By Olom, UJ; Agi, JI; Ogbaje, H (2022). Greener Journal of Science, Engineering and Technological Research, 11(1): 1-13.
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ISSN: 2276-7835
Vol. 11(1), pp. 1-13, 2022
Copyright ©2022, the copyright of this article is retained by the author(s)
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1Department of Agricultural and Environmental Engineering, Joseph Sarwuam Tarka University, Makurdi, Nigeria
2,3 Department of Agricultural and Bio-Environmental Engineering Technology, Kogi State Polytechnic, (Itakpe Campus), Nigeria.
E-mails: Jacobagi469@ gmail. com2, hopeogbaje@ gmail. com3
Type: Research
Full Text: PDF, HTML, PHP, EPUB
Published: 31/12/2022
Ogbaje, H.
E-mail: hopeogbaje@ gmail.com
1. INTRODUCTION
For years, human power has been the major power in agricultural production. The gradual replacement of human power with mechanical devices or systems has brought a tremendous improvement to agricultural yield. Agricultural mechanization has helped in agricultural production, processing, storage and so on which has reduced drudgery, improve timeliness of operation and efficiency of various farm operations, bringing more lands under cultivation, preserve the quality of agricultural produce, provide better rural living condition and markedly advance the economic growth of the rural sector [1].
One of the major challenges faced by the peasant farmers in Nigeria is the constraints experienced in seed planting as a result of manual power usage. Most of these peasant farmers cannot afford the money to procure or hire sophisticated machinery that can be used for their planting operation. The cost of the machine is going to be reduced by designing and constructing a simple planter/ fertilizer applicator to replace the bulky imported planters. The design of this planter is simple and easy to fabricate. The size of the machine, production cost, and transportation were reduced to the barest minimum. There are several advantages of seed planter cum fertilizer applicator over the traditional maize planting methods in the field. Those advantages include uniform seed and fertilizer distribution, calculated quantities of seed and fertilizer can be placed at the required depth with fertilizer below and besides the seed [2].
The aim of this work was to develop a simple mini corn planter/fertilizer applicator using locally available materials at relatively low cost for peasant farmers and garden use.
2. MATERIALS AND METHODS
2.1 Materials Used for the Planter
The manually operated single row planter for sowing seed and placement of fertilizer consists of the handles, seed/fertilizer hopper, furrow opener, front wheels, seed discharge tube, furrow covering device, and seed metering device, chain and sprockets.
2.2 Determination of the Engineering Properties of Maize Seeds and Fertilizers
In the design of this seed planter, the engineering properties of the maize seeds and fertilizers were put into consideration to avoid seed damage and for proper placement of seeds and fertilizers in the soil at the desired depth and compaction.
The determined properties are: moisture content, maize seed size and shape, arithmetic and geometric mean diameters, sphericity, seeds weight, bulk and true densities, porosity, the coefficient of friction and angle of repose.
2.3 Mode of Operation of the Planter
The design and material selection was to ensure that the machine was easy to construct, affordable for the target end users, with most of the components made with locally available materials, and low technology requiring little or no training for operation and maintenance. To operate the planter, seeds and fertilizers were poured into their separate compartments in the hopper; the planter is then positioned at the desired starting point, and pushed along the row by means of the handle. About two seeds were picked up by the metering plate and introduced into the chute. The furrow opener continuously opens the furrow and the seeds metered into the chute falls into the opened furrow which is then closed by the furrow closer. As the planter is pushed along the row, it plants continuously at 30cm intra – row spacing, until the seeds in the hopper gets finished to a level requiring refilling of the hopper. For the planting operation, the hopper was filled with seeds. The filling of the hopper depends on the area of the field to be covered. As the multi-crop planter was pushed forward in the direction of travel, at an average speed of 0.6m/s, the pointed bar type furrow opener penetrated the soil creating a furrow for seeds to be placed.
2.4 Fabrication of the Planter
The planter was fabricated and tested at Udeco Engineering Company Limited, kilometer 4, Gboko road, Makurdi, Benue State. All the parts of the maize planter were fabricated from mild steel material, except for the seed tube which was made from plastic material. The hopper was fabricated using 2 mm thick mild steel metal sheet. The main frame which supports every other component of the planter was fabricated using 50 mm angle bar of 4 mm thickness. The handle for the planter was fabricated using a 40 mm mild steel square pipe. The adjustable furrow opener and furrow closer were both fabricated using a combination of 20 mm x 5 mm mild steel flat bar and 20 mm rod. Plates 1 show the fabricated planter.
