Low-Cost Local Materials
Substrate Protocol

Cut all materials to uniform sizes: banana leaves to 5cm, maize stalks/rice straw to 2–3cm, legume pods to 3–4cm. Uniform size ensures even hydration, pasteurisation, and colonisation.

• Remove thick midribs (>1cm) from banana leaves — they colonise slowly
• Discard mouldy, insect-damaged, or chemically treated material
• Store cut material in clean, dry containers if not processing immediately

Submerge cut materials in clean water with 1.5% lime (calcium hydroxide) to raise pH to 8.0–8.5, suppressing tropical contaminants.

• Timing varies by region: See climate section above (8–20 hours depending on zone)
• Agitate/stir at least twice during soaking to ensure dense stalk pieces fully hydrate
• Use potable or filtered water; avoid stagnant pond water

Remove materials from soak and drain in perforated containers or mesh bags. Duration varies by climate zone (see Section 2).

• Spread on clean tarp and fluff/turn 3–4 times to break up moisture pockets
• Perform hand-squeeze test in 5 different zones (edges, centre, top, bottom, mixed)
• Target: substrate forms a cohesive ball that releases exactly 1 drop when squeezed firmly

Combine all three materials on a clean tarp in the correct ratios. Mix thoroughly by hand or with clean tools for at least 5 minutes.

• Weigh materials individually before mixing for accurate ratios
• Wear clean gloves; minimise airborne exposure during mixing
• Bag immediately after mixing to reduce contamination risk

Fill 35cm × 25cm polypropylene bags with ~5kg of mixed substrate. Pack firmly but not tightly — allow space for steam penetration during pasteurisation.

• Tie bags with breathable closure: micropore tape or cotton-plugged neck (NEVER airtight seals)
• Label each bag with batch ID, date, and substrate source for traceability
• Stack bags loosely on clean pallets; do not compress

Use steam pasteurisation in a clean 200L steel drum with false bottom. Capacity: 15–20 bags (75–100kg substrate) per batch.

┌─────────────────┐
│ Loose lid /     │ ← Steam vents freely (DO NOT SEAL)
│ vented cover    │
├─────────────────┤
│                 │
│ SUBSTRATE BAGS  │ ← 15–20 bags, stacked loosely
│ (15–20)         │   Leave 2–3cm gaps for steam flow
│                 │
├─────────────────┤
│ FALSE BOTTOM    │ ← Perforated metal, 8–10cm above base
│ (wire mesh /    │
│ drilled plate)  │
├─────────────────┤
│ WATER (15–25L)  │ ← Must NOT touch substrate bags
│                 │
├─────────────────┤
│ HEAT SOURCE     │ ← Wood/charcoal/gas under drum
└─────────────────┘

Pasteurisation Steps:

• Add water: 15–25L clean water to drum base (below false bottom). Humid regions: 20–25L; Dry regions: 15–18L.
• Pre-heat: Bring water to gentle simmer (80°C+) before loading bags (20–40 min).
• Load bags: Place bags loosely on false bottom in 2–3 layers max. Insert thermometer probe to monitor core temperature.
• Cover & heat: Place loose/vented lid. Adjust heat to maintain 80°C ±5°C at substrate core.
• Hold: Maintain 75–85°C for 90 minutes (extend to 100 min in high humidity/rainy season).
• Cool: Extinguish heat; keep covered; cool naturally to 24–28°C (3–5 hours). Do NOT uncover during cooling.

After pasteurisation, allow substrate to cool to 24–28°C under covered, low-airflow conditions.

• Cool in shaded, ventilated area (not open air) to minimise airborne spore exposure
• Verify temperature with probe before handling — substrate >30°C risks killing spawn
• Wipe drum interior with 70% ethanol between batches
• Humid regions: Add tray of lime or silica gel near (not in) drum during cooling in rainy season

In a dedicated sterile area, inoculate cooled substrate with high-quality rice grain spawn.

• Spawn rate: 275–300g per 5kg blend (increased to outcompete contaminants in warm conditions)
• Distribute spawn evenly: add thin layer after every 8–10cm of substrate
• Seal bags with breathable micropore tape; label with batch details
• Inoculate early morning (5–8 AM) when ambient spore load is lowest