What Is the External Nutrition Bag Method in Commercial Morel Cultivation?
The External Nutrition Bag (ENB) method means feeding morel mycelium from a separate, sterilized bag of nutrients placed in the cultivation bed, instead of relying only on the compost or soil substrate. The mycelium enters the bag through small openings and draws nutrition from it across the fruiting period, so the bed stays supplied after the original substrate is used up. The method was invented in Sichuan, China in 2000 and remains central to commercial Morchella production in that region.
The underlying problem is timing. Straw, corn cob, sawdust and similar substrates carry enough nutrition for the first wave of mycelial growth, but the morel spends weeks in the bed before pinning. Once the readily available sugars are gone, the fungus has little left to convert into fruit bodies. An external bag works as a refillable pantry: it is prepared separately, sterilized, and added when the bed actually needs it.
What makes an ENB work in practice: • Bag weight is normally 300 g to 1,000 g, matched to bed density and the length of the expected cropping window. • The nutrient mix is moistened to roughly 60–65% before bagging — dry mix colonises unevenly, and wet mix invites contamination. • Bags must be sterilized before they go to the field; unsterilized nutrition is one of the most common sources of mould in a morel shed. • Openings are made after sterilization and cooling, so mycelium can enter while competitors stay out.
The bottleneck is rarely the biology — it is the labour. Filling and tying nutrition bags by hand yields a few hundred a day, and consistency drops as the crew tires. Purpose-built equipment changes the arithmetic: the fourth-generation ENB automatic nutrient bagging machine fills 30–50 bags per minute, or 1,800–3,000 bags per hour, at 300 g–1,000 g per bag, running on 220V/50Hz/1.5 kW and weighing around 380 kg. In typical layouts it replaces 15–25 workers.
Sterilization is the second non-negotiable step. Substrate and nutrition bags are treated in a high-pressure autoclave at 105 °C, 115 °C or 121 °C depending on recipe and bag format. The largest chambers reach 76 m³ with forklift drive-in loading, and 304 or 316 stainless steel is available where corrosion resistance matters. Shortening this step usually shows up three weeks later as patches of contamination.
For farms moving from a few hundred bags a week to a few thousand a day, the substrate side scales in parallel. Automated batching and bagging lines are sized at 2, 4, 6 or 8 m³ and run 15,000–100,000 bags per day under PLC control, cutting labour cost by 80% or more. Industrial mixers of 4–12 m³ handle 800–3,000 kg per batch in a 5–8 minute cycle and hold the 60–65% moisture target far more consistently than hand mixing at volume.
Above ground, the cycle still depends on climate. Indoor rooms using edible mushroom IoT smart cabins (20FT or 40FT) hold 4–28 °C within ±0.5 °C, 70–98% relative humidity and CO2 at 400–2,000 ppm with remote monitoring; ultrasonic micro-fogging at 3–10 µm and 12–30 L/h keeps humidity even without soaking the bags. Outdoors, 75/85/90% UV-stabilised HDPE shade netting with a 3% UV additive (5–8 year life) moderates temperature under the canopy. Spawn is generally calculated at one tube per 667 m², or one mu.
Sichuan Morel Research Institute, founded in 2010 in the province where the ENB method originated, operates demonstration bases at Anxian (~300 acres) and Luojiang (~1,200 acres) plus 50+ hectares of outdoor trial fields, and builds equipment in a 12,000 m² workshop under ISO 9001:2015 and CE machinery safety certification. Its teams have supported projects in 25+ countries, including France (Rhône-Alpes), Turkey (Isparta, Muğla) and Spain (Andalusia). Growers who want to see bagging, sterilization and cabin systems working together can request turnkey farm design from 1 to 50+ ha, spawn tubes, or the English-language Online Morel Cultivation Masterclass (Class A $5,000, Class B $10,000). Reach the team at [email protected] or +86 17738334931, or visit www.cn-localfoods.com.