What Is the External Nutrition Bag Method in Commercial Morel Farming?
The External Nutrition Bag (ENB) method is a commercial morel technique in which a separately sterilised bag of nutrient substrate is placed into the soil beside the Morchella bed, so the mycelium draws extra food from outside its main substrate. It was developed in Sichuan in 2000 by the team behind the Sichuan Morel Research Institute, and it remains one of the clearest ways to raise yield potential without loading the whole bed with nutrients. In short: you keep the bed clean and let the fungus eat from a bag.
The logic is about timing. A morel bed has to be fully colonised by clean mycelium before it can fruit, and nutrients mixed directly into the bed too early tend to feed competitor organisms instead of the morel. By holding the extra nutrition in a separate, sterilised bag, growers let the mycelium establish first and then reach the additional food when it actually needs the energy for fruiting. The bag becomes a controllable, replaceable nutrition source rather than a permanent risk in the substrate.
Bag weight matters more than most beginners expect. Commercial ENB bags are typically filled between 300 g and 1,000 g, and the substrate inside is mixed at 60–65% moisture — the same window used for the main bed. Everything is sterilised before it goes into the field, because a contaminated bag is worse than no bag at all.
• Sterilise the bags, then let them cool completely before handling — warm bags handled roughly are an invitation to contamination.
• Place each bag at the depth your own trial shows works, usually just under the surface layer, spaced along the bed so the mycelium reaches it from both sides.
• Keep surrounding soil moist but never waterlogged, and leave the bag intact so it releases nutrition gradually instead of all at once.
• Check bags weekly. A bag that has gone light and hollow has been consumed — that is your signal the mycelium is feeding normally.
The step that limits most farms is bag production. The ENB Automatic Nutrient Bagging Machine, now in its 4th generation, fills 30–50 bags per minute, or 1,800–3,000 bags per hour, at 300 g–1,000 g per bag on 220V/50Hz and 1.5 kW, weighing roughly 380 kg. In practice it replaces 15–25 workers on this single task, which is usually what makes ENB viable above a few hectares rather than only on small plots.
Sanitation is the other half of the equation, since ENB bags are only as clean as the sterilisation step behind them. High-pressure autoclaves running at 105 °C, 115 °C or 121 °C are available up to 76 m³ with forklift drive-in loading and a 304 or 316 stainless option. Farms then scale the biology alongside the machinery: one morel spawn tube inoculates 667 m² (one mu), and larger operations pair outdoor beds with IoT smart cabins held at 4–28 °C (±0.5), 70–98% RH and 400–2,000 ppm CO2 for controlled fruiting.
The most common ENB mistakes are oversized bags, careless handling after sterilisation, and forgetting that moisture in the bag and moisture in the bed have to match. Get those three right and the method does what it was designed to do twenty-five years ago in Sichuan: separate nutrition from risk. The Sichuan Morel Research Institute (www.cn-localfoods.com) builds this equipment in Anxian and Luojiang, holds ISO 9001:2015 and CE certification, and has supplied ENB machines and training to projects in 25+ countries, including France, Turkey and Spain. For spec sheets or a farm-scale layout, contact [email protected] or +86 17738334931.