journal of agricultural engineering and technology … · abdul-fatah, (1997) developed an animal...

Journal of Agricultural Engineering and Technology (JAET). Volume 14, 2006

Nigerian Institution of Agricultural Engineers © 1

JOURNAL OF AGRICULTURAL ENGINEERING AND TECHNOLOGY (JAET) EDITORIAL BOARD

Editor-In-Chief Professor A. P. Onwualu

Raw Materials Research and Development Council (RMRDC) Plot 427 Aguiyi Ironsi Street, Maitama District, PMB 232 Garki, Abuja, Nigeria.

E-mail: [email protected] Phone: 08037432497 Dr. B. Umar – Editor, Power and Machinery Agricultural Engineering Department, University of Maiduguri, Maiduguri, Nigeria. E-mail: [email protected] Phone: 08023825894 Professor A. A. Olufayo – Editor, Soil and Water Engineering Agricultural Engineering Department, Federal University of Technology, Akure, Nigeria. E-mail: [email protected] Phone: 08034708846 Professor A. Ajisegiri – Editor, Food Engineering Agricultural Engineering Department, Federal University of Technology, Minna, Nigeria. E-mail: [email protected] Phone: 08033805960 Dr. A. El-Okene – Editor, Structures and Environmental Control Engineering Agricultural Engineering Department, Ahmadu Bello University, Zaria, Nigeria. E-mail: [email protected] Phone: 08023633464 Dr. D. S. Zibokere – Editor, Environmental Engineering Agric. and Environmental Engineering Dept., Niger Delta University, Wilberforce Island, Yenegoa. E-mail: [email protected] Phone: 08037079321 Dr. C. C. Mbajiorgu – Editor, Emerging Technologies Agricultural Engineering Department, University of Nigeria, Nsukka, Nigeria. E-mail: [email protected] Phone: 08037786610 Dr (Mrs) Z. S. Osunde – Business Manager Agricultural Engineering Department, Federal University of Technology, Minna, Nigeria. E-mail: [email protected] Phone: 08034537068 Mr. Y. Kasali – Business Manager National Centre for Agricultural Mechanization, PMB 1525, Ilorin, Nigeria. E-mail: [email protected] Phone: 08033964055 Mr. J. C. Adama – Editorial Assistant Federal Department of Rural Development, 4 Onitsha Rd., Enugu, Nigeria. E-mail: [email protected] Phone: 08052806052 Mr. B. O. Ugwuishiwu – Editorial Assistant Agricultural Engineering Department, University of Nigeria, Nsukka, Nigeria E-mail: [email protected] Phone: 08043119327

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Aims and Scope The main aim of the Journal of Agricultural Engineering and Technology (JAET) is to provide a medium for dissemination of high quality Technical and Scientific information emanating from research on Engineering for Agriculture. This, it is hoped will encourage researchers and engineers in the area to continue to develop cutting edge technologies for solving the numerous problems facing agriculture in the third world in particular and the world in general. The Journal publishes original research papers, review articles, technical notes and book reviews in Agricultural Engineering and related subjects. Key areas covered by the journal are: Agricultural Power and Machinery; Agricultural Process Engineering; Food Engineering; Post-Harvest Engineering; Soil and Water Engineering; Environmental Engineering; Agricultural Structures and Environmental Control; Waste Management; Aquacultural Engineering; Animal Production Engineering and the Emerging Technology Areas of Information and Communications Technology (ICT) Applications, Computer Based Simulation, Instrumentation and Process Control, CAD/CAM Systems, Biotechnology, Biological Engineering, Biosystems Engineering, Bioresources Engineering, Nanotechnology and Renewable Energy. The journal also considers relevant manuscripts from related disciplines such as other fields of Engineering, Food Science and Technology, Physical Sciences, Agriculture and Environmental Sciences. The journal is published by the Nigerian Institution of Agricultural Engineers (NIAE), A Division of Nigerian Society of Engineers (NSE). The Editorial Board and NIAE wish to make it clear that statements or views expressed in papers published in this journal are those of the authors and no responsibility is assumed for the accuracy of such statements or views. In the interest of factual recording, occasional reference to manufacturers, trade names and proprietary products may be inevitable. No endorsement of a named product is intended nor is any criticism implied of similar products that are not mentioned. Submission of an article for publication implies that it has not been previously published and is not being considered for publication elsewhere. The journal’s peer review policy demands that at least two reviewers give positive recommendations before the paper is accepted for publication. Prospective authors are advised to consult the Guide for Authors which is available in each volume of the journal. Four copies of the manuscript and processing fee should be sent to: The Editor-In-Chief Journal of Agricultural Engineering and Technology (JAET) ℅ The Editorial Office National Centre for Agricultural Mechanization (NCAM) P.M.B. 1525 Ilorin, Kwara State, Nigeria. Papers can also be submitted directly to the Editor-In-Chief or any of the Sectional Editors. Those who have access to the internet can submit electronically as an attached file in MS Word to [email protected]. All correspondence with respect to status of manuscript should be sent to the E-mail address above.

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CONTENTS

Performance Evaluation of an Improved Animal Drawn Ground Metered Shrouded Disc (GMSD) Sprayer. B. B. Shani, M. L. Suleiman and U. S. Mohammed 4-11 Design, Construction and Evaluation of Ginger Slicing Machine. S. O. Aniyi. 12-17 Determination of Rheological Properties of Shea Nuts (Butyrospermum Paradoxum). D. Adgidzi, F. B. Akande and F. A. Dakogol. 18-28 Testing of an Engine-Powered Groundnut Shelling Machine. J. N. Maduako, M. Saidu, P. Mathias and I. Vanke. 29-37 Development of a Manually Operated Vegetable Blender. E. J. Upahi. 38-45 Development and Performance Evaluation of a Motorized Bambara Groundnut Sheller. K. J. Simonyan. 46-51 Design, Fabrication and Testing of Cashew Nut Shelling Machine. Z. D. Osunde and O. E. Oladeru. 52-57 Some Engineering Properties of Palm Kernel Seed (PKS). L. Gbadamosi. 58-66 Field Testing of Agency-Farmer Joint Irrigation Management Concept and its Impact on System Operation and Maintenance in Hadejia Valley Irrigation Project Nigeria. S. Z. Abubakar, B. Lidon and O. J. Mudiare. 67-78 Optimum Tillage System for Okro Production in an Ultisol of South Eastern Nigeria. A. N. Nwagu and S. I. Oluka 79-85 Instructions 86-88

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PERFORMANCE EVALUATION OF AN IMPROVED ANIMAL DRAWN GROUND

METERED SHROUDED DISC (GMSD) SPRAYER

B. B. Shani, M. L. Suleiman and U. S. Mohammed Department of Agricultural Engineering, Ahmadu Bello University, Zaria.

E-mail: [email protected]

ABSTRACT An improved animal drawn controlled droplet application ground metered shrouded disc (CDA-GMSD) herbicide sprayer based on very low volume (VLV) spraying system was evaluated. The sprayer is made up basically of the mainframe, four peristaltic pumps, traction wheel, spray tank, power source, and four shrouded spray heads on a boom length of 6m. A 12V lead acid electrolyte battery powers the disc at 2100rpm and atomizes the liquid from the tank into droplets. Laboratory evaluation revealed nozzle and pump average discharge rates of 54.8ml/min and 10.27ml/min with coefficient of variation of 0.9% respectively and calibrated application rate of 5.59l/ha. Field performance test, revealed application rate of 4.62l//hr and average swath width of 5.814m. Field capacity and efficiency were 1.89ha/hr and 92.1% respectively with a slippage of 1.16%. The test results of the improved prototype showed a better performance, hence an improvement recorded. KEYWORDS: Performance evaluation, animal drawn sprayer, shrouded disc.

1. INTRODUCTION Most of agricultural crop production cannot be realized successfully without the control of weeds. Weeds are referred to as group of plant species that are undesirable (Aaron, 1994). They can be competitive in the early stages of the crop growth and when uncontrolled, can cause more yield loss and time consuming in their removal. Hence they must be adequately controlled in order to cultivate crops profitably. Worldwide crop losses from all pests have been estimated to exceed 140 billion U.S. dollars annually (Aaron, 1994). The economic loss caused by weeds has not been estimated. However, weeds may cause higher losses than insects, since besides competing with crops, they harbor insects, disease and other pests. The general effects of weeds in agriculture are: reducing crop yield, lowering product quality, interfering with harvest equipment and other machinery and harbouring other pests. Recent studies and development in pesticides application technology revealed that different droplet sizes and distribution (droplet spectra) are required for different pest situation. The use of high volume (>600L/ha) for field-crops (Suleiman, 1986) for spraying has certain limitations, including: non-compatibility with:- hydraulic nozzle sprayer in areas where water is scarce; narrow swath, and the need for a lot of mixing of chemicals during spraying to avoid chemical settlement beneath tank; large droplets produced (about 500micron vmd) may sometimes become unstable resulting in possible run off, causing chemical and environmental pollution and in major changes in population of non-target organisms such as earthworms (Suleiman, 1994); and poor bush penetration, and high capital investment especially for tractor mounted trail, or self-propelled hydraulic boom sprayers. In order to overcome the above limitations, a controlled droplet applicator (CDA) was developed. It emphasizes the importance of applying correct droplet size for a given target, the uniformity of droplet size to optimize the use of minimum volume and dose to achieve effective control of pests. Based on this principle, a ground metered shrouded disc sprayer was developed (Abdulfatah, 1997), to overcome all the above shortcomings. However, it was observed to have the following problems: low capacity in terms of swath produced per passes of the sprayer as suggested by Abdulfatah (1997), over dosing due to incorrect rubber used for the peristaltic pump, low discharge efficiency of the peristaltic

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pump, poor machine maneuverability and operators comfort, poor re-circulation of spray due to the low pressure at the tank and non-uniform spray on undulating field. Chouldhury, et al (1981) developed a ‘Ground – metered’ shrouded disc herbicide applicator which is a CDA spinning disc manually operated herbicide sprayer based on very low volume (VLV) spraying system. Their study was an attempt to improve both the spray volume distribution pattern of a convectional CDA herbicide applicator and the application rate, by employing the principles of disc shrouding and the use of peristaltic pump. The pump, which is ground metered, is able to supply liquid to the center of the shrouded disc at a rate that is proportional to the walking speed of the operator. They however, noted that the spray application rate was controlled and the spray volume distribution pattern improved. There was an attempt by Bitrus (1985) to improve the efficiency and capacity of existing manual CDA herbicide applicator technique. The sprayer has a boom of two Micron Herbi spinning shrouded discs of a speed of 1800rpm at 95cm apart and positioned 60cm above the ground. The obtained results based on his laboratory and field investigation gave a coefficient of variation of spray distribution of 34.6% at disc spacing and height of 95cm and 60cm respectively. Imam (1981) also in an attempt to improve the GMSD sprayers obtained a similar result with a swath width of 2.9m and field capacity of 0.84ha/hr. Abdul-fatah, (1997) developed an animal drawn controlled droplet application ground metered shrouded disc (CDA – GMSD) herbicide sprayer based on very low volume (VLV) spraying system. The sprayer consists of the main frame, ground wheel, peristaltic pump, an 85 liters single tank feeding 4 spinning discs on a boom length 4.8m, two 6V acid electrolyte batteries to power the discs which rotate about 1900rpm and atomize the liquid from the tank into droplets. He obtained from laboratory test, an even spray volume distribution with coefficient of variation of 16.9% at nozzle spacing of 120cm and at vertical height of 45cm above the target. Droplet spectrum – volume and number median diameters were 250µm and 225µm respectively with a low dispersion ratio of 1:1. Droplet density of 16 droplets/cm2 and calibrated application rate of 4.35L/ha while field performance test gave an application rate of 4.8L/ha with maximum swath of 5.82m at nozzle spacing of 120cm and boom height of 45cm above the target. Field capacity and efficiency were 1.03 ha/hr and 89.6% respectively with slippage of 1.13%. The broad objective of this study was to evaluate the performance of the prototype sprayer under laboratory and field conditions. 2. MATERIALS AND METHODS 2.1 Description of the Improved Prototype Animal Drawn GMSD Sprayer The sprayer is made up of the main frame, four peristaltic pumps, traction wheel, spray tank, power source and shrouded spray heads, (Fig. 1). Generally, the mode of operation of the sprayer is based on ground metering of the spray chemical onto the shrouded rotating disc, and shrouding the disc is to collect and recycle the indisposed fraction of the spray chemical which is directed upward over an arc of 1800. Ground metering is achieved by the employment of a positive displacement type of peristaltic pump attached to the main frame. The spray chemical, which is intercepted and recycled by the shroud, is scavenged and sucked back into the spray tank.

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Fig. 1. Prototype sprayer being tested on the field 2.2 Performance Evaluation Both laboratory and field tests were carried out on the prototype sprayer to evaluate its performance. 2.2.1 Laboratory Performance Test The laboratory evaluation was carried out to determine the flow rate, application rate and discharge from peristaltic pump by calibrating both the sprayer and the peristaltic pump. Each pair of nozzles was mounted on the patternator and discharge at the same time interval were collected in five replicates. Flow rate for each and overall or total flow rate were determined for the nozzles. This flow rate was determined using the expression given below (Matthews, 1992):

( )min/lTQ

Vav

av= ----------------------------------------------- 2.1

where V = flow rate (discharge per unit time), Qav = Average discharge in litres and Tav = average time for discharge in minutes. The recommended method of calibration of spinning disc sprayers by Kaul and Suleiman (1990) was employed to calibrate the prototype sprayer. The tank of the sprayer was filled and the sprayer mounted on a pair of metal stool to enable the wheels to be suspended.). The wheels were then rotated for five minutes and effective spray discharge was collected. This was done in five replicates. The same procedure as outlined for the sprayer calibration was also employed for the calibration of the peristaltic pumps. The wheels were turned for 10 revolutions and discharge per pump was recorded. This was done in 10 replicates. The total swath width of the four nozzles of the sprayer was determined in five replicates. Then based on the total flow rate for five minutes and using the recommended speed of 1m/s by Kaul and Suleiman (1990), the application rate in litres per hectare was determined for the prototype sprayer. Using also, the expression as given below (Kaul and Suleiman 1990):

( )halWSVA /

30= -------------------------------------------- 2.2

where: A = application rate (l/ha), V = amount of liquid from the four nozzles in five minutes (l/min), S = traveling speed (m/s) and W = swath width (m)

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2.2.2 Field Performance Test The field evaluation was carried out in order to determine the following parameters under field conditions: a. Slippage of the ground wheel; b. Theoretical and effective field capacities; c. Field efficiency; The experimental field was 0.33 hectares located in Samaru, Zaria. Soil test analysis confirmed it to be loamy with fairly flat slope. The test was carried out on the flat surface. The plot was harrowed and cross-harrowed based on the field layout. The prototype sprayer was set and hitched to a pair of bullocks for operation. The swath of the sprayer at different height above the ground was determined by spreading cardboard paper on the ground along the sprayer boom. Spray deposits were noticed on the cardboard and the width of the area covered was measured for each height as the swath width. The spray liquid application rate is determined using the mathematical expression as given below: (Kaul and Suleiman, 1990)

Ap = t

t

AV

----------------------------------------------------------2.3

Where: Ap = field application rate, Vt = total volume of effective spray (litres), AT = total area sprayed or treated (hectares). (See table 6 for all relevant field times used for the performance analysis recorded during the field test) The sprayer tank was filled with a known quantity of spray liquid. The sprayer was then run until all the designated portion of the field was sprayed. The time and amount of spray liquid used were noted. The spraying was done in three replicates. The slippage test was done by noting the times taken for the prototype sprayer to cover 100m distances with and without load respectively in three replicates. The data collected was employed to determine the effective and theoretical field capacity, field efficiency and slippage respectively. Effective field capacity (EFC) as defined by Culpin (1986);

(EFC) = takentimeTotal

treatedarea

Theoretical field capacity (TFC). This is defined as the rate of performance obtained if a machine were performing at 100% of the time at the rated operating speed and 100% of rated width (Hunt, 1994).

(TFC) = )/(10

hrhaSW

Field efficiency (E)-: is the ratio of effective field capacity to theoretical field capacities and it is expressed as percentage (Hunt, 1994).

E = capacityfieldltheoretica

capacityfieldEffective

and Wheel slip (S) is defined as (Culpin, 1986):

S = loadwithoutspeed

loadwithspeedloadwithoutspeed −

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= loadwithoutspeed

loadwithspeed−1

It is usually expressed as a percentage. If t1 and t2 are the times taken to cover a known distance (100m), with and without loads respectively, then:

Speed without load = )/(100

1

smt

---------------------------(2.4a)

Speed with load = )/(100

2

smt

---------------------------(2.4b)

Substituting equation (2.4a) and (2.4b) into (1) and simplifying;

Slip, S = 1 - ( )( )1

2

/100/100tt

= 2

12

ttt −

= 1 - 2

1

tt

% Slip, S = %10012

1 ×−tt

3. RESULTS AND DISCUSSION 3.1 Laboratory Test Results In Table 1, the discharge per unit time (flow rate) of the four spinning disc nozzles have a mean discharge of 54.8ml/min, standard deviation of 0.52 and coefficient of variation of 0.90%. It could be deduced here, that both the standard deviation and coefficient of variation values are small. Consequently, from minimal Nodby (1978), the coefficient of variation is less than 10, the result obtained can be said to be particularly good. This however, gives a clear tendency of high degree of uniformity of discharge per unit time of the nozzles used, thereby reducing the possibility of over or under dosage by any of the nozzles. Table 1: Average Discharge Rate for each Nozzle using chemical ratio; (Glyphosate) 1: (water) 3 Parameters Nozzle discharge rate (ml/min) Nozzle 1 Nozzle 2 Nozzle 3 Nozzle 4

54 54.67 55.33 55.20

Mean (X) 54.8 Standard deviation (SD) 0.52 Coefficient of variation (CV) 0.9% Boom discharge 219.2 ml/min

The result obtained from the pump discharge measurement per revolution of the ground wheel has a mean discharge of 10.27ml/rev, standard deviation of 0.212 and coefficient of variation of 2.06%. The value of coefficient of variation between the four peristaltic pumps indicates a satisfactory result, (Nodby, 1978) hence, good uniformity of discharge from the pumps. The small difference noted in discharge of the four pumps was as a result of the material used for the pump tube.

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Table 2: Average Peristaltic Pump Discharge using chemical ratio (Glyphosate)1: (water) 3 Parameters Results (ml/rev) Pump 1 Pump 2 Pump 3 Pump 4 Mean (X) Standard deviation (SD) Coefficient of variation (CV)

9.8 10.94 9.89 10.45 10.27 0.212 2.06%

The calculated application rates at various heights as shown in Table 3 has an average of 7.53 L/ha and small value for both standard deviation and coefficient of variation of 0.25 and 3.3% respectively. The slight variations in the application rates at the different boom heights as compared with the calibrated application rate showed some degree of non-uniformity of the application for the unit target area. This non-uniformity could be related to the material used for the pump tube and the patternator that was not big enough to accommodate large swath produced at higher nozzle height. Thus increase in swath width and use of correct material for the pump tube could reduce the variations to the minimum and hence, better spray chemical economy. Table 3: Application rates at various boom heights with Glysophate as test fluid. Boom height (cm) Application rates (L/ha) 15 30 45 60 Average Standard deviation Coefficient of variation

7.65 7.41 7.80 7.23 7.53 0.25 3.3%

3.2 Field Test Results The measured spray swaths at various boom heights are given in Table 4 with an average swath, standard deviation and coefficient of variation of 5.814m, 0.051 and 0.26% respectively, and calculated application rate of 4.61L/ha. The average swath and the application rate obtained as compared to the predicted values of 6m and 5.59L/ha, appeared to be less for the swath and greater for the application rate. It can be seen that, the higher the boom height, the smaller the swath. This could be attributed to the fact that there was drifting of the droplets from the target. Table 4: Measured Swath of prototype at various boom heights Boom height (cm) Swath (m) 15 30 45 60 75 Average Standard deviation Coefficient of variation

5.74 5.79 5.82 5.85 5.87 5.81 0.051 0.26%

The field performance of the improved prototype shows great improvement over the with respect to the theoretical and effective field capacities and field efficiency of 1.89ha/hr, 1.74ha/hr and 92.1% respectively as shown in Table 5.

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From Table 5 also, the result of the slippage test showed that there was negligible slipping of the wheel, during performance test. This could be as a result of the additional lugs on the wheels. Table 5: Theoretical and effective field capacities and efficiency of the prototype sprayer Parameters Improved prototype Theoretical field capacity Effective field capacity Efficiency Slippage

1.89 ha/hr 1.74 ha/hr 92.1% 1.16%

Table 6: Field performance test data Rep no Lost

time (min)

Effective time (min)

Total time (min)

Volume Of chemical sprayed (l)

Swath width (m)

Time for covering 100m distance

T2 With load

T1 Without load

Voltage (v)

Current (A)

1. 2. 3. Mean x

1.57 1.89 2.28 5.74 1.91

9.7 10.2 11.7 31.58 10.53

11.27 12.07 13.98 37.32 12.44

1.595 1.529 1.608 4.732 1.577

5.740 5.85 5.82 17.41 5.80

49.72 51.48 50.6 151.8 50.6

49.28 51.04 49.72 150..04 50.05

12.0 11.9 11.8

0.80 0.78 0.77 3.83 0.766

4. CONCLUSIONS The prototype evaluated was an animal drawn ground metered shrouded disc sprayer, which is based on controlled droplet application of very low volume spraying technique. Essentially, the sprayer consists of an 85 litres single tank, feeding four ground metered peristaltic pumps; Each pump is connected to four spinning discs spray nozzles which are connected in parallel and driven by a 12V electric motor powered by a 12V battery. Both laboratory and field test results showed a better performance of the improved prototype. The laboratory test gave 54.84ml/min nozzle flow rate. The field test result obtained gave theoretical and effective field capacities of 1.89 and 1.74 ha/hr respectively with field efficiency of 91.2% with an average swath width of 5.814m. The prototype sprayer has a potential role in the field of crop protection in general and weed control in particular.

REFERENCES

Aaron, K. 1994. Chemical Application Management, Farm Business Management. Illinois Publication pp 31-51. Abdul-Fatah, Y. 1997. Development of Animal Drawn GMSD Sprayer. M.Sc Eng (Agric.) Thesis. Dept of Agric. Eng. A.B.U., Zaria, Nigeria. Bitrus, H. A. 1985. Studies on volume Distribution Patterns and Droplets Spectrum From Boom of Shrouded Spinning Disc herbicide Applicator nozzles. B. Eng. (Agric.) thesis, Dept. of Agric ulture. Chouldhury, M.S., Kaul, R. N. and J.E.A. Ogborn 1981. Development of GMSD-VLV Herbicide applicator. Samaru J. Agric Res, Vol. 2 (1). Claude Cuplin 1986. Farm Machinery. Collins Professional and Technical Books, London, 450pp Hunt, D 1994. Farm Power and Machinery Management.9th Edition, Iowa State University Press,Armes.U.S.A. Imam, A.H. 1987. Design and construction of an improved ‘GMSD’ herbicide sprayer. B.Sc. Eng (Agric.) Thesis. Dept. of Agric. Eng., A.B.U., Zaria, Nigeria.

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Kaul, R.N. and M.L. Suleiman 1990. Introduction to crop protection machinery. ABUCONS (nig.) Ltd. Book Series. A.B.U., Press, Zaria, Nigeria, 100pp. Matthews, G.A. 1992. Pesticide application methods. Longman Scientific and Technical, New York, 2nd Edition, 405pp. Matthews, G.A. And E.C. Hislop 1993. Application Technology for crop protection. International, Wallingfor, U.K., 360pp. Nordby, A. 1978. Dyseposisjon Pa Spredebommer dysehlyde-arbeidstrykk - vaeskedordeling. N.J.F. Seminar, Akersproyter og a kersprlyting, As, NHL Norge. Suleiman, M. L. 1986. Comparison of selected factors influencing selection of spraying machines. Nig. J. Agric Ext., 4 (1 and 2). Suleiman, M. L 1994. Multipurpose CDA sprayer development. Ph.D. Thesis, Dept. of Agric Engin. A.B.U., Zaria, Nigeria.