2.5 Machine Components and Design Analysis
a. Hopper design
The seed hopper assumes the shape of a frustrum of a truncated pyramid with the dimensions of 100 mm x100 mm at the bottom, 300 mm x 300 mm at the top and 300 mm height. The angle of inclination of the hopper will be fixed at 300, which is modestly higher than the average angle of repose of the seeds to ensure free flow of seeds. The hopper is divided into two segments/compartments, the seed segment and the fertilizer segment. The seed compartment is designed to accommodate 2 kg of seeds while the fertilizer compartment accommodates 4 kg of fertilizer. The hopper is made of light durable mild steel metal sheet of 3 mm thick. Figure 1 shows a schematic representation of the hopper.
Figure 1: Schematic diagram of the hopper
The volume of hopper was gotten from the mass of seeds/ fertilizers and their respective bulk densities.
The volume of seeds in the hopper was calculated using equation 1.
The volume of fertilizer in the hopper is given as
The top area of the hopper A1is given as
The bottom area of the hopper A2is given as
Where; A1 = Top area of hopper (mm2), a = Top length (mm).
A2 = Bottom area of hopper (mm2), and b = Bottom length (mm).
The height of the hopper, h is gotten from equation 5
The height of the hopper obtained is 483.3mm
b. The frame
The frame forms the platform on which other components will be mounted. The materials used for the main frame was selected on the basis of its strength and reliability from readily available materials. In this work, mild steel angle iron of 50 mm by 50 mm by 4 mm thickness was considered useful to give the required rigidity. Angle iron made of carbon steel has high strength properties and is used for general engineering purposes [3].
c. Seed chute
This is the channel through which seeds are conveyed from the seed meter to the device that deposits the seed on the soil surface or in the furrow. The seed chute is located on the outer part of the hopper by the side on which the vertical seed plate is attached. The material used for the design is a cylindrical funnel made of mild steel pipe with a diameter of 30 mm in order to accommodate at least two seeds at a time.
d. Furrow opener
Furrow opener opens the soil where seeds metered out through the chute will be dropped and covered. The type of furrow opener used for this design is the adjustable ‘shovel type’ furrow opener which gives a ‘v’ shaped furrow opening and is suitable because it cuts and displaces the soil sideways for easy planting [4]. The material used for the design of the furrow opener is mild steel angle bar because of its high strength to withstand soil resistance.
e. Furrow coverer
The furrow closer was also designed to be adjustable. It was designed to allow for proper covering and compaction of the soil over the seeds in the furrows. The design of the seed covering device on a planter depends on many factors, including: the soil type and soil condition, the design of the furrow opener, and the speed of operation, etc. [4]. The Furrow covering device was placed perpendicular to the direction of travel of the machine to facilitate proper covering of the soil.
f. The Front wheel
The front wheel was designed to enhance free movement on loose soils. It is made of 6 mm thick mild steel flat bar cut out into 80 mm width and folded into a circle of 360 mm diameter. Pieces of metal rods were attached alternately throughout the circumference of the wheel to provide lugs on its periphery which increase traction and reduce slip. The front wheel provides drive for the metering mechanism through a chain and sprocket system.
g. The rear wheel
The rear wheel is the driven wheel or seed firming device. Seed firming devices are designed to press uncovered seed into the soil at the base of the seed furrow to improve seed to soil contact [4]. For this design, a standard wheel size for equipment similar to wheel barrows with the diameter of 200 mm as proposed by Murray et al [4] was adopted on the basis of its strength to enhance stability and manoeuvrability during operation.
h. The handle
The handle of the planter was designed to meet the different height of operators which can be adjusted accordingly to reduced drudgery. The handle helps the operator to push the planter at the time of operation [5]. The length of the handle was calculated based on average standing elbow height of an operator of 120cm. Distance of wheel centre from the operator in operating condition is 130cm.
So, the angle of inclination (θh) with the horizontal is
i. Seed metering mechanism
The metering mechanism is a major component in a planter. It picks the required number of seeds and delivers them into the soil through the chute at required depths created by furrow openers. Therefore, the design considered the size of the seed, the intra and inter – row spacing for each seed, which usually differs from one crop to another. According to Murray et al. [4], seed plate thickness should be between the ranges of 3 mm to 6 mm to enable easy picking up of seeds and also to avoid damage of the seeds.
