N S K TECHNICAL , TRANSACTI(I>N;S ATechnical Publication of The Nigerian Society 0 4 Engineers IN THIS ISSUE 1. The Effects of Motor Starting in a Steel Processing Plant, - E. E. llochi, E. 0.O koye & E. V. Madujke 2. Development of an Oil Palm Fruit Digester. - 0.I ghodalo and L. Eigbodion 3. A Synthesis of Monte Carlo and Noise-In-Variable Model Techniques for Energy Demand Modelling. - A. 0.A degbul~gbeE~. I. Ibituye and 0.A . Opaleye 4. Problems and Prospects of Metal Silos for Grain Storage in Western Nigeria. , & - Yahaya Mijnya wa 5. Prediction of Minimum Spouting Velocity. - Engr. (Mrs) K B. Oyoh 6. Appropriate Solid Waste Disposal Method for Developing Countries, - Engr. ~lernen~f . '~zoigwe 1 L- 7, Parameter Estimation of Dynamic Real-Time System Via on Line Identification. - C.I . Omogbemeh, M. I, Onogu & K K. KScbnjuh 1 8. Uncoupled Lateral Buckling Ensrgy Function for Thin-Walled Beams with Double Symmetry. - F! N. Jjki UNIVERSITY OF IBADAN LIBRARY NSE TECHNICAL TRANSAMIONS Vol. 32! No. 2 6 , Yahaya Mljlny awa PROBLEMS AND PROSPECTS OF SLOS FOR GRAIN STORAGE IN YAHAYA MIJINYAWA ' Department of A ~ k ~ u EmngIin eering Facutiy of l i i n o b g y Unive~i toyf ibadan ABSTRACT the United States Department of Agriculture in 1957 as a component of the m-apsratlve grain storage pro- A survey involving the use of structured question- gramme of Western Nigeria. The first two metal silos naires and personal mmmunic8tion was carrid out in in the counfry were therefore erected at Hero in Oyo Western Nigeria to ascertain the type and extent of State in 1957 and at Ilara in Ogun State in 1 958. Plates use of silas for the storage of grains. Steel and PJu- 1 and 2. These first two silos were to be tested as minim were fwnd to be the predominant rncltedds possible starage sbvctures for grains. Following the used for the constrarction of the silos. They are mainly initial success recordad from the tests" more metal si- used 1Po store shePM corn and in a few instances, rice, los were erected at various locations in Western Ni- eowpea and soybean. The prohibiie cost of silo ac- geria for the Storage Programme while Educational quis$bn Dmits their ownership and use to the Minis- and Research Institutions also acquired some for the tries of Agriculture, Co-op&ative Societies, agro-bsed purpose of teaching and research (1 1. The use of metal industries, Teaching and Research 1nstituresa nd a few silos especially in the execuLkm of the oosperative large d e pr ivate farms. Silos are ncrt used by the storage programme was popular in the 196% but if small to medium scale farms. The withdrawal of the gradually faded out as one farmer after the other pulled Ministries of Agriculture from direct grain production out of the ~OperatRrers( 2). and the collapse of co-operatkre grajn storage pro- Metal dlos rw'wsd a boost in ths a r t y 1980s fol- grammes have resulted in the abandonment of many lowing the various agrarian programmes of the gov- sitos. The metal sibs experience the p h i e mo f mois- ernment such as the "Green Revolution of 19 79" and ture condensatian"ont he roofs and walls which leads the 'Back to Land Programme of 1985'. The result of to the deterioratton of stored grains through moulding, both programmes was a bumper harvest of grains for caking and rapid mult$lication of Insects. bsses of which the traditional storage structures especially the as much as 10% of Itatal storage through these sources crib proved inadequate in terms of storage capacity. have been tecorded for some sib. Adequate funding Silm were themfore imported M h b y th6Govemrnent, of cumnt research efforts to develop local materials Corporate bodies and private entrepreneurs. Since far grain silo censtnrcl"ion k recommended, 4hen, the importation of Metal Silos into the country has been on the increase and without a detailed sur- Keywords: Condensation, Fluctuation, Posthawest, vey which win be prohibitive in cost, It is not possible Prohibitive, Silos. to estimate the number of metal silos In Nigeria at present. With almost four decadas of use of metal siIos in The silo, a basically huge container, is used for the Nigeria, severe losses are still associated with stored storage of agricultural produce. it is more popularly Nigeria The grains resulting to as much as 30-5046 of total produc- ussd for the storage of grains in sfrudure tion (3). The efficiency of the existing metal silos in has the advantages of &go storage capacity and of long duration. Although Nigeria to reduce storage loses is therefore in doubt. Steel, Alurninirnum, Concrete, Woud, Clay and Rubber can be used for the m n m - This paper dlscusscw the results of a survey con- tion of sib, the steel and Aluminium types are more du'cted In Western Nigeria to identify the types of silos commonly used in Nigeria. in use, their limitations and potentials as grain storage In Nigeria, the metal silos were first introduced by structures. UNIVERSITY OF IBADAN LIBRARY I WSE TECHNICAL TRANSACTIONS Vol. 32. No, 2 METHODOLOGY wall material ofFers very little resistance to the flow of In arder to collea