draught requirements of tillage implements operating on sandy loam soil

J . agric . Engng Res . (1997) 66 , 177 – 182

Draught Requirements of Tillage Implements Operating on Sandy Loam Soil

Saleh A . Al-Suhaibani ; Abdulrahman Al-Janobi

Agricultural Engineering Department , College of Agriculture , King Saud University , Riyadh , Saudi Arabia

( Recei y ed 2 1 July 1 9 9 5 ; accepted in re y ised form 2 8 October 1 9 9 6 )

The ef fects of speed and depth on the draught of a chisel plough , an of fset disk harrow , a mouldboard plough and a disk plough were investigated on two dif ferent sites . Soil classification , implement specifications and results of tillage experiments are reported . A significant increase in draught was observed for all the implements with an increase in depth . The specific draughts of the four tillage implements tested were af fected significantly by speed and depth also . The relationships between specific draught and speed are presented graphically .

÷ 1997 Silsoe Research Institute

1 . Introduction

The availability of data relating to draught requirements is an important factor in selecting tillage implements for a particular farm situation . Farm managers and consultants use draught and power requirement data of tillage implements in specific soil types to determine the size of tractor required .

Many studies have been conducted to measure draught and power requirements of tillage implements under various soil conditions . Grisso et al . 1 reviewed work reported by dif ferent researchers in measuring draught and power requirements of the most common tillage implements . The ASAE Standards 2 provide mathematical expressions for draught and power requirements for tillage implements in several soil types as part of ASAE D497 . As many changes in tillage and planting equipment have occurred during the past 15 yr , periodic updating of the ASAE data on draught and power requirements is required . New information is available from research and machinery manufac- turers to update the ASAE data (Harrigan and Rotz 3 ) .

The draught required to pull a tillage implement is basically a function of implement width , operating depth and the speed at which it is pulled . Draught also depends on soil conditions and geometry of the tillage

implement (Upadhyaya et al . 4 ) It has been widely reported that the draught forces on implements increase significantly with speed and the relationship varies from linear to quadratic (Grisso et al . 1 ) . Har- rigan and Rotz 3 proposed a simple function for a range of soil conditions to model tillage draught under general conditions , where draught per unit width or cross-sectional area of the tilled zone is a function of soil type and the speed at which the implement is pulled . In the proposed model the authors categorized soil as fine , medium and coarse . These categories were described as corresponding to clay , loamy and sandy soils respectively .

All the draught data presented in the ASAE Standards 2 and the data presented by Harrigan and Rotz 3 were based mostly on USA lands . Presently , there is a shortage of data available on draught requirements of agricultural implements operating on sandy loam soils . For Saudi Arabia this point is of great concern , since sandy loam soil is the most common type of soil in the middle region . Al- Suhaibani , 5 in a field study , found that in Saudi Arabia most of the farms were over-powered with an average tractor power provision of 1 ? 84 kW / ha which is about double that in Indiana and more than three times that in Nebraska (USA) . The explanation for this was the farmers’ lack of experience with farm machinery and the non-availability of suf ficient data on draught of tillage implements to select the proper tractor for a particular farm situation . The object of this study was to measure the ef fects of speed and depth on the draught of four commonly used tillage implements on sandy loam soils .

2 . Materials and methods

2 . 1 . Field

Experiments were conducted at two dif ferent sites at King Saud University’s Agricultural Research and

177 0021-8634 / 97 / 030177 1 06 $25 . 00 / 0 / ag960130 ÷ 1997 Silsoe Research Institute

S A L E H A . A L - S U H A I B A N I ; A B D U L R A H M A N A L - J A N O B I 178

Table 1 Soil classification , cone index , and moisture content of the tested fields

Site 1 ( wheat ) Site 2 ( fallow )

