Metal drums are constructed from sheet metal and were originally designed as oil drums; some used for grain storage may be thoroughly cleaned, second-hand oil drums. The drums are gas-tight (hermetic) so that some weeks after being filled with grain and tightly closed, a modified atmosphere is created that will kill insect pests. They range in capacity from 90kg to 180kg and are typically kept inside house on pallets to avoid moisture from the floor corroding the metal.
When store filled with grain and closed, a modified atmosphere is created that will kill insect pests.
Capacity: 90kg - 180kg
Lifespan: 15 year - 20 year
Initial cost: US$ 292 - 333
Cost per tonne per year: US$ 17 - 19
Mostly maize but are suitable for any dried cereal grains or pulses
Usually purchased from a developing country source, typically China or Vietnam. However, local manufacture is not difficult as the technology is 19th century and simple. Importation of sheet metal is much more efficient than the import of drums which occupy a large volume in stowage. Local manufacture would be the way to go for large drum distribution programmes.
Can certainly last for 20 years, their durability is one of the attractions. Durability is improved by placing drums on a stand of wood or brick so that the base is not in contact with moist ground. Not likely to be much variation in lifespan as they are very robust.
Marketing and promotions:
Metal drums have been promoted in East Timor since 2010 by ‘Drums on Farms’ and CARE, plus other NGOs such as: Mercy Corps, CRS, World Vision, Hivos, Trocare, Oxfam. Concern and Child Fund switched from supplying metal silos to metal drums.
Success and nature of marketing:
Campaigns in East Timor were successful but couldn’t provide enough drums. Drums on Farms used direct extension advice to poor highland farmers growing new higher yielding maize varieties.
Training as part of the campaign:
Metal drums for storage use was demonstrated in villages, building on the successful introduction by the Indonesians some years before. No instruction leaflet or stickers on the drum summarising how to use it were supplied, but the drums were numbered.
Degree of adoption:
There has also been adoption of metal drums in Senegal for cowpeas (CRSP project, Purdue), and they are used for maize storage around Arusha area of Tanzania. In East Timor, 379 (1 drum/HH) were purchased by farmers during the 'Drums on Farms' project; and 3,000 (2 drums/ HH) during the CARE project. More were distributed by other NGOs but no numbers available.
Reason for adoption:
- Robustness and resistance to fire (common problem in East Timor)
- Excellent hermetic qualities,
- Relatively cheap,
- Relatively difficult to remove grain from store so much easier to control food consumption and ‘unwanted removals’.
Gender study found no complaints from women about the use of drums, just real enthusiasm that they work so well. This mirrors the very positive experiences with drum storage for cowpea in Senegal under the CRSP project (Purdue University).
Weaknesses of this store:
As with all hermetic stores:
- they must be closed for a period before grain can be removed, so grain that is to be stored for less than 6 weeks it must be left out,
- the store must be more or less full so that the volume of oxygen is low at the start (consequently farmers should receive a drum size appropriate to their needs), and
- the grain should be below 14% mc (but that applies to most (all) store types).
Drums have to be well cleaned out if has been used previously for oil or other chemicals (usually done with a sand detergent mix). In some situations it may be better to use new drums and have these prepared as custom grain stores. With ‘Drums on Farms’ aviation fuel drums were cleaned out with six cycles of water and detergent, under project supervision, and checked to be odour-free before distribution. In the case of CARE, drums from the Pertamina oil company were cleaned as part of a contract with the supplier and also checked to be odour-free before distribution. Farmers interviewed about drums were well aware of the need for them to be clean and one farmer who had adopted drum storage on her own behalf had cleaned them herself using water, detergent and sand. In view of the fact that people are in any case exposed to high levels of fuel residues by inhalation of road transport fumes, it was concluded that the use of well cleaned drums previously used for petrol or diesel presented little or no risk of contamination, this is backed up by long experience of the use of such drums (25+ years), where no concerns appear to have been voiced and apparently no problems reported.
Barriers to adoption:
Largely the perceptions of development agencies. They don’t like the idea of old oil drums, they don’t like the relative difficulty of grain removal (despite this being expressed as a plus point by users). Going well in East Timor but needs champions elsewhere.
Good promotional material that includes the evidence of satisfied users
Use by institutions:
Their capacity and relative difficulty of unloading make them less suitable for larger scale operation.
What to like:
Low cost, hermetic, robust, and very popular with its users.
What to dislike:
Nothing to dislike. However, it may not suit all circumstances.