infomation relevant to this solar heat into the stored grain which give rise to tem- paper, a survey was carried out in Western Nigeria. perature gradients within the grain bulk. The ideal con- The susvey invokred the use of structured question- ditions for ttie storage of most grains for which silos naires which sought for information on the type of are commonly used are 11 -1 3.5% M?. 27% and 9OoA materials used for silo construetion; average number RH. Variation In climatic factors could raise the Mc of of silo units erected at a location and range of unit stored produce to as much as 20% while ternperat$e capacities; type, sources and utilization of grains rises up to 35-400C. Unless there is a method of ven- stored, frequency of silo use and percentage of silo tilation for the control of temperature and moisture, capacity utilization, cost of sib acquisition and instal- these changes in the ~nditiono f the stored grain will lation, problems experienced with their use and at- promote tha development of insect in the event of any tempts made at reducing such bottlenecks. Additional Infestation, rnoukl growth, development of hot spots information items were gathered through personal wm- and caking which renders the produce valueless. Sur- munication and an-the-sport assessment while adrnin- vey reports indicate varied degrees of losses due to istering the questionnaires. these sources. As much as 4% viability has been re- corded, 5% loss in food value, 4% of total stored pm- The surveyed sites were not selected but rather duce destmyerd by insects while up to 5% of total stored visits were made to places where silos were known to produce has gone mouldy. Where the facilities are be in use. These cut across the Ministries of Agricul- available, ventilation of the stored grain using heated ture: feed and flour milts, breweries, private wmmer- dry air is done at regular intervals to curtail these prob- cia! farms, Teachhg and Research Institutions, co- lems. operative societies and grain storage centres. RESULTS AND DISCUSSION (B) LOW CAPACITY UTILIZATION The results of the survey are surnrnatised in Table The first silo to be erected in 1957 had a capacity 1 and furlher discussed. Steel and Aluminium are the of 20 tonnes but at present, the capacities of silos In most txmrnan materials used for the mnstnrction of the area (except those for experiments) range from the silos identiied. Out of over 85 sites surveyed, con- 15 to 2,500 tonnea as found during the survey. This crete silos were found in four sites while moden a d high unit capacities of silos was responsible for their clay silos were each found in anly one location Shelled popularity among co-operative societies En the 1950s corn is the most common grain far W i h t he sibs were who used them for grain storage. used to store; and on very rare occasions, they could The Ministries of Agriculture also maintained some atso be used to store rice, T e aan d soybean. These farms the harvest from which were stored in some of grains are all cultivated in Western Nigeria. the silos. At present, the ministries have withdrawn from direct grain production while many of the co-op- 3.1 PROBLEMS IDENTIFIED erative societies have either folded up or changed theEr The problems that confront the use of silos as grain , objeGtives from grains storage to other crops such as storage structures In Wastsrn Nigeria are moisture Cocoa which is more lucrative. This change in the type condensation; low capacrty utilization and prohibitive of crop handled requires other types of storage struc- .cost of acquisition and maintenance. tures and has thus resulted in the abandonment of some ef the metal silos previously erected. (A) MOISTURE COMDWSAVlOM The annual production of tt;re various grains and The Climate of Western Nigeria is the warm humid legumes commonly cultivated in Nigeria is below ten type where as much as 1Q OC daily temperature range tonnes for most small scale farmers (4). With the ml- and relative humid@ of over 705% are often recorded. metal h i ~ h conductivity lapse of the cu-operative grain storage practhe, the The use d sl'Ios of thermal (12 - 16 W/M°C far steel present day Nigerian peasant farmer is only interest& and 204WMPC for Aluminium) un- in individual on-farm storage practice and for a maxi- der th t climatic cocondit~nsle ads to moisture mnden- mum perido f between one hawest end the next. The sation on the roof and walls of the stntdure and its individual farmer may not be able to produce enough redistribution within the core of the stored grains. The NIVERSITY OF IBADAN LIBRARY I NSE TECHNICAL TRANSACTIONS Vol. 32. No. 2 Yahaya Mljinyaws I - graln to fill a silo and where the structure is avaifable, Eng mechanisms, fans and heaters depend on #.cannot be effectivelyu tilized. Thb reason of inad- electricity for their source of power and in a country equate grains to sfore has rendered many s i bo wned with unreliable pub!ic power supply such as ours, pro- by the Ministries and f~titutionsu nder-utilized while vision must be made for a standby generator which is only those belonging to large scdls farms and indus- an additional mst. The bottleneck involved in the im- tries who can either produce enough or b y f rom the portation of spare parts to repai~th e silos when re- peasant farmers through mntractors to fill their silos quired has resulted in a number of silos being a m - are being fully utilized. Unless adequate arrangement doned (2). 