Clay ratio * Clay ratio *

Soil composition † , per cent

Sand Silt Clay

55 27 18 22

79 11 10 11 ? 1

Classification Sandy loam Sandy loam Range A y erage Range A y erage

Soil cone index (kPa) at depth

70 – 140 mm 140 – 210 mm

1204 – 1634 1692 – 2160

1582 1925

480 – 632 1061 – 1278

550 1174

Moisture content (% d . b . ) at depth of 70 – 210 mm

8 ? 3 – 13 ? 4 12 ? 5 7 ? 3 – 10 ? 4 9 ? 5

* Clay ratio 5 % clay

(% silt 1 % sand) (Elbanna and Witney) . 6

† Hydrometer test . 7

Experimental Farm at Dirab . At both sites , the soil was sandy loam . The clay ratio varied significantly from one site to the other as shown in Table 1 . The first site was a wheat field and the stubble after harvesting was present in the field until tillage was carried out . The field at the other site was more sandy , where alfalfa was grown during 1992 . The residues were shredded and the field was left fallow until tillage on April 5 , 1995 .

The field at each site was irrigated by using sprink- ler irrigation system for 4 d prior to performing the

tillage experiment . Soils from the two fields were classified by mechanical analysis . Soil samples were collected during the tillage experiments to determine the average moisture contents . The samples were weighed and oven dried at 110 8 C for 48 h and the moisture contents were calculated on a dry weight basis . Cone index values were obtained by taking penetrometer readings over the implement depth . The cone used was of ASAE standard with a 30 8 cone angle and a diameter of 12 ? 83 mm . Table 1 shows soil test data from the two fields .

Table 2 Specification of implements used

Implement Width ( mm ) Specification

Chisel plough 2100 Heavy duty type with 13 shanks each of width 70 mm arranged in two rows . Shank stem angle 55 8 , 355 mm between shanks in each row and 450 mm between rows . Mas- sey Ferguson (Denmark) , model MF 38 . Serial No . L4078 .

Of fset disk-harrow 1800 Thirty six disks each of 510 mm diameter , 18 each in two rows , 34 8 inclined to the direction of travel , with 210 mm between disks in each row . Massey Ferguson (Den- mark) , model MF 38 . Serial No . L4082 .

Mouldboard plough 1150 General purpose type . Three bodies in the frame each of width 360 mm . Overum- S(Sweden) , model 7073331 .

Disk plough 1115 Three disks each of 660 mm diameter with tilt angle of 22 8 , disk angle of 45 8 and 600 mm between disks . EBRO (Spain) , model ADE 300 .

D R A U G H T R E Q U I R E M E N T S O F T I L L A G E I M P L E M E N T S O P E R A T I N G O N S A N D Y L O A M S O I L 179

2 . 2 . Tillage implements

Four primary tillage tools comprising a chisel plough , an of fset disk harrow , a mouldboard plough and a disk plough were used for evaluating draught requirements . All these are standard primary tillage implements most commonly used for seed bed pre- paration in Saudi Arabia . Implement specifications are given in Table 2 .

2 . 3 . Experiment layout

The parameters investigated for the draught measurements were forward speed and tillage depth . Four speeds at one depth for the four tillage implements were used in combination for 16 treatments in the

wheat stubble field , whereas six speeds , three depths and the four tillage implements were used to give a total of 72 treatments in the fallow field . The selected speeds and depths for the tillage experiment are presented in Table 3 . In the wheat stubble field , treatments were made at a single depth for each implement because insuf ficient area was available to provide enough experimental blocks . During the field operations , for each tillage implement , the tractor was operated in a gear range to get the same forward speeds at dif ferent operating depths . An experimental block of length 50 m was used for each treatment in both fields . A block of approximate length 30 m was used as a practice area prior to the beginning of the experimental runs to enable the tractor and the implement to reach the required speed and depth . Field tests were conducted for each tillage implement and a total of 88 treatments were made in all .

