2. S. O. Nkakini Ndor. M. Vurasi
http://www.iaeme.com/IJARET/index.asp 70 editor@iaeme.com
Cite this Article: Nkakini, S. O. and Vurasi, N. M. Effects of Moisture
Content, Bulk Density and Tractor Forward Speeds on Energy Requirement of
Disc Plough. International Journal of Advanced Research in Engineering and
Technology, 6(7), 2015, pp. 69-79.
http://www.iaeme.com/IJARET/issues.asp?JType=IJARET&VType=6&IType=7
_____________________________________________________________________
1. INTRODUCTION
Tillage as one preliminary and basic step for any agricultural production demands
huge amount of energy. Tillage is generally regarded as the most fundamental
operation in agricultural production. It can be defined as the cutting, pulverizing and
inversion of the soil to create conducive environment for crop growth and good yield
[1]. According to researchers tillage operation is any physical loosening of the soil as
carried out in a range of cultivations either by hand or mechanical methods [2]. The
implement plough is used in farming activities for initial cultivation of soil in
preparation for seeds planting. Tillage operation such as ploughing is an effective
means of controlling weeds especially perennial weed species, because trash and
weeds are buried relatively deeply in the soil. The use of energy is substantial mostly
in agriculture where drudgery is set to be reduced to the barest minimum. This is the
fact that most farmers still go subsistence farming, reason being that they cannot
afford the higher rate of energy consumption including the labour requirement during
the process.
Energy requirement of a tool during tillage operation is affected by three main
factors which are: soil, tool and operational parameters. Hence for proper evaluation
of total energy expended, the energy requirement of each factor should be taken into
consideration. Factors such as soil texture, soil moisture content, and soil compaction,
and tool geometry, tool operating depth, tool forward speed and tool rake angle
obviously affect the energy requirement of a tillage operation [3]. Two additional
factors such as tools shape and manner of tool movement were reported as factors
affecting energy requirement of tillage operations [4]. In tillage operation, energy
could be expressed in terms of energy per unit area or per volume of disturbed soil as
well as the rate of energy per depth of operation [5, 6].
Soil properties that contribute to tillage energy are moisture content, bulk density,
cone index, and soil texture [7, 8].
In fact, in the case of loosing hardpan layer of soil, it becomes obvious that a high
energy input is required to improved root development and increased draught
tolerance. A significant savings in tillage energy could be achieved through site
specific management of soil compaction [9]. Energy requirements of tillage tools are
important consideration in selecting tillage system.[7]
In agricultural cultivation, there is this problem of determining the energy values
or fuel consumption as it is to be used by machineries and other implements. It is of a
great important to farmers, to have the full knowledge of the energy required and fuel
consumption for any particular farming operation. This has been a renounced problem
for farmers. When a predetermined actual energy requirement and fuel consumption
are obtained, the farmers can easily choose the best conservation practices to manage
farm equipment and operations. This is to say, if agricultural industries or firms can
calculate the energy requirements in any farm practices, agricultural operation would
be easy and hence increase in productivity.
3. Draught Force Requirements of a Disc Plough at Various Tractor Forward Speeds in Loamy
Sand Soil, During Ploughing
http://www.iaeme.com/IJARET/index.asp 71 editor@iaeme.com
Thus objectives of the research is to determine the energy requirement and the
optimal forward speed for disc plough in tillage operation at various tractor forward
speeds. The effects of moisture content and bulk density on energy requirements
2. MATERIAL AND METHODS
Description of Study Area: The experiment was conducted between September,
2010 and January 2011 at National Root Crops Research Institute (NRCRI)
Experimental Farm, in Umudike, Umuahia, Abia State of Nigeria. Umudike is within
under the derived tropical humid ecological zone of Nigeria and is 122 m above sea
level and lies on latitude 05° 29°N and longitude 07° 33°E. It is approximately 64 km
south-east of Owerri and 128 km west of Port Harcourt capital of Rivers State of
Nigeria. The weather data during the period of the field operations in terms of rainfall,
relative humidity and sunshine for 2010 and January, 2011 were obtained from the
Agro-meteorological Department Umudike Station. Annual rainfall in the research
area is between 2500 mm to 300 mm per year. The monthly mean weather condition
for 2010 to January 2011, when the tillage operations were carried out is also given.
