What Is the External Nutrition Bag Method for Growing Morel Mushrooms?
The External Nutrition Bag (ENB) method is a morel cultivation technique developed in Sichuan, China, in 2000 in which a sealed, sterilized bag of nutrients is placed in the soil bed beside the morel mycelium, giving the fungus a concentrated food source it can colonise just before fruiting. Rather than depending on background soil fertility, the grower delivers nutrition in a measured dose at a chosen moment. The method is now standard in commercial Morchella farming and is taught alongside the machinery that Sichuan Morel Research Institute exports to more than 25 countries.
Morels are not like oyster or shiitake mushrooms. Morchella is a soil-dwelling fungus with a narrow fruiting window: the mycelium must first build reserves in the bed, then switch to fruiting when temperature and moisture move into range. An external bag lets the grower decide how much nutrition is available and when it becomes available, instead of guessing what the field already holds. That single change is why the technique spread from Sichuan across commercial morel regions.
In practice, an ENB cycle follows a short, repeatable sequence:
• Mix the substrate to a steady 60–65% moisture — uneven moisture is the most common reason bags fail. • Fill and seal bags at 300 g–1,000 g each. Very small bags dry out quickly in the field; very large ones colonise slowly and waste material. • Sterilise the filled bags thoroughly before they leave the clean area — unsterilised bags carry contamination straight into the bed. • Place bags in the prepared beds at the spacing and depth suited to your soil, then inoculate with morel spawn. • Hold the bed under shade netting and monitor temperature, humidity and CO2 through the spawn-run and fruiting phases.
The bagging step is where labour costs explode at scale. The ENB Automatic Nutrient Bagging Machine (4th generation) produces 30–50 bags per minute, or 1,800–3,000 bags per hour, with fill weights from 300 g to 1,000 g, running on 220V/50Hz at 1.5 kW and weighing about 380 kg. It typically replaces the work of 15–25 people on the bagging line, which is usually the difference between a 2-hectare farm and a 20-hectare one.
Two machines feed that line. The Industrial Substrate Mixer handles 4–12 m³ per batch (800–3,000 kg) in a 5–8 minute cycle and is the simplest way to hold moisture at 60–65% across a whole day's production. The High-Pressure Sterilization Autoclave then treats the filled bags at 105, 115 or 121 °C, with chambers up to 76 m³ and forklift drive-in loading, in 304 or 316 stainless steel where required.
Downstream, the numbers are equally concrete. One morel spawn tube inoculates 667 m², or one mu — a useful unit for planning how much spawn a field needs before ordering. Outdoor beds are then covered with UV-stabilised shade netting at 75%, 85% or 90% density (HDPE with 3% UV, 5–8 years of service life), which buffers the bed against the temperature spikes that abort fruiting bodies.
Most failed ENB cycles come down to a handful of avoidable errors: bags filled too wet, sterilisation cut short to save time, bags placed too deep or left in contact with standing water, and inoculation done when bed temperature is drifting rather than stable. Each is a process discipline problem rather than a biology problem, which is why growers who standardise mixing, filling, sterilising and placement see far more consistent results.
For growers moving from trial beds to commercial area, the institute behind the method — founded in 2010, with demonstration and manufacturing bases in Anxian (~300 acres) and Luojiang (~1,200 acres), 50+ hectares of outdoor demo fields and a 12,000 m² equipment workshop — offers turnkey farm design for 1 to 50+ hectares and an English-language Online Morel Cultivation Masterclass (Class A $5,000, Class B $10,000). Details are at www.cn-localfoods.com, or contact [email protected] / +86 17738334931 to discuss a specific site.