




































 
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. 

 