The instrument and equipment used are as follows, two tractors of the same model
and horse powers, dynamometer, measuring tape, disc plough, stop watch, core
sampler, polythene bag for soil sample collection and auger.
Experiential design: The experiential 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 trips
of 90 m by 2 m wide with a space of 3 m between each strip.
Experimental procedure: Ploughing operations were carried out on each of the
blocks, 24 hours after each rainfall event. Three replications of ploughing operations
were conducted after every rainfall events. The total treatments were 9 × 20 rainfall
events. The sequence of tillage operation was “Rainfall event” ploughing on block 1,
strip 1, block 2, strip 1” and block 3, strip 1. Rainfall event 2: ploughing on block 1,
strip 2” block 2, strip 2 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 was established.
Moisture content determination: Soil moisture was replenished only through
rainfall. The soil moisture content on each rainfall event was determined
gravimetrically (oven dry method). In order to define the relevant soil condition, soil
samples were collected from various soil depths before any tillage operation. The soil
samples were collected at depth of 0–50 mm, 50–150 mm, and 150–12 mm, using soil
auger at three replications per sample point. Different spots in the test plot were
randomly selected for the soil sample collections for soil moisture content level. The
tillage operation started only after each rainfall event.
100 (1)
Mws Mds
Mc
Mds
−
= ×
where, Mc = Moisture Content %, Mws = Mass of wet soil, Mds = Mass of dry soil
Determination of Bulk density: The bulk density was obtained using cylindrical
cores to collect some soil samples randomly. With Vanier Calliper the diameter and
length of cylindrical core were measured. The soil samples were collected at different
depths. To determine the bulk density of the soil equation 2 was used.
4. S. O. Nkakini Ndor. M. Vurasi
http://www.iaeme.com/IJARET/index.asp 72 editor@iaeme.com
3
/ (2)
Ms
Db g cm
Vb
=
where, Db = Bulk density (g/cm3
), Ms = Mass of oven dry soil sample (g), Vb =
Volume of core sample (cm3
)
Determination of Power: When the draught force is given in (Newton) and the speed
in (metre per second). The power is then calculated by using equation 3.
P = F × V (3)
Also note that Power can be known from the draught, the area and the force. That is,
Force = (Draught × Area) N
Determination of Energy: Power and energy are related as in equation 4
E = P × T (4)
where, E = Energy, P = Power , T = Time
Determination of draught: To determine draught (p) used in pulling the implement,
the equation 5 is applied.
P = P2 − P1 (4)
where, P = the draught (N), P1 = the force required to pull the implement in
transportation position, P2 = the force required to pull the implement during tillage
operation.
The differences between the force to pull the implement and transportation
position determine the required draught
3. RESULTS AND DISCUSSION
The moisture content was obtained before any tillage operation. Table 1, shows
results of moisture content levels db% and bulk density (g/cm3
) of the rainfall events.
The rainfall events of 15th
and 6th
days recorded the lowest and highest soil moisture
content levels of 1.53% and 24.14% respectively. The lowest and highest bulk
densities of 1.61 (g/cm3
) and 1.94 (g/cm3
) were obtained on 6th
and 11th
days of
rainfall events.
The drawbar-pull force was determined using trace-tractor techniques. This
reflects the force a tractor can generated over the primary forces resisting to
movement, consisting of rolling resistance, Table 2, represents the determined mean
drawbar-pull forces during ploughing operations at 1.94 m/s, 2.22 m/s and 2.5 m/s
forward speeds. The average drawbar-pull force obtained during ploughing operation
at forward speed of 1.94 m/s shows the mean drawbar-pull force of 3890.496 N, the
highest drawbar-pull force of 4688.33 N and lowest drawbar-pull force of 3,008.33 N
on 15th
and 6th
days of rainfall events. At tractor forward speed of 2.22 m/s, the mean
drawbar-pull force was 4908.997 N. The lowest and highest drawbar-pull forces of
4221.66 N and 5708.33 N were obtained on 4th
and 15th
days of rainfall events.
