83 † Corresponding author © 2014 Conscientia Beam. All Rights Reserved. EFFECT OF DISC AND TILT ANGLES OF DISC PLOUGH ON TRACTOR PERFORMANCE UNDER CLAY SOIL Omer A. Abdalla1 --- Eman A. Mohamed2 --- Ahmed M. El Naim3 --- Mohammed A. El Shiekh4 --- Moayad B. Zaied5 1,2,4Department of Agric. Engineering Faculty of Agriculture University of Khartoum-Sudan 3Department of Crop Sciences, Faculty of Natural Resources and Environmental Studies, University of Kordofan, Elobied, Sudan 5Department of Agric. Engineering, Faculty of Natural Resources and Environmental Studies, University of Kordofan, Elobied, Sudan ABSTRACT The three- bottom, fully mounted disc plough (DP) is widely used as a primary tillage implement in the irrigated sector in Middle and Northern Sudan. In the DP, two angles (tilt and disc) affect tractor performance and ploughing quality. This research was conducted at the Demonstration Farm of the Faculty of Agriculture, University of Khartoum to study the effect of two disc angles (43o and 45o) and three tilt angles (15 o, 20o and 25o) on tractor effective field capacity, rear wheel slippage, fuel consumption, ploughing depth and width of cut. Soil of experimental area was clay loam. The experiment was arranged in a split- plot design and replicated three times. Disc angles were assigned to the main plots whereas tilt angles were distributed in the subplots. Tractor forward speed was maintained at the most commonly used ploughing speed (9 km/h). Effective field capacity was increased by 16% with the decrease of disc angle, while the width of cut, was decreased by 15%. The decrease of tilt angle improved penetration of discs into the soil, the highest ploughing depth was recorded for the tilt angle o15 with the disc angle o45, which consequently led to an increase of both rear wheel slippage and fuel consumption rate. Keywords: Crop production, Seed bed, Effective field capacity, Land preparation. Contribution/ Originality This paper contributes in the existing literature by providing data and information concern with field capacities, field efficiency and fuel consumption using different disc and tilt angles on tractor performance in the clay soils of Shambat in Sudan 1. INTRODUCTION Crop production requires a number of operations like seed bed preparation, seeding, fertilizing, spraying, dusting, irrigation, harvesting and threshing. The first operation in production of crop is tillage. Tillage is a mechanical manipulation of soil to provide favourable Current Research in Agricultural Sciences 2014 Vol. 1, No. 3, pp. 83-94 ISSN(e): 2312-6418 ISSN(p): 2313-3716 © 2014 Conscientia Beam. All Rights Reserved. Current Research in Agricultural Sciences, 2014, 1(3): 83-94 84 © 2014 Conscientia Beam. All Rights Reserved. conditions for crop production. Soil tillage consists of breaking the compact surface of earth to a certain depth and to loosen the soil mass, so as to enable the roots of the crops to penetrate and spread into the soil. Tillage may be called the practice of modifying the state of soil to provide favourable conditions for plant growth. Tillage operation is the most labour consuming and difficult operation compared to all subsequent operations in the field. Farm machinery is an important element for agriculture development and crop production in modern agriculture of many countries. The main objective of the machinery is to reduce number of labor, the difficulties of farm operations and maximize production. Agricultural mechanization has been receiving a considerable interest in recent years due to increasing demand for food due to the expansion of world population [1]. The use of machines for agricultural production has been one of the outstanding developments in the global agriculture during the last century. The benefits of the application of the farm machinery can be seen in many aspects of human life as million of workers to be released for other activities in developed countries. The main source of power in agriculture is the tractor, which is now available in different sizes. Tractor power utilization is achieved through the driving wheels as traction to provide the drawbar power required for draught implements and to provide mobile support for attached machines. Field efficiency reported by Abu [2] and Theoretical and effective field capacity