For the design of the seed metering device the most important thing is that how many cells would be developed for desired crop; so that the requirement of the plant to plant spacing is achieved. So Number of cells on the seed metering device was obtained from equation 7 [6].
In this design, the metering mechanism was made with plate of 116mm diameter and 3mm thickness with spaced cell near and flushing with the circumference of the plate. The cell was designed to pick an average of two maize seeds and drop them at intra row spacing of 30cm. The seed cell measured 2 cm by 1.5 cm and 1.3 cm deep to accommodate two (2) to three (3) seeds while the fertilizer cell measured 2.5 cm by 1.5 cm and 1.5 cm deep. The seed cell was made adjustable in order to plant other seeds of different sizes. The plate is attached vertically on a horizontal shaft driven by the front wheel through a chain and sprockets transmission.
The weight of the metering plate, W is given as
J. Weight of seeds and fertilizers in the hopper
The weight of the grain, Wg will be determined using equation 9 [7]
The weight of the seeds in the hopper is given as
The weight of the fertilizers in the hopper is given as
Where; Wg= Weight of seeds (kg), Wf = Weight of fertilizers (kg).
Wg and Wf gotten were 19.62N and 39.24N respectively
k. Design of chain and sprockets
Chains are mainly used for transmission of power from one shaft to another, when the distance between the centres of shafts is short such as bicycles, agricultural machinery, rolling mill etc. The chains are used for velocities up to 25 m/s and for power up to 110 kw [3]. The driving sprocket was designed with an assumed speed of 65 r.p.m while smaller sprocket (follower) moves at 180 r.p.m. Figure 2 shows an open chain drive system connecting two sprockets.
Figure 2: Sprockets and chain showing centre distance
The velocity ratio of a chain drive is giving as.
Where;
N1 = speed of rotation of smaller sprocket in r.p.m, N2 = speed of rotation of larger sprocket in r.p.m, T1 = Number of teeth on the smaller sprocket, T2 = Number of teeth on the larger sprocket.
For this design, the smaller sprocket of 14 teeth was selected because of the low speed requirement. The number of teeth on the larger sprocket is given as
The service factor (Ks) is the product of various factors K1, K2 and K3. The values of these factors are given as follows [3]:
Load factor (K1) =1.25, for variable load with mild shock, Lubrication factor (K2) = 1.5, for periodic lubrication, and Rating factor (K3) = 1, for 8 hours per day .
Therefore, service factor,
The pitch circle diameter of the smaller sprocket is given as,
The pitch circle diameter of the larger sprocket is given as,
Where; d1 and d2 = Pitch circle diameters the sprockets, and P = pitch of the chain in meter.
The average velocity of the smaller sprocket is given by
Load on the chain, w is given by,
The minimum centre distance between the two sprockets should be 30 – 50 times the pitch [3]. Taking the value of 35,
In order to accommodate initial sag in the chain, the value of centre distance is reduced by 2 to 5 mm [3].
The number of links may be obtained from equation 19 as
The length of the chain is given by the expression in equation 20
l. Maximum bending moment on the shafts
The power delivered to the shaft by some tangential force and the resultant torque (or twisting moment) set up within the shaft permit the power to be transferred to various machines linked up to the shaft in order to transfer the power from one shaft to another, the various members such as sprockets, pulleys etc., are mounted on it. These members along with the forces exerted upon them causes the shaft to bend [3]. Figure 3 show the load distribution on the driving shaft and metering shaft respectively.
Figure 3: Load distribution on the driving shaft
The maximum bending moment can be determined from the following expressions:
From the principles equilibrium, the sum of upward forces equals the sum of downward forces.
The maximum bending moment of 2.75N-m is chosen as the bending moment of the shaft
m. Diameter of the driving shaft
The equivalent twisting moment, Te is given in equation 34 [3].
For the hollow shaft, the ratio of inside to outside diameters is assumed to be 0.8.
The equivalent twisting moment transmitted by the hollow shaft is given as
n. Maximum bending moment on the metering plate shaft
The maximum bending moment on the metering shaft was determined from figure 4 below.
Figure 4: Load distribution on the metering shaft
From the principles of equilibrium, the sum of upward forces equals the sum of downward forces.
The maximum bending moment of 0.99 N-m is chosen as the bending moment of the metering shaft plate shaft.
T = Torque (N-m), p = Power transmitted (W) and N = Speed of shaft (r.p.m).
