Supplement PRO — nitrogen and mineral supplement for sterilized wood substrates

Powdered supplement for fruiting substrates based on hardwood sawdust, hardwood fuel pellets and wood chips intended for sterilization. It corrects the two structural limits of plain sawdust: a very high carbon-to-nitrogen ratio (too little nitrogen for a heavy fruiting block) and the absence of minerals and pH buffer. Formulated for wood-loving species: Hericium erinaceus (lion’s mane), Pleurotus ostreatus (oyster), Pleurotus eryngii (king oyster), Lentinula edodes (shiitake) and other lignicolous gourmet mushrooms. 1 L jar, handmade in Italy in small batches.

Composition

• Wheat bran
• Rice bran
• Soy hulls
• Calcium sulfate dihydrate (gypsum, CaSO4·2H2O)
• Calcium carbonate (CaCO3)
• Kelp, Ascophyllum nodosum (brown seaweed), dried and milled

No synthetic fertilizers, no fungicides, no fillers.

What each ingredient does

Wheat bran. The primary nitrogen source. Rich in protein (organic nitrogen), residual starch, hemicellulose fibre, phosphorus and B-group vitamins. It is the reference supplement in sawdust cultivation because mycelium degrades it quickly and converts it to biomass during the first weeks of colonization: this is what drives the weight of the first flush.

Rice bran. Complementary profile to wheat bran: higher in lipids, which the mycelium uses as a high-density energy source, and with a protein fraction that releases more gradually. Combining the two brans spreads nitrogen availability across the whole colonization instead of concentrating it in the first days.

Soy hulls. Structural fibre (cellulose, hemicellulose, pectins) with a significant protein fraction. They are the basis of the Master’s Mix (sawdust and soy hulls 50/50) and work on two fronts here: slow-release nitrogen and porosity. Hull particles keep the block aerated and raise water retention without compacting.

Gypsum (calcium sulfate). Controls the physical structure of wood substrates: it stops fine sawdust from packing into an anaerobic mass, keeps the channels for gas exchange open and improves water distribution through the block. Supplies calcium and sulfur.

Calcium carbonate. pH buffer. Fermenting brans and the metabolism of the mycelium both acidify the substrate; calcium carbonate brings it back toward neutral and holds it stable for the whole run, from colonization to fruiting.

Kelp (Ascophyllum nodosum). Brown seaweed. Brings a broad spectrum of trace elements (iodine, potassium, magnesium, iron, zinc, manganese), alginates, mannitol, betaines and natural plant growth regulators. It covers the micronutrients a substrate made only of wood and bran does not contain.

Protocol

1. Weigh the dry substrate (hardwood sawdust or hardwood pellets).
2. Dose: 10–20% by weight of the dry substrate. Use 10% for aggressive, fast species such as Pleurotus and for lower-risk runs; 15–20% for Hericium, Lentinula and whenever you are pushing first-flush yield. Higher rates mean more yield and a more selective substrate, so full sterilization becomes mandatory.
3. Mix dry until homogeneous, before adding any water. Dry mixing gives an even distribution that wet mixing does not reach.
4. Hydrate to 60–65% moisture (field capacity: a handful squeezed hard releases only a few drops).
5. Fill autoclavable filter bags and sterilize at 15 psi (121 °C) for 2.5 hours. The nutrient load of the supplement requires full sterilization: it is not suitable for pasteurized substrates such as straw or straw pellets treated at 65–80 °C.
6. Cool completely, then inoculate with grain spawn.

Yield

One 1 L jar is enough for about 2 to 5 blocks, depending on the rate you choose and the size of the block. Handmade in Italy in small batches.

Storage and warnings

Keep the jar tightly closed, cool and dry. For mycological use only. Not for human or animal consumption. Keep out of reach of children.