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DESIGN, CONSTRUCTION AND EVALUATION OF A GINGER SLICING MACHINE

S. O. Aniyi Department of Agricultural Engineering, Institute of Technology,

Kwara State Polytechnic, Ilorin. E-mail: [email protected]

ABSTRACT A ginger slicing machine was designed, fabricated and evaluated. The slicing unit consists of cylinder, piston, connecting road, crankshaft, blades, blade separators and blade holders. The slicing of ginger was effected using reciprocating principle with fixed blades, powered with an electric motor. The machine was evaluated with “Tarin Giwa” ginger specie for cutting efficiency (CE) and percent meat loss (PML). The cutting efficiency (CE) was 77% at 30% moisture content of the ginger on dry basis (db) and 65% at 22% moisture content. This result shows that higher cutting efficiency is obtainable at higher moisture content. The percent meat loss (PML) was found to be lower at higher moisture content. It was found to be 23% at 30% MC (db) and 35% at 22% MC (db). KEYWORDS: Ginger, slicing machine, cutting efficiency, meat loss. 1. INTRODUCTION Ginger (Zingiber offiniale roscoe) is an important source of foreign exchange to Nigeria. It is grown all over the country, but most largely produced as a cash crop in the southern part of Kaduna State namely: Jaba, Jama’a and Kachia Local Government Areas. It is an annual crop propagated vegetatively to yield fleshy underground rhizomes (Simonyan et al, 1997). The branching fleshy rhizomes have a sweet spicy pungent flavour composed of 40-60 starch, 10-40% yellow colour votatile oil responsible for its flavour and the remaining percentage for protein, mineral matter and fibre content (Rahda 1995). Ginger is essentially raw material in the food confectionary, perfumery, pharmaceutical and wine industries (Akumas and Oti, 1988). Ginger enters the international markets in fresh (green), preserved or dried forms. However, the most important commercial form is the dried ginger (split or whole), ground as spice and for extractives – ginger oil and ginger oleoresin. Split dried ginger commands higher prices in the market because the pungency reduction is less and it has pleasing combination of aroma, flavour and pungency (Ebewele and Jimoh, 1988). Slicing is mechanical separation process on a solid body using cutting tool whose wedge formed cutting parts are under pressure and overcome the cohesion of the material due to the higher specific normal and thrust forces along the cutting edge (Feller, 1959). Feller (1959) quoting Bossi reported that slicing cut requires less power than non-slicing cut. The knife in slicing cut has a component of velocity in the direction of the edge. The moisture content and the cross sectional area have significant influence over the cutting energy (Prasad and Gupta, 1975; Chancellor, 1958: Liljedah et al 1961). Other parameters influencing cutting are the cutting velocity, shear angle of cut and bevel angle of the knife (Balasubramanian et al, 1993; Kachru et al, 1996). Mechanization of ginger production and processing has received little attention in Nigeria. Its production operations need to be mechanized to increase the production and use (Nwandikom and Njoku 1988). Presently, slicing of ginger is done mostly by women and children manually using knives. In recognition of the constraints imposed by the manual method of slicing ginger which is hazardous, time consuming and labour intensive, an appropriate motorized ginger slicer for small scale farmers was developed using locally available materials. The paper describes the ginger slicer, its operation and performance evaluation.

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2. MATERIAL AND METHODS 2.1 Design Criteria Ginger possesses some unique characteristics which were taken into consideration in designing the slicer. Ginger rhizomes have irregular shapes and sizes. They have fingers and are highly fibrous. Some of the criteria considered in the design include: use of local materials, adequate capacity and affordability. 2.2 Description of the Slicing Machine The machine consists of the feeding unit, slicing mechanism, driving mechanism, frame and the housing. Figs. 1 and 2 give the orthographic and isometric views of the motorized ginger slicer respectively. The components of the machine include: (i) Feeding unit – the hopper is a frustrum with a rectangular base dimensioned 280mm by

200mm at the top and 280mm by 100mm at the base. It is constructed from gauge 18 sheet metal. The ginger rhizomes are introduced through the hopper to the cylinder by gravity.

(ii) Slicing mechanism – comprise the cylinder, the piston, the connecting rod, crankshaft, blades, blade separators and blade holders.

(a) The cylinder is rectangular box like structure with two open opposite sides dimensioned 420mm by 560mm by 140mm. It has 280mm by 100mm for the rhizomes intakes through the hopper into the cylinder.

(b) The piston – this is the main component of the slicer. The piston reciprocates within the cylinder from the Top Dead Centre (TDC) to the Bottom Dead Centre (BDC). It opens the inlet space to receive ginger rhizomes from the hopper to the cylinder at the bottom dead centre of its intake stroke. It closes the inlet space, pushing and forcing the rhizomes against the fixed blades for slicing, ejecting the slices at the top dead centre of the compression stroke. The clearance volume is 3mm. The piston is rectangular with attachment for the gudgeon pin, a shaft on which the connecting rod turns when transmitting power from the crankshaft. It is constructed using gage 18 folded to 270 mm by 150mm by 130mm with 185mm by 129mm flange at the sides to guide it in the cylinder.

(c) The connecting rod – this transmits the rotary motion of the crankshaft to reciprocating motion of the piston. The pinion pins connects it to the crankshaft and the piston. The pins are separated by a 2mm diameter pipe 150mm long and reinforced by two 10mm diameter roads at the two sides.

(d) The crankshaft – this unit translates the rotary motion of the electric motor to reciprocating movement of the piston. It has a central shaft 20mm diameter with projected pins constructed with flat bars. Two arm shafts are welded on the flat bars at right angles to connect bearing for effective turning and attachment of sprocket driving. The distance between the central shaft and the arm shafts indicates the radius of the piston stroke which is 75mm.

(e) Blades – the slicer has fixed stationary blades cutting the rhizomes. The blade constructed with stainless steel to prevent corrosion is 1mm thick with 220 blade bevel angel at one edge. It is 320 mm by 20 mm with 10mm drilled at the ends for blade holder.

(f) Blade separators – this determines the thickness of cut indicated by the clearance between the blades. The separator is 2mm thick. 20mm square metal with 10mm diameter hole at the centre.

(g) Blade holder – two 25mm U shaped structures welded to the front of the cylinder act as the blade guide. The blades and the separators are arranged horizontally between the holders. Two long screws hold the blades firmly in position.

(iii) Drive Mechanism – the ginger slicer is powered by a single phase 2KVA, 50Hz, 1420 rpm,

1500W electric motor. The motor is mounted on the frame to help stabilize the machine.

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(iv) Frame – The frame positions all the machine components to perform its operation satisfactorily. It is 700mm by 220mm by 650mm constructed from 25mm by 25mm angle iron.

(v) Housing – This comprises a metallic frame of 25mm by 25mm angle iron and wooden

cardboard covers. The side covers were perforated to provide adequate ventilation to the prime movers. It is a 750mm by 550mm box meant to minimize mechanical accident during operations and reduce environmental effects on the machine.

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2.3 Evaluation Procedure Tests were carried out to evaluate the performance of the slicer. Fully matured “Tafin Giwa” variety ginger rhizomes were bought from Kafanchan market, Kaduna State, Nigeria. The ginger rhizomes were fed by gravity into the machine and pushed by the reciprocating piston horizontally to the stationary knives. The push from the rhizomes forced the sliced ginger through the blades. The slicing was longitudinal. Three replications were made. Some ginger rhizomes were conditioned by soaking in water for 3 hours while some samples were used unsoaked. The moisture content of both were determined by putting the samples in oven at 130OC for 24 hours. Properly sliced, partially sliced and pounded ginger were separated and weighed. The partially sliced were manually sliced and weighed. The following parameters were used for the testing. Bevel angle of the knives = fixed at 220 Approach angle is fixed at 900 Shear angle = 900 Piston velocity is fixed at 168.42rpm. Cutting efficiency (CE) = W - WD X 100 ………………(5)

W Where: W = Weight of all slices; Wd= Weight of damaged slices Percent meat loss (Pml) = Weight of damaged ginger Wt. Of all slices 3. RESULTS AND DISCUSSION The result of the test (Table 1) shows that the slicing efficiency is dependent on the moisture content. At high moisture content 30% (db) the cutting efficiency was 77% while at 22% M.C. (db), the cutting efficiency was 65%. The water molecules in the fibrous ginger rhizomes determine the ease with which the knife passes through the rhizome. Table 1: Performance evaluation of the ginger slicing machine. 22% MC

db Average

Soaked 30% MC

db Average

Wt of Ginger Completely Sliced (kg) Wt of ginger Portally Sliced (kg) Wt of damaged Ginger (kg) Slicing Efficiency (%) Percent Damaged (PD)

7.9

1.7

3.4

64.6

35.4

10.9

2.9

3.2

76.8

23.2

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More crushing of the ginger rhizomes was observed at lower 22% M.C. (db) having percent meat loss of 35% while the percent meat loss of 23% was obtained at 30% M.C. (db). The fibrous nature of the ginger at lower moisture causes difficulty of slicing. The slicer has the following features: (i) the safety of the operator is assured; (ii) it is easy to operate and transport from place to place; (iii) various sizes and shapes of ginger can be accommodated; (iv) it produces slices of uniform thickness; (v) it can be operated by unskilled labour (vi) the slicer can be produced locally by artisans (vii) cooperative farmers, medium and large scale entrepreneurs stand to benefit from the slicer. 4. CONCLUSION A motorized ginger slicer was developed using locally available materials. Reciprocating principle with fixed blade was adopted. Results showed that the slicing efficiency was dependent on moisture content of the rhizomes 76.8% CE at 30% MC (db) and 64.6% CE at 22% MC (db). The cutting efficiency was higher at higher moisture content. The result also showed that percent damage was dependent on moisture content of the rhizomes. The PML of 23.2% at 30% MC (db) while 35.4% (PML) at 22% M.C. (db) were obtained. REFERENCES Akomas G.E.C. and Oti E. 1988. Developing technology for the processing of Nigeria Ginger (Zingiber Officinale Rosc). Proceeding of the 1st National Ginger workshop held at National Root Crop Research Institute Umudike Pp. 93-100. Balasubramanian, V.M; Screenarayanan, V.V.; Visanathan R. and Balasubranmanian, D. 1993. Design, Development and Evaluation of a Cassava Chipper. AMA 24(1) 60-64. Chancellor, W.J. 1958. Requirement for cutting forage. Agric Engineering Vol. 39 pp. 633 –636. Ebewele, R.O. and Jimoh. A.A. 1988. Local processing of ginger: prospects and Problems, Proceedings of the 1st National ginger workshop, National Root Crop Research Institute Umudike pp. 22-33. Feller, R. 1959. Effects of knife angles and velocities on Cutting stalks without a counter edge J. Agric Engineering Research 4(4): 277-298. Kahuru, R.P. Balasubramanian, D. and Nachiket, K. 1996. Designed, Development and Evaluation of Rotary Slicer for Raw Banana Chips AMA 27(4): 61-64. Lilijedah, J.B; Johnson, G.L; Degraff, R.P. and Schneder, M. E. 1961. Measurement of Shearing Energy, Agric Engineering 42 (6) 298-301. Nwandikom, G.I. and Njoku, N.I. 1988. Design Related Physical Properties of Nigerian Ginger. Proceedings of the 1st National Ginger workshop, National Root Crop Research Institute Umudike pp. 101-107. Prasad, J. and Gupta, C.P. 1975. Mechanical Properties of Maize Stalk as Related to Harvesting J. Agric Engineering Res. 29(1) 79-87. Rahda S. 1995. Developments in Ginger Processing AMA 26(4) 59. Simonyan, K.J., Lycocks, S.W.J. and Jegede, K.M. 1997. Design and Development of a motorized Ginger slicer. Agric. Engineering Res. 20(3) pp. 90-97.

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DETERMINATION OF RHEOLOGICAL PROPERTIES OF SHEA NUTS (Butyrospermump paradoxum)

D. Adgidzi1, F. B. Akande1 and F. A. Dakogol2

1Department of Agricultural Engineering, Federal University of Technology, Minna. Nigeria. 2Department of Agricultural Engineering, Federal Polytechnic, Nasarawa, Nigeria.

ABSTRACT The forces and the corresponding deformations of shelled and unshelled nuts at three chosen moisture contents were determined at points of linear limit, bioyield points and rupture points under compressive load tests. The minimum force and corresponding deformation to rupture shelled nuts was found to vary from 980.00N, 4.90 mm to 1615.38N, 9.59 mm for moisture range of 20%-48% (wb) while for the unshelled nuts, the maximum force and the corresponding deformation to rupture the shell with minimum kernel breakage varied from 142.19N, 1.13 mm to 249.40N, 2.07 mm within the moisture range of 25%-48%(wb). KEYWORDS: Rheological properties, shea nuts, shelled-nuts, un-shelled nuts. 1. INTRODUCTION The ever-increasing world’s population requires the need to increase agricultural production, processing and marketing of plants and animal materials to meet with the consequent food demand. In developed countries, this has been made possible by the application of modern technology, which involves essentially the subjection of these materials to mechanical, thermal, electrical, optical and sonic treatments (Dakogol, 2001). For machines for processing and handling operation to be designed for higher efficiency and best quality of the end products of plants and animal materials, their engineering properties are required.

The shea butter tree belongs to the family – sapotaceae genus – butyrospermum and species – paradoxum. It is wide spread in the savannah area of West Africa where it is often protected. In Nigeria, the tree is mostly found in Bauchi, Kwara, Niger, Zaria, Kaduna, Oyo, Ibadan, Abeokuta and in Ogoja provinces (Adgidzi, 1999). Shea- nut fruits are ellipsoidal, about 5.5 cm long with fleshy pulp usually one seeded. The seed is more or less oval, about 4.0 cm long and 2.5 cm broad, with a shining dark brown hard bonny testa and a white scar down one side. The seeds are removed after decomposition of the pulp and drying (Purseglove, 1984). Shea nut constitute one of the major oil bearing agricultural produce among groundnuts, palm fruits, cottonseeds, sunflower seeds, melon seeds, beniseeds and coconut. It contains 45-60% fat (shea butter) and 9% protein (Purseglove, 1984). Shea nut is used for the production of shea butter, which is used as fat. It is also used as source of edible oil in Nigeria. Basically, shea butter is used as a source of raw materials for the production of soaps, lubricants, cosmetics, paints, medicinal ointment and hairdressing. It can also be used for the manufacture of candles. The residue after extraction (cake) can be used for animal feed preparation (Adgidzi, 1999). According to Amusa (1998), the production processes of Shea butter in some part of Niger and Kwara States are traditional using little or no modern technology. Olaniyan and Oje (1999) observed that the shelling method in the villages throughout the Middle-Belt and South-West zones of Nigeria is by pounding the nuts in a mortar using pestle which results in a lot of breakages. The separation of shell from kernels is by local winnowing techniques. Where shelling machine exists, kernels are usually cracked during shelling. The extraction efficiency of Shea butter by these processes is very low, about 15% and usually of poor quality.

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The objective of this study therefore was to determine the maximum force and deformation required for shelling of Shea nut with minimum kernel breakage and the minimum force required to mill the shelled nuts. These forces and deformation were obtained from the rheological properties of the nuts. 2.0 MATERIALS AND METHODS 2.1 Review Work The determination of compressive properties of agricultural materials require the production of a complete force-deformation curve from which modulus of elasticity, toughness, maximum normal contact stress or stress index at low levels of deformation can be obtained (Mohsenin 1984). Under small strains, most agricultural materials are assumed to exhibit extensive elasticity such that the Hertz’s theory of contact stresses is applicable (Mohsenin, 1970). To this effect, Dinrifo and Faborode (1993) applied Hertz’s theory of contact stresses to determine the stiffness modulus and stress index of cocoa pod from Force-Deformation curve of the pod using equations 1 and 2.

)1(]11[)1(531.02

1

'114

3

2−−−−−−−−−−−−−−−−−−+

−=

RRD

FS µ

And )2()411)(1(531.03

1

'11

2

43

−−−−−−−−−−−−−++−=idRRD

FSi µ

where S= Stiffness modulus, F=Applied force, μ= co-efficient of friction, D= deformation, di=diameter of the indenter, R1, 1

1R = minimum and maximum radius of curvature of the body for rigid flat plate and spherical indenter respectively. In determining the visco-elastic behaviour of shea nut under application of force, Olaniyan and Oje (1999) performed compression tests with the Mansnato Tensiometer universal testing machine. Each nut was fed onto the machine by hand between two end faces of the compression plates and loaded to rupture. The force at rupture point and the corresponding deformation for each nut specimen were read from the in-built Force- Deformation curve. 2.2 Sample Preparation Nuts (shelled and unshelled) were randomly taken and divided into three groups each. The first group was oven dried; second, sun dried and third was sprinkled with an amount of water arbitrarily and tied in a polythene bag and left overnight, in order to obtain different moisture content. The moisture content of the respective samples were determined and found to be 25%, 30% and 48% (wb) for oven dried sun dried and wetted unshelled nuts respectively while that of shelled nuts was 20%, 25% and 48% (wb) respectively. Ten (10) nuts were selected from each group and their principal dimensions as well as weight were determined . The radii of curvature (R1 and R1

1) of each nut was calculated using the following expressions by Mohsenin (1984) and presented in Fig. 1.

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)4(2

4

)3(2

22'

1

1

−−−−−−−−+

=

−−−−−−−−−−−=

H

LHR

HR

Where H= Height of the circle inscribing the minor diameter of nut traced and Radius of Curvature R1 and R1

1 for a convex body. 2.3 Compression Test Quasi-static, uniaxial parallel plate compression test was performed on shelled and unshelled nuts to determine the maximum rupture force and deformation at three arbitrarily chosen levels of moisture content. The tests were performed in the Materials’ Testing Laboratory of the National Centre for Agricultural Mechanization (NCAM), Ilorin , Kwara State at an average room temperature of 28 oC. The machine used was a 50 kN capacity automated universal testing machine (Testometric, series 500-532) shown in Fig. 2.

Each nut was placed in the machine under the flat steel compression tool, ensuring that the re Fig. 2: Universal Testing Machine

L

H

Fig 1: Approximation of Radius of Curvature R1 & R11 for a convex body

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Each nut was placed in the machine under the flat compression tool, ensuring that the centre of the tool was in alignment with the peak of the curvature of the nut. The tested speed was set at 25 mm per minute (ASAE, 1986) and the nut loaded to point of rupture. Force-deformation curves were produced automatically. Each test was carried out using ten (10) nuts. The moisture content of the representative samples were determined by oven drying method (Oje, 1993) and found to be 25%, 30% and 48% (wb) for oven dried, sun dried and wetted unshelled nuts respectively while that of shelled nuts were 20%, 25% and 48% (wb) respectively. 2.4 Force and Deformation at Linear Limit, Bioyield and Rupture Points The Force and Deformation at Linear limit, Bioyield and rupture points were determined from the graphs by noting the calibration along Y-axis for the force and x-axis for deformation. 2.5 Modulus of Deformability This is defined by Hertz’s expression for modulus of Elasticity (equation 1) except that the values of force and deformation used are the sum of both elastic and plastic deformation (Mohsenin, 1984). In calculating modulus of deformability, the values of forces, F and deformation, D were half of those at the point of linear limits. The value of Poisson ratio was taken to be 0.35 (Mohsenin, 1970). Consider shelled nut with the following dimensions: Axial length (L) = 460 mm; Height (H) = 233 mm. Radii of curvature R1 & R!

1 from equations (3) & (4) are: R1 = 11.7 mm ; R11 = 23.0 mm. F

and D at point of linear limits are 410N and 2.72 mm respectively, so half of these are 205N and 1.361mm. Substituting these values into equation (1) yields; S = 2.216 x 107Pa. This method was used for all the nuts and to obtain average results. 3. RESULTS AND DISCUSSION The average (summary) results of the rheological properties of both shelled and unshelled shea-nut 25%, 30% and 48% (wb) mc are as presented in Table 1. Table 1. Rhetorical properties of the nuts Moisture

Content %(Wb)

Linear Limit Bioyield Point Rupture Point Modulus of Deformability

Force NDeformation (mm)

Force N

Deformation (mm)

Force N

Deformation (mm )

Pa x107

S N

48 25 20

363.1 122.0 137.2

2.750 3.065 1.571

479.8 621.0 662.6

3.455 5.991 8.177

610.1 909.7 1414.5

5.287 7.946 10.967

1.915 0.698 1.876

U S N

48 30 25

178.9 120.9 109.2

1.265 1.110 0.849

- - -

- - -

249.4 158.8 142.2

1.674 1.484 1.132

2.638 2.437 3.297

S N – Shelled Nuts US N - Unshelled Nuts 3.1 Interpretation of Force- Deformation Curves of Shelled Nuts Figures 3-5 show the Force-Deformation curves of shelled nuts at 48%, 25% and 20% moisture content respectively. In Fig.3, at small loading, all the force goes into stretching the cell walls of the nut resulting in an initial straight-line portion of the curve AB which approximately obeys Hooks’ law. As the load increases beyond point B, elasticity of the cell wall is exceeded thus, cell sap which is assumed to be viscous now bear the load

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resulting into change in linearity of the curve attempting to follow that of viscous materials. At point C, the cell wall punctures and the air spaces are displaced hence the abrupt changes in the curve. This point is regarded as a bioyield point. Continuous loading results into puncture of skin of the nut at point D. Thus, the value of the force at point D is that which is required to fracture the nut. DE is the breakage region where the material completely synapses. In Fig. 4, from 0 to A, there is relatively large deformation in response to initial small loading and is approximately linear. From point A to B, the line curve towards the force axes signifying that deformation decreases as load increases. This may be explained in terms of variation of moisture within the nut. At the surface, the materials is soft thus the elastic deformation; beyond the periphery the moisture content decreases so that the material becomes hard thus more force is required and the material deforms faster. The inner core of the nut is harder thus, the steep nature of the curve between points B and C. The curve dropped from point C to D as the little void in the centre of the nut is being closed up: the loading continues until the nut ruptures at point E. In the analysis of this curve, point B is assumed to be the bioyield point. In Fig. 5, the curve follows, the same trend as in Fig 4, except that it gives relatively larger deformation at the initial loading (0-A) than that in Fig 4. Also, there are no fluctuations in the curve, which indicate that there are no voids. The absence of voids show that the cellulose material at the centre of the nut are held closely together hence, becoming tougher. This results in the steep nature of the curve at high loads. Point B is assumed to be the bioyield point.

