Specific energy consumption and field performance in ploughing and cultivating

Gerhard Moitzi1*, Martin Haas1, Helmut Wagentristl2, Josef Boxberger1, Andreas

Gronauer1

University of Natural Resources and Life Sciences (BOKU), Vienna, Austria 1Department of Sustainable Agricultural Systems; Division of Agricultural Engineering,

Peter Jordan-Strasse 82; A-1190 Vienna 2Department of Crop Science; Experimental farm Gross Enzersdorf, Schlosshoferstraße 31,

A-2301 Gross Enzersdorf

*Corresponding author: gerhard.moitzi@boku.ac.at

Soil tillage in conventional tillage systems is one of the most energy consuming process. The intensity of soil tillage depends on the number of soil tillage operations, kind of device (active driven by PTO or passive by drawbar power), implement geometry and depth of operation. Fuel consumption of soil tillage is correlated with intensity of soil tillage. In the energy flow from engine to implement there are efficiency loses in the engine, transmission and wheel-soil interface. Moreover slippage, which is an expression of the traction efficiency, effects the field performance and the fuel consumption. The paper deals the influence of working width of mouldboard plough (mounted and semi-mounted) and T-trailed cultivator (3 bars; row spacing: 27 cm; 18 tines; tine spacing; 27 cm) on field performance, fuel consumption, slip and specific energy consumption. The ploughs and the cultivator are provided by the Austrian farm machinery manufacturer Pöttinger®. The experiments were conducted on the arable fields at the experimental farm Gross Enzersdorf (Lower Austria) of the University of Natural Resources and Life Sciences (BOKU) Vienna. For measuring of the real and theoretical speed (parameters for slip calculation), the tractor was equipped with a radar and wheel hub sensor. The fuel consumption was measured for each trial run in threefold repetition volumetrically. The results shows, that the technical field performance increases with the working width of the plough. The fuel consumption for ploughing rises discontinuously with the working width, which is a result of the luxury engine power in the 2x5 mouldboard plough-tractor combination. The increase of the working depth from 15 cm to 25 cm for the cultivator enhances the fuel consumption by 70 % and the slip by 265 %, whereas the specific fuel consumption is on the same level. The traction control system in ploughs reduces fuel consumption between 10 and 11.5 %. With increasing working width of the plough the potential of subsoil compaction is increasing, because of risen load of the rear furrow wheel. Keywords: Fuel consumption, soil tillage, mouldboard plough, cultivator, traction control

1. Introduction

Soil tillage is one of the most energy consuming process in plant cropping. The intensity of soil tillage depends on the number of soil tillage operations, kind of device (active driven by PTO or passive by drawbar power), implement geometry and depth of operation (Loibl 2006, Godwin 2007). Fuel consumption of soil tillage is correlated with intensity of soil tillage. In the energy flow from engine to implement there are efficiency loses in the engine, transmission and wheel-soil interface (Schreiber et al. 2004, Jahns & Steinkampf 1982). Moreover

slippage, which is an expression of the traction efficiency, effects the field performance and the fuel consumption. The paper deals the influence of working width of mouldboard plough (mounted and semi-mounted) and T-trailed cultivator (3 bars; row spacing: 27 cm; 18 tines; tine spacing; 27 cm) on field performance, fuel consumption, slip and specific energy consumption. Additional a traction increasing system in ploughing was analysed in regard to slippage and fuel consumption.

2. Material and methods

2.1. Experimental Site The field experiments took place at the experimental farm of the University of Natural Resources and Life Science (BOKU) in Gross Enzersdorf (Lower Austria; 48° 15´N/16° 37`E). The climate at the experiment site is characterised with an average temperature of 9.8°C and rainfall of 546 mm respectively, which is typical for semiarid regions. The soil (silty loam of Chernozem) is well suited for arable cropping with a measured bulk density (0-25 cm) of 1.57 g/cm3. 2.2. Tractor-Implement combinations In TABLE 1 the analysed tractor-implement combinations for the tillage operation are shown.