The transmitted torque by the metering shaft is = 39.58 N-m
The equivalent twisting moment, Te is given as
For the hollow shaft, the ratio of inside to outside diameters is assumed as 0.8.
The equivalent twisting moment transmitted by the hollow shaft is
o. Design of Bearing
Bearings are selected based on their load carrying capacity, life expectancy and reliability. Ball bearings are fixed in the bushing provided at the two ends of the frame in other to support the eccentric shaft on which the wheels are attached. They allow the carrying of an impressive load without wear and tear and with reduced friction. This device ensures the smooth operation of the wheels.
Life of a bearing is the number of revolution which the bearing runs before the first evidence of fatigue develops. For machines used for short periods such as hand tools, domestic machines and agricultural machines, the life of bearings is given as 4000 to 8000 hours [3].
Let the life of the bearing, at the working speed of 65 r.p.m. The life of the bearing in revolution corresponding to the reliability of 99% is gotten as
Where; LH = life of bearing (hours), N = speed (r.p.m) and L99 = life at 99% reliability
Let L90 = life of the bearing (in revolutions) corresponding to 90% reliability
The bearings operate with an equivalent load of 39.24N. The dynamic load rating of the bearing is given as
Where k = constant = 3 for ball bearing.
Where; C = Basic dynamic load rating, and W = Equivalent load on bearing.
To select the most suitable bearing, the dynamic load rating is multiplied by the service factor, (KS) to get the load capacity. KS =1.5 for light shock load [3].
p. Determination of the Maximum Draft on the Planter
The maximum draft on the planter is a function of the soils resistance on the machine and the area of contact of the furrow opener with the soil. The maximum draft on the planter is the horizontal component of push parallel to the line of motion in order to overcome the soil resistance on the planter [8]. The maximum draft may therefore be obtained from the following expression in equation 32.
Afo = Recommended depth of cut width of furrow opener (33)
The soil resistance, RS for various soil types as given by Ikechukwu et al. [9] are:
For sandy loamy soils, RS = 0.210 kg/cm2, for silt loamy soils, RS = 0.385 kg/cm2, and for clay loamy soil, RS = 0.455 kg/cm2.
Therefore, for
Sandy loamy soil = 20.6 N
Silt loam soil = 37.8 N
Clay loamy = 44.6 N.
Sandy loamy soil with the draft of 20.6 N was used for the testing of this design.
2.6 Performance Evaluation on the Planter
The standard code by Mehta et al. [10] for seed drill as reported by Bamgboye and Mofolasayo [11] was adopted in the evaluation of the machine performance. Laboratory and field tests were conducted to determine the performance of the machine. The machine was calibrated in the laboratory to determine the rate of discharge, uniformity of seed spacing and seed damage during operation.
Figures 5, 6 and 7 represent the pictorial view, sectional and exploded view of the planter respectively while Plate 1 show the picture of the fabricated planter.
Figure 5: Pictorial View of the Planter
Figure 6: Sectional View of the Planter
Figure 7: Exploded View of the Planter
Plate 1: The fabricated planter
Test for uniformity of seed spacing and seed damage
To determine the uniformity of seed spacing, the hopper was loaded with grains and fertilizer and the machine run within the length of about 10 m at walking speed, and the time of travel was recorded. A measuring tape was used to measure the distance between successive drops of seeds. This process was repeated five consecutive times and measurement of distance between successive drops of seeds was recorded. The seeds discharged from the seed tube during the run were observed for damage and recorded. The percentage seed damage was calculated from equation 34 [7]
% Seed damage was = 2.43 %
Determination of field efficiency
To determine the field efficiency, the planting operation was performed longitudinally with a constant forward speed as determined by noting the distance of travel using measuring tape and corresponding time to complete the distance with the aid of a stop watch. The field efficiency of the planter will be calculated from equation (35) suggested by kepner et al. [6]. An area of 90m2 was used for the evaluation and it was covered in 196 seconds. The effective operating time was 145 seconds while the idle time was 51 seconds.
The total time, Tt comprised of the actual working time, time for turn at the end of the field, time for loading grains, time for clog remover and resting time.
Field efficiency determined = 73.98 %
Effective field capacity
The capacity of the planter may be determined in terms of the area of land covered per hour during planting or the number of seeds planted per hour of planting. The capacity of the planter in terms of the area of land covered per hour was obtained from equation 36.