Table 3 Parameters set and measurements made during the tillage experiments

Site 1 ( Wheat ) Site 2 ( Fallow )

Implement Speed ( m / s )

Depth ( mm )

A y g . draught ,

kN

Std . de y i - ation ,

k N Speed ( m / s )

A y g . draught ,

kN for

depth D 1

1 0 0 mm


kN

A y g . draught ,

kN for

depth D 2

1 5 0 mm


kN

A y g . draught ,

kN for

depth D 3

2 0 0 mm


kN

Chisel plough

0 ? 74 1 ? 03 1 ? 55 1 ? 70

94 4 ? 28 4 ? 78 5 ? 47 5 ? 84

0 ? 106 0 ? 160 0 ? 341 0 ? 170

0 ? 84 1 ? 39 1 ? 75 2 ? 10 2 ? 33 2 ? 60

1 ? 98 2 ? 34 2 ? 95 3 ? 62 4 ? 04 4 ? 31

0 ? 192 0 ? 077 0 ? 128 0 ? 907 0 ? 192 0 ? 255

2 ? 27 3 ? 14 3 ? 54 4 ? 54 5 ? 24 5 ? 98

0 ? 435 0 ? 097 0 ? 070 0 ? 157 0 ? 048 0 ? 322

5 ? 38 6 ? 19 7 ? 38 8 ? 40 9 ? 12

10 ? 54

0 ? 125 0 ? 061 0 ? 355 0 ? 561 0 ? 274 0 ? 446

Of fset disk harrow

0 ? 73 0 ? 98 1 ? 42 1 ? 71

73 3 ? 14 3 ? 22 3 ? 55 3 ? 89

0 ? 109 0 ? 148 0 ? 082 0 ? 193

0 ? 84 1 ? 39 1 ? 76 2 ? 02 2 ? 31 2 ? 50

2 ? 15 3 ? 26 4 ? 81 5 ? 46 6 ? 25 6 ? 78

0 ? 517 0 ? 440 1 ? 735 0 ? 156 0 ? 412 0 ? 498

3 ? 08 4 ? 39 5 ? 53 6 ? 57 7 ? 43 7 ? 88

0 ? 060 0 ? 410 0 ? 617 0 ? 587 0 ? 637 0 ? 520

5 ? 62 6 ? 91 7 ? 40 9 ? 56

10 ? 57 11 ? 37

0 ? 456 0 ? 388 0 ? 835 0 ? 656 0 ? 596 0 ? 788

Mouldboard plough

0 ? 64 0 ? 99 1 ? 42 1 ? 62

130 9 ? 88 10 ? 46 11 ? 07 12 ? 31

0 ? 126 0 ? 214 0 ? 480 0 ? 246

0 ? 80 1 ? 32 1 ? 68 1 ? 94 2 ? 23 2 ? 53

4 ? 08 4 ? 51 4 ? 99 5 ? 36 5 ? 98 6 ? 79

0 ? 110 0 ? 219 0 ? 250 0 ? 093 0 ? 705 0 ? 594

5 ? 29 5 ? 99 6 ? 69 7 ? 29 7 ? 97 9 ? 21

0 ? 111 0 ? 071 0 ? 298 0 ? 165 0 ? 240 0 ? 100

8 ? 03 8 ? 56 9 ? 01

10 ? 02 11 ? 40 13 ? 00

0 ? 115 0 ? 364 0 ? 241 0 ? 348 0 ? 172 0 ? 398

Disk plough

0 ? 72 0 ? 96 1 ? 38 1 ? 57

152 9 ? 54 10 ? 24 11 ? 41 12 ? 22

0 ? 064 0 ? 113 0 ? 298 0 ? 327

0 ? 86 1 ? 27 1 ? 60 1 ? 90 2 ? 18 2 ? 54

3 ? 50 4 ? 15 5 ? 10 6 ? 11 7 ? 30 8 ? 96

0 ? 102 0 ? 146 0 ? 185 0 ? 174 0 ? 617 0 ? 225

5 ? 34 5 ? 51 6 ? 25 6 ? 96 7 ? 99 9 ? 91

0 ? 134 0 ? 173 0 ? 113 0 ? 168 0 ? 449 0 ? 229

6 ? 76 7 ? 15 8 ? 09 8 ? 76 9 ? 56

11 ? 13

0 ? 078 0 ? 059 0 ? 661 0 ? 308 0 ? 532 0 ? 305


An instrumented tractor was used in all the experiments . The instrumentation system consisted of a datalogger , a three-point linkage dynamometer , a rotary position transducer and a ground speed sensor consisting of a fifth wheel mounted on the tractor . The onboard datalogger in the tractor cab measured and recorded draught , implement working depth and tractor speed during field operations . The three-point linkage dynamometer was calibrated prior to the experiments using a specially built calibration rig and the fifth wheel was calibrated at the beginning of the experiment for each surface . A rotary position transducer , with its hollow rotor coupled to a small D profile shaft welded to the rockshaft , was operated by the movement of the three-point linkage and was calibrated for known vertical positions of the ball end of the lower link and angular displacement of the three-point linkage dynamometer . This calibration was used to obtain the implement working depth and the angular position of the three-point linkage dynamometer respectively . The complete description of the instrumentation system and the calibration of transducers are given by Al-Suhaibani et al . 8 A performance test program was developed and documented for the datalogger to scan the transducers every 1 s to give a set of readings during the field operation . Therefore , the number of readings made in each treatment depended on the forward speed of the tractor . The minimum number taken in each tillage experiment was 22 , so at least this number was taken from the sampled data and averaged for each measured parameter .