Tractor forward speed of 2.5 m/s recorded mean drawbar-pull force of 5,958.99 N,
lowest and highest drawbar-pull forces of 5,068.33 N and 6,758.33 N on 6th
and 15th
days of rainfall events. This has shown that drawbar-pull force increased with
increase in ploughing speeds and decreased with increase of moisture content level.
5. Draught Force Requirements of a Disc Plough at Various Tractor Forward Speeds in Loamy
Sand Soil, During Ploughing
http://www.iaeme.com/IJARET/index.asp 73 editor@iaeme.com
This is in line with the findings of others, that said, increasing the speed of operation
of disc plough increase the draught of implement[10][11].
Table 1 Mean moisture content (db %) and bulk density (g/cm3
) for days of field operations
Determination of energy requirements: Energy requirements were calculated on
each day of field operation at three different tractor forward speeds. In Table 3, the
calculated total and means energy requirements for ploughing operation at the
forward speeds of 1.94 m/s, 2.2 m/s and 2.5 m/s are shown to be 36,722.34 KJ,
1,836.12 KJ, 55,173.61 KJ, 2,758.58 KJ and 69,464.823 KJ, 3,473.241 KJ
respectively. The results showed that energy requirements increased with increase in
tractor forward speeds. This is in accordance with the findings of others which stated
that increasing the forward speeds of operation would increase the draught and energy
requirement of the implement[1].
Moisture content level plays a vital role during tillage operations. Its effects on
energy expended during tillage operations at different tractor forward speeds were
shown in Figures 1–3. At every tractor forward speed, there was a decrease in energy
expended with coefficient of determinations of R2
= 0.698, R2
= 0.336 and R2
=
0.545.The results displayed the highest coefficient of determination of R2
= 0.698
with tractor forward speed of 1.94 m/s.
Days
Amount of rainfall,
mm
Soil moisture content
db% (0–200 mm)
depths
Bulk density (g/cm3
) (0–
200 mm) depths
1 50.7 15.50 1.80
2 66.9 16.04 1.70
3 48.2 15.44 1.86
4 15.3 17.71 1.84
5 42.2 14.42 1.84
6 149.3 24.14 1.61
7 11.6 13.92 1.90
8 3.8 11.58 1.78
9 93.7 17.66 1.86
10 90.6 17.62 1.88
11 30.1 14.83 1.94
12 23.1 14.44 1,92
13 23.3 14.48 1.93
14 1.3 6.31 1.75
15 0 1.53 1.67
16 0 2.24 1.78
17 0 2.01 1.76
18 2.1 6.86 1.88
19 0 2.70 1.77
20 4.6 11.94 1.79
6. S. O. Nkakini Ndor. M. Vurasi
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Table 2 Determined mean drawbar-pull forces during ploughing for each day of field
operation at 1.94 m/s, 2.22 m/s and 2.5 m/s forward speeds
Days of
field
operation
Rainfall
amount on days
of field
experiments
Average
drawbar-pull at
1.94 m/s
Average drawbar-
pull at 2.22 m/s
Average
drawbar-pull at
2.5 m/s
1 50.7 3,580.00 4,586.66 5,636.66
2 66.7 3,406.66 4,420.00 5,470.00
3 48.2 3,725.00 4,745.00 5,795.00
4 95.3 3,201.66 4,221.66 5,271.66
5 42.2 3,776.66 4,816.66 5,866.66
6 149.3 3,008.32 4,018.33 5,068.33
7 11.6 4,005.00 5,015.00 6,065.00
8 3.8 4,050.00 5,060.00 6,110.00
9 93.7 3,253.33 4,273.33 5,323.33
10 90.6 3,316.66 4,336.66 5,386.66
11 30.1 3,801.66 4,861.66 5,911.66
12 23.1 3,940.00 4,960.00 6,010.00
13 23.3 3,930.00 4,950.00 6,000.00
14 1.3 4,083.33 5,103.33 6,153.33
15 0 4,688.33 5,708.33 6,758.33
16 0 4,643.33 5,663.33 6,713.33
17 0 4,616.66 5,636.66 6,686.66
18 2.1 4,063.33 5,083.33 6,133.33
19 0 4650.00, 5,670.00 6,720.00
20 4.6 4,030.00 5,050.00 6,100.00
Mean 3890.4965 4,908.997 5,958.997
Figures 4–6 showed the effects of bulk density on energy expended during tillage
operations at various tractor forward speeds of 1.94 m/s, 2.22 m/s and 2,5 m/s. Energy
expended increased with increase in bulk density at these speeds, with coefficient of
determinations R2
= 0.668, R2
= 0.504, R2
= 0.665. The results showed the highest
coefficient of determination R2
at tractor forward speed of 1.94 m/s
Figure 1 The effect of Moisture Content on Energy during tillage operation at 1.94 m/s
forward speed
y = -62.374x + 2681.2
R² = 0.6981
0.00
500.00
1,000.00
1,500.00
2,000.00
2,500.00
3,000.00
0 10 20 30
Energy(KJ)
Moisture Content db %
ENERGY VS MOISTURE CONTENT AT 1.94m/s
Series1
7. Draught Force Requirements of a Disc Plough at Various Tractor Forward Speeds in Loamy
Sand Soil, During Ploughing
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Table 3 Energy requirements of tillage operations at forward speeds of 1.94 m/s, 2.22 m/s
and 2.5 m/s.