Ca = Effective field capacity of the planter in ha/hr
Time required to plant one hectare (1ha) of land is giving as
Metering efficiency
The machine was run over a distance of 10m and the total number of seed stand and the number of stand with no seeds were recorded. The metering efficiency (ME) was computed from equation 37 [12].
M.E obtained = 94.5%
Seed Rate per Hectare
The seed rate (kg/ha) was determined by placing the planter on its stand with a container placed under the seed tube to collect seeds and fertilizers by turning the drive wheel for 20 revolutions. The seed and fertilizer rates were calculated.
Seed rate (kg/ha) obtained
Fertilizer rate (kg/ha) obtained = 74.6 kg/ha.
Cost Analysis
The breakdown of the cost analysis for the fabrication of the planter is given in Table 1 below.
Table 1. Cost of producing the Planter.
3. RESULTS AND DISCUSSION
3.1 Results
The results obtained from the engineering properties determinations of the seeds and fertilizers are presented in Table 2.
Table 3 shows the summary of the performance evaluation of the planter. As shown in Table 4 the value of field efficiency obtained from the trials was 73.98%. Also, the effective field capacity of the planter was gotten as 0.17 ha/hr. The seed damage was found to be 2.45%. The metering efficiency for the planter was obtained as 94.5%.
The mean length, width, and the thickness, of the maize seeds were found to be 11.11 mm, 8.53 mm, and 4.85 mm while the sphericity, arithmetic and geometric mean diameters, were found to be 69%, 7.71 mm and 8.16 respectively as shown in Table 2. The moisture content of the maize seeds was found to be 8.5 %. The average 1000 seed weight was found to be 300 g. The average bulk and true densities of the maize seeds at the moisture content of 8.5% were found to be 450.30 kg/m3 and 1120.87 kg/m3 respectively while the bulk and true densities of fertilizers were found to be 745 kg/m3and 1200 kg/m3 respectively. The porosity of maize seeds was found to be 51.30 %. The angle of repose for maize seeds and fertilizers were found to be 26.96o and 28.37o respectively while the coefficient of friction for maize seeds and fertilizers were determined as 0.38 and 0.26 as presented in table 2.
Table 2: Engineering Properties of Maize Seeds and Fertilizers
Table 3: Performance Evaluation on Planter
Table 4: Field Efficiency and Field Capacity
Field capacity =0.17 ha/hr
3.2 DISCUSSION
As shown in Table 4 the value of field efficiency obtained from the trials was 73.98%. This shows a good and satisfactory performance as it was within the range of values obtained for planting operation by Olajide and Manuwa [13] which was 71%. Also, the effective field capacity of the planter was 0.17 ha/hr. This is higher than that of the single row maize planter with a capacity of 0.048 ha/hr developed by Ikechukwu et al. [9]. This satisfactory result is due to its maneuverability which saves time in moving and turning the planter from one point to another.
From the results obtained from the calibration of the planter, it was observed that at lower speed (25 rev/min), the weight of seeds discharged was 43g which is higher than that of higher speed (30 rev/min) with a discharge of 39g while fertilizer discharge was 140g at 25 rev/min and 110g at 30 rev/min. The planter effectively metered out two seeds per hole on the average. This was satisfactory performance and the design was such that the number of seeds metered out could be regulated by using adjustable seed/fertilizer cells.
The average percentage of seed damaged of was 2.45%. The observed low average value of percentage seed damage of 2.45% observed in this work is due to minimal clearance between the metering device and its housing. The mean depth of furrow opened at the medium setting of the opener was 2.76 cm. The distance between successive seeds of 34cm was obtained.
4. CONCLUSION
The engineering properties of maize seeds and fertilizers relevant for the design of this planter were all determined. The manually-operated corn planter with fertilizer applicator for the needs of small holder farmers has been designed, fabricated and its performance evaluated. The machine has an overall field capacity of 0.17 ha/hr with average intra-row seed spacing of 34 cm and the field efficiency of the planter was 73.98 %.The planter was able to effectively meter a maximum of two to three seeds per hole with minimum damage of 2.45% to the seeds.The metering efficiency obtained was 94.48% with a seed rate of 22.5 kg/ha and fertilizer rate of 74.6 kg/ha. With these features, the manually operated corn planter cum fertilizer applicator will relief peasant farmers of the difficulties encountered in maize production at a very low cost.
REFERENCES
[3] Khurmi, R.S. and Gupta, J.K. (2005).A Textbook of Machine Design.Eurasia Publishing House (Pvt.) Ltd., Ram Nagar, New Delhi-110055, India.
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