TABLE 1: Tractor-Implement combinations

Tractor Implement Working width [cm] Working depth [cm]

4-WD tractor (59 KW) 2x3 Mouldboard

plough - three-point hitch

99 25

4-WD tractor (160 KW) 2x5 Mouldboard1

plough*

- three-point hitch 250 25

4-WD tractor (160 KW) 2x7 Mouldboard plough* - semi

mounted 350 25

4-WD tractor (160 KW) T-trailed cultivator - semi mounted 500 25

4-WD tractor (160 KW) T-trailed cultivator - semi mounted 500 15

1with slatted body, *equipped with Traction Control-System

FIGURE 1: Full mounted 2x3 mouldboard plough with 59 kW 4-WD tractor

FIGURE 2: Full mounted 2x5 slatted mouldboard plough with 160 kW 4-WD tractor

FIGURE 3: Semi-mounted 2x7 mouldboard plough with 160 kW 4-WD tractor

The 2x5 mouldboard mounted plough and the 2x7 mouldboard semi-mounted plough Pöttinger® were equipped with the Traction Control (TC) system - an additional hydraulic cylinder. In contrast to 2x7 semi-mounted plough, the 2x5 mouldboard plough is connected to the tractor with the three point linkage. The additional cylinder operates in case of applying oil pressure resulting in the increase of axle load of the rear wheel, because of the dynamic load transfer from plough and front axle of the tractor. The shift in the axle load are shown in TABLE 2. This Traction Control system should help to reduce wheel slip and fuel consumption.

TABLE 2: Change of axle weight through Traction Control - System in the 2x7 mouldboard plough with 160 KW 4-WD tractor (Haas 2010).

Oil pressure in the Traction Control hydraulic cylinder

[bar]

Front axle - Tractor

[kg]

Rear axle - Tractor

[kg]

Support-wheel- Plough

[kg] 0 5190 6130 2615

150 4605 (-585) 6945 (+815) 2385 (-230) 180 4440 (-750) 7175 (+1045) 2320 (-295)

FIGURE 4: Semi-mounted T-trailed cultivator 2.3. Used Tractors and measurement equipment A four wheel driven tractor (Steyr 8090) with an engine power of 59 kW (4 cylinder) was used for ploughing with the 2x3 mouldboard plough. For the other tillage operation a four wheel driven tractor (Massey Ferguson 6499 Dyna6) was used. The Agco Sisu engine with 6 cylinders was equipped with intercooler and turbocharger, so the engine performance was 160 kW at 2200 rpm. The transmission disposed of 4 groups and 6 powershift speeds. Wheel dimensions in the front: 600/60R30, Dimensions of the rear axle: 710/60R42, both type Michelin XeoBib. For measuring of the real and theoretical speed (parameters for slip calculation), the tractor was equipped with a radar and wheel hub sensor (Moitzi et al. 2006). Fuel consumption was measured for each trial run in threefold repetition volumetrically.

3. Results and Discussion

3. 1. Technical field performance, fuel consumption and slip The results in TABLE 3 show, that the technical field performance increases with the working width of the plough. The discontinuous fuel consumption in ploughing is explained by the high engine power of tractor (160 kW) with the 2x5 MP, where the operating point of the engine is in an inefficient area in comparison to the matching of the 160 kW tractor with 2x7 MP. The specific fuel consumption (MJ/t soil) decreases with increased working width for ploughing. The increase of the working depth from 15 cm to 25 cm for the cultivator rises the fuel consumption by 70 % and the slip by 265 %, whereas the specific fuel consumption is on the same level.

TABLE 3: Measured mean technical parameters of three mouldboard ploughs (MP) and T-trailed Cultivator.

