DRAUGHT FORCE REQUIREMENTS OF A DISC PLOUGH AT VARIOUS TRACTOR FORWARD SPEEDS IN LOAMY SAND SOIL, DURING PLOUGHING

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International Journal of Advanced Research in Engineering and Technology

(IJARET) Volume 6, Issue 7, Jul 2015, pp. 52-68, Article ID: IJARET_06_07_008

Available online at

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ISSN Print: 0976-6480 and ISSN Online: 0976-6499

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___________________________________________________________________________

DRAUGHT FORCE REQUIREMENTS OF A

DISC PLOUGH AT VARIOUS TRACTOR

FORWARD SPEEDS IN LOAMY SAND SOIL,

DURING PLOUGHING

S. O. Nkakini

Department of Agricultural/Environmental Engineering, Faculty of Engineering,

P. M. B. 5080, Rivers State University of Science and Technology Port-Harcourt,

Nigeria

ABSTRACT

Tillage operation in loamy sand soil for disc ploughing on an experimental

plot of twenty different soil moisture levels at tractor forward speeds of 1.94

m/s, 2.2 m/s and 2.5 m/s were conducted using trace tractor techniques. The

variables: draw-bar pull force, moisture content, cone index, tractor forward

speeds, widths of cut and depths of cut were measured. In determining the

effect of moisture content and forward speeds on draught forces, results

revealed that at lowest moisture content of 1.53% draught forces of 4688.33

N, 5708.33 N and 6758.33 N at tractor forward speeds of 1.94 m/s, 2.2 m/s

and 2.5 m/s, were obtained. The draught forces of 3008.32 N, 4018.66 N and

5068.os33 N were obtained at highest moisture content of 24.14% with tractor

forward speeds of 1.94 m/s, 2.2 m/s and 2.5 m/s. The tractor forward speeds of

2.5 m/s recorded the highest draught force of 6758.33 N. The lowest draught

forces at respective moisture levels were obtained at tractor forward speed of

1.94 m/s. It is clear that, draught forces increase with increase in tractor

forward speeds. This result indicates that the best tractor forward speed for

ploughing operation is 2.5 m/s which took place within the range of the

optimum soil moisture of 2.5–25% for soil under consideration.

Key words: Draught, Tillage, Disc plough, Tractor forward speeds, Ploughing

operation.

Cite this Article: Nkakinii, S. O. Draught Force Requirements of a Disc

Plough at Various Tractor Forward Speeds in Loamy Sand Soil, During

Ploughing. International Journal of Advanced Research in Engineering and

Technology, 6(7), 2015, pp. 52-68.

http://www.iaeme.com/IJARET/issues.asp?JType=IJARET&VType=6&IType=7

_____________________________________________________________________

IJARET

Draught Force Requirements of a Disc Plough at Various Tractor Forward Speeds in Loamy

Sand Soil, During Ploughing


1. INTRODUCTION

Tillage may be described as the practice of modifying the state of the soil in order to

provide conditions favorable to crop growth [1]. Three things are involved in soil

tillage, which are the power source (tractor or animal), the soil and the implement

(Disc plough [2]. It can be defined as any positive action when forces are reasonably

applied with the aim of altering the soil conditions for agricultural purposes [3].

Tillage aims to create a soil environment favorable to plant growth [4][5]. According

to researchers, soil tillage is the mechanical manipulation of soil to develop a

desirable soil structure for a seedbed and a specific surface configuration for planting,

irrigation, drainage and harvesting operations[1] [6]. Soil tillage plays very important

role in soil productivity as it creates optimum soil condition for crop growth [1][7]

Ploughing is a primary tillage operation which is performed to shatter and achieve

soil inversion [8]. It is the initial soil working operation and also the deepest tillage

operation of about 150 to 300 mm, [9]. Ploughing is the most important primary

tillage operation for arable farming in preparation for the production of vegetable and

cereal growing crops. It creates a suitable soil condition for plant growth which

increases crop productivity and boosts the agricultural economy [9].

Disc Plough is a tillage implement used for primary soil tillage operation. It is

used in tropical region where condition is very hard and rough and totally unsuitable

for use of the conventional mould board plough [10]. Consequently, disc plough has a

tilt adjuster with which the angle of tilt of the blade is adjusted. The width of cut per

disc (Disc plough) depends upon the spacing and the angle (adjustable) between the

gang axis and the direction of travel [11]. It was observed that disc plough has a

higher total and specific draught than other tillage implements, for a given soil type

and tractor forward speed [8].

