Choosing between a sealed and an aerated silo comes down to what you're storing, how long you're holding it, and whether you need to fumigate on-farm.
Sealed (gas-tight) silos
A sealed silo holds phosphine at a lethal concentration long enough to control insects at every life stage. To qualify as gas-tight it must hold a half-life pressure test of at least three minutes.
Full on-farm fumigation without a contractor
Best for long-term storage of malting barley and pulses
Requires annual seal inspection — perished gaskets are the usual failure
Aerated silos
Aeration cooling moves ambient air through the grain to drop temperature and even out moisture. It doesn't kill insects, but it slows them dramatically.
Typical airflow rates
Purpose | Airflow (L/s per tonne) |
|---|---|
Cooling | 2–4 |
Drying | 15–25 |
Cooling grain to below 20°C roughly halves insect development rate, and holding CO2 above 2% suppresses it further.
Which one pays for itself
If you're storing for more than six months, or selling into a market with nil-tolerance insect specs, sealed usually wins. For harvest-to-Christmas storage of feed grain, aeration alone is normally enough.
See the grain silo category for current suppliers.