Fig 3: Deformation curve of shelled nut at 48% Mc (wb)

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 2 4 6 8 10 12 14 16

Deflection (mm)

Load

(N)

Ref 1: M.C. @ 48% wb Ref 2: SHELLED NUT Ref 3: Ref 4:

Test: SHEANT 2 Test Type: Compression Date 26 -07-00 File: C: SHEANT 2 TST002.DA Test Speed: 025.00mm/min Sample Type: IRREGULAR Pre – Load: OFF

A

B D

E

C

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Fig 4: Deformation curve of shelled nut at 25% Mc (wb)

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 2 4 6 8 10 12 14 16 18 20

Deflection (mm)

Load

(N)

Test: SHEANT 2

Test Type: Compression Date 26 -07-00 File: C: SHEANT 2/ TST002.DAT Test Speed: 025.00mm/min Sample Type: IRREGULAR Pre – Load: OFF


0

500

1000

1500

2000

2500

3000

3500

4000

0 2 4 6 8 10 12

Fig 5: Force – Deformation curve of shelled nut at 20% Mc (wb)



A

B

C

E

F

A

B D

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3.2 Interpretation of Force-Deformation Curves of Unshelled Nuts Figures 6- 8 show the Force- Deformation curves of unshelled nut at 48%, 30% and 25% moisture contents respectively. From Fig. 6, the curve is approximately linear until at point B where there is a sudden drop; BC. At point B, the shell of the nut ruptures hence there is a sudden drop in the load and no deformation as a result of empty space between the shell and the nut. At C loading of the nut (kernel) begins, the curve is approximately linear until the point where the nut yields and finally ruptures at point E. For unshelled nuts, only force and deformation to point of shell ruptures is considered. From Fig. 7, the initial portion of the curve 0A is steep and short meaning that the shell of the nut ruptures under small load and deformation. Portions B, C, D and E follow almost the same trend as in Fig. 5 From Fig. 8, the initial point of the curve 0A is steep and shorter than the curve shown in Fig. 7 meaning that the force required to rupture the shell at this moisture content is smaller as compared to that at 30% moisture content. From the curves of shelled and unshelled nuts there are clear indications that the initial part of the curves all-concave towards the load (force) axes. For unshelled nuts, the initial portion of curve (from zero point to point of shell rupture) is steeper than that of the shelled nuts. This means that curves of hard materials are steeper than those of soft materials. This implies that the unshelled nuts can only be cracked and separated (cleaned) in order to obtain the shelled nuts whereas shelled nuts need to be crushed (milled)

Fig 6: Force – Deformation curve of unshelled nut at 48% Mc (wb)

Deflection (mm)


Ref 1: M.C. @ 48% wb Ref 2: UNSHELLED NUT Ref 3: Ref 4:

0

100

200

300

400

500

600

700

800

900

0 2 4 6 8 10 12 14 16 18 20A

B

C

D

E

Load

(N)

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A

B

C

D

E

Load

(N)

Deflection (mm) Fig 7: Force – Deformation curve of unshelled nut at 30% Mc (wb)



2 4 6 8 10 12 14 16 18 0 20

500

1000

1500

2000

2500

3000

3500

4000

4500

0

500

1000

1500

2000

2500

3000

3500

4000

4500

2 4 6 8 10 12 14 16 18

A B

C

D

Fig 8: Force – Deformation curve of unshelled nut at 25% Mc (wb)

Load

(N)

Deflection (mm)



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3.3 Linear Limit For each curve, a straight edge (scale rule) was placed on the force-Deformation curve and the point where the slope of the curve changes was taken as the linear limit (Mohsenin, 1984). The value of the force and the corresponding deformation at this point was read from the graph. Table 1 shows the average values of forces and the corresponding deformation at linear limits of shelled and unshelled nuts. For shelled nuts with moisture contents of 48%, 25% and 20% (wb), the average forces and deformations at point of linear limits are – 363.1N and 2.750 mm, 122.0N and 3.065 mm and 137.2N and 1.571 mm respectively For unshelled nuts at moisture content of 48%, 30% and 25 %(wb), the average forces and deformations at point of linear limits are: - 178.9N, 1.266 mm, 120.9N, 1.110 mm and 109.2N, 0.849 mm respectively. From these, the linear limit of unshelled nuts increases with increase in moisture content. This is because at lower moisture content, the shell becomes brittle and breaks up easily, whereas at higher moisture content, the shell is soft and so can exhibit some degree of elasticity. 3.4 Bioyield Point In biomaterials, bioyield point is an indication of initial cell rupture in the cellular structure of the materials. Bioyield point was noticeable only in curves of shelled nuts. From table 1, forces and the corresponding deformation at bioyield point for nuts at 48%, 25%, and 20% mc (wb) are: 479.8N, 3.455 mm, 621.0N, 5.991 mm and 662.6N, 8.177 mm respectively. This shows that bioyield point increases with decrease in moisture content. This is because at low moisture content, the cellulose wall of the nuts can withstand considerable amount of loading and deformation before yielding. 3.5 Rupture Point This is the point on the force-deformation curve where the material ruptures. The force at this point is the minimum required to break the material. From table 1, the average rupture force and the corresponding deformation for shelled nuts at 48%, 25% and 20% m.c. (wb) are: 610.1N, 5.287 mm, 909.7N, 9.946 mm and 1414.5N, 10.967 mm respectively. The values obtained show that as the moisture content of the shelled nut decreases; rupture force increases. This is because as the moisture content reduces, the tissues of the nuts become tougher From the values summarized in table 1, the average rupture force and the corresponding deformation for unshelled nuts at 48%, 30% and 25%(wb) are: - 249.4N, 1674 mm; 158.7N, 1.484 mm and 142.2N, 1.132 mm respectively. This shows that as the moisture content of the unshelled nut is decreased; the rupture force and the corresponding deformation decrease to a certain point (Olaniyan and Oje, 1999). This is because at higher moisture content, the nut fits closely inside the shell leaving no clearance thus, it becomes structurally turgid so that more force is required to rupture it. At lower moisture content however, the nut (kernel) shrinks, leaving a clearance between it and the shell; so any load applied will be borne only by the shell. From these findings, the nuts should be properly dried to facilitate shelling. Milling should be done at higher moisture content.

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3.6 Modulus of Deformability Modulus of deformability of a material is a measure of stiffness or rigidity of that material. As summarized in Table 1, the modulus of deformability of shelled nuts at 48%, 25% and 20% m.c (wb) was found to be average: 1.915 x 107, 0.698x107 and 1.876x107 Pa respectively. For unshelled nuts at moisture content of 48%, 30% and 25% (wb), the modulus of deformability was 2.638x107, 2.437x107 and 3.297x107 Pa respectively. The modulus of deformability of most soft biomaterials increases with increase in strain (Mohsenin, 1970). It means that for the same material, there will be different values of modulus of deformability depending on the point at which it is calculated. In this work however, the values of force and deformation used were from the initial portion of the curve because it is assumed that under small load, the material is elastic or visco-elastic enough to meet the requirements of Hertz’s theory of contact stresses. From the values, the modulus of deformability of unshelled nuts are higher than that of the shelled nuts – conforming to what was stated by Mohsenin (1970), as: “soft plant figures have usually flat curve (low Modulus while hard plant tissues have steep curves (high modulus).” This is because unshelled nut is stiffer to deformation than the shelled nuts. 4. CONCLUSION The rheological properties i.e. the modulus of deformability, the force and deformation at linear limit, bioyield and rupture points at 48%, 25% and 20% for shelled nuts and 48%, 30% and 25% m.c for the unshelled shea nut were determined. The shelled shea nut has mean modulus of deformability of 1.915 x 107 Pa, 0.698 x 107 Pa and 1.876 x 107 Pa at 48% 25% 20% m.c respectively and average deformation of 2.462 mm at an average force of 257.4N at linear limit, 5.874 mm and 587.8N at bioyield point and 8.733 mm and 978.1N at rupture point. The unshelled nuts have average modulus of deformability at 48%, 30% and 25% m.c of 2.638x107 Pa, 2.437x107 Pa and 3.297x107 Pa respectively and has an average deformation of 1.072 mm at an average force of 136.3N at linear limit, 1.430 mm and 183.4N at rupture point. The rheological properties are moisture dependent hence, shelling should be done at moisture content of 20% (wb) or below by impact forces (using beaters) while milling should be done at much higher moisture content by shear force action such as the one provided by the burr mill because of the elastic tendency of the nuts. Simple processing equipment could be designed and fabricated with the information provided above to enhance high performances of the processing equipment. REFERENCES Adgidzi D. 1999. Mechanization of Shea-Butter (Butyrospermum paradoxii) production in Niger State: progress & propects. Proceedings of the Nigerian Society of Engineers, Minna branch. First Annual conference held at Shiroro Hotel, Minna, 7-8th July. Amusa, T.R. 1998. Design and Construction of a manually operated mixer for milled Shea nuts. Unpublished B.Eng Thesis, Department of Agricultural Engineering, Federal University of Technology, Minna Nigeria ASAE, Standards 1986. Standard Engineering Practices and Data. American Society of Agricultural Engineers, St Joseph Ml. Pp 93-96. Dakogol, F.A. 2001. Determination of some engineering properties of Shea nut (Butyrospermum paradoxii): An M.Eng. Thesis (unpublished). Dept of Agric. Engineering, F.U.T. Minna. Dinrifo, R.R. and Faborode, M.O. (1993):- Application of hertz’s theory of contact stresses of Cocoa pod deformation. Journal of Agric. Engineering and Technology, 1:63-73. Mohsenin, N.N. 1984. Physical properties of Food and agricultural Materials: A teaching manual. Gordon and Breach scientific publishes, New York. Mohsenin, N. N. 1970. Physical properties of plant and Animal materials. Gordon and Breach scientific publishers New York.

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Oje, K 1993. Some Engineering properties of Thevetia nuts. Journal of Agricultural Engineering Technology 1 :38-45. Olaniyan, M.A. and Oje, K. 1999. Visco elastic – behaviour of shea nuts under Application of force. A paper presented at the 21st Annual conference of the Nigerian Society of Agricultural Engineers (NSAE) at the Federal polytechnic, Bauchi. Purseglove, J. W. 1984. Tropical Crops: Dicotyledons, Longman Group Limited (pp.704). Notation D – Deformation F – Applied force K – Shape constant R1, R2 – Minimum radius of curvature of body I and II respectively

'2

'1, RR - Maximum radius of curvature of the body I and II respectively

E – Young modulus N/m2 µ - Poisson’s ratio, coefficient of friction S – Stiffness modulus di- Diameter H- Height of diameter of the circle inscribing the minor diameter of nut traced L- Length of the diameter of the circle circumscribing the major diameter of the not traced Si – stress index

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TESTING OF AN ENGINE-POWERED GROUNDNUT SHELLING MACHINE

J. N. Maduako, M. Saidu, P. Matthias, I. Vanke Department of Agricultural Engineering

Federal University of Technology P.M.B. 2076, Yola. Adamawa State, Nigeria.

E-mail: [email protected] ABSTRACT Lack of groundnut processing machines, especially groundnut sheller, is a major problem of groundnut production, especially in Adamawa State of Nigeria. This paper therefore presents the testing of an engine-powered groundnut shelling machine with three varieties of groundnuts, namely ICGV-SM-93523, Samnut 10-Rmp 12 and Samnut 10-Rmp 9. The performance of the machine was evaluated in terms of throughout capacity, shelling efficiency, material efficiency and mechanical damage. The throughout capacity of the machine was found to be 64.6,69.3 and 60.8 kg/h for the ICGV, Rmp 12 and Rmp 9 varieties respectively, giving an average throughout capacity of 64.9 kg/h for the three groundnut varieties. The material efficiency of the machine was found to be 87.6%, 83.1% and 85.8% for the ICGV, Rmp 12 and Rmp 9 varieties of groundnuts, which averaged 85.5%. The shelling efficiency of the machine was found to be 90.2%, 91.9% and 85.7% for the ICGV, Rmp 12 and Rmp 9 varieties of groundnuts, respectively. The shelling efficiency of the machine was therefore found to be 89.0% on the average for the three groundnut varieties. The mechanical damage of the machine was evaluated to be 14.5% on the average for the three varieties of groundnuts. The machine is recommended for use in both urban and rural areas because it can be used with a 5.0 hp petrol engine or electric motor, whichever is available. KEY WORDS: Testing, engine-powered, groundnut shelling machine.

1. INTRODUCTION Groundnut (Arachis hypogaea) is one of the most important food legumes in the world (Norde et al, 1982). It has been identified as one of the leguminous species with the greatest potential for both food and industrial purposes in the tropical regions of Africa (Milner, 1973). It is an important economic crop in many states of Northern Nigeria to the extent that some states in the producing areas depend mostly on the revenue from its sales to finance rural development. Preliminary studies reported by Young (1982) showed that groundnut seed contains 42 to 52 % oil, which is obtained by mainly crushing the seed. The oil is a desirable cooking and salad oil, because of its high quality, containing about 80 % unsaturated fatty acids, such as oleic and linonoic acids. Groundnut is an excellent source of protein to balance diets high in cereals and starchy foods, and to supplement animal proteins. Groundnut cake contains concentrated proteins, minerals and vitamins (Hamman and Caldwell, 1974). Groundnut processing is highly mechanized in developed countries, while in most of the developing countries, manual processing is still the norm despite the drudgery and time wastage involved. A typical groundnut sheller removes the seeds from the pods. The pods are fed into the shelling unit made up of cylinder and concave where the pods are shelled. The kernels fall through the slots and the shells and other foreign materials are separated from the seeds by an air stream supplied by a blower or by gravity through agitated and inclined sieve openings. The available machines for shelling groundnuts in Adamawa State are mostly manually operated and therefore consume much human energy and time. Some imported large-scale plants are increasingly replacing small groundnut processing units, but due to high foreign exchange rate, the cost of such imported machines is clearly out of reach of poor farmers in Nigeria.

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Several groundnut shelling machines currently in use around the world, as reviewed by Carruthers and Rodriquez (1985), include: (a) Dandekar Groundnut Sheller: The machine consists of frames, shelling chamber and sieve.

The shelling chamber is a sheet metal case, which contains a sieve, which helps to break the shells. The nuts fall into the shelling chamber from a feeder hopper. They are shelled and discharged from a chute. The output is just 50-60 kg/h of shelled groundnuts.

(b) Baby Groundnut-Decorticating Machine: In this type of machine, the groundnuts are shelled by revolving wooden beaters against a roll bar screen and separated by winnowing. Unshelled pods can be fed back into the sheller. The machine is operated by a 0.75 kW single-phase electric motor. Shelling capacity of this machine is just 40 kg/h of shelled nuts.

(c) Cayor Rotary Groundnut Sheller: The machine is made from galvanized steel body sheets. It consists of a beater that revolves within the shelling chamber. The output from this machine is about 100 kg/h of shelled nuts. Seed breakage is about 12-14 %.

(d) Hand-operated Groundnut Sheller. This machine is manually operated. It consists of a curved screen at the base of an open tank, mounted on a frame. Shelling is achieved by pushing the handle back and forth, and this sweeps a scraper across the bottom of the tank.

(e) Power-Rubber Groundnut Sheller: This machine is similar to the hand-operated unit, but also has an integral winnowing fan. Its shelling efficiency is about 99.5 % and requires a 1.5 kW electric motor to operate. The output is 300 kg/h.

(f) Foot-operated Decorticator: This is a treadle-powered machine and has a flywheel to help in maintaining rotation. An electric motor may be fitted as an option.Output is about 25 kg/h. There is also a pedal-operated groundnut sheller, which is made from mild steel and requires two operators.

(g) Rubber-type Groundnut Sheller: This is one of the smallest types of groundnuts shellers. It consists of feed hopper and rubber-type roller and a fixed cover, concave decorticating plate and discharge chute. The output is in the range of 40-60 kg/h.

(h) Mobile Groundnut Decorticator: This is a large groundnut decorticator mounted on a chasis with pneumatic-type wheels and a straw bar with a screw jack. The nuts fall into a cylindrical shelling chamber from the integral feed hopper and are moved against a screen by rotating beaters. The kernels and shells then fall into an aspiration box through which an adjustable airflow passes to remove the shells. The machine can be powered by electric motor, diesel or petrol engine. Power requirement is 5.5 kW and capacity is 100 kg/h

It was reported that good performance of a sheller depends on its cylinder size, concave clearance, fan speed and sieve shaker speed (Kaul and Egbo, 1985). The factors affecting the performance of a sheller have been classified by Asota (1996) into three categories, namely machine-based factors (e.g. cylinder speed, cylinder-concave clearance, type of cylinder and fan speed), crop-based factors (e.g. crop moisture content and orientation) and operator-based factors (e.g. feed rate, skill and experience).

Some test parameters, such as throughput capacity (kg/h), shelling efficiency (%), material efficiency (%) and mechanical damage (%), as earlier used by Kutte (2001) in evaluating a rice threshing machine, can be applied in testing a sheller as follows: Throughput capacity (kg/h) = Qs --------------------------------(1) Tm Shelling efficiency (%) = Qs x 100 -------------------------------(2) Qt Material efficiency (%) = Qu x 100 ------------------------------(3) Qu +Qd Mechanical damage (%) = Qd x 100 ----------------------- (4) Qu+Qd

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where: Qt = total weight of shelled and unshelled groundnut pods (kg) Tm= time of shelling operation (h) Qs= quantity of shelled groundnut pods (kg). Qu= quantity of undamaged groundnut seeds (kg). Qd= quantity of damaged groundnut seeds (kg) The objective of the work was to carry out a comprehensive technical evaluation of an engine powered groundnut shelling machine. 2. MATERIALS AND METHODS 2.1 Description of the Groundnut Sheller The groundnut sheller, as shown in Fig.1, consists of feeding unit, driving unit, shelling unit and separation unit. The feeding unit is a hopper (1) through which the unshelled pods are introduced into the shelling chamber. The shelling chamber is the clearance between the rasp bars on the shelling drum and the perforated stationary concave (4) underneath the drum. The hopper (1) is located on top of the drum cover (2). The drum shaft (14) is supported by bearings at its ends and powered by a 5.0 hp petrol engine (12) through a drum belt (13) and pulley (15) drive, at a speed of 300 rpm. The separation unit consists of two sieves underneath the concave. The first sieve (5) receives the seeds and shells that fall through the perforated concave (4) and retains the unshelled pods, if any. The second sieve (6) retains the broken shells and lets the seeds drop through its apertures to an inclined tray pan or chute beneath it, for collection in a container or sack. The sieve pulley (10) and sieve belt (11) drive transmits power to the sieve crankshaft (9) from the engine (12) and drives the two sieves (5 & 6) in reciprocating motion. The crankshaft (9) rotates at a speed of 500 rpm while the sieves reciprocate to and fro in a linear motion, being driven by the connecting rod (8) and crankshaft mechanism, as shown in Fig. 1. The supporting frame (3) of the entire assembly is made of angle iron bars. Orthographic projections of the shelling machine are shown in Fig. 2.

Figure 1: Isometic Drawing of the groundnut shelling machine

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Figure 2: Orthographic third angle projection of the groundnut shelling machine. 2.2 Sampling of Groundnuts Samples of three varieties of groundnuts, namely ICGV-SM-93523, Samnut10-Rmp12 and Samnut-10 Rmp 9, commonly grown in Adamawa State were collected from the Research Farm of the School of Agriculture and Agricultural Technology (SAAT) of Federal University of Technology, Yola-Nigeria. 2.3 Testing of the Shelling Machine The groundnut shelling machine was tested in the Department of Agricultural Engineering of the Federal University of Technology, Yola. The test was carried out in two phases: firstly, the free run (without load) and secondly, testing with load (i.e. shelling of groundnuts). A weighing balance and stop watch were used for measuring the quantity of unshelled groundnut pods and the duration of shelling, respectively. 2.3.1 Free Run (without load) of the Machine The machine was operated without any load of groundnuts. The machine was set to run freely for about 15 minutes to check for any abnormal vibrations and noise, or any malfunctioning.

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2.3.2 Shelling Test with ICGV-SM-93523 Groundnut Variety About 0.95 kg of groundnut pods were fed into the shelling chamber through the hopper and the engine was started. The rasp bars on the shelling drum in conjunction with a concave located under the shelling drum struck and pressed the groundnut pods against the inside of the hood and the concave. The groundnut seeds and the broken shells were pushed through the slots in the concave. The sieves separated the shells and other foreign materials from the groundnut seeds which were collected in a sack attached to the inclined pan or chute under the second sieve. The time taken to complete the shelling was recorded. The wholesome groundnut seeds collected were weighed, using the weighing balance. The damaged seeds were also collected and weighed. The test was repeated three more times with 0.75, 0.65 and 0.64 kg of groundnut pods, using the same procedure. 2.3.3 Shelling Test with Samnut-10 Rmp 12 Groundnut Variety This test was carried out using 1.50, 1.10, 1.05 and 1.45 kg of Samnut 10-Rmp 12 variety of groundnut pods and the procedure reported in section 2.3.2 was followed for the shelling operations.

2.3.4 Shelling Test with Samnut 10-Rmp 9 Groundnut Variety This test involved 0.55, 0.60 and 0.69 kg of Samnut 10-Rmp 9 variety of groundnut pods which were shelled separately using the same procedure reported in section 2.3.2.

2.3.5 Test Parameters The performance of the shelling machine was tested in terms of throughput capacity (kg/h), shelling efficiency (%), material efficiency (%) and mechanical damage (%), using equations 1,2,3 and 4, respectively, as earlier indicated in section 1.2 3. RESULTS AND DISCUSSION The results obtained during the testing of the shelling machine with ICGV-SM-93523, Samnut 10-Rmp 12 and Samnut 10 Rmp 9 varieties of groundnut pods are shown in Tables 1, 2 and 3, respectively. The machine’s performance parameters calculated from the results are also shown in the same tables.

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Table 1: Test parameters of the shelling machine with ICGV-SM-93523 groundnut variety S/No Weight of

groundnut pods fed into the hopper, Qt (kg)

Weight of shelled groundnut seeds Ws (kg)

Weight of groundnut husk removed Wh (kg)

Weight of unshelled groundnut pods, Wu (kg)

Effective time of shelling, Tm (min.)

Weight of undamaged groundnut seeds, Qu

(kg)

Weight of damaged groundnut seeds, Qd (kg)

Mechanical damage (%)

Throughput capacity (kg/h)

Shelling efficiency (%)

Material efficiency (%)

1 2 3 4 Total Mean

0.95 0.75 0.65 0.64 2.99 0.75

0.63 0.49 0.46 0.47 2.05 0.51

0.22 0.16 0.14 0.12 0.64 0.17

0.100 0.100 0.050 0.050 0.300 0.075

0.75 0.58 0.58 0.58 2.49 0.87

0.53 0.43 0.41 0.42 1.79 0.45

0.100. 0.060 0.050 0.050 0.260 0.065

15.9 12.3 10.9 10.6 49.7

12.4 ± 2.1

68.0 67.2 62.1 61.0

258.3 64.6 ± 3.0

89.5 86.7 92.3 92.2 360.7

90.2 ± 2.3

84.1 87.7 89.1 89.4 350.3

87.6 ± 2.1

Note: Qs =Ws +Wh, Qt =Ws + Wh + Wu, Ws = Qu + Qd Table 2: Test Parameters of the shelling machine with SAMNUT 10-RMP 12 groundnut variety.

S/No Weight of groundnut pods fed into the hopper, Qt (kg)

Weight of shelled groundnut seeds, Ws (kg)

Weight of groundnut husks removed, Wh (kg)



Weight undamaged groundnut seeds, Qu (kg)






1 2 3 4 Total Mean

1.50 1.10 1.05 1.45 5.10 1.27

1.00 0.72 0.75 0.97 3.44 0.86

0.40 0.28 0.20 0.38 1.43 0.35

0.10 0.10 0.10 0.10 0.40 0.10

1.10 0.92 0.92 1.10 4.04 1.04

0.80 0.62 0.65 0.77 2.84 0.71

0.20 0.10 0.10 0.20 0.60 0.16

20.0 13.9 13.3 20.6 67.8

16.9 ± 3.3

76.4 65.2 61.9 73.6

277.1 69.3 ± 5.9

93.3 90.9 90.5 93.1 367.8

91.9 ±1.2

80.0 86.1 86.7 79.4

332.2 83.1 ±3.3

Note: Qs =Ws +Wh, Qt =Ws + Wh + Wu, Ws = Qu + Qd

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Table 3: Test Parameters of the Shelling Machine with SAMNUT 10-RMP 9 Groundnut Variety

S/No Weight of groundnut pods fed into the hopper, Qt (kg)

Weight of shelled groundnut seeds, Ws (kg)

Weight of groundnut husks removed, Wh (kg)



Weight undamaged groundnut seeds, Qu (kg)






1 2 3 4 Total Mean

0.55 0.60 0.65 0.69 2.49 0.62

0.37 0.36 0.40 0.41 1.54 0.385

0.13 0.14 0.15 0.17 0.59

0.147

0.05 0.10 0.10 0.11 0.36 0.09

0.50 0.52 0.54 0.54 2.10

0.525

0.33 0.31 0.34 0.34 1.32 0.33

0.04 0.05 0.06 0.07 0.22 0.05

10.8 13.9 15.0 17.1 56.8

14.2 ± 2.2

60.0 57.7 61.1 64.4

243.2 60.8 ± 2.4

90.9 83.3 84.6 84.1

322.9 85.7 ±3.0

89.2 86.1 85.0 82.9 343.2

85.8 ±2.2 Note: Qs =Ws +Wh, Qt =Ws + Wh + Wu, Ws = Qu + Qd

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3.1 Throughput Capacity (kg/h) The throughput capacity of the groundnut sheller was found to be 64.6, 69.3 and 60.8 kg/h on the average for ICGV-SM-93523; Samnut 10-Rmp 12 and Samnut 10-Rmp 9 varieties of groundnuts, respectively, as shown in tables 1,2 and 3, respectively. Samnut 10-Rmp 12 was found to be easier to shell than ICGV and Rmp 9 varieties, as evidenced by the machine’s highest throughput capacity of 69.3 kg/h. However, the throughput capacity range of 60-69 kg/h for the three varieties, which averaged 64.9 kg/h, is higher than those of Dandekar sheller (50-60 kg/h), Baby decorticator (40 kg/h), foot-operated decorticator (25 kg/h), and rubber-type sheller (40-60 kg/h) as reported by Carruthers and Rodriquez (1985).