mentioned by Smith and Wilkes [3] are the main performance parameters, therefore, it is important to select the suitable machine or machines to carry out the specific operation with minimum cost of energy and in the required time under suitable field condition. Disk plows, which are primarily suitable for the tillage of virgin, stony and wet soils, cut through crop residues and roll over the roots. Blades on disk plows are concave, usually representing sections of hollow spheres. The action of a concave disk blade is such that the soil is lifted, pulverized, partially inverted, and displaced to one side. The disk blades are set at an angle, known as disk angle from the forward line of travel and also at a tilt angle from the vertical; the disk angles vary from 42° to 45°, whereas tilt angles vary from 15° to 25°.Kepener, et al. [4] and Al-Hashimy [5]concluded that the increase of tilt angle decreased discs penetration in the soil which led to an increase in the effective field capacity due to the increase of the actual cutting width. Bukhari, et al. [6] and Osman, et al. [7] found that as disc and tilt angles increased, the field capacity and fuel consumption rate increased. Mckyes and Maswaure [8] and Kheiralla, et al. [9] found that tensile force increase with the increase of the width of agricultural implements. The increase of tilt angle increases rear wheel slippage percentage. Abu-Hamdeh and Reeder [10] stated that the reason of increasing slippage when tilt angle increased may be attributed to the increase of the tensile force. The general objective of this research was to study the effect of changing a three bottom disc plough angles (tilt and disc angles) on tractor performance. The specific objectives were: i. To measure the effect of changing disc and tilt angles on the effective field capacity and field efficiency of a disc plough. Current Research in Agricultural Sciences, 2014, 1(3): 83-94 85 © 2014 Conscientia Beam. All Rights Reserved. ii. To study the effect of using different disc and tilt angles on tractor rear wheel slippage and fuel consumption. iii. To study the effect of changing disc and tilt angles on ploughing depth and width of cut. 2. MATERIALS AND METHODS 2.1. The Experimental Site The experiment was carried out at the Demonstration farm of the Faculty of Agriculture, University of Khartoum in Shambat. The experiments were conducted during the December of 2013. The total of the area of the experiment was 1440 m2. The soil of experimental area was generally clay loam. Some physical and chemical characteristics of value soil are shown in Table 1 Table-1. Physical and chemical characteristics of the soil Depth (cm) Mechanical analysis(%) pH Soil class Moisture content Bulk density Particle density Sand Silt Clay 0 – 15 - - - - - 3.30 1.30 2.65 0 – 30 37.1 13.9 49.0 7.9 Clay loam 4.14 1.29 2.65 2.2. Experimental Design and Layout Theexperiment included six treatments (two disc angles 45o and 43o with three tilt angles15o, 20o and 25o), which were replicated three times. The experimental area was divided into three blocks; each block was subdivided into six plots with an area of 10 m × 8 m. Each experimental unit was not separated by an area due to the short length and width of experimental area. The distribution of treatments within the plots was random. The experiment was arranged in a split plot design with disc angles assigned to the main plots while tilt angles were distributed to the sub-plots. The experiment implement medium size standard disc plough. The specifications of the implement are presented in Table 2 Table-2. Disc plough specifications Parameter Specifications Make Baldan Country Brazil No. of discs 3 Hitching Fully tractor mounted on the three poinlinkage Disc 3 each of 60cm in diameter and 70cm cutting Width 75 cm Model AF Standard disk plough was pulled by Massey Ferguson (440) tractor. 2.3. Measurements 2.3.1. Measurement of Field Capacities For calculation field efficiency by Abu Zaid [2] Current Research in Agricultural Sciences, 2014, 1(3): 83-94 86 © 2014 Conscientia Beam. All Rights Reserved. FE (% For calculation Theoretical field capacity the following equation as stated by Smith et al. [3] was used. … For calculation Effecting filed capacity … Where: EFC = Effective field capacity (fed/h). FE = field efficiency (%). TFC = Theoretical field capacity (fed/h). S = Speed (km/h). W = Rated width of the implement (m) . C = Constant (8.83). 