Figure 2 The effect of moisture content on energy during tillage operation at 2.22 m/s
forward speed
y = -65.365x + 3547.5
R² = 0.3364
0.00
500.00
1,000.00
1,500.00
2,000.00
2,500.00
3,000.00
3,500.00
4,000.00
0 10 20 30
Energy(KJ)
Moistuer Content db %
ENERGY VS MOISTURE CONTENT AT 2.22m/s
Series1
Series2
Days of
field
operations
1.94 m/s 2.22 m/s 2.5 m/s
Time (s) Energy ( KJ) Time (s)
Energy
(KJ)
Time
(s)
Energy
(KJ)
1 185 1,284.862 182 1,853.194 151 2,127.839
2 187 1,235.87 184 1,805.482 175.5 2,399.963
3 180 1,300.77 177 1,864.500 169.5 2,455.631
4 265 1,645.97 162 1,518.278 257.5 3,393.632
5 175 1,282.18 172 1,839.194 166 2,434.664
6 283.5 1,654.55 280.5 3,747.674 273 3,459.135
7 240.5 1,868.61 237.5 2,646.159 231 3,502.538
8 290 2,278.5 287 3,223.928 281 4,292.275
9 269 1,697.26 260 2,466.566 260 3,460.165
10 262 1,685.79 259 2,493.493 253 3,407.062
11 275.5 2,053.25 272.5 2,941.061 266.5 3,938.643
12 239.5 1,830.64 235.5 2,593.137 230.5 3,463.263
13 240.5 1,833.62 236 2,593.404 231.5 3,472.500
14 289.5 2,293.32 286.5 3,245.871 280.5 4,315.023
15 289.5 2,633.11 286.5 3,630.669 280.5 4,739.278
16 289 2,603.83 286 3,595.762 280 4,699.331
17 289 2,588.38 286 3,578.828 280 4,680.662
18 290 2,286.03 287 3,238.793 281 4,308.664
19 290 2,616.09 287 3,612.584 282 4,737.600
20 242.5 1,895.913 239.5 2,685.035 238.5 3,637.125
Total 36,722.34 KJ
55,173.61
KJ
69,464.82 KJ
Means 1836.12 KJ 2,758.58 KJ 3,473.24 KJ
8. S. O. Nkakini Ndor. M. Vurasi
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Figure 3 The effect of moisture content on energy during tillage operation at 2.5 m/s forward
speed.