Draught of tillage implement (Disc plough) however plays a vital role in

developing more efficient tillage system by selecting suitable combination of tractor

and implements [12]. Farmers employ draught requirement data from tillage

implement (Disc plough) in specific soil type to determine the matching size of tractor

for operation [13]. The draught of the disc plough is very enormous when compared

with other tillage implement. Draught requirement and soil disturbance of tillage

implements depends on the soil and tool operating conditions [8]. Draught is the

horizontal component of pull force, parallel to line of motion, while side draught, is

the horizontal component of pull, perpendicular to the line of motion [14]. The force

required to overcome the soil resistance and move the tillage implement at the

required speed is called the cutting force. The horizontal component of this cutting

force is called the draught [14]. Draught is the total horizontal force parallel to the

direction of travel required to propel the implement. It is the sum of the soil and crop

resistant and the implement rolling resistance [9] [14].

In the study of draught force, researchers have discovered that increasing tractor

forward speed increases the depth of cut which is relative to increase in draught that

caused much pulverizing of the soil surface and energy requirement of the implement

[15] [16] [17]. It was discovered that when the tractor forward speed increased from

1.33 m/s to 2.6 m/s, the draught increased from 40% in the clay loam and 90% in the

fine sandy loam. The researchers conducted an experiment and observed that the

draught requirement for tillage drastically increased by soil compaction [18]. It was

imperative to note that draught force increases with increase in tillage depth of cut

[19] [20].

S. O. Nkakini


Soil type and condition are the most implement factors that contribute to the

draught force of agricultural implement. The draught required to pull a tillage

implement (Disc plough) is basically a function of soil properties, implement width,

operating speed and depth of cut at which it is pulled, moisture content and bulk

density[20] [11] [21] [22][18]. According to some research findings, the increase in

soil bulk density increased the draught forces of tillage implement (Disc plough) [23].

It is clear that the low state of moisture content increased draught forces, while

high moisture content decreased draught forces [18]. However, the extent of influence

of these factors has not been fully studied in Nigeria; therefore draught requirement of

a plough is necessary. A comprehensive, draught force data requirement for

ploughing operation is still a problem under consideration in Nigeria.

This research was ventured into, as part of forming a data base of draught of a disc

plough in loamy sand soil. The draught force data obtained from the research would

assist the farmers acquire the knowledge that would enable them select proper size of

tractor to match an implement (disc plough). In doing this, operational cost involves

in ploughing is minimized, hence maximizing agricultural profits. These research

objectives are to investigate the draught force of a disc plough at various tractor

forward speeds in loamy sand soil. To study the relative effect of the parameters

involved with the draught.

2. MATERIAL AND METHODS

Experimental Site and Design: The experiment was conducted at National Root

Crop Research Institute (NRCRI) Experimental Farm, Umudike, Umuahia, Abia state

of Nigeria. Umudike is under the derived tropical humid ecological zone of Nigeria.

The soil particle size distribution analysis indicated that the soil is loamy sand (clay –

11.04%, silt – 4% and sand – 84.96%).

The experimental layout area is 90 m by 90 m and was designed with three

different blocks of 90 m by 27 m each. Each block was divided into 9 strips of 90 m

by 2 m wide with a space of 3 m between each strip. The materials used for the study

included two tractors of the same model and horse powers, soil cone penetrometer,

dynamometer, measuring tape and three bottom disc plough.

Experimental Procedure: Ploughing operations were carried out, 24 hours after each

rainfall event. Three replications of ploughing operations were conducted after every

rainfall event. There were altogether 20 rainfall events. Hence the total treatments

were 9 x 20 rainfall events. The sequence of tillage operation were as follows: rainfall

event 1, ploughing on block 1, strip 1, block 2,strip 1 and block3,strip 1,rainfall event

2, ploughing on block 1,strip 2, block 2, strip2 and block 3, strip 2, rainfall event 3,

ploughing on block 1, strip 3, block 2, strip 3 and block 3 strip 3. This pattern was

followed for the remaining number of rainfall events up to the last day when

minimum moisture content level was achieved.