2.3.2. Rear Wheel Slippage The tractor rear wheel slippage(S) was calculated as percentage follows: Wheel slippage (%) 100 Where: D1=distance traveled without load in(m). D2=distance traveled with load in(m) 2.3.3. Measurement of Fuel Consumption Fuel consumption rate for each implement in operation was measuring by starting working the plot with full tank capacity. After finishing the plot the fuel tank was refilled with a graduated cylindering .the amount of fuel with was used for refilling the tank was recorded and the time taken to finish specific plot was also recorded. The fuel consumption rated in (l/fed) was calculated as follow: Fuel consumption (l fed) 2.3.4. Measuring Width of Cut and Plough Depth A measuring tape 50 m long was used for calculation of width of cut and ploughing depth at selected randomized points along study area. The average of the width of cut and plough depth were then calculated. Current Research in Agricultural Sciences, 2014, 1(3): 83-94 87 © 2014 Conscientia Beam. All Rights Reserved. Disc angle is the angle between the plane of cutting edge and the line of travel. It is normally 420 – 470. . Reducing this angle increases the disc rotation with respect to ground speed and reduces the tendency of the plough to over cut. Increasing the disc angle improves the disc penetration. Tilt angle is the angle between the plane of the cutting edge and the vertical line. It ranges from 150 - 250 in heavy, sticky soils. Decreasing the tilt angle improves disc penetration in loose and brittle soils. 3. RESULTS AND DISCUSSION 3.1. Effect of Disc and Tilt Angles on Tractor Effective Field Capacity It can be observed Fig.2 and Table.3 that the disc angle 45o with tilt angle 25o recorded low effective field capacity (0.80 fed/h) as compared to the disc angle 43o with tilt angle 25o, which recorded the highest effective field capacity (0.93 fed/h). This result agrees with the result of Kepener, et al. [4] and Al-Hashimy [5] who reported that the increase of tilt angle led to decrease discs penetration in the soil which led to an increase in the effective field capacity due to the increase of the actual cutting width. Table-3. Effective field capacity Source Type III Sum of Squares Df Mean Square F Sig. Corrected Model 0.046a 5 0.009 4.764 0.012 Intercept 13.676 1 13.676 7114.916 0.000 Angle A 0.042 1 0.042 21.876 0.001 Angle B 0.001 2 0.000 0.165 0.850 Angle A * Angle B 0.003 2 0.002 0.806 0.469 Error 0.023 12 0.002 Total 13.745 18 Corrected Total 0.069 17 a. R Squared = .665 (Adjusted R Squared =0 .525) A = disc angle. B = tilt angle. 3.2.Effect of Disc and Tilt Angles on Tractor Field Efficiency Fig.3 and Table.4 show that the disc angle 45o with the tilt angle 25o recorded the lowest filed efficiency (67%) while the disc angle 43o with the tilt angle 25o recorded the highest field efficiency (78%). These results agrees with the results of Kepener, et al. [4] and Al-Hashimy [5] who reported that increasing the effective filed capacity increases the field efficiency because of the proportional relationship between them. On the other hand, the results disagree with the results of Bukhari, et al. [6] and Osman, et al. [7] who stated that the field capacity increases with the increase of disc and tilt angles. Current Research in Agricultural Sciences, 2014, 1(3): 83-94 88 © 2014 Conscientia Beam. All Rights Reserved. Table-4. Field efficiency Source Type III Sum of Squares Df Mean Square F Sig. Corrected Model 304.500a 5 60.900 5.454 0.008 Intercept 95484.500 1 95484.500 8550.851 0.000 Angle A 280.056 1 280.056 25.080 0.000 Angle B 2.333 2 1.167 0.104 0.902 Angle A * Angle B 22.111 2 11.056 0.990 0.400 Error 134.000 12 11.167 Total 95923.000 18 Corrected Total 438.500 17 a. R Squared = .694 (Adjusted R Squared = 0.567) A = disc angle. B = tilt angle. 