Implement _Working depth

Working width [cm]

Technical field

performance [ha/h]

Fuel consumption

[l/ha]

Slip [%]

Specific energy consumption

[MJ/t soil]

1)2x3 MP_25 cm 99 0.53 20.25 4.28 0.16 2)2x5 MP_25 cm 250 1.94 20.50 7.65 0.17 2)2x7 MP_25 cm 350 2.30 14.87 6.99 0.12 2)Cultivator_25 cm 500 2.58 17.03 21.02 0.15 2)Cultivator_15 cm 500 3.70 10.03 5.76 0.15 1) 4-WD tractor (59 kW); 2) 4-WD tractor (160 kW) 3.2. Soil pressure in the furrow-ground during ploughing In conventional ploughing the furrow-wheel are running on the furrow-ground, with pressure effects to the ground soil. The formation of a plough pan is supported, with results in limited penetration of crop roots and reduced infiltration of water. The ploughed top soil is separated from ground soil trough compacted plough pan. In TABLE 4 the percentage of tracking area is calculated for the 2x3-, 2x5- and 2x7-mouldboard plough.

TABLE 4: Percentage of tracking area in the furrow-ground.

Implement Tyre width [cm]

Working width [cm]

Tracking area in the furrow [%]

1)2x3 MP_25 cm 52 99 53 2)2x5 MP_25 cm 71 250 28 2)2x7 MP_25 cm 71 350 20

1) 4-WD tractor (59 kW); 2) 4-WD tractor (160 kW)

Ploughing with 2x3 moldboard plough requires 53 % of the furrow area, where the furrow wheels with a maximum wheel load of 1511 kg are running (TABLE 5) . The increased working width reduces this area to 20 % but with increased load of the rear furrow wheel for the 2x5 plough with 4097 kg and 2x7 plough with 4522 kg.

TABLE 5: Drawbar, static and dynamic loads in the rear axle for ploughing

2x3 mould board plough

2x5 mould board plough

2x7 mould board plough

Drawbar 1) [N] 16751 42086 56151 Static rear axle load [kg] 1920 5700 6130 Dynamic rear axle load [kg] 2361 6401 7066 Load of the rear furrow wheel2) [kg] 1511 4097 4522 1)calcuated after Gorjatschkin-equation 1927 in Kalk (1981) 2)after Renius (1987): 64 % of the dynamic rear axle load

3.3. Traction improvement with TC-System in 2x5 mouldboard plough TABLE 6 shows, that the Traction Control (TC) systems reacts more sensitive than the normally tractor equipped electronic linkage control (ELC), which results in the reduction of slip (-31.2 %) and fuel consumption (-10.2 %). TABLE 6: Mean parameters for ploughing with 2x5 full-mounted mouldboard plough with two

different control-strategies.

without Traction Control (TC) with Electronic Linkage Control

(ELC)

with Traction Control* (TC) without Electronic Linkage

Control (ELC)

Field performance [ha/h] 1.94 2.07

Fuel Consumption [l/ha] 20.50 18.40

Slippage [%] 4.80 3.30 * 150 bar

3.4. Traction situation with TC in 2x7 mouldboard plough The mean fuel consumption indicated a reduction of 11.5 % for 150 bar (TABLE 7), which is not explained by the slippage decrease. Two possible effects could explain this result. Firstly, the decreased traction of the front wheel due to the load removal in the front axle and/or secondly the varied effect of working depth trough load transfer from the plough via TC to rear axle. TABLE 7: Mean parameters for ploughing* with 2x7 semi-mounted mouldboard plough with 0

bar and 150 bar in the Traction Control System.

0 bar (oil pressure in TC) 150 bar (oil pressure in TC)

Field performance [ha/h] 2.29 2.30

Fuel consumption [l/ha] 14.87 13.16

Slippage [%] 6.99 6.71 *without Electronic Linkage Control

4. Conculsions

• The slip in soil tillage is an important factor for analysis of fuel consumption. • With increasing working width of the plough, the field performance and the slippage

increases. • With increasing working width of the plough, the potential of subsoil compaction is

increasing, because of risen load of the rear furrow wheel. • The traction control system in ploughs reduces fuel consumption between 10 and

11.5 %.

Acknowldgements

The authors are sincerely thankful to the company Pöttinger ® for providing the ploughs and

cultivator.

Reference list

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Jahns, G. & Steinkampf H. (1982). Einflussgrößen auf Flächenleistung und Energieaufwand beim Schleppereinsatz. Grundlagen der Landtechnik Bd. 32. Nr. 1. p. 20 – 26.

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