Determination of Soil Moisture Content: The beginning of tillage operation was a

function of rainfall. The rainfall source was through a natural rainfall event. Prior to

the field tillage operations, soil samples were collected at depth of 0–50 mm, 50–150

mm and 150–200 mm with the aid of soil auger at three replications per samples

points for determination of soil parameters. A field test samples were randomly

selected for determination of soil moisture content level using oven dry method

(gravimetric). The moisture content of soil was obtained using equation 1.




Moisture (%) = 100xW

WWw

D

D−

(1)

Where, Ww = weight of wet soil sample, g, WD = weight of dry soil sample, g

Determination of Bulk Density: At randomly selected field spots, soil samples at

various depths were collected using cylindrical cone for determination of bulk

density. The bulk density value was calculated using equation 2.

Bulk density of soil, Bd = b

S

V

M (2)

Where, Bd = bulk density, g/cm3, Ms = mass of over dry soil sample (g), Vb = volume

of core sample (cm3)

Measurement of Cone Index: The soil cone index (CI) was measured to ascertain

the soil strength profile, using cone penetrometer having an enclosed angle of 300,

with a base area of 3.23 m2 (323 mm

2) mounted on a shaft of 0.203 cm (20.27 mm)

marked with respect to depths on the shaft. At three different depths (0–100, 100–150,

and 150−200) mm, soil resistance (cone index) to penetration of implements were

obtained before tillage operation. Cone penetromter testing involves pushing a cone

into the soil at a certain rate and recording the resisting force exerted by the soil on

the penetrometer [24]. The force required divided by the area of the base of the cone

provides a “pressure” measurement, referred to as cone index in KN/m2 (Kilo Pascal)

in SI unit.

Determination of Draught force: The drawbar pull (draught force) was determined

using trace-tractor techniques. The Dillion EDjunior dynamometer was attached to the

front of the tractor mounted with implement. Another auxiliary tractor was used to

pull the implement mounted tractor through the dynamometer both in their

transportation positions and tillage operating positions for ploughing. The average

drawbar-pull (Draught to pull the implement) is the difference between the towing

force, while in neutral gear without implement in tillage operation and the towing

force while the implement is in tillage operation respectively.

Figure 1a Tractors–Dynamometer, Implement Mounted Position during Transportation.

S. O. Nkakini


Figure 1b Tractors–dynamometer, implement mounted in tillage operation.

P = P2 – P1 (3)

Equation 3 is used in determining the draught force. Where, P = draught force, P1

= the force required to pull the Implement in transportation position, P2 = the force

required to pull the Implement during tillage operation.

Calculation of the specific draught (N/m2): The specific draught to pull the

implement: is the Actual draught/Area ploughed. Mathematically expressed as:

Specific draught (n) = A

P (5)

Where, P = Actual Draught (N), A = Area ploughed (m2)

Measurement of Depth of Cut and Width : These parameters were determined by

setting the level that controls the lifting mechanism at a particular level corresponding

to the required depth of cut and setting the tractor to a gear best suited for a targeted

speed of 1.94 m/s, 2.2 m/s and 2.5 m/s. The depths of cut were measured with a steel

tape, from the bottom of the furrow to the surface level of the soil at randomly

selected points [25].

3. RESULTS AND DISCUSSIONS

In Table 1, is presented the data obtained in respective rainfall events. The results

revealed that the lowest moisture content of 1.53% db was obtained on 15th

rainfall

event and the highest, 24.14% db on the 6th

rainfall event. The highest cone index

value of 196.92*KN/m2 was obtained on 16

th rainfall event and the lowest, 56.4

KN/m2 on the 6

th rainfall event. The reading with asterisk indicates that the

penetrometer could not penetrate into the soil while reading was taken. The highest

bulk density of 1.94 g/cm3 was on the 11

th rainfall event and lowest, 1.50 g/cm

3 on the

6th

rainfall event.




Table 1 Average soil moisture content %, soil resistance (KN/m2 and bulk density (g/cm

3)

Days Amount of

rainfall, mm

Soil moisture

content %

wb

AVERAGE

PENETROMETER

READINGS KN/m2 (0–

200)mm

Average Bulk

Density(g/cm3)

(100–200)mm

1 50.7 15.50 98.46 1.80

2 66.9 16.04 184.62 1.70

3 48.2 15.44 107.78 1.86

4 15.3 17.71 84.09 1.48

5 42.2 14.42 116.4 1.84

6 149.3 24.14 56.4 1.50

7 11.6 13.92 143.06 1.90

8 3.8 11.58 149.22 1.78

9 93.7 17.66 89.73 1.86

10 90.6 17.62 96.91 1.88

11 30.1 14.83 125.63 1.94

12 23.1 14.44 131.78 1.92

13 23.3 14.48 133.83 1.93

14 1.3 6.31 163.57 1.75

15 0 1.53 190.77 1.80

16 0 2.24 196.92* 1.78

17 0 2.01 190.77* 1.76

18 2.1 6.86 184.62* 1.88

19 0 2.70 194.39* 1.77

20 4.6 11.94 161.02 1.79

Table 2, presented the draught forces during ploughing operations at 1.94 m/s,

2.22 m/s and 2.5 m/s and also days of field operations.