Figure 4 The effect of bulk density on energy during tillage operation at 1.94 m/s forward
speed
Figure 5 The effect of bulk density on energy during tillage operation at 2.22 m/s forward
speed
y = -96.241x + 4807.7
R² = 0.5453
0.00
500.00
1,000.00
1,500.00
2,000.00
2,500.00
3,000.00
3,500.00
4,000.00
4,500.00
5,000.00
0 10 20 30
Energy(KJ0
Moisture Content db%
Energy Vs Miosture content at 2.5m/s
Series1
Energy Vs
Miosture content
Linear (Energy Vs
Miosture content)
y = 65.387x + 1241.9
R² = 0.668
0.00
500.00
1,000.00
1,500.00
2,000.00
2,500.00
3,000.00
0 10 20 30
Energy(KJ)
Bulk Density g/cm3
ENERGY Vs BULK DENSITY AT 1.94m/s
Series1
Energy Vs Bulk
Density
Linear (Energy Vs
Bulk Density)
y = 85.766x + 1858.1
R² = 0.5043
0.00
500.00
1,000.00
1,500.00
2,000.00
2,500.00
3,000.00
3,500.00
4,000.00
0 10 20 30
Energy(KJ)
Bulk Density g/cm3
ENERGY VS BULK DENSITY AT 2.22m/s
Series1
9. Draught Force Requirements of a Disc Plough at Various Tractor Forward Speeds in Loamy
Sand Soil, During Ploughing
http://www.iaeme.com/IJARET/index.asp 77 editor@iaeme.com
Figure 6 The effect of bulk density on energy during tillage operation at 2.5 m/s forward
speed.
Tables 4–6 show analyses of variance for effects of moisture content levels on
energy expended at various tractor forward speeds of 1.94 m/s, 2.22 m/s and 2.5 m/s.
The results indicated that there are significant differences (P ≤ 0.05) between moisture
content levels and energy expended at the respective tractor forward speeds.
Table 4 Analysis of variance (ANOVA) for effect of moisture content on energy during
tillage at 1.94 m/s tractor forward speed
Sources of
Variance
SS df MS F P-value F crit
Between
Groups
3.72E+13 1 3.72E+13 332.0367 2.24E-20 4.098172
Within
Groups
4.26E+12 38 1.12E+11
TOTAL 4.14E+13 39
Table 5 Analysis of variance (ANOVA) for effect of moisture content on energy during
tillage at 2.22 m/s tractor forward speed
Sources of
Variance
SS df MS F P-value F crit
Between
Groups
7.2E+13 1 7.4E+13 317.99 4.7E-20 4.02
Within
Groups
8.92E+12 38 2.35E+11
TOTAL 8.36E+13 39
Figure 7 depicts the trend of energy expended in the various tractor forward
speeds during ploughing operation. The energy expended increased with increase in
tractor forward speeds. The less energy expended was obtained with tractor forward
speed of 1.94 m/s.
y = 113.91x + 2450.2
R² = 0.6652
0.00
1,000.00
2,000.00
3,000.00
4,000.00
5,000.00
0 10 20 30
Energy(KJ)
Bulk Density g/cm3
ENERGY VS BULK DENSITY AT 2.5m/s
Series1
Linear
(Series1)
10. S. O. Nkakini Ndor. M. Vurasi
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Table 6 Analysis of variance (ANOVA) for effect of moisture content on energy during
tillage at 2.5 m/s tractor forward speed.
Sources of
Variance
SS df MS F P-value F crit
Between
Groups
1.33E+14 1 1.33E+14 389.432 1.44E-21 4.09
Within
Groups
1.3E+13 38 3.41E+11
TOTAL 1.46E+14 39
Figure 7 The effect of tractor forward speeds on mean energy expended during tillage
operations
4. CONCLUSION
This study has determined the various total and means energy expended for three
different tractor forward speeds of 1.94 m/s, 2.22 m/s and 2.5 m/s respectively in
loamy sand soil of rainforest zone of Nigeria. The results have shown that energy
expended decreased with increasing moisture content level at various tractor forward
speeds. This is evident from the coefficient of determinations of R2
= 0.698, R2
=
0.336 and R2
= 0.545 at tractor forward speeds of 1.94 m/s, 2.22 m/s and 2.5 m/s. The
effect of bulk density, revealed increase in energy expended as the bulk densities
increase with corresponding increase in tractor forward speeds. The tillage operations,
ensured increase in energy expended with increase in tractor forward speeds. The
analysis of various parameters on effects of energy expended showed significant
difference (p ≤ 0.05) between, moisture content levels and energy expended at various
tractor forward speeds. In fact, R2
= 0.698 stands out for less energy expended. Thus,
1.94 m/s stands the best tractor forward speed for ploughing operations in terms of
energy consumption.
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humid Africa. 1990
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Series1
11. Draught Force Requirements of a Disc Plough at Various Tractor Forward Speeds in Loamy
Sand Soil, During Ploughing
http://www.iaeme.com/IJARET/index.asp 79 editor@iaeme.com
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