3.2 Shelling Efficiency (%) The shelling efficiency was found to be 90.2, 91.9 and 85.7 % on the average for ICGV-SM-93523, Samnut 10-Rmp 12 and Samnut 10-Rmp 9 varieties of groundnuts, respectively, as shown in Tables 1, 2 and 3, respectively. The shelling efficiency of the machine was found to be highest (91.9 %) in the shelling of Samnut 10-Rmp 12 variety of groundnuts. Also, the average shelling efficiency of 89.0% for the three varieties of groundnuts is quite commendable. Moreover, it compares favorably with those of the Cayor rotary groundnut sheller (89.0%) and the Mobile groundnut sheller (89.3%) reported by Carruthers and Rodriquez (1985). 3.3 Material Efficiency The material efficiency of the sheller was found to be 87.6, 83.1 and 85.8 % on the average for ICGV-SM-93523, Samnut 10-Rmp 12 and Samnut 10-Rmp 9 varieties of groundnut, respectively, as shown in Tables 1, 2 and 3 respectively. The shelling machine can be seen to be consistent in the quality of shelled groundnut seeds, judging from the fact that its material efficiencies of 87.6, 83.1 and 85.8 % compare favourably, and averaged 85.5 % for the three varieties of groundnuts. The quality of its material handling and the final product (groundnut seeds) is steady, no matter the variety of groundnuts involved. 3.4 Mechanical Damage The mechanical damage of the sheller was found to be 12.4, 16.9 and 14.2 % on the average, for ICGV-SM-93523, Samnut, 10-Rmp 12 and Samnut 10-Rmp 9 varieties of groundnut, respectively, as shown in Table 1,2 and 3, respectively. The average mechanical damage of 14.5 % obtained with this machine for the three varieties of groundnuts compares favourably with that of Cayor rotary groundnut sheller, which is reported to be 14.0% also (Carruthers and Rodriquez, 1985). 4. CONCLUSION Mechanized shelling at the rate of 64.9 kg/h obtainable with this machine, and at an efficiency of 89.0 % will make the groundnut shelling operation faster and more thorough than manual shelling. Also, the material efficiency of 85.5 % with only a little damage of 14.5 % ensures a neat operation and high quality product. The fact that the machine can handle all the varieties of groundnut tested makes it very attractive to the market. Moreover, since the sheller is operated with a 5.0 hp petrol engine, it can be used in rural areas where there is no electricity supply, but in urban areas, when there is electricity supply, the engine can be replaced with a 5.0 hp electric motor for the shelling operation.

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REFERENCES Asota, C.N. 1996. Cowpea/Soyabeans shelling: principles and practice. Proceedings of a

Commonwealth-sponsored Workshop on Technology, Tools and Processes for Women. Institute for Agricultural Research, Samaru. Ahmadu Bello University, Zaria-Nigeria p.111.

Carruthers, I and M. Rodriquez 1985. Tools for Agriculture: a buyer’s guide to appropriate equipment. 3rd edition. IT Publications, London. pp. 99, 100. 117.

Hamman, A. and P. Caldwell 1974. Oil crops of the world. Heineman Education Books, Ibadan. Nigeria. pp. 319-320.

Kaul, R.N. and C.O. Egbo 1990. Introduction to agricultural mechanization. Macmillan Education Ltd., London. pp. 132, 133, 135.

Kutte, M.T. 2001. Reactivation and performance evaluation of the threshing unit of a combine harvester scrap for stationary threshing of rice. M.Eng. Thesis, Dept of Agricultural Engineering, Federal University of Technology, Yola-Nigeria. pp. 47-48

Milner, H.G. 1973. Traditional extraction of oil from Nigerian foodstuff. Heinemann Education Books, Ibadan-Nigeria.

Norde, E.N.; C.Jensen and J.D. Helsel 1982. Priorities and strategies for groundnut research in Nigeria. National workshop on Groundnuts. Institute for Agricultural Research, Samaru. Ahmadu Bello University, Zaria-Nigeria. p.34.

Young, T.S. 1982. Field crop production in tropical Africa. Macmillan publishers, New York.

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Nigerian Institution of Agricultural Engineers ©

38

DEVELOPMENT OF A MANUALLY OPERATED VEGETABLE BLENDER

E. J. Upahi Department of Agricultural Engineering Kaduna Polytechnic, Kaduna, Nigeria

e-mail: [email protected] ABSTRACT The project was conceived to provide an alternative to the electrically operated blenders for vegetables. The machine was designed, constructed and tested for blending and leakage efficiencies. It had Blending Efficiencies (BE) of 96.76%, 88.40%, 50.73% and 34.88% and Leakage Efficiencies (LE) of 3.68%, 3.70%, 0.42% and 0.70% respectively for tomatoes, onions, green beans and carrot, when they were reduced to a quarter of their original sizes before blending. It was observed that pre-blending reduction in size enhances the blending efficiency for each of the vegetables blended. Also fruity vegetables were best blended using the machine. Production cost of the machine was N2,643:02. KEYDWORDS: Vegetable blender, blending efficiency, tomatoes, onions, carrot, beans, design. 1. INTRODUCTION Kochhar (1986) defined vegetables as “..the plants or plant parts that are usually eaten with the main meal and which are commonly salted, boiled or used for deserts and salads”. Thus, crops such as tomatoes, pepper, okra, eggplants, garlic, onions, etc are regarded as vegetables. Vegetables could be classified into: earth or root vegetables e.g. garlic, onions and carrot; herbage or leafy vegetables e.g. spinach, lettuce, cabbage, brusselle and sprouts; fruity vegetables e.g. sweet corn, tomato, pumpkin, pea, eggplant and soybean. (Kochhar, 1986; William et al, 1991).

Vegetables have become major components of human diets all over the world. Though they are not major sources of energy, they have been found to provide the much-needed minerals and vitamins, which serve as food supplements (Oomen and Gruben, 1978). They also serve as seasoners by providing flavour and taste to diets, thus increasing the appetite of the consumer (Kinton and Ceserani, 1995). They are usually, processed as soon as they are harvested, principally due to their high degree of perishability. Where they need to be stored for a time lag, thermal and environmental conditions must be modified to ensure their keeping quality. A temperature range of 7-100C and an environmental relative humidity (rh) of about 90% are recommended for the storage of vegetables (Williams et al, 1991). Depending on the nature of the vegetable, various means have been developed for processing the vegetables. These, according to Kinton and Ceserani (1995), include:- using the local stone mills Chopping of the vegetables by the use of knives; using mortar and pestle; using electrically operated blenders. In all of these, vegetables pass through size reduction by fracturing, which is a primary requirement before they are converted to the needed forms (such as sauce or garnishes). The first three means of size reduction above are labourious, slow and inefficient (as uniform grind cannot be got), though they have the advantage of non-dependence on conventional sources of power for running. Lewis (1990) reported that most vegetables have water content ranging from 74 to 95%. The mechanical properties of vegetables are determined by their shear and compressive strengths. Physically, the fleshy and root vegetables have definite shapes but the leafy vegetables have irregular shapes. The physical extents can be measured out since there are no reported anthropometric data for vegetables. In the blending of vegetables three major actions are carried out. These are cutting, grinding and mixing. While cutting and grinding are size reduction processes, mixing is the dispersal of one

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39

component of the product through another. For a specific vegetable, the proportions of constituents are already known and all that is needed to bring them to a state of homogeneity. To ensure size reduction, an energy level that will produce a force above the crushing strength is required. Energy requirement for crushing the vegetable can be estimated from the relation, (Lewis, 1990): dEdD

kD

r mn=

− (1)

Where dEr = Energy required to cause a small change (dD) in diameter (Joules) Km = Characteristic constant, depending on the product D = Diameter of the specimen (m) n = Constant (depending on the type of vegetable). It is pertinent therefore, to determine the energy that will be required to crush or grind a vegetable. The most useful relation for the determination of this energy is the Bond’s equation given as;

E kD Dr m= −

2 1 1

2 1

(2)

Where, Er = Energy required (kWh) D2 = final diameter (m) D1 = initial diameter (m) Km = Strength characteristic constant There is the need for motorised blenders to reduce drudgery, improve speed and uniformity of grind. As advantageous as this might seem, there lies the limitations of power inconsistency in the urban areas and non-existence of electrical power in most of Nigerian rural dwellings. Thus there is a requirement for a means of blending to compliment the conventional electric blender especially for the rural areas. The objective of this work was to develop a domestic and rural-based blender for efficient blending of vegetables. 2. METHODOLOGY 2.1 Design Specifications The followings were chosen as the design standards Machine hopper capacity = 1 litre (1x10-3m3). This was chosen for operational convenience. Speed of rotation of blades = 1,500 rpm (The recommended speed for blending vegetables). 2.1 The Cutting Blades The cutting blades are chosen as they appear on the motorised blenders. They are of sizes 30mm x5mm x10mm and are made of stainless steel material. The blades are mounted on a base carrier and oriented at 30o to the horizontal on the carriers at a spacing of 20mm to accommodate minimal sizes of the vegetables. The blade carrier is mounted on a rotating vertical shaft within the blending housing. 2.2 The Hopper The hopper is frustum shaped of circular cross section. The minimum diameter (d) is chosen to accommodate the blades when mounted. At mounted position, the blades will take a longitudinal expanse of 117mm. With a clearance of 5mm both sides of the blades, a total minimal diameter of 120mm was computed. Since a volume of 1 x 10-3 m3 was chosen, and using the relation of volume (V) for frustrum.

( )V R r h= −13

2 2 (3) Where R and r are the top and bottom radii of the hopper respectively and h is the height of the hopper.

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With a convenient height of 200mm and a free board of 20% of h, an overall height of 240mm was taken and a top radius of 75mm was computed. Side angles were calculated to be 860 to the horizontal which is 40 to the vertical. Maximum density of 1,095kg/m3 for vegetables was reported by Lewis (1990). This translates to 1.095kg of product in the hopper. Using this as the maximum load and a factor of safety of 1.5, a design load on the hopper of 1.64kg was computed which translates to 16.2N of normal load on the hopper wall. Using a material of thickness 3mm a stress of 6,400N/m2 was computed. A compressing stress of 637.7N/m2 on the base was also computed. Stainless steel was chosen for the hopper base while glass was chosen for the hopper. 2.3 The Hopper Cover The hopper cover is a circular plate of thickness 3mm, outer diameter 250mm and a circular ring of thickness 3mm and height 3mm and external diameter 246mm The ring is fixed on one side of the plate cover concentrically. 2.4 The Blending Shaft Desired rotation of shaft is 1500rpm. Hall, et al (1961), gave the relation for computing diameters of shafts carrying load as:

( )dS

k Ms

t t3 216

=π

………. (4)

Where d = diameter of the shaft (m); Ss = Shear Stress (N/m); Kt = Combined shock and fatigue factor applied to torsional moments = 1.5 (for shafts under torsion); Mt = Torsional moment (N/m)

Mt = ( )8 476 9, . hprpm

N/m ……… (5)

When reducing from an infinitely large particle size to a particle size of 100 µ m , the Bond’s equation is used to determine the energy required and consequently the power. Using a maximum size of vegetables to be 52mm(D1) and a final size(D2) to be 100 µ m and using equation (3) a power of 0.24 hp was computed and using equation (6) and (5) the shaft diameter was computed to be 4.8mm. A diameter of 10mm is therefore chosen for the shaft in construction. 2.6 The Drive The drive consists of a gear train, a cranking shaft and a cranking handle. The cranking is about the horizontal. This is to be converted to rotational motion about the vertical for the blending action. The gear train consists of a driven bevel gear attached to the vertical shaft. The configuration in Fig 1 illustrates the driving system.

Fig. 1 The Drive System

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From the configuration, G2 and G4 are to serve as pinions (driven gears) while G1 and G3 are the driving gears. Speed on G1 is to be multiplied by G2. G2 and G3 will thus rotate at the same angular speed. G4 is to multiply the speed from G3. While G1 and G2 are straight spur gears, G3 and G4 are bevel gears. Experimenting, it was estimated that an average man can crank about 50 revolutions per minute thus a maximum of 50rpm was chosen for the cranking. Thus G1 will be at 50 rpm. This will be multiplied to 500rpm at G2. G1 has 100 teeth. Using the relation after Shigley (1972), ωω

1

2

2

1=

NN

(6)

Where ω1= angular speed of G1; ω2 = angular speed of G2; N2 = No of teeth of G2; N1 = No of teeth of G1. N2 was computed to be 10.5. G2 therefore has 10 teeth. With r1 chosen as 110mm, r2 = 11mm; Diameter of G1 = 220mm; Diameter of G2 = 22mm; G3 rotates at the speed of G2 = 500rpm; G4 is expected to rotate at 1500rpm. Gear ratio of G3 to G4 = 1:3 (i.e. 1 rotation of gear to 3 of the pinion). Shigley (1972) specified minimum number of teeth for bevel gears. Based on this, 39-tooth gear is selected against a 13-tooth pinion to conform to Shigley’s specification. Table 1: Gear and pinion parameters Parameter Gear Pinion Face (mm) Pitch angle (deg) Pitch diameter (mm)

12 71.6 70

12 18.4 30

The cranking arm is of size 100mm x 15mm x 5mm with a 10mm hole on the swinging end to hold the handle. The handle is of wood material, cylindrical in shape and of length 70mm and diameter 25mm. The handle is impregnated with a metal rod of diameter 10mm. 2.7 The Base Housing The base housing is made from 3mm thick mild steel sheet with dimensions of 200mm x 150mm x 250mm to house the gear train. The blending shaft attached to the pinion (G4), carries a square top of 10 x 10mm. The part attached to the blades, carries a square hole 10mm x 11mm to fit into that of the driven bevel gear. 2.8 The assembly The machine basically comprises of two major parts – the blending cup and the base casing. The blending blades were fixed by screws to the vertical shaft fitted to a housing, which carries the cup. The gear train was mounted on the housing. Fig. 2 shows the orthographic projections of the manual blender while Fig. 3 shows the pictorial presentation.

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Fig. 2. Orthographic projection of the Fig. 3. The pictoral drawing of the Vegetable Blender Vegetable Blender PARTS: 1 = Hopper Cover, 2 = Blending Hopper, 3 = Blending blades, 4 = Blending shaft, 5 = Spur Gears, 6 = Straight Gears, 7 = Bearings, 8 = Rotating shaft, 9 = Base Housing, 10 = Cranking Arm, 11 = Craning Handle 2.9 Power Requirement for the Machine At the cranking level, the power required to turn the shaft is given by (Hannah and Stephens, 1972): P T= ω (7) With the cranking arm producing a rotation of 1,500rpm on the blades, an equivalent angular speed ω = 157 rad/s. The Equivalent torque is given by: T I= ω 2 (8)

For I d m=π 4

4

64 (Khurmi, 1981) and diameter of 10mm, a torque of 1.21x10-5 N-m and using equation

(8) a power of 1.90x10-3 hp was computed. 2.10 Machine Evaluation The performance of the machine was evaluated through twelve tests. Three levels of tests were carried out on the machine for four vegetables. In the first, the vegetables were introduced in whole sizes into the machine. In the second, the products were introduced after reducing them into half sizes and in the third, when reduced to quarter sizes using a knife. The mass of product introduced (W1), that of full paste (W2) and that of unblended pieces (W3) were measured for the six vegetables. In each case, a 2-minute blending time was maintained. The unblended materials were removed from the paste by the use of a sieve with mesh size of 3mm.

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Blending efficiency (BE) and Leakage Efficiency (LE) were computed from the relations below;

Blending efficiency (BE) = Weight of paste wWeight roduced w

x

( )int ( )

2

1100 (9)

Leakage Efficiency (LE) = w w ww

x1 2 3

1100

− +( )( )

(10)

w3 = Weight of unblended vegetable 3. RESULTS AND DISCUSSION 3.1 Blending and Leakage Efficiency Table 2 presents the results of the blending tests using equation (9) and (10), the Blending Efficiency (BE) and Leakage efficiency (LE) as determined, are as presented in Table 3. Table 2. Results of blending tests Vegetables Blending

time (mins) Wt of materials (g) Wt. Introduced (w1)

Fully Blended (w2)

Unblended (w3)

Tomatoes (whole size) Tomatoes (½ size) Tomatoes (¼ size) Onions (whole size) Onions (½ size) Onions (¼ size) Green beans (whole size) Green (½ size) Green (¼ size) Carrot (whole size) Carrot (½ size) Carrot (¼ size)

2 2 2 2 2 2 2 2 2 2 2 2

93.0 92.5 92.5 84.5 85.0 86.5 96.5 90.0 96.0 102.0 92.0 86.0

76.5 83.0 84.5 66.5 70.5 76.5 30.5 35.5 48.7 16.5 22.2 30.6

14.2 6.60 4.60 16.90 13.60 6.80 65.7 53.90 46.90 85.20 69.50 54.80

Using equations (9) and (10), the Blending Efficiency (BE) and Leakage Efficiency (LE) as determined, are as presented in Table 3. Table 3. Blending and leakage efficiencies Vegetable Type Blending Efficiency (BE)

(%) Leakage Efficiency (LE) (%)

Tomatoes(whole size) Tomatoes (½ size) Tomatoes (¼ size) Onions (whole size) Onions (½ size) Onions (¼ size) Green beans (whole) Green beans (½ size) Green beans (¼ size) Carrot (whole size) Carrot beans(½ size) Carrot (¼ size)

82.26 89.73 96.76 78.70 82.94 88.44 31.61 39.44 50.73 16.18 24.13 34.88

2.47 3.14 3.68 1.30 1.06 3.70 0.30 0.70 0.42 0.30 0.33 0.70

Prior reduction in size of the vegetable increased its efficiency of blending. Leakage efficiencies are higher for the fleshy vegetables owing to their higher moisture content. Blending is a function of

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surface area. At fully blended state, the surface area is increased considerably and this accounts for the amount of energy that is dissipated in the blending operations. The results got conform to the ranges obtained using conventional blenders. The blending efficiency of carrot is generally low. This is attributed to the low moisture content and the fibrous nature of carrots, which demand for higher shearing forces to separate the particles. 3.2 Cost of Production The costing of the machine is based on Material Costs; Fabrication and Labour Costs; Energy Costs and Logistic Costs. The cost of materials are presented in Table 4. Table 4. Costs of materials S/No Material Size Qty Unit Cost (N) Total Costs(N) 1 5mm Stainless steel sheet 50x100cm 2 250 500 2 3mm Mild steel sheet 350x350cm 1 275 275 3 25mm Steel rod 100cm 1 150 150 4 10mm Mild steel plate 25x25cm 1 200 200 5 1

2 " Roller bearings 5 65 325 6 Glass chips 3kg 50 150 7 Screws 1

2 " 2 10 20 8 Bolts and nuts 6mm 3 10 30 9 Wooden handle 1 40 40 10 G12 welding electrodes 10 15 150 11 Paint 1

4 gallon 600 150 Total N 1,965 The cost of fabrication are as presented in Table 5 Table 5. Fabrication labour costs S/No Activity Average Cost(N) 1 Gear Cutting 200 2 Glass Moulding 100 3 Shaft Cutting 50 4 Welding works 100 4 Body Filling and painting 50 Total 500 Energy cost was estimated based on the power ratings as in Table 6. Table 6. Energy consumption S/No Equipment Rating (kW) Hours of Use Total power Use

(kWh) 1 Lathe Machine 2.32 7 5.38 2 Drilling Machine 0.746 1

2 0.373 3 Grinding machine 0.746 1

2 0.373 4 Milling Machine 3 1

2 1.50 5 Arc welding Machine 0.746 2 1

2 1.865 6 Power Saw 0.746 3 2.238 7 Spraying Machine 1.20 1

2 0.60 Totals 10.25 14.50 12.329 With an electric power charge of N 4.30 per kWh, a total energy cost of N53.02 was computed.

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Costs of transportation and enquiries stood at N125. Thus a production cost of N2,643.02 was computed. 4. CONCLUSION The manually operated vegetable blender was designed, constructed and tested. Test revealed that higher blending efficiencies are obtained when there is reduction in size prior to introduction into the blender. The fleshy vegetables have both higher blending and leakage efficiencies owing to their higher moisture contents. This presupposes that the higher the moisture content, the higher the blending and leakage efficiencies. Further improvement on the machine should concentrate on the increase in its blending efficiency. The production cost of the machine is N2,643.02. REFERENCES Hall, J.A.S., A.R. Holowenko and H.G., Lauglin 1961. Machine Design; McGraw Hill Book Co. New York. Hannah,J and R.C. Stephens 1972. Mechanics of Machines; Edward Anold Pub. Ltd. Pp371-374 Khurmi R.S. 1981. Strength of materials; S. Chand and Co. Ltd Kinton, R. and V. Ceserani 1995. The Theory of Catering; ELBS pub. With Hodder Stoughton, Seven oaks, Kent. Kochhar, S.L 1986. Tropical Crops, (2nd ed). The Interstate Printers and Pub. Inc. USA,. Lewis, M.J 1990. Physical Properties of Food and Food Processing Systems; Ellis Hormod ltd; Mohsenin, N.N 1970. Physical Properties of Plant and Animal Materials; Gordon and Branch Science pub. Inc., New York. Oomen, H.A. P.C. and G.J.H. Grubben 1978. Tropical Leaf Vegetables In Human Nutrition; Royal Tropical Institute, Amsterdam Shigley, J.E 1972. Mechanical Engineering Design; (2nd ed.) McGraw Hill Book Co. New York. Ware, G.W 1975. Producing Vegetable Crops, (3rd ed.); The Interstate Printers and Pub. Inc. USA, Williams, C.N.; J.O. Uzo, and W.T.H. Pergerine 1991. Vegetable Production in The Tropics, (1st ed.) Longman pub. Ltd, (U.K.).

