18 February 2000

CAgrain storage can be rival to fumigation

CONTROLLED atmosphere grain storage could provide a viable alternative to phosphine fumigation and offer organic farmers a safe solution to decontaminating infested grain.

"Research for the system has been going on since the late 1980s, the technology for the system is right there waiting to be produced commercially and could provide a very viable alternative to existing fumigation techniques," says Christopher Bell, senior research consultant at Central Science Laboratory.

Sealing bulk

The modified atmosphere is produced by sealing the bulk and feeding exhaust gas from a propane burner into the bulk, bringing oxygen down to a level sufficient to extinguish insect life.

The amount of gas produced is automatically metered to ensure the bulk atmosphere remains constant.

The system can be used in either a bin or flat store and trial work suggests running costs can be as low as 50p/t, says Dr Bell.

"With a bin you have a nice in-built structure, you simply need to seal the bulk by laying a plastic sheet across the surface and shrink wrap any auger to prevent gas leakage. Gas then enters the bin through the ventilation system at the base."

"A flat store may require additional sealing along the walls and ventilation ducts prior to grain intake. Extra care should also be taken tucking in the edges of the surface sheet." Gas is then fed through one or more of the ventilation ducts.

Trial work shows that burner running costs for a 1000t silo for a four week period would be 50p/t. Burners are not currently available commercially, although Dr Bell believes the initial cost of manufacture would be about £20,000.

"As the future of some fumigants begins to look bleak, this system could provide a viable alternative with no residual affect," confirms CSL storage expert Ken Wildey.