Two platforms have been used for hermetic storage since 1987. Each consists of a reinforced concrete floor with a 1 m high peripheral retaining wall. Grain is loaded either directly on the concrete floor or onto a polyethylene underliner 0.25 mm thick. A UV-protected PVC liner 0.8 mm thick is used to cover the grain. Where the floor is covered by a polyethylene liner, the overliner and underliner are brought together over the walls, folded over at the outer base of the walls, and weighted with sandbags, thus forming a hermetic seal.
The first platform is 75 m by 25 m and has a capacity of about 4,000 t of barley. The second platform is 50 m by 25 m and has a capacity of about 2,500 t of barley. The height of grain at the peak is 6.5 m.
Both platforms are used for storing local barley with a maximum m.c. of 11%. Normally, incoming grain is already infested by insects when it arrives at the platforms. However, no chemicals are used during loading or during storage of the grain on the platforms.
Grain has been stored on these platforms for 8-10 months, and in some cases 2 or 3 years. During storage grain samples have been taken from different depths and locations to monitor moisture content (m.c.), insect infestation, germination and mycotoxin deterioration. Grain temperature and intergranular oxygen (O2) and carbon dioxide (CO2) concentrations have also been measured. In addition, both mould losses and total loss have been evaluated.
Estimates were also made, for comparison, of losses caused in 1992 and 1995 by heavy rain during storage of grain in the open.
Finally the cost of on-platform storage per ton for 1, 2 and 3 years was calculated.