The results indicated average draught forces of 38904.96 N, 49089.97 N and

59589.97 N with respective tractor forward speeds of 1.94 m/s, 2.22 m/s and 2.5 m/s.

The highest draught force was obtained due to increase in tractor forward speed which

resulted from rapid acceleration of the soil.

It was observed that the draught force decreased with increased in moisture

content levels available in soil during tillage operation. This is evidence from the data

in Table 2, which depicted average draught forces of 3008.32 N, 4018.33 N and

5068.33 N on 6th

rainfall event. This day’s event recorded the highest rainfall amount

of 149.3 mm, where the maximum cohesion of soil had been overcome by water

molecules. This corresponded to some findings of other’s results [13] [26] [27].

S. O. Nkakini


Table 2 Average Draught Force (N) at 1.94 m/s, 2.22 m/s and 2.5 m/s

Days

Amount of

rainfall,

mm

Soil

moisture

content %

wb

Average

Draught

Force (N)

at 1.94 m/s

Average

Draught

Force (N) at

2.22 m/s

Average

Draught Force

(N)

at 2.5 m/s

1 50.7 15.50 3580.00 4586.66 5636.66

2 66.9 16.04 3406.66 4420.00 5470.00

3 48.2 15.44 3725.00 4745.00 5795.00

4 15.3 17.71 3201.66 4816.66 5271.66

5 42.2 14.42 3776.66 4816.66 5866.66

6 149.3 24.14 3008.32 4018.33 5068.33

7 11.6 13.92 4005.00 5015.00 6065.00

8 3.8 11.58 3253.33 5060.00 6110.00

9 93.7 17.66 3316.66 4273.33 5323.33

10 90.6 17.62 3316.66 4336.66 5386.66

11 30.1 14.83 3841.66 4861.66 5911.66

12 23.1 14.44 3930.00 4960.00 6010.00

13 23.3 14.48 3930.00 4950.00 6000.00

14 1.3 6.31 4083.33 5103.33 6153.33

15 0 1.53 4688.33 5708.33 6758.33

16 0 2.24 4643.33 5663.33 6713.33

17 0 2.01 4616.66 5636.66 6686.66

18 2.1 6.86 4063.33 5083.33 6133.33

19 0 2.70 4630.00 5670.00 6720.00

20 4.6 11.94 4030.00 5050.00 6100.00

Average 38904.96 49089.97 59589.97

Table 3, presents the depth and width of cuts at tractor forward speeds of 1.94 m/s,

2.22 m/s and 2.5 m/s. At 1.94 m/s tractor forward speed, the 6th

rainfall event recorded

the highest depth of cut 0.214 m and 0.118 m the lowest on 16th

rainfall event. The 5th

rainfall event recorded the lowest width of cut of 0.451 m and on 17th

rainfall event

recorded highest width of cut 0.903 m, with means of 0.163 m and 0.689 m. At tractor

forward speed of 2.22 m/s the highest depth of cut of 0.224 m was recorded on the 6th

rainfall event and the lowest of 0.126 m on 15th

rainfall event. On the 5th

rainfall event

was recorded the lowest width of cut of 0.464 m and on 17th

rainfall event the highest

width of cut 0.912 m, with their means as 0.173 m and 0.704 m.

With tractor forward speed of 2.5 m/s, the highest depth of cut of 0.372 m was on

14th

rainfall event and lowest of 0.105 m on 17th

rainfall event. The 5th

rainfall event

recorded the lowest width of cut as 0.473 and 0.976 m the highest width of cut on 17th

rainfall event with means of 0.183 m and 0.718 m respectively.