1 for grain collection is made, the silos at the various strategic Grain Resenre Cornptexes may remain empty. 3.1 PROSPECTS SF SILOS (C) PROHIBITIVE COST OF SILO ACQUIS1TlON The prospect of metal silos for grain storage in AND MAlMTENANCE Nigeria are associated with their large storage capaci- ties and ability to preserve grains over a long period Silos and their aacessopies have aJways h e n e x- under good management. These prospects could be pensive right from when they were first infrduced in exploitedb oth by the government and industries in the Nigeria but the cost did not initially pose a problem foElowing ways:- because it had to be borne by a number of farmers forming a co-operative society. When some years af- (A) FACiLITIES FOR mRATEGlES GRAIN ter their introduction the co-operathe grain storage STORAGE- programme coIlapsed. the oost of acquisition and in- Strategic grain storage centres are locations stallation became the sole rasp~nsibilityo f the Indi- established and managed by governments where vldual farmers who were interested En using the silos. grains are stored and to be released during emergency From information gathered during the survey, between periods such as when there is crop failure, flood or fire 1! XI0 and 19 90 when a goad number of the silos were dbaster. Since these events are unpredictable, grains acquired and installed, and the Naira was still very may have to be stored for upward of fiie yeam espe- strong compared tothe Dollar and Pound Sterling, the cially if the subsequent annual harvests are not enough currencies in which payment is made; far the imported to raplace what Is in stare. Some functional and well silos, the cost of the structure and its installation var- managed metal silos were reported to have eff d e l y ied from M15,000.00 for a 50-tonne capacity silo, stored grains for wer three years in the area of study M35,000.00for a 100-tonnet o N375,000.oafor a 250- and hence the structure could be employed for strate- tonne capacity silo. With the current devaluation of gic grain storage. The silos have the advantages of the Naira, the cast of these sizes of silos have dsen to eliminating the cost of bags and bagging, and reduce between 100 and 150 times the figures quoted above. pilferage of produce by empioyees compared to ware- These costs are beyond the income of the peasant houses. farmers who are the major producers of grains and (B) SECUWTY OF INDUSTRIAL RAW under whose custody most of the post-hawest losses MATERIALS are incurred. When an amount is taken of the fact that this group offarmers usualiy have no caHatera!f ar loans It is a common occurrence for industries to work of reasonable magnitude, the peasant farmers cannot below capacity or to even close production ternporar- individually afford the cost of these silos. For this rea- [ly due to shortage of raw materials. For Afiro-allied son, the use sf metal silos Is limited to large scale industries, this is most pronounced during the planting ' agricultural establishments and industries that can af- season when previous harvests have almost been ford them. exhausted. Atthough farmers prefer individual on-farm storage to a cwoperative programme, they are always The existing metal silos were and are still being prepared to sell their produce at anytime provided the imported in pre-fabricatd forms and often unaccom- price is good. lndmtrles can buy grains at period of panied with spare parts only to be assembled on site. harvest and store to ensure the availability of raw In the event of any fauk the relevant spare part must materials all year round. A well equipped and be imported or as an alternative;t he silo is abandoned. managed silo will be very useful for such storage Mast of the accessodes such as loading and unload- requirement. UNIVERSITY OF IBADAN LIBRARY I NSE TECHNICAL TRANSACTlONS Vol. 32. No, 2 Yahaya Mijinyawa I CONCLUSION Nigeria (5,63 should be encouraged through adequate Steet and Alurniniurn are the predominant materi- funding. als used for the construction of grain silos found in - Western Nigeria. Concrete silos are occasionally used REFERENCES for grain storage while wooden and clay ssilos are still WILLIAMS, 5. K T. (1971), kin Storage Pro- being tested for possible use. The s i ba re used mainly gramme in Western Nigeria Case Historie$suc- for the storage of shelled corn and to a very little ex- cess or Failure". A paper presented at the Regional tent, other crops such as rice, cowpea and soybean AgriculturalqResearch Seminar on Grain sto;age could also be stored in the silos. A rnajorii of the silos in the Humld Trqics organised by the Ford Fdun- with a unit capacity range of 15-10 0 tonnes are owned dation, IlTA and IAR & T, Ibadan and held at the by the Ministries of Agriculture and operators of GO- Conference Centre, University of of badan, 26-30 operative storage programmes. The withdrawal of the July, 19 71,5 pages. Ministries f rom direct crop production and the cdllapse of the co-operarive storage programmes have resulted 2. ABOABA, F. 0.