3 . Results and discussion

The average values for draught of the four implements during the tillage experiment at dif ferent speeds and depths are given in Table 3 . This shows a significant increase in draught in all the treatments with an increase in tillage depth . For all the tillage implements , draught was divided by the implement width to obtain specific draught per unit width . The data points corresponding to specific draught versus speed at various tillage depths (D) for the four tillage implements in both fields are shown in Figs 1 – 4 . An increase in specific draught was observed with an increase in tillage depth and speed for all the implements tested in both fields .

If comparisons are made ( Figs 1 – 4 ) at approxim- ately the same tillage depths in both fields , the draught requirement for the wheat field is found to be greater for all four tillage implements because of the greater strength of the soil of the wheat field (Table

6

5

4

3

2

1

00 0·5 1 1·5 2 2·5 3

Speed, m/s

Sp

eci

fic d

rau

gh

t, N

/mm

Fig . 1 . Ef fect of speed and depth on specific draught of a chisel plough . Site 1 ( wheat ) ; 1 D 5 9 4 mm . Site 2 ( Fallow ) ;

r D 1 5 1 0 0 mm ; d D 2 5 1 5 0 mm ; j D 3 5 2 0 0 mm

1) . It was more firm and compact owing to the presence of stubble of wheat plants and higher values of clay ratio , moisture content and cone index . How- ever , the specific draught of the chisel plough and the of fset disk harrow showed lower values than the specific draught of the other two implements in the wheat field . This was because of the smaller tillage depths used for the chisel plough and the of fset disk harrow in the wheat field .

8

6

4

2

00 0·5 1 1·5 2 2·5 3

Speed, m/s

Sp

eci

fic d

rau

gh

t, N

/mm

Fig . 2 . Ef fect of speed and depth on specific draught of an of fset disk harrow . Site 1 ( Wheat ) ; 1 D 5 9 4 m m . Site 2 ( Fallow ) ; r D 1 5 1 0 0 mm ; d D 2 5 1 5 0 mm ; j D 3 5 2 0 0 mm

D R A U G H T R E Q U I R E M E N T S O F T I L L A G E I M P L E M E N T S O P E R A T I N G O N S A N D Y L O A M S O I L 181

12

10

8

6

4

2

00 0·5 1 1·5 2 2·5 3

Speed, m/s

Spe

cific

dra

ught

, N/m

m

Fig . 3 . Ef fect of speed and depth on specific draught of a mouldboard plough . Site 1 ( Wheat ) ; 1 D 5 9 4 mm . Site 2 ( Fallow ) ; r D 1 5 1 0 0 mm ; d D 2 5 1 5 0 mm ; j D 3 5 2 0 0 mm

Figures 5 – 7 show the variation of specific draught acting on the four implements in the fallow field at various tillage depths . For the same depth and range of speed , the specific draughts acting on the mouldboard plough and the disk plough in the fallow field were greater than the specific draughts acting on the chisel plough and the of fset disk harrow . This could be owing to the influence of the dif ferent shapes and sizes of the cultivating elements of the implements . The mouldboard plough showed a tendency to give a greater increase in specific draught with increased