3.3.Effect of Disc and Tilt Angles on Tractor Rear Wheel Slippage It is clear that the disc angle 43o with tilt angle 20o recorded the highest slippage (14.9 %), while the disc angle 45o with the tilt angle 20o recorded the lowest value of slippage (5.7%) Fig.4 and Table.5. These results disagree with Bukhari, et al. [6] who stated that increasing disc and tilt angles led to an increase in the wheel slippage . The increase in the disc angle results in an increase in the wheel slippage due to the increase of tensile force, Mckyes and Maswaure [8] and Kheiralla, et al. [9] found that tensile force increase with the increase of the width of agricultural implements . The increase of tilt angle increases rear wheel slippage percentage. Abu-Hamdeh and Reeder [10] stated that the reason of increasing slippage may be attributed to the increase of the tensile force. Table-5. Rear wheel slippage Source Type III Sum of Squares Df Mean Square F Sig. Corrected Model 243.578a 5 48.716 9.687 0.001 Intercept 1784.036 1 1784.036 354.757 0.000 Angle A 217.709 1 217.709 43.292 0.000 Angle B 1.721 2 0.861 0.171 0.845 Angle A * Angle B 24.148 2 12.074 2.401 0.133 Error 60.347 12 5.029 Total 2087.960 18 Corrected Total 303.924 17 a. R Squared = .801 (Adjusted R Squared =0 .719) A = disc angle. B = tilt angle. Current Research in Agricultural Sciences, 2014, 1(3): 83-94 89 © 2014 Conscientia Beam. All Rights Reserved. 3.4. Effect of Disc and Tilt Angles on Tractor Fuel Consumption The results in of fuel consumption rate are shown in Table 6 and presented in Figure 5. Highest fuel consumption rate (10.8 l/fed) was recorded by the disc angle 45o with tilt angle 20o, while disc angle 43o with tilt angle 15o recorded the lowest rate (6.1 l/fed). These results agree with Bukhari, et al. [6] and Osman, et al. [7] who found that fuel consumption increased as disc and tilt angles were increased. Table-6. Fuel consumption Source Type III Sum of Squares Df Mean square F Sig. Corrected Model 56.843a 5 11.369 0.667 0.656 Intercept 1198.867 1 1198.867 70.334 0.000 Angle A 7.347 1 7.347 0.431 0.524 Angle B 44.634 2 22.317 1.309 0.306 Angle A * Angle B 4.861 2 2.431 0.143 0.869 Error 204.545 12 17.045 Total 1460.255 18 Corrected Total 261.388 17 a. R Squared = .217 (Adjusted R Squared = -0.109) A = disc angle. B = tilt angle. Table-7. Width of cut Source Type III Sum of Squares df Mean square F Sig. Corrected Model 0.031a 5 0.006 7.274 0.002 Intercept 8.681 1 8.681 10279.605 0.000 Angle A 0.029 1 0.029 34.105 0.000 Angle B 0.000 2 0.000 0.184 0.834 Angle A * Angle B 0.002 2 0.001 0.947 0.415 Error 0.010 12 0.001 Total 8.721 18 Corrected Total 0.041 17 a. R Squared = .752 (Adjusted R Squared =0 .649) A = disc angle. B = tilt angle. 3.5. Effect of Disc and Tilt Angles on Width of Cut It is clear in Fig 6 and Table 7 that the highest width of cut (0.75 m) was obtained under disc angle 45o with tilt angle 25o, while the disc angle 43o with tilt angle 25o recorded the lowest width of cut (0.64 m), this result agrees with the result of Yousif and Elashri [11] who found that increasing disc angle led to an increase in the width of cut ,it also agrees with Kepener, et al. [12] who found direct relationship between disc angle and width of cut. Mahboubi, et al. [13] and Current Research in Agricultural Sciences, 2014, 1(3): 83-94 90 © 2014 Conscientia Beam. All Rights Reserved. Abdalla [14] found that the increase of tilt angle led to an increase in the rate of soil cut, which led to an increase in the quantity of cut soil thus increasing the actual width of cut. 3.6. Effect of Disc and Tilt Angles on Ploughing Depth As presented in Fig 7 and Table 8 great ploughing depth (0.32 m) was recorded by the disc angle 45o with tilt angle 15o while the disc angle 43o with tilt angle 20o recorded low value of ploughing depth (0.25 m). These result agree with the result obtained by Abu-Hamdeh and Reeder [10] who observed that a decrease in the tilt angle resulted in an increase in implement penetration. It also agrees with Kepener, et al. [12] who found inverse relationship between tilt angle and ploughing depth. Gasim [15] reported that the increase in the disc angle up to 45o with tilt angle 15o resulted in an increase in implement penetration. Increasing the tilt angle improves disc penetration in heavy sticky soils. Decreasing the tilt angle improves disc penetration in loose and brittle soils [16] Table-8. Ploughing depth Source Type III Sum of Squares Df Mean square F Sig. Corrected Model 0.017a 5 0.003 4.770 0.012 Intercept 1.520 1 1.520 2136.945 0.000 Angle A 0.016 1 0.016 21.945 0.001 Angle B 0.001 2 0.001 0.805 0.470 Angle A * Angle B 0.000 2 0.000 0.148 0.864 Error 0.009 12 0.001 Total 1.545 18 Corrected Total 0.025 17 a. R Squared = .665 (Adjusted R Squared =0 .526) A = disc angle. B = tilt angle. 