( 1 988);" TheR ole of Government in the abanhnonmt of some of these silos sincethere and Private ~ntrep~eneuirns Grain DryZng and are no grains to store in them. The high unit capacity Storagen. A lecture'delivered at a short course on ones which range be twm 200-1 000 tonnes per silo Grain Processing, Drying and Storage orgmised are owned by feed and flour mills and breweries. These by the Department of Agricultural Engineering, Uni- are being fully used as the owners have the capital to versity of Ibadan. Oetober 10-28, 1988. 7 pages. buy enough grains and equally meet the prohibitive 3. MIJINYAWA, Y. (19 93), "Class%cationa rid Evalu- cost of maintenance. The metal silos experience the ation of Crop Storage Structures in Western Ni- problem of moisture condensation on the roofs and geria". NSE Technical Transactions 28 (4); 34-37. walls and its redistribution within the bulk grain which Jeads to the deterioration of the stored grajns. 4. MIJINYAWA, Y. AND I. AFOLAYAN 1995," Diag- nostic Survey of Post-Hawest Technology Prac- tices in Kwam State". Technical Report, Federal (a) Since the metal silos are prefabricated and Agricultural Co-ordinating Unit, Abuja. can be dismantled without any damage, the abandoned ones should be dismantled and transferred to the stra- 5. MIJIWAWA,Y. (1989), "Theuseof Wood Prod- tegic storage centres far re-erection and use. They ucts in the Design and Construction of a Grain could also be sokl to entrepreneurs who might he in- Silo for the Humid Tropics". A Doctoral Thesis at terested and have tho capacitr to pay. This will be the University of Ibadan. cheaperfor the interested users rather than importing 6. OSUNADE, J. A. AND FOLA LASISB (9I8 8), 'Use new ones. Some money will also accrue to the goy- of Laten'zed Concrete Sflas for on-the-farm Grain ernment. %rageu. Proceeding of the 1988 International En- (b) Even if metal silos are subsidized, the high gineering Conference of the Nigerian Society of capacity ones may still not be attractive to the small Engineers. November 30: December 3,1988. pp. peasant famsrs for fear of not producing enough to 64-69. fill the silo. It is recommended that small sized slIos (be twh 5-1 0 tonnes) should be constructed so that this group of farmers in the remote areas can Met- tively stere their small produc2ians. (c) As a panacea to the problems of prohibiie aost and climatic diflIcuMes with metal silos; R Is necessary to consider some local materials for slb construction that will be cheap and reducet the wide temperature fluctuations within the stlo enclosure. Current research efforts aimed at adapting wood products and laterite as possible materials for grain silos construction in UNIVERSI Y OF IBADAN LIB ARY TABLE 1 Information on Metal Silos Surveved in western Niqeria Ownership & Users As '10 of Average No. Range of Sources of Utilization of Frequency of Silo use and of Silos Total of Silo Unit Silo Grains Stored Stored Grains Percentage of capacity Sites Unit per Capacities Utilization. Surveyed Site (Tonnes) Ministries of Agriculture & Natural Resources 55 3 15 -10 0 Harvest from Livestock feeding Direct involvement of MANR - (MANR) farms owned sale to contractors/ in grain production has been by the MANR. produce merchants. discontinued and most of the silos are not being used. Co-operative 10 2 45 -1 00 Harvests from For sale to industries This programme has become Societies individual and & redistributiont o moribund and the silos abandoned jointly owned co-operators for C farms of co-operations consumption. *, .$ Feed & Flour ,mills, 25 5 200-10 00 Some have farms Used as raw materials Almost always in use and breweries and where the stored for various industrial percentage of capacity utilization a few private grains are cultivated products. between 75 -1 00% commercial farms. but where this is not I the case, the grains are purchased through contractors. Teaching & Research 7 4 0.15 - 45 Harvests from where Livestock feed if healthy A good number of them especially Institutions owned & supply otherwise the produce is in the research institutes are by contractors. destroyed. always with grains & percentage of capacity utilization high. Strategic Grain 3 1000-2500 Supply by contractors To be released in case of Some are still under construction Reserve Centres. or produce gmergency & natural while those already completed ture merchants. disasters. yet to be fully ope.r.at-io nal. UNIVERSITY OF IBADAN LIBRARY 1N SE TECHNICAL TRANSACTIONS VOI. 32. NO. -2 S. B. Adeyemo .' - 5 ' . ..< - -, - - Plate 1: FirskMetal Sio-hstaHatjon in Western Nigeria, llero in 1957. -. - - , (new bandoned) I - J . ' . ... - * , -77. $4 Plate 2: Second Metal Silo Installation in Western Nigeria; llaro in 1958. 4-. i UNIVERSITY OF IBADAN LIBRARY