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in them are dried by means of a fire which is kept burning in the corridor. In some regions, these granaries are covered with a straw roof or built completely of mud.
Some are more or less round with the tip pointing downwards and resting on stones. These mud granaries are common in Nigeria, Chad, Mali, Mauritania and Niger and are a cheap means of storage well suited to the dry climate ofthese countries. While some are quite small, others have a capacity of up to 5 tons. Because they can be hermetically sealed, insects are unable to
penetrate and find it difficult to develop once inside because of reduced oxygen.
The complete lack of ventilation means moisture content of the grain must not exceed 10% and the humidity must be less than 70%. These granaries are not resistant to persistent or heavy rainfall and care must be taken to seal up promptly the cracks which easily form with this type of material.
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iii.Orientation of the Crib:The long side of your crib should face the direction of the prevailing wind. This enables the wind to blow through the mass of maize cobs more easily and allows efficient drying. Most rapid drying can be achieved in the 90 cm. wide crib and to enable
free passage of air, the crib should never exceed
150 cm in width.
iv.Construction of the Crib:The crib is constructed in two basic parts (a) The platform carrying the weight of the maize cobs and (b) The frame-work which supports the sides and roof of the Procedure
(i) Select the location, size and orientation of your crib and mark out the basic dimensions on the ground.
(ii) Poles to support the platform for the maize should be let into the ground to a depth of 3Cf- 40 cm. at points corresponding to the corners of the crib and at reasonable intervals along the length and middle of each end of the crib. The overall length of these poles should be 160 - 170 cm. so that, when let into the ground, they are able to support the platform at a height of not less than 120 cm. from the ground.
The number of these poles you require, will depend on the size and shape of your crib. Bamboo is recommended, where available.
(iii) Horizontal poles are fixed by nails or ropes to the top of platform supporting poles, first lengthwise along the outer edges of your platform and then across the width.
You will now have a rigid platform to support your maize.
(iv) Two long poles of about 400 cm. length are let into the ground at the midpoint of each end of your crib. These will support your ridge pole. Depending on the length of the crib, additional centrally located ridge-supporting poles may be required.
(v) A series of vertical poles - 300 cm. long should then be erected corresponding to, and
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close to the poles supporting your platform frame. These poles will support the side of the maize compartment and, together with the ridge pole, the roof of the crib.
(vi) To stabilize the structure, a horizontal pole is lashed or nailed at each end of the crib to the top of the corner poles and to the ridge supporting poles, the ridge pole is fixed in position and further poles to support the outer edge of the roof are fixed horizontally along the outer top edges of the crib. You should now have a rigid upper framework for your crib.
(vii) A light framework of palm-leaf midrib or split bamboo can now be fixed from the ridge poles to the upper horizontal poles at the side of the crib and by weaving in further material in a lattice base for your crib roof is constructed.
(viii) The roof is made of grass (preferably - ekong grass), or raffia leaves which is knitted or woven in the traditional way and then fixed to the roof framework of the crib.
(ix) A retaining wall for your maize must now be constructed. This consists of horizontal poles nailed or lashed to the roof supporting poles up to the level to which the maize cobs are to be stored. You should, of course, leave a gap at one end of the crib for loading and access.
(x) From the inside of the crib – 2cm mesh chicken wire netting should be used to cover the walls and floor of the crib. This should be firmly fixed to the main framework of the crib. Alternatively, a palm midrib or split bamboo lattice may be used. This must be firmly secured to the main frame of the crib and made strong enough to support the weight of the maize cobs especially across the crib floor
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(xi) If you have used bamboo for the vertical poles of your crib framework, you may not get a problem with rats attacking your maize, provided your platform is at least 120 cm. above ground level as rats are not easily able to climb the bamboo poles. Where you have used other poles for your crib frame, you must make rodent guards for all the ‗legs‘ of your crib to prevent rats from getting to your maize.
Rodent guards are made from iron or aluminium sheet which is cut to shape so that when wrapped around the leg of the crib, a complete cone is formed. These rodent guards should be fixed at a height offrom the ground with the open end of the cone facing down-wards. When in position, the outer edges of the cone should be about 12 cm. from the leg of the crib and no space should be left at the top end through which a rat may pass.
A further precaution is to keep the area around your crib clear. Rats can climb up plants growing close to, or farm implements etcetera, carelessly left leaning against your crib, and from there gain entry into your crib.
(xii) Variations in Materials: The description given above is for the basic structure of a crib which can be made entirely from local materials (except for the rat guards). It is possible to construct cribs of a more permanent kind using other materials, i.e.
by using treated timbers for the framework and galvanized iron sheeting for the roof. Another type can be made entirely of iron.
3.1.2 Methods of Storage and Insect Control
1. After harvesting, the husk is removed from the maize ear leaving the cobs which will be at about 25% moisture content at this time.
2. The cobs are carried to the site of your crib in baskets or in bags and loaded into the crib for storage.
3. As each bag is emptied and spread in the crib, one of the insect control measures, described below is applied to the maize from that bag. In this way, you will get an even distribution of your insecticide
4. The application of Insecticide Dusts:
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(a) The application of Pirimiphos Methyl 2% dust for the protection of maize in cribs at a dosage rate of 10 ppm should be effective for 4 months. This dust is available from Chemical and Allied Products Nigeria (Ltd.) formerly ICI (Nigeria) Ltd. The procedure of application is detailed below. The quantity to be used per bag of maize would quarter fill a cigarette tin. Where scales or balances are available, the quantity required is 45 gmsper bag of maize.
(i) Obtain a cigarette tin or any other tin of the same size.
vii. Perforate its closed end with a number of small holes.
viii. Fill the tin up to ¾ full with (45 gm) of Pirimiphos Methyl dust and replace the lid.
ix. Apply the contents of this tin evenly over the contents of one bag (produce bag) of maize after loading into the crib.
x. Repeat this procedure for each bag of maize loaded into the crib.
xi. Treat all the maize loaded into the crib bag by bag until the crib is full.
xii. The maize should now be protected against heavy insect attack for about four months.
xiii. If further storage after four months is desired, further dust may be applied to the top and sides of the maize in the crib.
xiv. Maize treated with insecticide should not be used for eating for about two months after application. After two months, it is considered that the treated maize is safe for consumption after normal processing.
(c) Pirimiphos methyl is also available as 2% emulsifiable concentrate called Actellicwhich is mixed with about 3 times its volume of water and used to spray the maize cobs evenly as they are loaded into the crib. This also protects the maize for 4 - 5 months. At intervals of about 3 months, the surface and outer cobs can be re-sprayed with liquid Actellic.
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