Table 3 Average depth of cut and width of cut for days of field operation at 1.94 m/s, 2.22

m/s and 2.5 m/s tractor forward speeds

The specific draught forces were calculated on days of field operations. Table 4,

shows the calculated average specific draught forces at tractor forward speeds of 1.94

m/s, 2.22 m/s and 2.5 m/s. Their average specific draught forces of 341212.2 N/m2,

432256.0 N/m2 and 481955.6 N/m

2 were achieved. The implication is that draught

forces increased with an increase in tractor forward speeds

Days of

field

operation

Depth of

cut(m)

at 1.94 m/s

Width of

cut(m) at

1.94 m/s

Depth of

cut (m) at

2.22 m/s

Width of

cut(m) at

2.22 m/s

Depth

of cut (m)

at 2.5 m/s

Width of

cut(m)

at 2.5 m/s

1 0.158 0.487 0.166 0.503 0.176 0.513

2 0.169 0.502 0.179 0.516 0.189 0.525

3 0.146 0.464 0.154 0.489 0.156 0.495

4 0.195 0.576 0.216 0.525 0.216 0.525

5 0.136 0.451 0.143 0.464 0.155 0.473

6 0.214 0.590 0.224 0.603 0.234 0.613

7 0.176 0.782 0.184 0.790 0.194 0.799

8 0.174 0.816 0.184 0.827 0.195 0.837

9 0.174 0.535 0.183 0.526 0.190 0.545

10 0.178 0.521 0.187 0.529 0.197 0.539

11 0.198 0.521 0.208 0.725 0.329 0.765

12 0.186 0.689 0.195 0.701 0.205 0.711

13 0.181 0.697 0.192 0.69 0.202 0.696

14 0.128 0.891 0.136 0.898 0.372 0.905

15 0.127 0.880 0.126 0.889 0.136 0.899

16 0.118 0.885 0.128 0.896 0.138 0.906

17 0.135 0.903 0.146 0.912 0.105 0.979

18 0.169 0.868 0.179 0.878 0.136 0.910

19 0.126 0.888 0.136 0.874 0.146 0.885

20 0.180 0.826 0.188 0.836 0.198 0.846

Mean 0.163 0.689 0.173 0.704 0.183 0.718

S. O. Nkakini


Table 4 Average specific draught forces for days of field operations at 1.94 m/s, 2.22 m/s and

2.5 m/s tractor forward speeds.

y = -73.63x + 4740.

R² = 0.821

0

1000

2000

3000

4000

5000

0 10 20 30

DR

AU

GH

T (

N)

MOISTURE CONTENT (%)

DRAUGHT Vs MOISTURE CONTENT

DRAUGHT Vs

MOISTURE CONTENT

Linear (DRAUGHT Vs

MOISTURE CONTENT)

Figure 2 The effect of moisture content on draught force at tractor forward speed of 1.94 m/s

Days of

Operation

Area

ploughed

(m2)

Specific

Draught

(N/m2) at

1.94 m/s

Area

ploughed

(m2)

Specific

Draught

(N/m2) at

2.22 m/s

Area

ploughed

(m2)

Specific

Draught

(N/m2)at

2.5 m/s

1 0.077 46493.51 0.083 55260.96 0.090 62629.56

2 0.085 40078.35 0.092 48043.48 0.093 58817.20

3 0.068 54779.41 0.075 63266.67 0.077 75259.74

4 0.112 28586.25 0.113 37359.82 0.113 46651.86

5 0.061 61912.46 0.067 71890.45 0.073 80365.20

6 0.126 23875.56 0.135 29765.40 0.143 35442.87

7 0.138 28521.74 0.145 34586.21 0.155 32677.42

8 0.142 28521.13 0.152 33289.47 0.163 37484.66

9 0.093 34982.04 0.096 44513.85 0.104 51185.87

10 0.093 35663.01 0.099 43804.65 0.106 50220.09

11 0.103 37297.67 0.150 32411.07 0.252 21375.65

12 0.128 30703.13 0.137 36204.38 0.146 40490.82

13 0.126 31190.48 0.132 37500 0.141 41164.38

14 0.114 35818.68 0.122 41830.57 0.337 18259.14

15 0.112 4688.44 0.112 50967.23 0.122 55396.15

16 0.104 44647.40 0.115 49246.35 0.125 53706.64

17 0.117 39458.63 0.133 42380.90 0.103 64919.03

18 0.147 27641.70 0.157 32377.90 0.124 49462.34

19 0.112 41517.86 0.119 47647.06 0.129 52093.02

20 0.149 27046.98 0.157 32165.61 0.168 36309.52

Mean 341212.2 432256.0 481955.6




y = -70.63x + 5791.