4. CONCLUSIONS From the results of this study the following conclusions can be drawn: i. Decreasing ploughing depth led to increasing effective field capacity and field efficiency. ii. Increasing the disc angle increases the width of cut. iii. Decreasing tilt angle increases ploughing depth. 5. ACKNOWLEDGEMENT My thanks to Department of Agricultural Engineering, Faculty of Agriculture, University of Khartoum for their help. Current Research in Agricultural Sciences, 2014, 1(3): 83-94 91 © 2014 Conscientia Beam. All Rights Reserved. REFERENCES [1] E. A. Hebiel, "Tillage implements performance as affected by tractor power and forward speed," M.Sc. Thesis, Faculty of Agriculture, University of Khartoum, Sudan, 2006. [2] Z. F. S. Abu, Principle of agricultural mechanization management, faculty of agriculture. Egypt (In Arabic): University of Elexandria, 2011. [3] A. E. Smith and L. H. Wilkes, Farm machinery and equipment, 6th ed. New York: McGraw-HilI Book Company, 1976. [4] R. A. Kepener, R. Bainer, and E. Barger, Principle of farm machinery, 3rd ed. Westport, Connecticut: AVI Publishing Co., Inc, 1982. [5] L. A. Z. Al-Hashimy, "Study of some technical and economical indicators and physical soil characteristics under different tillage systems, faculty of agriculture," M.Sc Thesis, Dept. of Agricultural Machinery, University of Baghdad, 2003. [6] S. Bukhari, J. M. Baloch, G. R. Marani, M. S. Panhwar, and M. S. Zafarullah, "Effect of disc and tilt angle on filed capacity and power requirements of mounted plow. Agriculture mechanization in Asia," African and Latin America, vol. 23, pp. 9-12, 1992. [7] A. N. Osman, L. Xia, and L. Dongxing, "Effect of tilt angle of disk plough on some soil physical properties, work rate and wheel slippage under light clay soil," Int. J. Agric. Biol. Eng., vol. 4, pp. 1- 7, 2011. [8] E. Mckyes and J. Maswaure, "Effect of design parameters of flat tillage tools on loosening of a clay soil," Soil Tillage Research, vol. 43, pp. 195-204, 1997. [9] A. F. Kheiralla, A. Yahya, M. Zohadie, and W. Ishak, "Modelling of power and energy requirements for tillage implements in serdang sandy clay loam, Malaysia," Soil and Tillage Research, vol. 78, pp. 21-34, 2004. [10] N. Abu-Hamdeh and R. C. Reeder, "A nonlinear 3D finite element analysis of the soil forces acting on a disk plough," Soil and Tillage Res., vol. 74, pp. 115–124, 2003. [11] M. S. Yousif and E. R. Elashri, "Tractors and agriculture machinery, faculty of agriculture," University of Alexandria, Egypt (In Arabic), p. 335, 2009. [12] R. A. Kepener, R. Bainer, and E. Barger, Principle of farm machinery, 3rd ed. Westport, Connecticut: AVI Publishing Co., Inc, 1990. [13] A. Mahboubi, R. Lal, and N. R. Fausey, "Twenty-eight years of tillage effects on two soils on ohio," Soil Sci. Soc. Am. J., vol. 57, pp. 506–512, 1993. [14] A. E. Abdalla, "The effect of disc plow tilt angles and soil structure on some power requirements and performances," University of Tikreet Journal for Agricultural Sciences, vol. 8, pp. 345-349, 2008. [15] M. I. Gasim, Agricultural machinery, 1st ed. Faculty of Engineering, University of Sinnar, 2005. [16] B. U. PVT, "Mounted disc plough operations manual." Available WWW Fieldking.com, 2008. Current Research in Agricultural Sciences, 2014, 1(3): 83-94 92 © 2014 Conscientia Beam. All Rights Reserved. Figure-1. Angle of disc plough Figure-2. Effect of disc and tilt angles on tractor effective filed capacity Figure-3. Effect of disc and tilt angles on tractor field efficiency Current Research in Agricultural Sciences, 2014, 1(3): 83-94 93 © 2014 Conscientia Beam. All Rights Reserved. Figure-4. Effect of disc and tilt angles on tractor slippage Figure-5. Effect of disc and tilt angles on tractor fuel consumption Current Research in Agricultural Sciences, 2014, 1(3): 83-94 94 © 2014 Conscientia Beam. All Rights Reserved. Figure-6. Effect of disc and tilt angle on width of cut Fig-7. Effect of disc and tilt angle on ploughing depth Views and opinions expressed in this article are the views and opinions of the author(s), Current Research in Agricultural Sciences shall not be responsible or answerable for any loss, damage or liability etc. caused in relation to/arising out of the use of the content.