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46

DEVELOPMENT AND PERFORMANCE EVALUATION OF A MOTORIZED BAMBARA GROUNDNUT (Vigna subterranean) SHELLER

K. J. Simonyan

Agricultural Engineering Technology Programme College of Agriculture, Ahmadu Bello University

Samaru – Zaria, Nigeria E-mail: [email protected]

ABSTRACT A motorized Bambara groundnut sheller was developed. The sheller was evaluated to determine the effects of speeds of the shelling cylinder, blower and air on the shelling efficiency, percent damage and the cleaning efficiency. Results showed that there was an increase in the shelling efficiency (SE) and percent damage (PD) with increasing speed. At low shelling cylinder speed of 85 rpm, the shelling efficiency was 81% and the percent damage was 4.7%. At shelling cylinder speed of 267 rpm, the shelling efficiency was 95% while the percent damage was 5.1%. The cleaning efficiency increases with increasing air speed. At blower speed of 680 rpm and air speed 20 m/s, the cleaning efficiency was 89% while at blower’s speed of 2403 rpm and 156 m/s; the cleaning efficiency was 98%. The sheller is recommended to farmers for adoption. KEYWORDS: Shelling, speed, efficiency, damage, cylinder, cleaning. 1. INTRODUCTION Bambara groundnut (Vigna subterranea (L.) Verdc) is a leguminous crop of great promise because of its enormous potentials (Okigbo, 1973). It is grown in a variety of soils with few pests and disease attacks (Doku, 1977). It is one of the two most drought resistant legumes second only to cowpea (Goli, 1997; Rachie and Silvester, 1977). Virtually every part of Bambara is useful, the seed has a balanced nutrient content of 50-63% carbohydrate; 16-21% protein and 4-7% oil (Rachie and Silvester, 1977). It also has traces of riboflavin, vitamin A and other essential amino acids. The gross energy value of Bambara is reported to be greater than cowpea, groundnut and pigeon peas (Goli., 1997). It is used in the preparation of a wide variety of dishes, soup snacks in Nigeria (Tanimu, 1996) and in Zimbabwe as a substitute for coffee. It was also discovered that milk of better flavour, colour and composition than soymilk, cowpea and pigeon pea can be produced from Bambara (Poulter and Caygill, 1980). Shelling, the first major post-harvest operation, involves application of mechanical forces to detach kernels from pods. The applied forces fall on the pod at random, breaking the pods stochastically, to free the enclosed kernels. Some physical phenomena involved in shelling crops are: breakage of the pod which is dependent on the intensity of force, the orientation of the pod and moisture content; freedom of the kernel from the pod and the passage of the kernel and broken pods through the concave. Bambara shelling at present is predominantly traditional manual method using a short wooden stick to beat it, or by pounding with pestle in mortar. These methods of shelling consume high man-hour with the associated fatigue and low output. The shelling operation is particularly tasking due to the thickness and hardness of the nut. Singh (1993) reported that the pod thickness influences shelling efficiency and the kernel diameter affects breakage. Developing a Bambara groundnut sheller to ease the labour associated with shelling would enable the high potentials of the crop to be exploited. It is the general objective of this study to develop a motorized machine, which shells and winnows Bambara groundnut. The specific objectives are to determine the effect of shelling cylinder speed, blower speed and air speed on the shelling efficiency, percent damage and cleaning efficiency.

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2. MATERIALS AND METHODS 2.1 Design Considerations The following factors were considered in developing the Bambara groundnut sheller: reduction in time and energy spent in shelling Bambara groundnut; ability to separate the kernel from the pod using a blower; use locally available materials for constructing the Sheller; detachable components, using bolts to attach, for easy repair and maintenance. 2.2 Description of the Bambara Groundnut Sheller The shelling machine consists of the following basic units: frame, hopper, shelling, the winnowing and the delivery. The complete isometric drawing of the Bambara groundnut sheller is given in Fig. 1.

Fig. 1. The Bambara groundnut sheller. A – Blower, B. Collector, C – Shelling cylinder, D – Prime mover seat, E – Chaff outlet, F – Frame, G – Hopper. The frame carries the entire components of the machine. It is a trapezoidal shaped structure, 1120 mm by 400 mm at the base and 850 mm by 280 mm at the top, constructed from 38.1mm by 38.1 mm angle iron. This is to provide stability and reduce vibration. The hopper feeds the Bambara groundnut pods to be shelled into the shelling unit. The hopper is semi circularly shaped and extended upwards, with the inlet tilted 60o to the horizontal to prevent splashing out of pods during shelling. The inlet is dimensioned 40 mm by 270 mm at the upper part and 270 mm by 320 mm at the lower part, which houses the shelling unit. The height of the hopper is 480 mm. The pods to be shelled fall into the shelling unit by gravity through the hopper.

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Fig. 2. Pictoral view of the Sheller The shelling unit comprises the shelling cylinder and the sieve. This unit carried out the function of actually breaking the pod, releasing the nut from the pod. It is an open ended rotating cylinder with metallic studs welded on flat bars. It is made up of two circular plates of thickness 3.5 mm and 210 mm diameters, which is drilled at the centre to allow 24 mm diameter shaft to pass through. Four (4) metallic studded flat bars 610 mm long are bolted on the 2 discs. There are slots where it is bolted to be able to vary the clearance. Fig. 3 gives isometric view of the shelling cylinder. Fig. 3. Isometric drawing of the Shelling Cylinder

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The sieve is half concave made from 420 mm by 250 mm sheet metal drilled with 13 mm diameter holes. The sieve hole diameter was based on the average size of the kernel and pod of Bambara groundnut. Table 1 gives the average diameter of the Bambara groundnut for the pod and kernel. The sizes were obtained using vernier caliper to measure the minor, major and intermediate diameters. The sieve is 320 mm semi-circular concave with five, 4 mm metal rods welded equidistant across the width of the sieve to hold the pods in position for the beater. The sieve is bolted to the frame. Table 1: Average Diameter of Bambara Groundnut Pod and Kernels

Pod (mm) Kernel (mm)

d1 d2 d3 t d1 d2 d3

Small Medium Large

12.4 14.5 15.5

13.0 14.6 20.0

16.5 19.1 29.5

0.4 0.5 0.5

5.1 8.7

11.4

8.9 10.4 12.1

9.9 11.9 18.6

where, d1 = minor diameter; d2 = intermediate diameter; d3 = major diameter. The blower separates the kernel from the pod pneumatically with high velocity air. The blower consists of 4 straight blades dimensioned 230 mm by 110 mm each, welded on 25 mm diameter shaft inside a casing. The blower casing is spirally shaped for greater blowing efficiency with outer casing diameter 330mm and the inlet 200 mm. The dimension of the outlet is 270 mm by 160 mm by 140 mm. The delivery unit ensures that the shelled nuts are delivered to the collecting pan. It is 270 mm by 950 mm. 2.3 Operational Principles of the Sheller The machine shells the pods by impact action. The pods are fed by gravity into the shelling cylinder. The cylinder rotates anticlockwise, impacts the pod until it is shelled. The metal rods welded across the width of the sieve holds the pod for the beater to beat it. The shelled kernels and the broken pods passed through the perforated hole on the sieve. As the shelled kernels and broken pods fall, they move across the air current cross flow wise. The broken pod are separated aerodynamically and blown away while the kernels being heavier drops to the delivery unit to be collected. 2.4 Evaluation of the Bambara Groundnut Sheller Performance evaluation was carried out on the Bambara groundnut sheller to determine the effects of the shelling speed on the shelling efficiency and percent damage; also to determine the effects of air speed on the cleaning efficiency. Fresh Bambara groundnut (Giwa white variety) samples at 13.4% wet basis,(wb) were purchased in the open market at Giwa LGA, Kaduna state in November 2002. The samples were sun dried until the moisture was reduced to 10.5% (wb). A 2-stroke Bernard moteurs petrol engine 1.9 kW was used to operate the sheller. Tachometer (Smith Industrial Division London H W 2) was used to determine the speeds while vane anemometer (Prufschein fur anemometer L-N R: 3010/112546) was used to obtain the air speed. Four replications were taken for the tests. The moisture content was fixed at 10.5% (wb) and the concave clearance was fixed at 12 mm throughout the test. The 1 kg of Bambara groundnut samples was weighed before being fed into the sheller continuously. The time to shell the weighed sample was taken and recorded. After the shelling operation, the shelled

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pods, unshelled pods, broken nuts were collected, separated, and weighed individually. The following were used for the analysis of the results. There were three replications.

Shelling Efficiency (SE) = 100XMM

T

s ................................................................................. (1)

Where Ms is mass of shelled kernel; MT is total mass of pods

Cleaning Efficiency (CE) = 100xMM

Muc

c

+ ...................................................................................... (2)

Where Mc is mass of cleaned chaff; Mu is mass of unclean chaff

Percentage damage (PD) = 100xMM

Mxb

b

+ ……………………………………………………(3)

Where Mb is mass of broken or partially damaged nuts; Mx is mass of unbroken nuts 3. RESULTS AND DISCUSSION Table 2 gives the summary of the performance parameters of Bambara groundnut sheller, the shelling speed, blower speed, air speed, are given with the corresponding shelling efficiency, cleaning efficiency and the percent damage. Table 2:Summary of the performance parameters of the Bambara groundnut sheller.

S/No Shelling speed (rpm)

Blower speed (rpm)

Air speed (m/s)

Shelling efficiency

(%)

Cleaning efficiency

(%)

Percentage damage (%)

1 2 3 4

85 125 175 267

680 1000 1575 2403

20 45 80 156

81 85 92 95

89 90 95 98

4.7 4.8 4.9 5.1

The table shows the shelling efficiency of the sheller against the shelling cylinder speed. It shows an increase in shelling efficiency with increasing shelling cylinder speed. At low shelling cylinder speed (85 rpm), the shelling efficiency was 81% while at 264 rpm shelling cylinder speed, the shelling efficiency increased to 95%. The percent damage of the nut also increases with the shelling cylinder speed. Table 2 also gave the relationship between the percent damage and the shelling cylinder speed. At low shelling cylinder speed of 85 rpm the percent damage was 4.7% while at shelling cylinder speed of 267 rpm, the percent damage was 5.1%. This was in agreement with Ige (1978) who reported an increase in shelling efficiency and mechanical damage with increasing the drum speed of a cowpea thresher. The effect of the air speed and blower speed on the cleaning efficiency of the shelled nut are also given in Table 2. There was an increase in cleaning efficiency with increasing air speed. At air speed of 20 m/s and blower speed of 680rpm, the cleaning efficiency was 89%. The cleaning efficiency further increased to 98% at blower speed of 2403 rpm and 156 m/s air speed.

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4. CONCLUSIONS A motorized Bambara groundnut sheller was constructed using available local materials. Performance evaluation of the sheller in terms of the effect of shelling cylinder speed and air speed on the shelling efficiency, percent damage and cleaning efficiency respectively were carried out. Results showed that there was in increase of the shelling efficiency, percent damage and cleaning efficiency by increasing speed. At shelling cylinder speed of 85 rpm, the shelling efficiency and percent damage was 81% and 4.7% respectively while at shelling cylinder speed of 267 rpm, the shelling efficiency and percent damage was 95% and 5.1% respectively. The cleaning efficiency increases by increasing air speed and blowers speed. At blower speed of 680 rpm and air speed of 20 m/s, the cleaning efficiency was 89% while at blower speed 2403 rpm and 156 m/s; the cleaning efficiency was 98%. Acknowledgement The author acknowledges the efforts of Messrs Amorighoye, M.O. and E.C. Ogbeh during the construction of the prototype sheller. REFERENCES Doku, E.V, 1977. Grain legume production in Ghana: Proceedings of the University of Ghana Council for Scientific and Industrial Research symposium in grain legumes in Ghana 10-11 December 1976, Legon, Ghana. Goli, A.E, 1997. Bambara groundnut: Bibliographical review in Heller, J.;F. Begemann and J. Mushonga (Eds.). Bambara groundnut. Proceedings of the workshop on conservation and improvement of Bambara groundnut 14-16 November 1995, Harare, Zimbabwe. Ige, M.T, 1978. Threshing and separation performance of a locally built cowpea thresher. J. Agric. Engineering Research 23:45-51. Okigbo, B.N, 1973. Grain legumes in the farming systems of the humid lowland tropics. Proceedings of the first IITA grain legumes improvement workshop 29 October - 2nd November 1973, Ibadan, Nigeria. Poulter, N.H. and J.C. Caygill,1980. Vegetable milk processing and rehydration characteristics of Bambara groundnut. J. Science, Food and Agriculture 31(11):1158-1163. Rachie, K.O. and P. Silveste, 1977. Grain legumes in C.L.A. Leakey and J.B. Wills (Eds.). Food crops of the lowland tropics, London UK, Oxford University Press p. 41-44. Singh, G, 1993. Development of a unique groundnut decorticator. Agricultural Mechanization in Asia, Africa and Latin America 24(1): 55-59, 64. Tanimu, B. 1996. Effects of sowing date, fertilizer level and intra-row spacing on the agronomic characters and yield of Bambara groundnut (Vigna subterranea (L.) Verdc). Unpublished Ph.D. Thesis. Department of Agronomy, Ahmadu Bello University, Zaria.

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52

DESIGN, FABRICATION AND TESTING OF CASHEW NUT (Anacardium occidentale) SHELLING MACHINE

Z. D. Osunde and O. E. Oladeru

Department of Agricultural Engineering Federal University of Technology, Minna, Nigeria.

E-mail: [email protected] ABSTRACT The physical and mechanical properties of cashew nut relating to shelling were studied. Based on the result of the study a cashew nut shelling machine was designed and fabricated from locally available materials. The fabricated sheller was tested and the test result indicated that it has Shelling efficiency of 80%, and whole kernel recovery of 66.7%. These are higher than with the manual method of shelling. The shelling rate of the machine is 0.52kg/hr. KEY WORDS: Design, cashew nut, shelling 1. INTRODUCTION Cashew (Anacardium occidentale) which belongs to the family Anacariaceae is native to the tropical parts the USA, Mexico, Brazil and the West Indies. However, it has since become naturalized in many lowland tropical areas. It is one of the most nutritious food crops of the tropical world, with high protein and fat content. It has appreciable amount of minerals (calcium, phosphorus and iron) and vitamins compared to other nuts such as almonds, walnuts and peanuts (Olaoye, 1992). The tree is a spreading, fast growing, evergreen up to 8 meters in height. The leaves are leathery and ovate with prominent veins. The fruit is a kidney shaped nut on a base of the large fleshy stalk called the ‘cashew apple’, which is thin skinned, and edible. The largest African producers of cashew nut are Mozambique and Tanzania with smaller amount being produced in Kenya, Malawi, Nigeria and Senegal (Fellows, 1997). There is a great deal of current interest in this crop since it will thrive in relatively dry areas of low fertility and also requires few expensive inputs. It offers attractive local income and good export potential both in the unshelled and shelled form. The local price of raw or unshelled nut is N85.00 for 1 kg, whereas that of shelled nut is N600.00 per kg depending on their appearance and size. It takes approximately 4 kg of unshelled nuts to make 1 kilogram of kernels. Therefore it is obvious that good profit can be obtained from the crops, either at the village level industry or large scale industry. The cashew nut is kidney shaped and has the sectional view shown in Fig. 1. It consists mainly of a nutshell (pericarp) and a kernel, which is the main product of the cashew. The pericarp consists of a hard shell (epicarp), a honey combed structure (mesocarp), in the cells of which is contained a useful but toxic natural resin, known commercially as Cashew Nut Shell Liquid (CNSL) and a hard and brittle inner shell (endocarp) which protects the kernel (Thivavarnvongs, 1995). There is a covering of thin membrane on the kernel known as testa or peel, which protects the kernel. The kernel seed is made up of two developed kidney shaped cotyledons and an embryo. The average weight of a whole fruit varies from 5 to18 g according to variety and cultivation (Pechnick and Gulmaraes ,1969). Generally the kernel accounts for about 22-24% of the whole fruit. The processing of cashew nut involves series of unit operations before it finally gets to the consumer. These operations are cleaning, sorting, roasting, shelling and packing. But the two main unit operations in cashew nut processing are the removal of the cashew nut shell liquid (CNSL), which is an irritant that could contaminate the nut and blister human skin if not handled properly, and

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shelling the nut to remove the kernel (Olaoye, 1992). The traditional method of removing the cashew nut shell liquid is to roast the nuts over an open fire. This removes the CNSL which is a valuable source of natural phenols. The improved technique is to roast the nuts in vats of hot (190 – 200oC) oil which removes the CNSL from the cashew nut. Shelling of the cashew nut is the act of removing the kernel from the cashew nut. Shelling is perhaps the greatest bottleneck along the processing line. Local shelling is carried out by hand with a hammer or using mortar and pestle. The shelling methods employed by cashew nut processing industries are the use of simple shelling devices, which usually are not efficient in their performances, and in few cases use of complex and expensive shelling machinery, which are usually imported. The aim of this work is to design and fabricate a semi-mechanized cashew nut shelling machine with locally available materials. The sheller will be easily maintainable, durable, portable and comfortable in use and competitive in the market. 2. METHODOLOGY 2.1 Properties of Cashew Nut Information on properties of the material, which a machine will handle, is very important in any engineering design, if the machine is to perform efficiently for the purpose for which it is designed. In designing a cashew nut shelling machine some physical and mechanical properties of the nut were measured. The physical properties measured include nut length, width, thickness, density, shell thickness, kernel weight and shell weight. These properties were measured using standard methods as given by Mohsenin, (1978). The mechanical properties measured were those having to do with the behavior of material under applied force. A study on deformation of the shell was carried out on raw nut and treated nut using a Universal Testing Machine. The nuts were subjected to compressive loads applied by a plane surface until nutshell breakage occurred. The load was applied along three different directions (i.e. the major, minor and intermediate diameter). The result indicated a force with magnitude in the range of 550-650N was required to break the raw nutshell and 200-220N was required for the treated nutshell. The samples used for the study were from the western part of Nigeria and have been stored for seven months. All the tests were carried out on 200 cashew nuts taking 20 each from 5 sacks of raw nuts and also 5 sacks of treated nut. The sacks were selected randomly from a number of sacks. 2.2 Design Considerations The design commenced with a study of two existing manually operated Shellers. These are the foot operated press blade type and the two-hand operated press separation blade type. The Sheller to be developed combined the two actions of pressing and twisting of the blade. This enables the Sheller to crack and open up the nutshell as required. The machine is constructed to shell two cashew nuts at a time in order to recover whole white kernel. The nuts to be shelled should be roasted and allowed to

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cool for 24 hours to improve shelling efficiency. The design was based on the physical and engineering properties studied. 2.3 Machine Components The designed cashew nut shelling machine is as shown in Fig. 2. The main components of the machine are the frame, the press/twist lever, upper and lower blade holder and blades to cut the nutshell open.

1, Frame; 2, Stopper; 3, Press/Twist lever; 4, Spring; 5, Upper blade; 6, Base; 7, Nut housing; 8, Upper blade holder; 9, Casing support; 10, Lower blade. Spring selection: The spring is an oil tempered wire type that is cold drawn to size, quenched and tempered. The choice was based on the force to be exerted (210N). The cost when compared with other wire is economical. The spring design was based on spring design procedure (Spott, 1988). The No 6 wire was chosen from table of values (Spott,1988) based on the required force. The selected wire has the following characteristics: Wire diameter d = 4.88mm Mean coil diameter D = 20 mm

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Minimum tensile strength St = 1.34448x109N/m2 Yield strength in shear Sy = 0.45 x St = 0.45 x 1.34448 x 109 = 6.0502 x 108 N/m2 Permissible stress Ss = Sy/Fs where Fs is the factor of safety = 1.5 Ss = 6.0502 x 108 /1.5 = 4.033343 x 108 N/m2

Where K =Shear stress correction factor = 1.392; F = Force required = 210 N

Actual stress is less than permissible stress, which means the selected spring wire is acceptable. Spring deflection: The deflection y is given as

n is the number of active coil which is chosen to be 6. c = D/d = 4.1

Spring rate T is given as follows

Upper blade holder: Its interior end is attached to press/twist lever while the posterior part is attached to the upper blade. The dimension of the upper blade holder (18.5mm) was chosen based on the blade size, which in turn is based on the average width of cashew nut (Table 1). The height was obtained based on the distance between the press/twist lever and the cashew nut after considering the distance it will travel before it cut the nutshell. The upper blade holder is made of circular mild steel rod and its length is 280mm. Table 1. Physical characteristics of cashew nut Physical parameter Maximum Minimum Mean Nut length (mm) 33.00 27.70 32.40 Nut width (mm) 30.1 21.12 20.00 Nut thickness (mm) 23.45 17.9 25.00 Nut density (g/cm3) 2.01 0.80 1.06 Shell thickness (mm) 2.56 2.00 2.34 Shell weight (g) 3.05 2.00 2.7 Kernel weight (g) 2.00 1.15 1.50 Upper blade: It is attached to the blade holder for opening of the nutshell from the top. It is made of mild steel of 1mm thickness and the length is based on the average cashew nut width (Table 1.) An allowance is given in case a large nut is encountered, making the length to be 23mm. Lower blade: The lower blade is designed for opening the nut from bottom and it is attached to the nut housing. It is made of the same material as upper blade and has the same dimension.

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Cashew nut housing: This is made from mild steel pipe of 30mm diameter. It holds the nut in position and underneath is the lower blade. The dimension was based on the cashew nut dimension (Table 1). Holder casing: It holds the spring in position and the upper blade holder moves through it up and down. The dimension was chosen based on the dimension of upper blade holder moving within it. The spring diameter is wound round the upper blade holder and an allowance was given for easy movement. Based on these, the casing was made of circular pipe of mild steel of 25mm diameter and of 60mm length for easy movement of the upper blade holder. The length was chosen based on the number of turns required on the upper blade holder. Holder casing support: This is made of circular mild steel rod of 18mm diameter. It attaches the holder casing to the frame. The dimension was chosen based on the size of the holder casing. Press / Twist lever: This is the handle for compressing the spring and for twisting the upper blade in order to open cashew nut from the top. When force has to be applied to a lever the diameter of the handle must be large enough so that the user’s hand and finger surface contact is maximized. However, a firm grip must be maintained. Frame: This is the support that carries the upper blade holder, spring, upper blade, press/twist lever and holder casing. It is made of mild steel squire pipe of 38.1mm by 38.1mm by 2.5mm. It is welded to the base in vertical position. The height of the frame was obtained by adding the upper blade holder heights, distance of travel of the upper blade holder to touch the cashew nut, the height of cashew nut and cashew holder casing height. Base: The base supports all other components of the Sheller. It is made of mild steel of 10mm thickness. The thickness was chosen on the basis of the strength required of the base to be able to withstand the impact of the press/twist lever. Also the area of the base was chosen so as to reduce the weight of the Sheller as well as making the sheller compact. 2.4 Mode of Operation The press/twist lever is placed in position (release position) with the upper blade holder. The nut is then inseted into the nut casing (under which there is the lower blade). The press/twist lever is then pressed down to cut the shell of the nut while the lower blade cut the nut from the bottom at the same time. When the press twist is pressed, the upper blade holder travel 50mm down and 2.5mm into the nut and at the same time the lower blade also travel 2.5mm into the nut from the bottom. The blade cuts the nutshell without cutting the kernel. The press/twist is then used to twist the nut to left and right in order to open up the nut. The press/twist lever is then released in order to open up the nut and come back to its normal position. The feeding is done manually. The total weight of the Sheller is 7.62kg. 2.5 Testing of the Machine To compare the efficiency of the machine with the manual method, three different methods of shelling were adopted for the test. These are hand shelling, using a hammer, mortar and piston and shelling using the fabricated Sheller. In each case, thirty roasted cashew nuts were used for the test and this was weighed before shelling commenced. Using the fabricated machine, the nuts were placed in the nut housing while the press/twist lever was in release position. The press lever was then pressed which made the upper blade holder to move down and crack the nutshell without cracking or cutting the kernel. The Sheller was shelling two nuts at a time. After the shelling operation, the total kernel obtained was packed and weighed and also the whole kernel collected from the total kernel was weighed.

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The following were the measurements taken before and after the shelling operation using the fabricated machine: Total weight of cashew nut used; weight of cashew nut shelled; weight of kernels obtained; weight of whole kernel obtained and shelling time. Based on the measured data, the Shelling rate, shelling efficiency and whole kernel recovery were calculated as follows:

. 3. PERFORMANCE EVALUATION RESULTS Table 2 shows the test result using the three different shelling methods. The shelling efficiency as well as the whole kernel recovery of the machine are better when compared to manual methods of shelling and the pedal operated Sheller. But the local methods of shelling have higher shelling rate. Whole cashew kernel has a higher market value compared to the broken kernel. Thus the target of any cashew nut shelling plant is to have higher whole kernel recovery and high shelling efficiency. Therefore, the use of the machine is better than use of the traditional methods. Table 2. Test result using different shelling methods Test result Shelling method

Manual / mortar Manual/hammer Shelling machine Shelling rate (kg/hr) 1.9 0.92 0.52 Shelling efficiency (%) 60 68 80 Whole kernel recovery (%) 15.9 28.5 66.7 4. CONCLUSION Cashew nut shelling machine was designed, fabricated and performance test was carried out using roasted cashew nut. The design was based on the physical and mechanical properties of cashew nut. The test result showed higher efficiency and whole kernel recovery and low shelling rate compared to the local shelling method. The machine is durable, portable, easy to operate and maintain. All the components of the machine are fabricated from locally available materials. REFERENCES Mohsenin N. N. 1978. Physical properties of plant and animal materials, Gordon and Breach Science Publishers, New York. pp 51-78. Olaoye A. O. 1992. Cashew nut processing; a hand book. Longman, London pp 320-329 Pechnick and Gulmaraes 1969. Fruit and vegetables. Longman, London pp120-135 Fellows P. 1997. Traditional foods, Processing for profit, Intermediate Technology Publication Ltd, London, pp 144-145. Spott M. F. 1988. Design of machine elements. Prentice Hall of India private Limited, New Delhi, India. pp 70-82. Thivavarnvongs T, Okamoto T. and Kitani O. 1995. Development of compact sized cashew nut shelling machinery. Journal of the Japanese Society of Agricultural Machinery. Tokyo, Japan pp 57-65.