R² = 0.878

0

1000

2000

3000

4000

5000

6000

0 10 20 30

DR

AU

GH

T (

N)



DRAUGHT Vs

MOISTURE CONTENT

Linear (DRAUGHT Vs

MOISTURE CONTENT)


y = -75.02x + 6864.

R² = 0.891

0

1000

2000

3000

4000

5000

6000

7000

8000

0 10 20 30

DR

AU

GH

T (

N)



DRAUGHT Vs

MOISTURE CONTENT

Linear (DRAUGHT Vs

MOISTURE CONTENT)


Figures 2–4 show that draught forces decreased with increase in moisture content

levels. This is in agreement with the findings of some researchers [18]. They stated

that increase in moisture content level would lead to decrease in draught forces. The

results shows acceptable agreement with coefficient of determinations R2 = 0.821, R

2

= 0.878, and R2 = 0.891 respectively.

Figures 5–7 show that bulk density has no effect on draught forces as they remain

constant with coefficient of determinations R2 = 0.000. This is due to the fact that

bulk density was obtained in untilled soil before carrying out ploughing operations.

This is contrary to the findings which stated that draught force of tillage implement

increases when the bulk density increases [23]

S. O. Nkakini


y = 148.01x + 3577.1

R² = 0.0005

0

1000

2000

3000

4000

5000

1.6 1.7 1.8 1.9 2

DR

AU

GH

T (

N)

BULK DENSITY (g/cm3)

DRAUGHT Vs BULK DENSITY

DRAUGHT Vs BULK

DENSITY

Linear (DRAUGHT Vs

BULK DENSITY)

Figure 5 The effect of bulk density on draught force at a speed of 1.94 m/s

y = 368.5x + 4253.

R² = 0.003

0

2000

4000

6000

1.6 1.7 1.8 1.9 2

DR

AU

GH

T (

N)



DRAUGHT Vs BULK

DENSITY

Linear (DRAUGHT Vs

BULK DENSITY)


y = 142.6x + 5693.

R² = 0.000

0

2000

4000

6000

8000

1.6 1.7 1.8 1.9 2

DR

AU

GH

T (

N)



DRAUGHT Vs BULK

DENSITY

Linear (DRAUGHT Vs

BULK DENSITY)





Figures 8–10 indicate that draught forces decreased with an increase in depth of

cut. The results show the variances in coefficient of determinations R2 = 0.529, R

2 =

0.449 and R2 = 0.112, the best cut has the highest coefficient of determination of R

2 =

0.529.

y = -13599x + 6074.

R² = 0.529

0

1000

2000

3000

4000

5000

0 0.05 0.1 0.15 0.2 0.25

DR

AU

GH

T (

N)

DEPTH OF CUT (m)

DRAUGHT Vs DEPTH OF CUT

DRAUGHT Vs DEPTH

OF CUT

Linear (DRAUGHT Vs

DEPTH OF CUT)

Figure 8 The effect of depth of cut on draught force at speed of 1.94 m/s

y = -10917x + 6824.

R² = 0.449

0

2000

4000

6000

0 0.05 0.1 0.15 0.2 0.25

DR

AU

GH

T (

N)

DEPTH OF CUT (m)


DRAUGHT Vs DEPTH

OF CUT

Linear (DRAUGHT Vs

DEPTH OF CUT)

Figure 9 The effect of depth of cut on draught force at a speed of 2.2 m/s

y = -2671.x + 6475.

R² = 0.112

0

2000

4000

6000

8000

0 0.1 0.2 0.3 0.4

DR

AU

GH

T (

N)

DEPTH OF CUT (m)


DRAUGHT Vs DEPTH

OF CUT

Linear (DRAUGHT Vs

DEPTH OF CUT)

Figure 10 The effect of depth of cut on draught force at speed of 2.5 m/s

S. O. Nkakini


Figures 11–13 depict the effect of width of cut on draught force. Draught forces

increased with an increase in width of cut with the coefficient of determinations

R2=0.505, R

2 = 0.640 and R

2=0.006. This is in agreement with others findings which

stated that draught force increases with an increase in width of cut [13].

y = 2127.x + 2387.

