France: Storage Advisers Set 100 m³/h Ventilation Benchmark for Heat-Stressed Crop
Key takeaways
- 100 m³/h of air per m³ of bulk potatoes during drying
- 60 m³/h per m³ of potatoes is the benchmark for box stores
- 12 to 15°C and about 90% humidity for wound healing
- 25 cm is the maximum recommended drop height at harvest
Why it matters
- For farmers
- Check ventilation capacity against the 100 m³/h per m³ benchmark before filling stores; limit drop heights to 25 cm at harvest.
- For processors
- Agree temperature and sprout-control plans with storing growers now to protect fry colour and sugar levels.
- For suppliers
- Offer store audits, refrigeration upgrades and sprout-control service to growers with heat-stressed crops.
60-second summary
A heat-stressed French crop is now moving into stores, and advisers warn that losses there could add to an already poor season. The core advice is to dry tubers fast, then let wounds heal before cooling. Arvalis suggests ventilation of 100 cubic metres of air per hour for each cubic metre of bulk potatoes, or 60 for box storage, where building costs run 20 to 25 percent higher. Healing works best at 12 to 15 degrees with humidity near 90 percent, and drop heights at lifting should stay under 25 centimetres. Store managers supplying crisp and fry plants need the tightest temperature control, as sugars react quickly to swings. Several sprout inhibitors remain available, from ethylene to plant oils, but stores must be sealed and managed well around treatment. The figures are general recommendations from French advisers; each store and variety may need its own settings.
Storing the 2026 French potato crop will need extra care, advisers say. The crop grew under drought and repeated heatwaves. Stressed tubers can lose quality quickly in store.
Florine Delassus is a potato specialist at the Nord-Pas-de-Calais Chamber of Agriculture. She told the farm weekly Le Betteravier français that storage quality starts at planting.
Key steps include choosing varieties suited to long storage, careful haulm destruction and precise harvester settings. Drop heights during harvest should not exceed 25 cm. This limits bruising and wounds.
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Drying comes first
When potatoes enter the store, they must dry quickly. Free water on tubers helps diseases spread.
The French research institute Arvalis recommends high ventilation capacity for this stage. The benchmark is 100 m³ of air per hour for each m³ of potatoes in bulk stores. For box storage, it is 60 m³ per hour per m³.
Box stores need less costly ventilation equipment. However, the initial investment is 20% to 25% higher than for bulk stores. Extra corridor space is needed for air extraction.
Wound healing
After drying comes wound healing. Recommended conditions are 12°C to 15°C and about 90% relative humidity. This helps harvest injuries to heal. It also reduces the risk of burns from later sprout-control treatments.
Cooling and precision
Jean-Marc Vigué, founder of the store equipment firm Klim’Top, said climate warming is changing store design. Refrigeration is increasingly replacing cooling with outside air.
Potatoes for crisps and fries need more precise temperature control than fresh-market potatoes. Stable temperatures help protect fry and crisp colour.
Sprout control options
French growers can use several sprout-control products in store: ethylene, orange oil (Argos), Dormir and spearmint oil (BioXM). Maleic hydrazide is applied in the field before harvest.
Stores should be closed 24 hours before a treatment. They should stay closed as long as possible afterwards. Air should circulate inside to avoid condensation.
Why it matters
France has one of its smallest potato crops in decades. Every tonne lost in store adds to the shortfall. Good drying, wound healing and temperature control protect both volume and processing quality, and help growers meet contract specifications through the season.
Photo: A wooden potato storage box (illustrative). Dietmar Rabich / Wikimedia Commons, CC BY-SA 4.0
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Sources
- Le Betteravier français — Le stockage des pommes de terre, vigilance à toutes les étapes — https://www.lebetteravier.fr/2026/09/23/le-stockage-des-pommes-de-terre-vigilance-a-toutes-les-etapes/
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