12

8

6

4

00 0·5 1 1·5 2 2·5 3

Speed, m/s

Spe

cific

dra

ught

, N/m

m

10

2

Fig . 4 . Ef fect of speed and depth on specific draught of a disk plough . Site 1 ( Wheat ) ; 1 D 5 9 4 mm . Site 2 ( Fallow ) ; r

D 1 5 1 0 0 mm ; d D 2 5 1 5 0 mm ; j D 3 5 2 0 0 mm

12

10

8

6

4

2

00 0·5 1 1·5 2 2·5 3

Speed, m/s

Spe

cific

dra

ught

, N/m

m

Fig . 5 . Variation of specific draught of the four implements in the fallow field at depth D 1 5 1 0 0 mm . j Chisel plough ; r Of fset disk harrow ; m Mouldboard plough ; d Disk plough

tillage depth than the other implements and this was probably owing in part to choking of the furrow slice in the curvature of the mouldboard . At a tillage depth of 150 mm and the same range of speed , the variation of specific draught of the mouldboard plough and the disk plough were close together , whereas at tillage depth 200 mm the specific draught of the mouldboard plough was greater than that of the disk plough . At all tillage depths , the chisel plough gave the lowest specific draught and the of fset disk harrow was next to it .

12

8

6

4

00 0·5 1 1·5 2 2·5 3

Speed, m/s

Spe

cific

dra

ught

, N/m

m

10

2



12

8

6

4

00 0·5 1 1·5 2 2·5 3

Speed, m/s

Sp

eci

fic d

rau

gh

t, N

/mm

10

2


4 . Conclusions

In all the treatments , a significant increase in draught was observed for all four tillage implements with an increase in forward speed and tillage depth . In both wheat and fallow fields , soil strength increased with depth as indicated by the larger values of soil cone index found at depths between 140 and 210 mm , compared with 70 to 140 mm . The greater draught requirement for the four tillage implements in the wheat field as compared with the fallow field was because of the presence of stubble in the wheat field and higher values of soil strength , clay ratio and moisture content . The specific draught of the four implements was af fected by tillage depth , soil strength and shape and size of the implements . The mouldboard plough showed a tendency to give a greater increase in draught with increasing tillage depth than

the other implements , possibly because of choking of the furrow slice in the curvature of the mouldboard at the largest tillage depth . The chisel plough gave the lowest specific draught and the of fset disk harrow was next to it at all tillage depths .

Acknowledgement

This research has been supported financially by the Agricultural Research Center , King Saud University .

References

1 Grisso R D ; Yasin M ; Kocher M F Tillage implement forces operating in silty clay loam . ASAE Paper No . 94-1532 , ASAE , St . Joseph , Michigan , USA , 1994 , pp . 17

2 ASAE Standards , 41st Edition , 1994 ASAE D497 Agricultural machinery management data . ASAE , St . Joseph , Michigan , USA

3 Harrigan T M ; Rotz C A Draft of major tillage and seeding equipment . ASAE Paper No . 94-1533 , ASAE , St . Joseph , Michigan , USA , 1994 , pp . 21

4 Upadhyaya S K ; Williams , T H ; Kemble L J ; Collins N E Energy requirement for chiseling in coastal plain soils . Transactions of the ASAE 1984 , 27 (6) , 1643 – 1649

5 Al-Suhaibani S A Use ef ficiency of farm machinery in Saudi Arabia . ASAE Paper No . 92 – 1044 , ASAE , St . Joseph , Michigan , USA , 1992 , pp . 11

6 Elbanna E B ; Witney B D Cone penetration resistance equation as a function of the clay ratio , soil moisture content and specific weight . Journal Terramechanics 1986 , 24 (4) , 41 – 46

7 AASHTO T87-70 and T88-70 Standard specifications for highway materials and methods of sampling and testing , part II . American Association of State Highway and Transportation Of ficials , Washington D . C ., 1982

8 Al-Suhaibani S A ; Bedri A A ; Babeir A S ; Kilgour J Mobile instrumentation package for monitoring tractor performance . Agricultural Engineering Research Bulle- tin No . 40 , King Saud University , Riyadh 1994 , pp . 26

draught requirements of tillage implements operating on sandy loam soil

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