R² = 0.505

0

1000

2000

3000

4000

5000

0 0.2 0.4 0.6 0.8 1

DR

AU

GH

T (

N)

WIDTH OF CUT (m)

DRAUGHT Vs WIDTH OF CUT

DRAUGHT Vs WIDTH

OF CUT

Linear (DRAUGHT Vs

WIDTH OF CUT)

Figure 11 The effect of width of cut on draught force at speed of 1.94 m/s

y = 2277.x + 3336.

R² = 0.640

0

1000

2000

3000

4000

5000

6000

0 0.2 0.4 0.6 0.8 1

DR

AU

GH

T (

N)

WIDTH OF CUT (m)


DRAUGHT Vs WIDTH OF

CUT

Linear (DRAUGHT Vs

WIDTH OF CUT)

Figure 12 The effect of width of cut on draught force at speed of 2.2 m/s

Figure 13 shows draught force to be slightly constant, with coefficient of

determination, R2=0.006 which is as a result of an increase in tractor forward speed of

operation.




y = -20.08x + 5975.

R² = 0.006

0

2000

4000

6000

8000

0 2 4 6 8 10

DR

AU

GH

T (N

)

WIDTH OF CUT (m)


DRAUGHT Vs WIDTH OF

CUT

Linear (DRAUGHT Vs

WIDTH OF CUT)

Figure 13 Effect of width of cut on draught force at speed of 2.5 m/s

Table 5 Anova effect of draught force and moisture content at 1.94 m/s, 2.22 m/s and 2.5 m/s

tractor forward speeds

Source of

Variation

SS

df

MS

F

P-value

F crit

Between 3.54E+08 2787.183 3.61E-3 4.098172

Group 1 3.54E+08 SS

126887.8

Within Groups 4821738 38

3.58E+08

Total 39

Table 5 shows that there are significant differences (p < 0.05) between draught

force and moisture content level at tractor forward speeds of 1.94 m/s, 2.22 m/s and

2.5 m/s.

Table 6 Anova effect of draught force and depth of cut at 1.94 m/s, 2.2 m/s and 2.5 m/s

tractor forward speeds

Source of

Variation

SS

df

MS

F

P-value

F crit

Between Group 3.55E+08 1 3.55E+08 2799.059 3.34E-37 4.098172

Within Groups 4820447 38 126853.9 SS

Total 3.6E+08 39

S. O. Nkakini


Tables 6, shows the analysis of variance for draught force and depths of cuts at

various tractor forward speeds of 1.94 m/s, 2.2 m/s and 2.5 m/s. The results indicated

that there are significant differences (P < 0.05) between draught force and depth of cut

at respectively.

Table 7 Anova effect of draught force and width of cut at 1.94 m/s, 2.22 m/s and 2.5 m/s

Table 7 shows the analysis of variance, for draught force and width of cut at

various tractor forward speeds of 1.94 m/s, 2.2 m/s and 2.5 m/s. The results indicated

that there are significant differences (P< 0.05) between draught force and width of cut

at respective tractor forward speeds of 1.94 m/s, 2.2 m/s and 2.5 m/s.

0

10000

20000

30000

40000

50000

60000

70000

1 2 3

Dra

uh

gt N

Speeds m/s

DRAUGHT Vs SPPED

DRAUGHT Vs SPPED

Figure 14 The relationship between draught force and tractor forward speeds

Figure 14 indicates that the draught forces increased as the tractor forward speeds

increased from 1.94 m/s, 2.2 m/s and 2.5 m/s. This is in agreement with the findings

which stated that increase in the tractor forward speeds of operation would increase

the draught force of the implement [17].

4. CONCLUSION

The soil moisture content levels, bulk density and cone index were collected before

tillage operation. The draught force requirements of a disc plough is dependent on the

moisture content levels of the soil, width of cut, depth of cut and tractor forward

speeds of the disc plough. The draught forces obtained at the highest moisture content

level of 24.14% wb were 3008.32 N, 4018.33 N and 5068.33 N at 1.94 m/s, 2.22 m/s

and 2.5 m/s tractor forward speeds respectively. The result obtained indicates that

increase in the tractor forward speeds of the implement (disc plough) would cause an

increase in draught force and that increase in moisture content levels would lead to

decrease in draught force of disc plough.

Source of

Variation

SS

df

MS

F

P-value

F crit

Between Group 3.55E+08 1 3.55E+08 2798.29 5.298-35 4.09817

Within Groups 4820974 38 126867.7 SS

Total 3.6E +0.8 39




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