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SOME ENGINEERING PROPERTIES OF PALM KERNEL (Elaesis guineanis) SEED (PKS)

L. Gbadamosi Department of Agricultural Engineering and Water Resources,

Kwara State Polytechnic, Ilorin Nigeria. E-mail:[email protected].

ABSTRACT Palm kernel seed (PKS) has been discovered to be a rich source of oil that can be used for industrial purposes. Some of the engineering properties of PKS were studied, namely: size, shape, surface area, angle of repose, static coefficient of friction for different materials, hardness, specific heat capacity and compression test. Major diameter varied from 6.43 to 17.33mm while the intermediate diameter varied from 5.69mm to 13mm and minor diameter varied from 4.22mm to 10mm for the three varieties. The mean values of 1.8 and 0.78 for roundness and sphericity respectively for the three variety shows the ability of the seed to roll. The mean densities values for the three varieties are 1.06g/cm3, 1.105g/cm3 and 1.366g/cm3 for the Tenera, Pisifera and Dura respectively. The seeds had highest coefficient of friction for galvanized steel and lowest for glass which ranges from 0.48 to 0.59 for steel and from 0.27 to 0.39 for glass. The average specific heat capacities are 3.98, 4.13 J/goC and 6.55 J/goC for Dura, Tenera and Pisifera respectively. The average hardness values are 38KN/m2, 21.8KN/m2 and 14.2KN/m2 for Dura, Tenera and Pisifera respectively. KEYWORDS: Palm kernel, sphericity, heat capacity, density, coefficient of friction. 1. INTRODUCTION

The oil palm plant (Elaesis guineanis) is one of the most important crops grown in the tropics. Nigeria is known as one of the leading exporters of palm-oil. Palm oil plant is grown abundantly in the eastern part of Nigeria and on average in the western part of the country. There are basically three distinct varieties of Palm Kernel fruit, they are the Dura, Tenera and Pisifera. In terms of kernel, Dura have large kernel, Tenera have medium kernel and Pisifera have small or no kernel. The palm oil plant is a cash crop that has a wide variety of uses through the oil extracted from the seed and from the fleshy part of the plant. Palm oil is mainly used for the manufacture of soap, production of margarine, lubricating oils, candle and also used in tin plate and sheet steel industries. Palm kernel oil has application in the making of soap and margarine and also uses for making drugs in pharmaceutical companies. Lack of basic engineering properties of plant material is an identified problem in the development of a new method of sowing the crop, development of a new equipment for processing and control conditions for crop storage, (Olaoye, 2000). According to Mohsenin (1978) and reported by Olaoye (2000), knowledge of physical and mechanical properties constitutes important and essential engineering data in the design of machines, storage structures, processes and control. These are basic information of great value not only to the engineers, but also useful to those who may exploit these properties and find new uses for the plant material. Alcali and Guven (1990) as reported by Olaoye (2000), observed that a rational approach to the design of agricultural machinery, equipment and facilities involves a theoretical analysis of the effects of the physical properties of the agricultural product on the characteristics of machinery, facilities and operation. It is also important to know the engineering properties of agricultural materials in the analysis and sorting of crop during handling, separation of corps from undesirable materials and designing post harvest equipment such as separator, dehullers, and designing seed hopper, belt conveyors. This paper examines some physical properties of the palm kernel seed at safe storage moisture content. The properties examined include: size, shape, sphericity, roundness, volume, weight, contact

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area, density, static coefficient of friction against different materials, angle of repose, hardness, specific heat capacity and response of the PKS to compressive loading. 2. MATERIALS AND METHODS The three varieties of palm kernel seeds (PKS) namely: Dura, Tenera and Pisifera which are the major palm kernel seed available in Nigeria were obtained from the National Institute of Oil Palm Research (NIFOR) in Benin City, Edo State. One hundred seeds were selected randomly for each variety from some kilogram of PKS. Some of the physical properties determination were made using standard equipment and apparatus of civil engineering department of the University of Ilorin, Mechanical Engineering Department of Kwara State Polytechnic, Ilorin and Physics laboratory of Government Day Secondary School, Adeta, Ilorin. The size was determined by measuring one hundred samples of each variety along the principal axes: major, intermediate and minor axes of the seed as contained in Sheperd et. al. (1986) and Dutta et. al. (1986) using vernier caliper (INOX made in Bulgaria) measuring to 0.001mm. The roundness and sphericity were determined for PKS by using expression states by Curray (1951),as contained in Mohsenin (1978) and used by Oje and Ugbor (1991) and Dutta et. al. (1986). Sphericity is defined as {(a* b* c)1/3 }/a and roundness is defined as Ap/Ac, were “a” is the major diameter “b” is the intermediate diameter normal to “a”, “c” is the minor diameter, normal to”a” and “b”. Where Ap is the largest projected area of object in its natural rest position in cm2 , Ac is the area of the smallest circumscribing circle in cm2. Surface area of the seed were determined by using the expression as stated by Fraser et. al. (1978). Surface area is defined, as S = (Dp)2 , where “Dp” is geometric mean diameter of the grain in mm and “S” is the surface area of single grain in cm2. The volume of the PKS were determined by the water displacement method as described by Dutta et. al. (1988). Fifty seeds of PKS were immersed completely in a measuring cylinder containing water, the volume of seeds is the difference in volume of water after immersion. This was done for each variety and replicated ten times. True density was obtained from the general expression which is defined as (mass of seeds in grams)/(volume of seeds in cm3), mass of 50 pieces sample was measured with a sensitive electronic scale meter (PE 360 of 0.1gm accuracy) replicated ten times. The volume obtained from water displacement was used. The angle of repose was determined by filling a steel hollow pipe of 40cm long with PKS and gently lifted up from the level surface of the cardboard paper. Conical heap of the PKS formed on the cardboard paper was determined for the vertical height and for the diameter of the heap. This was done five times for each of the variety from where the angle of repose was computed from the ratio of the vertical height of heap to the true length of the heap, Madueke, (1989). The coefficient of sliding friction of the PKS was determined for the structural surface, namely: plywood, glass and galvanised steel with the seeds parallel to the direction of motion. A four sided plywood container with neither bases nor lid and with dimension 150mm*100mm*40mm was filled with palm kernel seeds and placed on any adjustable tilting surface. One end of this surface, with the box resting on it was raised gradually using a screw device until the box just started to slide down. The angle of inclination was read from a graduated scale, (Oje, 1993). The contact area of the seed was determined by using the method described by Oje and Ugbor (1991). The impression of the surface of the nut was obtained by first coating the paint so that contact printing on a translucent sensitive paper could be produced. The contact area of the impression was then measured with an Aristol 1130L Planimeter. The specific heat capacity of the seed by the method of mixture as described by Oje and Ugbor (1991) was used. Hot water of known weight and temperature was poured into an adiabatic drop calorimeter containing twenty-five seeds of each variety at a time. The initial temperature of the seeds was taken and at equilibrium, the final temperature of the mixture was recorded. Specific heat capacity was computed from the following expression

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CS = {Cw MP ( Twi - Twf)}/MS (TSi - Twf) Where, Cs= specific heat capacity of the PKS; Cw = specific heat capacity of water; MS = mass of PKS (gm); Mw = mass of water(gm); Twi = initial water temperature (oC); Twf = final water temperature (oC); Tsi = initial temperature of the seed (oC) . The hardness test was carried out using hardness-testing machine, Rockwell hardness machine type 6402 model NO 32887. The machine had a cylindrical compression spindle. The seed was loaded on the loading surface. The compressing spindle was controlled by means of a knob to produce indentation on the stationary seed when moved in anti-clockwise on the loading surface. Direct reading of the hardness value was possible on a graduated scale. Experiment was carried out with a single seed at a time and repeated ten times for each variety. The compression test was performed with the Monsanto Tensonmeter universal testing machine following the standard procedure, (ASAE, 1993) for each seed of the varieties examined and repeated ten times. The load at peak, break, yield points with the corresponding energy of deformation and trains were obtained from the printed computer sheet and from the printed computer curves. 3. RESULTS AND DISCUSSION 3.1 Size Table 1 presents a summary of the result for all the parameters measured. Table 1 shows the size range of the three varieties of PKS of between 4.1mm and 17.3mm. The major diameter of the Tenera is greater than those of Dura and Pisifera varieties and it is also greater than the intermediate diameters of Dura and Pisifera and the diameter of the Pisifera has the minimum value. The difference in the size is important in the selection of sieve or screen size in the design of separator equipment and in the design of the auger and barrel for effective oil extraction of the palm kernel seeds. Table 1. Some physical properties of the three varieties of palm kernel seed, Dura, Tnera and Pisifera Mean Value and Spread Properties Number of observations Dura Tenera Pisifera Shape Roundness 100 1.74±0.182 1.97±0.25 NA Sphericities 100 0.80±0.20 0.70±0.05 0.85±0.03 Size(mm) Major Diameter 100 15.9±0.029 17.3±0.03 6.30±0.13 Intermediate 100 13.0±0.016 14.0±0.04 5.60±0.09 Minor Diameter 100 9.8±0.016 7.4±0.02 4.1±0.22 Contact Area (cm2) 100 0.76±0.02 0.56±0,01 0.30±0.09 Volume (cm3) 10 61.70±5.41 46.6±4.62 13.42±2.41 Mass (gm) 10 79.70±6.44 49.40±4.88 14.70±2.22 Densities (g/cm3) 10 1.31±0.19 1.06±0.04 1.105±0.07 Surface Area (cm2) 15 5.08±1.43 4.42±1.42 1.14±0.22 Angle of Repose (o) 5 32.6±1.29 31.4±2.23 28.5±3.94 Coefficient of friction (o) Plywood 5 0.38±0.039 0.45±0.045 0.44±0.015 Galvanized Steel 5 0.48±0.008 0.56±0.045 0.57±0.022 Glass 5 0.35±0.015 0.38±0.01 0.27±0.013 Specific Heat Capacity 5 3.98±0.34 4.13±0.38 6.55±0.36 J/goC Hardness Test (KN/m2) 5 38.0±0.11 21.8±0.01 14.2±0.05

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3.2 Sphericity The Pisifera was found to be the most spherical in shape with mean sphericity value of 0.85, followed by Dura of mean sphericity value of 0.80 and Tenera seed of mean sphericity value of 0.70. The minimum sphericity value is 0.75 and the maximum sphericity value is 0.88 for the three varieties examined. The sphericity difference between the three varieties is 0.13, when compared with standard value obtained by Oje et. al. (1991). It shows that the seed would rather roll than slide. This properties could assist in the design of hopper of the PKS processing equipment, design of drying and storage equipment. 3.3 Roundness The roundness value for the varieties considered are between 1.92 and 2.22.the difference in roundness between Dura and Tenera is 0.30. This value indicates that the seed can roll when compared with standard value obtained by Madueke (1989). This property could be useful in determining the proper shape of the metering unit and the best feeding orientation of the seeds in the design of the planter for the seed. The roundness value for the Pisifera seed variety cannot be obtained due to the small nature of its size. 3.4 Density Table 1 shows that the density of the palm kernel seed varies with the varieties. There is a relationship between the size of the seed and the density. Dura and Tenera varieties have mean densities of 1.13g/cm3 and 0.97g/cm3 respectively and Pisifera had 0.96/cm3. The variation in the volume and weight of the three varieties examined explains the difference in the observed densities of the seeds. The densities of the three varieties range between 0.95g/cm3 and 1.2g/cm3. This indicates that the seed is denser than water hence the seed will sink when placed in water. This characteristic can be used to separate the seeds from the lighter materials 3.5 Contact Area The average contact area of the Dura, Tenera and Pisifera are 0.76cm2, 0.56cm2 and 0.30cm2 respectively. The contact area ranges between 0.95cm2 and 0.39cm2 for the three varieties. The difference in the contact area could be due to the observed variation in the value of sizes of the seed varieties. This property is needed in the determination of accurate area of maximum cross section and generally of any normal section. These are the basic data for determining critical speed, resistance coefficient or Reynolds Number in the design of Winnower or blower for the seed. 3.6 Angle of Repose The mean angle of repose of the palm kernel seed is 32.6o for Dura, 31.4o for Tenera and 28.5o for Pisifera. This property is essential in the determination of the relative size of length (Diameter) and height of an appropriate storage structure for the seed. The maximum angle of repose for the three varieties falls within 32o and 34o. 3.7 Coefficient of Sliding Friction The coefficient of sliding friction is highest for galvanised steel for the three varieties. Pisifera has the highest value of 0.57 for galvniesd steel and Dura variety has the least mean of 0.48. Glass as a structural material had the lowest mean value of coefficient of sliding friction among the three structural materials that were examined of 0.27 for Pisifera and plywood as structural materials had coefficient of sliding friction greater than glass of 0.38 for Dura. Rolling of the seed took place on the steel surface and for the other two structural materials, the seeds showed high tendency to roll. This property is important in the determination of the steepness of the storage container, hopper or any

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other loading or unloading devices if any of these materials is to be used. This is because the vertical load on the wall of the storage container is determined by friction coefficient. 3.8 Hardness The average hardness value for the Dura, Tenera and Pisifera are 38kN/m2 , 21.88kN/m2 and 14.2kN/m2 respectively. The hardness value ranges between 38.11kN/m2 and 14.24kN/m2 for the three varieties examined. This property is important in the size reduction operation and in the selection of materials for the construction of oil extracting machine for oil extraction from PKS and in the evaluation of seed resistance to breaking under handling condition. It also assists to know the energy required in the processing of the seeds, thus it proffers the best approach to break the seed. 3.9 Specific Heat Capacity The specific heat capacities for the Dura, Tenera and Psisfera varieties are 3.98J/go C, 4.13J/goC and 6.55J/goC respectively. The specific heat capacity ranges between 6.91J/goC and 4.32J/goC. The variation in the surface area of the three varieties explains why the specific heat capacity of Psisfera variety was highest. This property can be used to determine the amount of heat required in the processing of the seed thus, assist in the selection of the best method to process the seed. 3.10 Compression Test The results of the compression test are presented in Table 2 and in Figure 1 to Figure 6. It is seed from the table and figure that the compressive load, energy of deformation and the strain at the peak, break and yield point for each of the varieties examined indicate a significant difference with respect ti the orientation of loading during the application of compressive load. The varieties examined except Tenera along the intermediate axis have the highest mean load at different point but with lowest energy of deformation and lowest mean strain at other different point. Tenera variety has lowest mean load along the intermediate axis and the highest mean load along the major axis. The above observation will assist in the designing of the appropriate machine for oil extraction from the seed variety, as well as assist in the design for the storage structure and gives the best approach to pile the seed for transportation. Along the major axis, Dura had the highest mean load at peak, break (rupture) and yield point of 515.09N, 409.14N and 378.95N respectively with corresponding energy of deformation of 0.9012Nm, 0.0075Nm and 0.343Nm. Table 2: Compression test results for the seeds . Load at Different Energy at Different Strain at Different Points (N) Points (J) Points (%) Variety Axis of Loading Peak Break Yield Peak Break Yield Peak Break Yield Dura Major 15.04 404.14 378.95 0.9012 1.0075 0.3430 14.066 15.404 7.871 Intermediate 544.17 473.42 361.21 0.4199 0.4393 0.1711 9.478 9.835 5.306 Tenera Major 481.71 319.61 127.75 2.0015 2.2473 0.0919 31.509 34.121 6.648 Intermediate 136.42 75.89 109.46 0.0369 0.0433 0.0231 5.0991 6.0471 3.4980 Pisifera Major 293.26 260.12 79.82 0.6668 0.8171 0.0387 34.094 39.382 7.215 Intermediate 297.54 273.93 162.26 0.2967 0.3249 0.0554 22.25 23.874 8.617

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Fig. 1. Load (N) vs Deflection (MM) for Pisifera along major and intermediate diameter

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Fig. 2. Load (N) vs Deflection (MM) for Tenera along major and intermediate diameter

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Fig. 3. Load (N) vs Deflection (MM) for Dura along major and intermediate diameter 4. CONCLUSIONS The following conclusions were drawn from the investigation conducted on some of the engineering properties of the Palm kernel seed (PKS).

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(i) The sizes of the three varieties of the PKS examined were characterized by the use of major, intermediate and minor axes with various sizes along these axes. The three varieties range in size from 4.1mm and 17.3mm.

(ii) The shape of the PKS was described by its roundness and sphericity, the average high value of its roundness and sphericity made it easier in getting the seed to roll. The minimum sphericity value is 0.75 and maximum sphericity value is 0.88 and the roundness value is between 1.92 and 2.22 for the three varieties examined.

(iii) The PKS average density ranges from 1.10 to 1.50g/cm3for the three varieties, which shows that, it is possible to use water as a medium of separation between PKS and other crops.

(iv) The compression test along the major axis gave the best position of placing the seed

as least force is required compared with the required force along intermediate axis

(v) The specific heat capacity depends on the surface area of the PKS, the more the surface area the less the specific capacity.

(vi) The coefficient of sliding friction was highest on steel and least on glass for all the

three varieties. ACKNOWLEDGMENT The author acknowledges Miss. A. H. Ayanda’s contribution to the research work REFERENCES Alcali, I. D. and Guyen, O. 1990. Physical properties of peanut in Turkey. Agricultural Mechanization in Asia, African and Latin America, 2(3) 5559 ASAE , 1993. Standard EPP-03 and FE-03. SI Joseph, MI. Curray, J. K. 1951. Sphericity and roundness of quartz grains. M.Sc Thesis, The Pennsylvania State University Park, PA, USA. Dutta, S. K., Nema, V. K., and Bhardwaj, R. K. 1988: Physical properties of gram. JAER. 39:259- 268. Fraser, B. M., Verma, S. S. and Muir, W. E. 1978: Some physical properties of fababeans. Journal of Agricultural Engineering Research. 23: 53-57. Mohsenin, N. N. 1978. Physical properties of plant and animal material. Gordon and Breach Publishers, New York. Oje, K. and Ugbor, E. C. 1991: Some physical properties of oil beans seed. Journal of Agricultural Engineering Research. 50: 305-313. Oje, K. 1993: Some engineering properties of the vetia nut. Journal of Agricultural Engineering and Technology. 1 : 38-45. Olaoye, J. O. 2000: Some physical properties of castor nut relevant to the design of processing equipment. Journal of Agricultural Engineering Research. 77 (1): 113-118. Shepherd, H; and Bhardwaj, R. K. 1986. Moisture dependent physical properties of pigeon pea. Journal of Agricultural Engineering Research 35:227-234.

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FIELD TESTING OF AGENCY-FARMER JOINT IRRIGATION MANAGEMENT CONCEPT AND ITS IMPACT ON SYSTEM OPERATION AND MAINTENANCE IN

HADEJIA VALLEY IRRIGATION PROJECT, NIGERIA

Abubakar, S.Z1 and B. Lidon2 and O.J. Mudiare3

1-NAERLS, Ahmadu Bello University, PMB 1067 Zaria, ([email protected]) 2-CIRAD, 34398 Montpellier, France, ([email protected])

3Dept. of Agricultural Engineering, Ahmadu Bello University, Zaria.

ABSTRACT An integrated approach called Agency-Farmer Joint Irrigation Management (AFJM) was designed and tested in Hadejia Valley Irrigation Project (HVIP) located in the semi arid region of northwestern Nigeria. The action-research was undertaken between 1997 to 2000 and was aimed at studying how Water Users Associations (WUAs) and Irrigation Agency Managers (IAM) plan, negotiate and take joint decisions on any aspect of the irrigation system management including crop production. The testing was undertaken in two stages : i) preparation of seasonal plans and targets based on wishes and expectations of both parties and ii) negotiation, tasks allocation, responsibility sharing and joint decision making. Institutionalization and capacity building of WUAs as well as reorientation and organizational reform of IAM were carried out to prepare each of the two parties to efficiently carry out his roles and responsibilities. Results revealed that the IAM came up with Continuous-Communication Arrangement (CCA) between gate operators at different locations and System Operational Guidelines (SOG) that defines the specific roles of the different gate operators. These changes resulted in improved Delivery Performance Ratios (DPRs) of the main system from ranges of 0.85 to 1.38 and of 0.80 to 1.30 for pre and post testing periods, respectively. A similar improvement was also recorded at the sector-turn-outs (STOs) where the DPRs ranged between 0.12 to 0.97 and 0.78 to 0.91 for the same periods, giving means of 0.37 and 0.86, respectively. The physical condition of the scheme network was also significantly improved where weeds infestation and breaching of field channels and cultivation of field drains were reduced from 89.0, 82.0, and 65.0% to 42.0, 39.0, and 21.0% at secondary and tertiary levels. Further results showed that mean Maintenance Performance Ratios (MPR) of 0.72, 0.53, 0.08 and 0.18 were achieved for distributary and field canals and collector and field drains, respectively, by both the IAM and WUAs. There was also improvement in the Maintenance Budget Ratio (MBR) from a mean of 0.26% in 1996 to 0.68% in 2001 pointing to higher commitment of funds in maintenance. The testing provided opportunity to assess the type conditions conducive for the adoption of the approach. Empowerment of the farmers and the WUAs in both technical, organizational and managerial skills is a pre-requisite. Similarly, re-orientation and capacity building of IAM and field staff to appreciate their new roles are equally essential. These are expected to lead to the provision of better quality services to farmers by agency and better incentive for participation and cost sharing for sustainability. KEYWORDS: Agency-Farmer Joint Irrigation Management (AFJM) ; Delivery Performance Ratios, (DPR); Maintenance Performance Ratios, (MPR); Maintenance Budget Ratio, (MBR); Hadejia Valley Irrigation Project, (HVIP). 1. INTRODUCTION Nigeria witnessed a rapid expansion of irrigated area between late 1970’s to late 1980’s where over 100,000ha were developed under the supervision of government agencies (RBDAs), (Musa, 1999). This was seen as socio-political strategy to combat the devastating drought of mid 1970’s and means of providing employment for the teeming population, among others. The Government however found

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it difficult to finance the operation and maintenance of running these schemes mainly due to decline in allocations and low recovery from water fees. Olugbemi, et al (1993) reported that 45% cost recovery from water charges was the highest ever recorded in the country (i. e. KRIP). Centrally financed procedures of the agencies tend to hinder the effective provision of quality services to farmers (Musa,1994); inconsistent Government policies particularly on subsidies and produce prices is additional disincentive to the farmers to pay higher water fees. These and other factors led to the rapid deterioration of infrastructure, shrinkage of area under irrigation, maldistribution and wastage of water. By 1999 the total irrigated area under the supervision of the RBDAs dropped to less than 30,000ha (Musa, 1999). Driven largely by financial pressures the government started contemplating to share management responsibilities of irrigation schemes with the users organised into associations. Because of the successful experiences of the approach in other countries, there was the upsurge in efforts by government and other interest groups to initiate the promotion of the approach in Nigeria. International Water Management Institute (IWMI) collaborated with HJRBDA between 1991 to 1994 to start this effort in Kano River Irrigation Project (Pradhan, 1993). The results of this effort reinforced the conviction on the positive values of the approach. Government saw that the promotion of Participatory Irrigation Management (PIM) concept has the potential to reduce the cost burden of irrigation on it and can increase the productivity and profitability of irrigated agriculture enough to compensate for any increase in the cost of irrigation service to farmers (Pradhan, et al. 1994). To realize this aspiration, another collaboration effort was initiated between CIRAD, NAERLS and HJRBDA under the sponsorship of French Embassy in Nigeria for the field testing of the approach in a relatively new scheme and still under construction –HVIP. The various options of PIM were studied and the joint management was selected, redefined, and developed into a package for testing. This article present the institutional perspectives of the testing as it relate the irrigation agency and the users associations and the impact recorded in the area operation and maintenance of the scheme network.

