|Bumper Crop Storage (Supplement:) (NRI)|
Grain storage capacity in a country is planned, or develops, according to requirements in a year of average harvests (Mitchell, 1988; Baker, 1988; FAO, 1983). Many tropical and semi-tropical countries have great variations in yearly or biannual harvests of cereals (FAO, 1986a). When the harvest is seriously deficient there may be a need for emergency storage for relief food as discussed in ODNRI Bulletin No. 10. A harvest significantly greater than average, described in this bulletin as a bumper crop, will also present difficulties if the quantity of grain is more than can be accommodated by the existing transport and storage system. Severe losses are often associated with bumper harvests (Friendship, 1988; FAO 1986a) because without adequate storage facilities in warm/humid conditions deterioration and/or pest attack are unavoidable. The cereal excess over available storage capacity requires protection through provision of rapidly erected, low capital cost, easily manageable facilities. Such facilities may also be appropriate in the early stages of a rising trend in cereal production while the long-term storage requirements are not clearly defined. Typically, a bumper cereal harvest is associated with lower-thanaverage cereal prices immediately post harvest. From the nutritional and economic standpoint therefore it is important to prevent cereal losses by providing safe storage until such time as prices rise or alternative uses for the bumper crop can be found. For example the crop might be exported to a country which has a deficit.
In some circumstances it may be possible to provide the additional storage capacity by utilizing as grain stores buildings constructed for other purposes. More often, some new facility will be required. While this may be regarded as temporary, it may be required to store the bumper crop for an extended period, until markets are found or alternative storage is constructed. The temporary facility must therefore permit all measures necessary to control grain quality and minimize losses. Storage systems suitable for bumper crops can consequently become cost-effective components of the regular storage system in some countries. In others, bumper storage may be truly temporary, occurring once every eight or nine years. This supplement to ODNRI Bulletin No. 10 aims to provide a framework for deciding between available proven methods of bumper crop storage. These include a traditional system for bulk paddy used in Burma, cover and plinth (CAP) bag storage used in India, flexible silos used in Africa, pit storage as used in Sudan and Argentina, and its close relative bunker storage used in Australia, Israel, Turkey, the United States and recently tested in Zimbabwe.
The requirements for bumper crop storage differ from those for relief food storage in a number of respects. The bumper crop does not materialize unexpectedly; there are usually two or three months' warning that harvests will be above average (FAO, 1986b). The grain flow is in the normal direction so bumper store location will be near to permanent stores. It is less likely that donor funds will be available for store construction, placing greater emphasis on available local resources. Only one crop need be considered (for seasonal storage or longer) rather than a mix of food commodities distributed in an emergency. Single structures with high capacity are therefore acceptable.