2. MATERIALS AND METHODS 2.1 Location of the Testing The HVIP lies within Auyo, Kaugama and Miga Local Government Areas of Jigawa State. It is located at latitude 12o-13oN and longitude 10o-11oE between the Hadejia River and its tributary the Kaffin Hausa River around Auyo town. The town of Auyo is situated near the center of the project area. The project involves land, water resources and irrigation development to enhance agricultural production in the predominantly farming communities within Hadejia Emirate (Hollis et. al.1993). The climate around HVIP consists of a warm (28oC) rainy season from June to September, a cool dry (17oC) season from October to February, and a hot dry (31oC) season from March to May. The warm rainy season is traditionally the farming period. Rainfall is highest in July and August during which precipitation exceeds potential evaporation. During the rainy season the cloudiness and the prevailing cool southwesterly wind have a moderating effect on daily temperatures. The average annual rainfall in the area is 550mm (Hollis et al. 1993). 2.2 Design and Development of Operation and Maintenance Modules The major activity carried out was designing of specific modules that would allow the individual farmers to interact amongst themselves as a group as well as with the agency staff to prepare seasonal plan of their farming activities. Based on this plan, they are able to draw up schedules for network maintenance activities and set targets on water delivery and allocation at the secondary and tertiary levels of the scheme. The agency is to carry out similar activities at main system and storage pond levels. The process is simultaneously carried out by the two parties under the guidance of facilitators who provide the channel for feed back to either party in order to avoid conflict between farmers and agency during the negotiation and decision making stage. The modules were introduced to the target beneficiaries using the following strategies (Abubakar, 2002):

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§ Adult education through extension campaign adopting Havelock (1976) and Morgan et al (1978) approahces ;

§ Capacity building of the direct actors using Adhikarya et al (1978) technique ; § Experintal learning and continuous training as practiced by Rolling (1982) and Laird (1972)

2.3 Participatory Implementation of the O and M Modules The following paragraphs provide how the modules on water delivery and network maintenance were put into use in HVIP between the period of 1996/97 to 2000/2001 dry seasons. Basically the process comprises of six steps as follows (Abubakar, 2002):

i. Preparation of seasonal plans on farming activities by farmers ; ii. Setting up of seasonal targets by the agency ;

iii. Joint review of seasonal plans and targets through negotiation ; iv. Feedback to grassroot (in case of WUAs to farmers and in case of agency to management)

for adjustment to reflect actual realities ; v. Implementation of agreed plans and targets through : R Timely allocation of materials, funds, and labour R On the spot supervision (where the job is handle by WUA members)

Vi. Monitoring and evaluation of implementation through : ü Weekly revisions of implementation at sector level led by farmers ü Weekly review of implementation at main system level led by agency ü Assessment of effectiveness (cost, time or labourwise) in executing the task ü Feedback to grassroot (in case of WUAs to farmers and in case of agency to

management) on the level of performance of the party responsible. Overlapping exist between these steps when executing the process in reality. The process commences early enough to allow for adequate interaction between the farmers, on one hand, to arrive at decisions for their blocks and sector, and between the farmers associations and the agency managers to arrive at decisions for the entire irrigation scheme. The use of geographic information system-database GIS to provide visual materials that truly represent the field reality for the two parties to use to negotiate and prioritize issues was very helpful in increasing the level of participation of the farmers. The data obtained were analyzed using the following relations (Ijir and Burton, (1998); Plusquellec et al (1990); Mao Zhi (1989) ; and Pitana, L.G. (1993): Manpower Service Ratio (MPSR), MPSR = M/Adcv …………………………..Eqn (1) Where: M = Total manpower numbers for 0& M of the system

Adcv = Total developed irrigable area, ha

Similarly, Manpower Quality Ratio (MPQR), MPQR =Mp/M.t 100% ………Eqn (2) Where : Mp = Number of professional and middle cadre personnel

employed in the scheme Mt = Total manpower numbers for O & M activities of the scheme, and

Finally, Maintenance Budget Ratio (MBR),= (Bm/Bt) x 100%………………...Eqn. (3) Where: Bm = Amount of annual recurrent expenditure actually applied to maintenance of the scheme

Bt = Total annual recurrent O & M expenditure

3. RESULTS AND DISCUSSION The results of testing the AFJM concept in HVIP are summarized subsequently.

3.1 Institutionalization of Farmers’ Associations and Organizational Reform of the Agency

The WUAs were formed on first-come-first-serve basis. The first sector (Gamsarka) located at the upstream of the scheme was first constructed and handed over in 1993 followed by Ayama sector the

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following year. Landowners in the scheme were mobilized at pre and during the construction period such that immediately a sector is handedover and commissioned for use, an association of water users is formed by some interested landowners in the sector. All the 8 eight WUAs have attained legal status at the three levels of HVIP, Local Governments Areas (LGAs) and Jigawa State Government between 1993 and 2000. The WUA also grew in membership from a total of 541 members in the first years of registration to 1799members in 2002 with mean membership size per association of 68 and 225 respectively (see Table 1). The membership of WUA in HVIP witnessed a significant rise during the 9 year period with a mean growth rate of 15 members per annum per association. The level of participation of landowners in WUA activities was quite low in the initial years but significantly increased from a mean of 17% in the first years to a mean of 53% in 2002 (see Table 1). Gamsarka sector recorded the highest levels of 26% and 75% while Marina sector had the least levels of 04% and 27% for both first year of registration and for 2002 respectively. This led to the initiation of generating internal revenues from membership registration fees and annual dues to improve the financial viability of the associations. In all the eight associations the least percentage of members that contributed to resource mobilization through these two sources was 40%. The agency was confronted with the option of either under going institutional reform to enable it interact with the WUA or drop the idea of promoting participatory irrigation management. The first option was viewed from two perspectives viz : rationalization of redundant staff or expansion of area under irrigation, to increase the manpower service ratio of the agency (Abubakar, 2002). None of these strategies wwa implemented mainly because the agency was fully dependent on government, thus could not improve its Manpower Service Ratio (MPSR) above 15.2. The agency was however able to increase its Manpower Quality Ratio (MPQR) from a mean of 20 to 24% through the emloyment of additional professional cadre staff. The organizational reform undertaken by the agency further allowed it to increase its Financial-Self-Sufficiency (FSF) where up to 26% of the Operation and Maintenance costs were internally generated as against only 15% prior to the testing period (Abubakar,2002).

Table 1: Legal status of WUAs, membership strength, growth rate and level of participation of landowners in HVIP (1993-2002)

Sector

No. of land owners

Yr of HVIP Reg.

Year LGA Reg.

Year State Govt. Reg.

Member-ship Size in 1st year of Reg.

Member-ship size in 2002

Annual member-ship growth rate

Level of participation in WUA activities by landowners in (%) First year of Reg.

2002

Garmsarka Ayama Zumoni Adaha Yamidi G/Kuka Marina Anyo

238 263 505 550 290 394 980 594

1993 1994 1995 1996 1996 1996 1997 1998

1995 1996 1997 1997 1998 1998 1999 1999

1996 1998 1998 1999 1999 1999 2000 2000

62 48 71 92 70 81 42 75

178 144 276 302 175 224 265 235

13 11 23 23 12 16 25 18

26 18 14 17 24 20 04 12

75 56 55 55 60 57 27 40

Totals Means SD

3814 272 269

541 68

1799 225 55

15

17

53

Source: Abubakar, (2002)

3.2 Improvement on the Physical Condition of the Network The physical condition of the scheme network was also significantly improved as a result of sharing the maintenance responsibilties between the agency and the users. Weeds infestation, breaching of canals and undercropping of field drains were reduced from 89.0, 82.0, and 65.0% to 42.0, 39.0, and 21.0% at secondary and tertiary levels before and after the testing of the approach, respectively. Further results show

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the mean Maintenance Performance Rratio (MPR) of 0.72, 0.53, 0.08 and 0.18 for distributary and field canals, and collector and field drains respectively. Table 2 presents the performance of WUA on network maintenance at secondary and tertiary levels of the system. An estimated amount of 2,306,790.00 naira was spent between 1997 to 2000 covering a total length of 500.56km. Seepage loss of 40.0 and 18.0l/s/km were obtained for feeder and north main canals. The result shows that although the canals were clay-lined, their water retention ability was, after seven years of use, comparable to the value of 97.30, 198.0 and 80.01l/s/km for unlined sandy, unlined alluvial plain and concrete lined canals, respectively. This situation improved greatly the conveyance efficiency of the main system. The high maintenance performance on the distributary and field canals were commendable while reasons for low performance on the collector and field drains were attributed to lack of machinery and the farmers’ urge for illegal expansion of their irrigated plots respectively. This bad habit has created a dangerous trend of waterlogging in some parts of the areas in less than 10 years of operation. Table 3 presents the level of performance of the Users’ associations on the restoration and desilting of field drains and the calculated Waterlogging Problem Index (WLPI, i.e the ratio between No of field drains available against No of field drains cultivated by farmers in a Sector ) between 1997 to 2000. In all the six sectors the WLPI declined over the four years where the least recorded was 10.70 in Gamsarka and highest 41.00 in Marina in 2000. Generally however, the agency seem reluctant to carry out adequate maintenance at the main system level due to lack of funds, on one hand, while the farmers associations performed creditably in maintaining the secondary and tertiary levels, on the other.

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Table 2: WUA Performance on Secondary and Tertiary System Network Maintenance (1997-2000) S/No.

Type of canals & maintenance work

Constructed Lengths under Use (km)

Annual length of canal maintained (km) Cumulative Total 1997 1998 1999 2000 Canal

lengths Maintained (KM)

Cost Estimates (N103)

Mean PMR (%)

CLM

MPR

CLM

MPR

CLM

MPR

CLM

MPR

1. Distributory canal (DCs)-cleaning

23,3 14,30 0,61 17,80 0,76 14,10 0,61 20,54 0,88 66,74 467,18 0,72

2. Field canal (FCs)-cleaning & desitting

149,93 128,00 0,85 15,10 0,10 65,26 0,44 108,68 0,72 317,04 951,12 0,53

3. Field drains (FDs)-restoration & desitting

146,65 1,35 0,01 6,23 0,04 5,20 0.04 92,55 0,63 105,33 315,99 0,18

4. Collector drains (CDs)-cleaning & desitting

37,65 0,50 0,01 0,90 0,02 1,10 0,03 8,95 0,24 11,45 572,50 0,08

Annual total Canal Length(km) 144,15 40,03 85,66 230,72 500,56 2306,79

0,30 Mean MPR (%) 0,37 0,23 0,28 0,62

Std Dev. 0,43 0,36 0,29 0,27 Annual Total Cost N103 513,15 233,59 365,08 1194,97

CLM = Length of canal maintained MPR = Maintenance performance ratio

Combined efforts of all WUAs operating in

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Table 3: Performance of WUAs on Restoration and Desilting of Field Drains in HVIP (1997-2000) Year

Sectors in HVIP Adaha

NFDs = 282 Auyo

NFDs =254 Ayama

NFDs = 165 Gamsarka

NFDs - 158 Marina

NFDs = 500 Zumoni

NFDs = 306 1997 1998 1999 2000

NFDUC WLPI NFDUC WLPI NFDUC WLPI NFDUC WLPI NFDUC WLPI NFDUC WLPI

230 81,54 185 65,62 107 37,93 66 23,41

N in Op N in Op

205 80,71 144 56,73 79 31,22

130 78,82 92 55,84 53 32,13 22 13,33

100 63,32 71 44,93 43 26,34 17 10,70

435 90,98 403 80,62 376 75,22 205 41,00

255 82,94 207 67,72 105 34,93 50 16,30

Mean 52,13 56,22 45,03 36,33 71,96 50,48 NFDs = No of Field Drains available in the Sector, N in Op= Not in operation in the year 1997 NDUC = No of Field Drains under Cropped in the Sector WLPI = Water logging Problem Index

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3.3 Improvement on the Water Delivery The scheme managers developed and put into use a linked-operation-strategy via continuous-communication arrangement between the nine (9) different gate operators covering a distance of over 28km from the barrage to the tail spillway. This communication facility allowed the operators at Feeder Intake Gates (FIGs) and North Main Division Works (NMDWs) to alert all the Sector Turn Out (STOs) operators along the North Main Canal (NMC) on when to expect the water wave into the sector taking into consideration the extraction pattern at the various STOs as the wave advances downstream. The new arrangement drastically reduced the waste in all the 8 sectors. To reinforce the latter, a water delivery schedule based on crop-growth-stage was also designed and put into use. This guided the operators on the levels of gate opening at different time in either dry or wet seasons. The STO operators were trained on how to use the schedule to select the right combination of Distributory Turn Out (DTO) gates so that neither shortage nor excess water is released into a sector. The use of the linked-operation-strategy and operation guidelines supported with the rating curves improved the DPRs at FIGs and at NMDWs, which ranged from 0.85 to 1.38 and from 0.80 to 1.30 for the pre and post testing periods, respectively (see Table 4). A similar performance was recorded at the three selected STOs (representing the head, middle, and tail sections) where the DPRs ranged between 0.12 to 0.97 and from 0.78 to 0.90 for the same period giving means of 0.37 and 0.86, respectively. The adoption of these new rules and guidelines also reduced water wastage at the main system as indicated by the drop in outflow at Yamidi spillway from 1.75 to 1.28m3/s. The overall impact of this can be summarized thus:

• timeliness of scheme operation and farming activities was ensured, • Reliable water delivery and equitable distribution at head, middle and tail ends of the network was

significantly attained, and • Adequacy of water supply at the main and secondary canasl was ensured

The efficiency and precision with which the Constant Head Orifice3 (CHO) is operated was improved upon through the use of gauges, appropriate time lag for the still basin to fill and matching the discharge with no of DTO gates opening. Table 4. Comparison of water delivery performance under two operational strategies (1999 & 2000)*

Type of Hydraulic Structure

Design discharge (m3/s)

Measured discharge (m3/s)

Adjusted Delivery Performance Ratio1 (%)

Seasonal Mean of DPRs (%)

NOSa LOSb NOS LOS NOS LOS Feeder Intake Gates (FIGs)

30.00 29.51 29.05 28.50

4.50 3.84 4.35 3.75 3.98 3.92 3.88 3.90

0.87 0.74 0.85 0.74 0.79 0.79 0.79 0.78

0.83 0.80

Standard Deviation 0.295 0.076 0.041 0.026 North Main Division Works (NMDWs)

14.90 14.12 13.30 12.40

3.30 3.05 3.27 3.15 3.24 3.09 3.20 2.89

1.28 1.19 1.34 1.30 1.41 1.35 1.50 1.36

1.39 1.30

Standard Deviation 0.043 0.111 0.095 0.077 Yamidi Spillway

(m3/s) 3.81 6.68 4.87 1.75 1.28

*(Abubakar, 2002), a= normal operation strategy, b = linked operation strategy, 1=actual DPR*5.82 (capacity utilisation index) 3.4 Ability of Agency and WUA to Take Care of More Maintenance Tasks Crop production was assessed to be a profitable venture in the project area. This financial upliftment witnessed by the farmers made it easier for them to pay water fee promptly and more regularly

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(Abubakar, 2002). The situation improved the cost recovery ratio of the agency from a mean of 47 to 72% obtained prior to and after the testing period, respectively (Table 5). In trying to justify the improvement recorded in cost recovery as well as in rate of recovery from water fee, the agency spent more funds on the system maintenance during the same period. This was evident by the increase in Maintenance Budget Ratio (MBR) from a mean of 0.26 to 0.68%. Suggesting that the scheme managers are committing more funds in the maintenance of the scheme, probably as a result of pressure from the farmers associations. 3.5 Lessons Learned The pilot case provided opportunity for the following lessons: § Evolution of the two actors from individual farmers and government controlled agency to

organized groups and autonomous agency ; § Evolution of the interests and needs of the two actors that must be satisfied for them to have the

legal ground to carry on with the initial goal of PIM. § Without a clear policy direction it is extremely very difficult for the two actors to proceed

despite any facilitation provided. § There must be a simple, interactive and participatory process through which the approach can be

adapted to the socio-cultural, technical, organizational and policy environments of both the actors;

§ The various actors need clear indications and incentives to motivate them to effectively participate not only in the process but also in sustaining the gains recorded, and

§ Above all very well motivated social organisers and technicians are a necessity for the sensitization and mobilization of the two actors towards the PIM concept.

4. CONCLUSION The testing of the AFJM approach using a five-step participatory process involving the users and the agency as equal partners led to the : a) institutionalized farmers’ associations and re-organized irrigation agency ; b) sensitized and mobilized users’ associations and reoriented agency management and field staff for effective participation ; and c) capacity building of both parties on how to proceed with the implementation and sustenance of the approach for improved irrigation management. These achievements necessitated the provision of qualitative services to the water users which can improve their ability to attain better agricultural productivity and higher incomes. Higher cost recovery, financial self-sufficiency and financial autonomy by the agency were what empowered them to address farmers’ interests. A successful experience provides opportunity for the evolution and strengthening of farmers’ associations which can effectively serve as the platforms for sustainable adoption of participatory irrigation management.

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Table 5: Operation and Maintenance Cost Recovery Performance by HVIP between 1997-2000. Year

Dev. Irrg. Land (ha)

Service Charge rates (N/ha/season)

Total Charges Expected (N103)

Total charges collected (N103)

Percentage of Collection (%)

Water fee Land lease fee Water fee Land lease fee

Water fee Land lease fee

Water fee Land lease fee

1997 1998 1999 2000

1870 2202 2202 2202

500.00 500.00 500.00 1500.00

1000.00 1000.00 1000.00 1000.00

993.90 1294.31 1288.17 2364.31

441.86 457.06 473.80 462.68

780.23 870.65 977.92 1992.34

151.10 429.96 416.22 426.73

0.79 0.67 0.76 0.84

0.34 0.94 0.88 0.92

Total Mean

5940.69 1485.17

1835.40 458.85

4621.14 1155.29

1424.01 356.00

0.76

0.77

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REFERENCES Abubakar, S.Z. 2002. Development and Application of Agency-Farmer Joint Irrigation Management in Hadejia Valley Irrigation Project, Nigeria. Unpublished Ph.D thesis submitted to Dept. of Agricultural Engineering, ABU., Zaria. Abubakar, S.Z., Abubakar, S.S., Murtala, G.B. 1999. Participatory Irrigation Management: the case study of Hadejia Valley Irrigation Project, Nigeria. 14-18 November, 1999, ICID international seminar on "The performance of large and small scale irrigation in Africa", Abuja, Nigeria. Adhikarya. R and H. Posamentier. 1978, Motivating farmers for action: How strategic Multi-Media Campaigns can help, Eschborn, Frankfurt: GIZ 1987: and R. Adhikarya, "Guideline Proposal for a Communication Support Component in Transmigration Project". Rome: FAO/United Nations, Project 6/INS/01/T. FAO. 1991a. Improved Irrigation System Performance for Sustainable Agriculture. In proc. of regional workshop. AGL/MISC/18/91, :3-24. FAO. 1991b. Nigeria: Irrigaiton Sub-sector Review, Report NO: 89/91/CP., NIR 45SR. Havelock, R.G. 1976. Planning for innovation through dissemination and utilization of knowledge. Ann Arbor, Mich. : Institute for Social Research/Center for Research on Utilization of Scientific knowledge, University of Michigan. Hollis, G.E., W.M. Adamas and M. Aminu-Kano. 1993. The Hadejia-Nguru Wetland. Cambridge, U .K. IUCN . Ijir, T.A. 1994. The performance of medium scale jointly managed irrigation schemes in sub-Saharan Africa: a study of the Wurno Irrigation Scheme, Nigeria. Unpublished Ph.D Thesis, University of Southampton, U .K. Ijir, T.A and M.A. Burton. 1998. Performance Assessment of the Wurno Irrigation Scheme, Nigeria. ICID Journal, Vol.47 (1):31-46. Jaujay , J. 1990. The Operation and Maintenance of a Pilot Rehabilitated Zone in the Office du Niger, Mali ODllIIMI Irrigation Management Network (NP 9011c): 4-15. Laird, D.H. 1972 Training methods for skills acquisition. AS for Training and Development. Lauraya, F .M., A.L.R. Sala, 1996. Alternative support systems to strengthen Irrigations' associations in Bicol, the Philippines, after irrigation management turnover. In Johnson (eds.) Irrigation management transfer: Selected papers from the International Conference on Irrigation Management Transfer, Wuhan, China, Rome:IIMI and F AO. Mao Zhi, 1989. Identification of causes in poor performance of atypical large-sized irrigation scheme in south China. Asian Regional Symposium on the Modernization and Rehabilitation of Irrigation and Drainage Schemes. Published by Hydraulics Research Wallingford, England; Asia Development Bank, and National Irrigation Administrative of the Philippines.

Morgan, B., Holmes, G.E., and Bundy, C.E. 1978. Methods in adult education. 3rd ed. Danville, III. Interstate. Musa, I.K. 1994. Irrigation Management Transfer in Nigeria; A Case of Financial Sustainability for

Operation, Maintenance, and Management. Paper presented at the International Conf. on Irrigation Management Transfer, Wuhan, China, September, 20-24.

Musa, I.K. 1999. Irrigation and Drainage Challenges of the 21st Centuary: Re-engineering the public irrigation schemes for sustainability. Presentation at orientation workshop for new management of RBDAs, organised by FMWR held at NWRI, Kaduna. Pitana, L.G. 1993. Performance Indicators: a Case of a \newly Developed FMIS in Bali, Indonesia. In Manor et.al (eds.) Performance Measurement in Farmer-managed Irrigation Systems Network. Colombo, Sri. Lanka: IIMI. Plusquellec, H.L., Kathryn M. P.and Christian P. 1990. Review of irrigation system performance with respect to initial objectives. Irrigation and Drainage Systems 4:313-327. Pradhan, P. 1993 Wurno farmers learn from Karfi farmers: An example of a farmer-to-farmer training

experiment in Nigeria in FMIS No.12. September 1993. Pranhan, P. and E.U. Nwa. 1993. Preliminary indications of research needs for Improved irrigation

management of RBDA projects in Nigeria. In: Ewem U. Nwa and Prachnda Pradhan (eds. ) irrigation research practices for Nigeria, Kano, IIMI - Nigeria field office.

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Pradhan, P.S. Abdulmumin and S. Ben-Musa, 1994. Participatory Irrigation Management in the context of Nigeria. In Pradhan et.al (eds.) Participatory Irrigation in Nigeria, organized by IIMI and NWRI, Kaduna. Rolling, N. 1982. Alternative approaches in extension. In G.E. Jones & M. J. Rolls ( eds.), Progress in rural extension and community development. Vol. 1 Extension and relative advantage in rural development (pp. 87 -115). Chinchester, U.K.: John Wiley. Vermillion, DL. and J.A.Sagardoy. 1999. Transfer of Irrigation Management Services: Guidelines. FAO Irrigation and Drainage paper No.58., Rome Italy. World Bank. 1995. The World Bank and Irrigation. Sector study report No.14908.http://www.worldbank.org/oedhome/on-line report/html.

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OPTIMUM TILLAGE SYSTEM FOR OKRO PRODUCTION IN AN ULTISOL OF SOUTH EASTERN NIGERIA

A. N. Nwagu* and S.I. Oluka

Department of Agricultural and Bioresource Engineering, Enugu State University of Science and Technology,

Enugu – Nigeria * Mr. A. N. Nwagu died in 2005.

ABSTRACT The effect of five tillage treatments: zero-tillage (T0), ploughing alone (T1), Harrowing alone (T2), ploughing and harrowing (T3), ploughing, harrowing and bedding (T4) on soil physical properties and yield of okra (Abelmoschus esculentus, L. Moench) was examined for three years. Results show that tillage practices significantly (P=0.05) affected soil strength, bulk density and porosity. Zero- tillage was significantly (P=.05) different from other tillage treatments in yield and growth parameters measured. Conventional tillage systems (T3 and T4) and zero tillage system (T0) are on the extremes considering conditions for optimum tillage selection. The reduced tillage system (Harrowing alone T2) is recommended as the optimum, tillage system for Okra production based on its highest yield record and most stable soil property when compared with other tillage treatments considered. KEY WORDS: Optimum tillage, Okro production, Ultisol, zero tillage, conventional tillage. 1 INTRODUCTION Tillage is the physical, chemical or biological soil manipulation to optimize conditions for seed germination, emergence, and seedling establishment (Lal, 1979). The seedbed is the place where the seeds germinate and the medium from which the resulting plants obtain moisture and mineral nutrients through their roots. The primary effect of any tillage operation is to change the soil physical condition. This implies a change in the soil air and water distribution characteristics, resistance to proliferation and penetration of roots, erosion and weed control characteristics. The success of any tillage operation depends on how well the complex interactions between these parameters are combined to achieve good crop growth and yield at reasonable cost in terms of input and soil deterioration (Anazodo and Onwualu, 1988). It is essential that the seedbed provides sufficient moisture, nutrients, and air to allow full penetration of the plant roots. The achievement of this objective depends on the quality of the tillage operation carried out. The conventional system of tillage emphasizes very fine tilth while recent trend is on minimum or reduced soil manipulation. Intensive cultivation depletes the naturally accumulated soil fertility. The slow natural soil building processes are reversed as excessive tillage leads to loss of topsoil, soil structure, and organic matter. Repeated passes of agricultural tractors of farm lands lead to reduced infiltration rates, poor soil aeration, reduced root exploration, reduced crop yield and soil erosion (Soane et al, 1979). Zero tillage agriculture is aimed at maintaining ecologically sound agriculture while at the same time increasing production and land use intensity. The advantages of the zero tillage system includes saving in labour and fuel expenses, the protection of the soil by a mulch cover and a decrease in erosion hazards on erosion susceptible soils, an increase in plant available water, and a possible extension of the vegetation period. Considerable success with zero tillage system was based on adequate use of mulch and herbicides and special management techniques (Lal, 1976).

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Choice of appropriate tillage system for a given crop and soils is important for continuous management of soil for sustained productivity. The short-term objective of seedbed preparation is maximizing yield while maintaining the productivity of a land over a long period of time is one of the long-term objectives. Any physical manipulation of the soil must therefore meet both the long-term and short-term objectives of crop production. This study compares the influence of zero – tillage, conventional tillage and reduced tillage practices on soil physical properties and yield of Okra fresh fruit under rain fed condition in a loamy sandy soil and thus determines the optimum tillage method for the crop. Okra is one of the major vegetable fruit crops in Nigeria. It is widely consumed across the country as food and in the making of the popular Okra soups. It also has some industrial uses. Currently, Nigeria is among the leading producers of the crop globally and if well cultivated and massively produced, it has the potential to earn foreign exchange for the country. 2 MATERIALS AND METHODS 2.1 Experimental Site This experiment was conducted at the National Horticultural Research Institute Sub-station at Mbato, Okigwe. The station lies on Latitude 05033’N and Longitude 07023’E and altitude of 130 meters above sea level. The experimental site was well-drained non-gravelly soil. Particle size distribution of the surface horizon was 79% sand, 3.8% silt, and 17.2% clay. The texture was classified as sandy loam and pH was 5. According to a reconnaissance soil survey of Southeastern Nigeria (FDALR, 1985) Okigwe belongs to soil map unit 408 characterized by undulating dissected plains derived from shale and sand stone, classified as Ultisol. 2.2 Experimental Design and Tillage Treatments Five tillage treatments were used and laid out in a randomized complete Block Design (RCBD). The treatments were:- zero tillage or no – tillage (T0), disc ploughing alone (T1), disc harrowing alone (T2), ploughing and harrowing (T3,), ploughing and harrowing followed by bed making (T4). These treatments were replicated five times. The tillage treatments were chosen because of their widespread usage as major tillage operations in the area. The tillage treatments were achieved by the use of different implements coupled to MF 260 tractor of 45 kW. The implements were 3-botom disc plough, tandem disc harrow, and rotary mower. The selected site was slashed and 5 blocks marked out on an area of 25m x 38m leaving space for tractor movement. This was necessary so that the tractor would not ride on the next plot while working on the other, to reduce compaction. Each block was divided into 5 units of 5m x 4m area for the purpose of imposing the tillage treatments. In zero – tillage systems, paraquat was sprayed at the rate of 250ml/ ha to kill weeds. Calibration was carried out to determine the volume of mix to use. All the plots where ploughing operation was involved (T2, T3, and T4), were ploughed once with a 3-bottom disc plough to approximately 20cm depth. This was followed by harrowing once to approximately 15cm depth for plots concerned (T2, T3, and T4). Beds were prepared on the plots by manually raising the soil level with the hoe. Final field preparation for planting involved neat marking of the plots, leaving a space of 2m between plots in each block. This was to minimize edge effect and take necessary precaution against overlapping of treatments during tractor operation.

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2.3 Cultural Practices Okra seeds (NHLe 47 - 4) were planted at a spacing of 100cm between rows and 30cm within rows with 2 to 3 seeds per hole. Replanting was done immediately after germination to take care of seeds that did not germinate and those that looked scotched. Thinning to one plant per stand was carried out according to agronomic practice. Insect attack was checked by applying Nuvaron (mixed at 25ml to 10 liters of water) two weeks after planting and subsequently every week until the fourth week when flower buds began to emerge. Karate 2.5 Ec also mixed at 25 ml to 10 litres of water was subsequently used at the 6th, 7th, 8th & 9th weeks. This treatment was carried out in all the blocks. Weed control was achieved effectively by the use of both manual method and herbicides application. Firstly, the whole area was manually weeded with hoe three weeks after seed germination. Two weeks later when the weeds were just emerging, herbicide was applied at the same rate on all plots. Dual 150ml was mixed with paraquat (30 ml to 10 litres of water) and carefully applied on the soil surface. Paraquat, which is a contact herbicide killed the weed regrowth, while Dual, a soil acting selective herbicides suppressed further regrowth or germination of weed seeds. Fertilizer (N.P.K 12-12-17-2mg) was applied at the rate of 500kg/ha at four weeks after seed germination. 2.4 Measurement of Plant Growth Plant growth were monitored and evaluated from the 4th week after planting. Fruit yield was measured beginning from the 9th week and lasted for 10 weeks. 2.5 Measurement of Soil Physical Properties Soil samples were collected at a depth range of 0-15cm for determination of some soil physical properties namely as soil strength, porosity and bulk density. Soil strength was measured using a pocket penetrometer (ModelCl-7.00). Randomly selected points were measured insitu by pushing the penetrometer piston with steady pressure in to the soil up to the calibration groove. The reading was taken and the instrument adjusted properly for other measurements. The means (from ten (10) points measured in each plot) were calculated and used in analyzing the penetrometer resistance for the treatments. The determination of bulk density involved the estimation of weight/volume ratio. Bulk density was determined from undisturbed soil collected with core sampler, which contains core cylinder of diameter 5.5cm and height of 6cm. The porosity of the soil samples were calculated from the known values of the bulk density. All the measurements on the soil physical properties were taken three months after the tillage treatments. 3. RESULTS AND DISCUSSION Analysis of variance (ANOVA) was done on the data collected for treatments under study to test for differences among treatments. Mean separation was done by the Fishers Least Significant Difference (F.LSD) mean separation method. The results obtained show that tillage treatments significantly (P =0.05) affected soil physical properties (soil strength, bulk density and porosity) over the three years studied. Tillage treatments significantly (P=0.05) affected crop yield in the first year but no significant difference was noted in the second year except in zero tillage, which consistently was significantly different from other treatments over three years.

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There was no significant difference (P =0.05) in growth parameters (Plant height, number of leaves and number of fruits) due to tillage treatments except in the case of zero tillage values which were consistently lower and significantly different in these parameters than the other treatments. 3.1 Soil Physical Properties Tillage treatments affected soil physical properties of the surface layer (0-15cm) at three months after land preparation (Table 1). The zero tillage (T0) treatment had the highest average penetrometer resistance over the three year: (2.52kgcm-2) followed by harrowing alone T2 (1.76kgcm-2) and the least was T4 (1.51kgcm-2). Ploughing alone T1 and the ploughing and harrowing T3 recorded equal penetrometer resistance of 1.59kgcm-2. Average bulk density values over the three years were highest for zero- tillage (1.40gcm-3) and least for bed making T4 (1.29gcm-3). Bed making was not significantly different (P=0.05) from ploughing alone T1 (1.30gcm-3) while harrowing alone T2 (1.38cm-3) recorded higher values than T1, T3 and T4. The average bulk density value for zero-tillage T0 (1.40gcm-3) was found to be higher than harrowing alone T2 (1.38gcm-3). This trend in bulk density was noted to be different in the case of porosity. Average porosity over the three years was highest for bed making T4 (49.89%) and least for zero-tillage T0 (46.95%). No major difference was noted between bed making T4 (49.89%) and ploughing alone T1 (49.55%). Both T4 and T1 recorded higher values than ploughing and harrowing T3 (49.10%). Incidentally T3 has a higher bulk density and therefore less porosity. Harrowing alone T2 (47.77%) is significantly (P=0.05) higher than zero tillage T0 (46.95%) and lower than ploughing and harrowingT3. 3.2 Yield and Growth Parameters Table 2 shows the effect of tillage on fresh okra weight over a harvest period of ten (10) weeks in the first year of study. Records on number of fruits per plots and plant stand (Table 3) were taken only in the first year as well as the growth parameters (plant height and number of leaves). TABLE 1: Tillage effect on soil physical properties at 0-15cm depth.

Soil properties Year Treatment To T1 T2 T3 T4 Soil Strength kgcm-2 1st

2nd

3rd

2.60a 2.55a 2.40a

1.60bc 1.53b 1.62c

1.75b 1.68b 1.86b

1.58bc 1.64b 1.52cd

1.51c 1.65b 1.37d

Mean (X)

2.52

1.58 1.76 1.58 1.51

Bulk Density gcm-3

1st

2nd 3rd

1.42a 1.41a 1.38a

1.34c 1.27d 1.28b

1.41a 1.36b 1.38a

1.37b 1.32c 1.27b

1.33c 1.28d 1.28b

Mean (X)

1.40 1.30 1.38 1.32 1.29

Porosity %

1st

2nd 3rd

16.44c 46.80c 47.6c

49.20a 49.60a 49.86a

46.82c 48.4b 48.10b

48.10b 49.54a 49.66a

49.58a 49.70 50.40a

Mean (X)

46.95 49.55 47.77 49.10 49.89

• Means with the same letter along the same row are not significantly different (P=0.05) • Means with different letters along the same row are significantly different (P=0.05)

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Table 2: Mean yield of fresh okra fruit (kg/plot) as affected by tillage methods. Years Treatments T0 T1 T2 T3 T4 1st Year 12.61c 17.35b 17.47b 19.46ab 21.41a 2nd Year 13.37b 18.39a 19.16a 19.95a 20.98a 3rd Year 13.78c 18.55ab 17.88b 19.52ab 21.61a X 13.25 18.10 18.17 19.64 21.33

Means followed by the letters in the same row are not significantly different (P=0.05). Means with different letters in the same row are significantly different (P=0.05). Table 3: Number of fruit per plot as affect by different tillage practices.

Blocks Treatments 1 11 111 IV V £ X Fruit per

plant T0 333 786 671 764 471 3025 605c 16 T1 850 797 869 749 733 3998 799.6b 21 T2 743 822 673 1114 730 4082 816.4ab 22 T3 828 766 981 976 969 4520 904.ab 23 T4 893 948 1063 1052 926 4882 976.4a 25

F-LSD(0.05) = 161.47 Table 4: Mean value of leaf number per plant as affected by different tillage practices.

Mean weekly until fruiting Treatment 4th 6th 7th 8th 10th Final value at

16th wk. T0 4.44 6.28 8.02 9.36 11.60b 22.99 T1 4.80 6.96 9.0 10.42 13.14a 27.76 T2 4.82 6.9a 8.7a 10.16 13.02a 27.24 T3 4.90 7.08 9.06 10.42 13.22a 27.20 T4 5.04 7.28 9.34 10.64 13.76a 29.28

F-LSD (0.05) =1.28 Table 2 shows the values of mean yield of fresh okra fruit ( Kg/ plot) as affected by different tillage practices. Bed making T4 has the highest average value (21.33kg per plot) of fresh fruit yield over the three years study followed by ploughing and harrowing T3 (19.64 kg/plot), harrowing alone T2 (18.17 kg/plot). Only zero tillage T0 was significantly different from all other treatments in yield and number of fruits per plot. The values of T4, T3, T2, and T1 in Table 3 are not significantly different in average yield but ploughing alone T1 has smaller number of fruits (800) than T4 (976), T3 (904) and T2 (816). The values for bed making T4 (976) are not significantly different from harrowing alone T2 (816), plough and harrow T3 (904). There were no significant differences in the growth parameters (plant height and number of leaves) due to tillage treatment except in zero-tillage values, which were consistently lower than the other treatments. Since penetrometer resistance has been found to be an indication of the mechanical impendence the roots of a crop will encounter in penetrating the soil (Soane et al, 1979), zero tillage would offer greater mechanical impendence to root growth and proliferation. Harrowing alone had a higher penetrometer resistance than ploughing alone because the minimal soil disturbance by harrowing alone could easily return to normal through compaction by raindrop energy and traffic during cultural operation. This might explain the slight increase noted in this property between the second year and the third year.

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The high bulk density recorded in the zero tillage plots and the low penetrometer resistance in the conventional tillage treatment agreed with the principle that changes in bulk density depends on the amount of soil loosening and traffic pressure. This agrees with the results from other studies (Asoegwu, 1987; Anazodo and Onwualu, 1988). Harrowing alone has tendency for high bulk density because standard tandem disc harrows work the soil at a shallow depth of about 10cm (Throckmorton, 1986). Ploughing and harrowing has significantly higher bulk density than ploughing alone. This is understandable since secondary tillage operation involving harrowing tends to re-compact the soil. Porosity was lowest with zero tillage. Therefore, compared to other tillage methods, zero tillage had the potential of reducing the free flow of air and water into and within the soil profile. No significant difference was noted between bed making and ploughing alone. Ploughing alone gave higher value of porosity than ploughing and harrowing. This could be explained by the fact that the disc created more space in the soil with its inversion of bigger clods. Ploughing and harrowing on the other hand re-compacted an originally well loosened soil. Moreover, the more finely the soil is made, the more the number of fine soil particles that is produced, and thus the greater the chances of sealing effect of the soil surface and tendency to compress during rain falls by rain drops. The poor performance of zero tillage in relation to others in providing high yield can be attributed to high soil density, very high soil penetrometer resistance and low porosity. This probably offered mechanical impendence to root growth and proliferation as well as aeration and water infiltration problems. Moreover, residue mulch cover was not adequate on zero tillage plots as to contribute or enhance yield. Similar results have been obtained by other researchers (Anazodo and Onwualu, 1988; Asoegwu, 1987; Anazodo, 1983). There was no significant difference (P=0.05) in average yield over the three years in the treatments T1, T2, T3 and T4. Similarly, there was no significant difference (F – LSD = 0.05) in the plant height and number of leaves as recorded in the first year between T1, T2, T3 and T4. These results show that these treatments are likely to produce the same effect and that the conventional tillage systems (T3 and T4) are unnecessary for okra production. 4. CONCLUSION Based on the results obtained, the following conclusions are drawn: Zero-tillage consistently gave very high penetrometer resistance, bulk density and lowest value of porosity; average okra yield over the three years was highest for bed making T4. followed by ploughing and harrowing T3, harrowing alone T2, ploughing alone T1 and zero-tillage To. The yields of T1, T3, T2, T4 were not significantly different at P=0.05. Harrowing alone T2 produced less changes in soil physical properties and appear to be a suitable modification between conventional tillage systems and zero-tillage, which are on the extremes. Although ploughing alone seemed to have more favourable soil characteristics for crop growth shown by lower average mechanical impendence (1.58kg cm-3); lower average bulk density (1.30gcm-3); lower average bulk density (1.30gcm-2) and higher average porosity (49.55%), harrowing alone had a relatively higher yield and higher number of fruits per plot and invariably higher economic returns. It is therefore recommended for use for soil conservation purposes and saving in energy than ploughing alone for okra production. The conventional systems (T3 and T4) are likely to hasten soil degradation. REFERENCES Anazodo U. G. N. 1983. A field evaluation of different tillage systems under maize production in derived savanna region of Nigeria. Proceedings of the First National Tillage Symposium, NSAE pp, 101-113. Anazodo U. G. N and Onwualu, A. P. 1988. Field evaluation and cost benefit analysis of alternative Tillage Systems for maize production in the derived savanna zone of Nigeria. Proceedings C.I.G.R. Inter-sections symposium, Sept. 1988. Ilorin, Nigeria. Pp.157-167.

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Asoewgu S. N. 1987. Tillage effects on Egusi-melon (Coocynthus Citrullus. L.) Production in Nigeria. Proceedings 9th Annual Conference of the Horticultural Society of Nigeria (HORTSON) held at FUTO, Owerri, Nigeria, pp. 84-91. FDALR 1985. Federal Department of Agricultural Land Resources (FDALR). 1985. The Reconnaissance soil Survey of Nigeria. FDALR Publications, Kaduna, Nigeria. Lal, R. 1976. No-tillage effect on soil Properties under different crops in Western Nigeria. Proceedings of American Soc. Of Soil Sci, 40: 762 – 768. Lal, R. 1979. Importance of Tillage System in soil and water Management in the tropics. In: Soil Tillage and crop production, 11TA Proceedings series No2. Ibadan. Pp 25-28. Soane, B. D; Dickson, J. W. and Blackwell, P. S. 1979. Some options for reducing compaction under wheels on loose Soil. 8th Conference of International Soil tillage research Organization. Bundesrepublik Deutsch Land. Throck Morton, R. I. 1986. Tillage and planting equipment for reduced tillage. In: No Tillage and surface-tillage Agriculture (Ed-Spragre, A and triplett G.B) pp. 59-91.

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INSTRUCTIONS FOR AUTHORS Publication Schedule: The Journal of Agricultural Engineering and Technology (JAET) is published annually (September) by the Nigerian Institution of Agricultural Engineers (NIAE), A division of the Nigerian Society of Engineers (NSE). Manuscript: The manuscript should be typed double spaced on A4 paper (216mm x 279mm) on one side of the paper only, with left, right and top-bottom margins of 25.4mm. The original and three copies are required for initial submission. The paper should not exceed 20 pages including Figures and Tables. Organization of the Manuscript: The manuscript should be organized in the following order; Title, Author’s name and address including E-mail address and telephone number; Abstract; Keywords; Introduction; Materials and Methods; Results and Discussion; Conclusion; Notation (if any); Acknowledgements; References. The main headings listed above should be capitalized and left justified. The sub-headings should be in lower case letters and should also be left justified. Sub-sub headings should be in italics. All headings, sub-headings and sub-sub-headings should be in bold font. Headings and sub-headings should be identified with numbers such as 1; 1.1; 1.1.1 etc. For the sub headings, the first letter of every word should be capitalized. Title: The title should be as short as possible, usually not more than 14 words. Use words that can be used for indexing. In the case of multiple authors, the names should be identified with superscripted numbers and the addresses listed according to the numbers, e.g. A. P. Onwualu1 and G. B. Musa2. Abstract: An abstract not exceeding 400 words should be provided. This should give a short outline of the problem, methods, major findings and recommendations. Keywords: There should be keywords that can be used for indexing. A maximum of 5 words is allowed. Introduction: The introduction should provide background information on the problem including recent or current references to work done by previous researchers. It should end with the objectives and contribution of the work. Materials and Methods: This section can vary depending on the nature of the paper. For papers involving experiments, the methods, experimental design and details of the procedure should be given such that another researcher can verify it. Standard procedures however should not be presented. Rather, authors should refer to other sources. This section should also contain description of equipment and statistical analysis where applicable. For a paper that involves theoretical analysis, this is where the theory is presented. Results and Discussion: Results give details of what has been achieved, presented in descriptive, tabular or graphical forms. Discussions on the other hand, describe ways the data, graphs and other illustrations have served to provide answers to questions and describe problem areas as previously discussed under introduction. Conclusion: Conclusion should present the highlights of the solutions obtained. It should be a brief summary stating what the investigation was about, the major result obtained and whether the result were conclusive and recommendations for future work, if any. Notation: A list of symbols and abbreviation should be provided even though each of them should be explained in the place where it is used. References: Follow the name-date system in the text, example: Ajibola (1992) for a single author; Echiegu and Ghaly (1992) for double authors and Musa et al. (1992) for multiple authors. All

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references cited must be listed in alphabetical order. Reference to two or more papers published in the same year by the same author or authors should be distinguished by appending alphabets to the year e.g. Ige (1990a, 1992b). All references cited in the text must be listed under section “References”. For Journal, the order of listing should be author’s name, year of publication, title of paper, name of journal, volume number, pages of the article: for books, the author’s name comes first followed by the date, title of book, edition, publisher, town or city of publication and page or pages involved. Examples are as follows: Journal Articles: Ezeike, G. O. I. 1992. How to Reference a journal. J. Agric Engnr. and Technology. 3(1): 210-205 Conference Papers: Echiegu, E. A. and Onwualu A. P. 1992. Fundamentals of Journal Article Referencing. NSAE paper No 92-0089. Nigerian Society of Agricultural Engineers Annual Meeting, University of Abuja, Abuja – Nigeria. Books: Ajibola O. 1992. NSAE: Book of abstracts. NSAE: Publishers. Oba. Abakaliki, Nigeria. Book Chapter: Mohamed S. J., Musa H. and Okonkwo, P. I., Ergonomics of referencing. In: E. I. U. Nwuba (Editor), Ergonomics of Farm Tools. Ebonyi Publishing Company, Oshogbo, Osun State, Nigeria. Tables: Tables should be numbered by Arabic numerals eg. Table 3 in ascending order as reference is made to them in the text. The same data cannot be shown in both Table and Figure. Use Table format to create tables. The caption should be self explanatory, typed in lower case letters (with the first letter of each word capitalized) and placed above the table. Tables must be referred to in the text, and positioned at there appropriate location. Figures: Illustrations may be in the form of graphs, line drawings, diagrams schematics and photographs. They are numbered in Arabic numerals e.g. Figure 5.m. The title should be placed below the figure. Figures should be adequately labeled. All Figures and photographs should be computer generated or scanned and placed at their appropriate locations. Units: All units in the text, tables and figures must conform to the International System of units (SI) Reviewing: All papers will be peer reviewed by three reviewers to be appointed by the Editors. The editors collate the reviewers’ reports and add their own. The Editorial Boards decision on any paper is final. Off Prints: A copy of the journal is supplied free of charge to the author(s). Additional reprints can be obtained at current charges. Page Charges: The journal charges a processing fee of N1000 and page charges are currently N500 per journal page. When a paper is found publishable, the author is advised on the page charges but processing fee (non refundable) must be paid on initial paper submission. These charges are subject to change without notice. Submission of Manuscript: Submission of an article for publication implies that it has not been previously published and is not being considered for publication elsewhere. Four copies of the manuscript and N1000 processing fee should be sent to: The Editor-In-Chief Journal of Agricultural Engineering and Technology (JAET) C/o The Editorial Office National Centre for Agricultural Mechanization (NCAM) P.M.B. 1525, Ilorin, Kwara State

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Nigeria. Papers can also be submitted directly to the Editor-In-Chief or any of the sectional Editors (See address in a current volume of the journal). Those who have access to the internet can submit electronically as an attached file in MS Word to [email protected] or to the Editor –in-Chiefs e-mail box.

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journal of agricultural engineering and technology … · abdul-fatah, (1997) developed an animal...

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