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Alleviation of Soil Compaction 5 ALLEVIATION OF SOIL COMPACTION After harvest machinery has passed over the soil, it might be appropriate, possibly necessary, to alleviate the compaction caused. The question is how a wheeled undercarriage system compares to a tracked undercarriage system in this respect and whether the differences seen in soil physical properties are transmitted to the draught force of a tine. Therefore this chapter investigates the required draught force of a subsoiler to loosen the soil after the passage of both a wheeled and a tracked undercarriage system in controlled laboratory conditions and in the field. The method for this chapter can be found in Section 2.2.6. 5.1 Literature Review For loosening soil an implement has to be driven or pulled through it inducing soil failure; most times the implements are pulled. Usually a tine or tine – similar – implement is util- ized for this purpose. Tines cause a crescent failure of the soil whereby soil shears at an angle of 45 degree down to the critical working depth which depends on tine geometry and can either be estimated (6 times the width of the tine in depth) or calculated according to Eq. 20 with the extensions of Eq. 21 to Eq. 23 in Godwin and Spoor (1977). Below this depth lateral failure occurs whereby the soil in front of the tine is only pushed sideways. Crescent failure causes a much higher working and draught efficiency than lateral failure and is consequently beneficial. The effects of soil conditions and tines geometry for the optimum soil loosening are discussed in detail by Spoor and Godwin (1978). Prediction models summarized and further developed by Godwin and O’Dogherty (2003) can be used to calculate both the vertical and draught force necessary for pulling a tillage implement. When loosening a deeply compacted soil care has to be taken not to cause severe re- compaction when traveling the soil subsequently as the loosened subsoil is very sensitive to re-compaction. This re-compaction can merely be evaded utilizing very light machinery, controlled traffic or by a combined operation of deep loosening and surface cultivation with drilling. Mouldboard ploughing following deep loosening can induce significant re- compaction independent of the tractor wheels operating in the furrow or on the surface (Soane et al., 1986). Practical suggestions are given by Spoor and Godwin (1981) for loosening soil compaction. Ph.D. Thesis Dirk Ansorge (2007) 82
Alleviation of Soil Compaction However, according to Arvidsson and Hakansson (1996) not all consequences of soil compaction in the topsoil can be alleviated by tillages. The authors reported an effect of topsoil compaction on yield up to 5 years after the whole field was trafficked, although annual ploughing was performed. 5.2 Draught Force for Subsoiler in Laboratory Study On uniform soil conditions after the pass of the track at 12 t followed by the 500-70/4.5/2.3 rear tyre, and after the 680/10.5/2.2 followed by the 500 – 85/4.5/1.4 a winged subsoiler tine was operated at 350 mm depth measured from the virgin surface and draught force recorded using an octagonal ring transducer. Afterwards the loosened area was measured using a profilemeter. The actual area in which the tine operated (“tine area”) was calculated by subtracting the measured rut area from the loosened area. All numbers are given in Table 23. Due to the large rut area, the draught force was smallest for the wheeled combi- nation and highest for the track. To correct for the rut area, specific draught force was calculated using the tine area. Draught force for the control was 40.7 kN/m 2 , after the track including a rear tyre it was 70.8 kN/m 2 and after the pass of the wheeled under carriage system it was 84.5 kN/m 2 . Table 23: Area and draught force of subsoiler Implement Loosened Area (m 2 ) Rut Area(m 2 ) Tine Area(m 2 ) Draught Force (kN) Control 0.1111 0 0.1111 4.5 Track 0.1108 0.0401 0.0707 5 Wheel 0.1147 0.0691 0.0456 3.86 5.2.1 Consequence of Draught Force for Subsoiler in Real Situations For practice specific draught force does not reveal the most important information. Abso- lute draught force at a given depth is more crucial to find a tractor being capable of the operation. The absolute draught force for a tine obeys the following relationship: Absolute Draught Force= Spec. Draught Force * Loosened Area Eq. 3 Ph.D. Thesis Dirk Ansorge (2007) 83
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Cranfield University School of Appl
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Abstract Ancillary experiments show
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Table of Contents TABLE OF CONTENTS
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Table of Contents 4.1.3 Analysis of
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Table of Contents 11.1.1.1 Comparis
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List of Figures and Tables Figure 3
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List of Figures and Tables Figure 1
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Nomenclature NOMENCLATURE Abbreviat
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Introduction 1 INTRODUCTION 1.1 Bac
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Introduction � Ansorge, D. and Go
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Introduction 1.2 Aim To elucidate t
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Introduction a) the soil compaction
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Experimental Methods 2.1.1.1 Test F
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Experimental Methods had been mount
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Experimental Methods track; the loa
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Experimental Methods 800/10.5/2.5 t
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Experimental Methods term. In the m
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Experimental Methods Soil Surface F
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Experimental Methods Depth (cm) 0 1
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Experimental Methods ence surface c
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Experimental Methods chine derives
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Experimental Methods depth. The dat
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Experimental Methods with water and
Page 47 and 48: Experimental Methods 2.4 Statistica
Page 49 and 50: Laboratory Studies Into Undercarria
Page 77 and 78: Field Study With Full Size Combine
Page 97: Field Study With Full Size Combine
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Page 107 and 108: Soil Compaction Models sibilities t
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Page 111 and 112: Soil Compaction Models Wroth (1968)
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Page 123 and 124: Soil Compaction Models ture content
Page 125 and 126: Soil Compaction Models with four ot
Page 127 and 128: Soil Compaction Models Predicted In
Page 129 and 130: Soil Compaction Models Depth (mm) -
Page 131 and 132: Soil Compaction Models and 13.7 % b
Page 133 and 134: Soil Compaction Models Rel. Density
Page 135 and 136: Soil Compaction Models VCL paramete
Page 137 and 138: Soil Compaction Models The approach
Page 139 and 140: Soil Compaction Models surface stay
Page 141 and 142: Soil Compaction Models This result
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Soil Compaction Models The response
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Soil Compaction Models On medium so
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Soil Compaction Models SOILFLEX tak
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Ancillary Experiments 7 ANCILLARY E
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Ancillary Experiments Average conta
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Ancillary Experiments In order to c
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Ancillary Experiments contrary, the
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Ancillary Experiments Figure 102: S
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Ancillary Experiments track and the
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Ancillary Experiments even when hav
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Ancillary Experiments 7.3.2 Influen
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Ancillary Experiments The results f
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Ancillary Experiments Figure 117: S
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Ancillary Experiments Contact Press
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Ancillary Experiments Figure 123: F
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Ancillary Experiments Sinkage (mm)
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Ancillary Experiments model which o
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Ancillary Experiments 7.3.5 The Inf
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Ancillary Experiments 7.3.7 Discuss
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Ancillary Experiments Terzaghi (194
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Ancillary Experiments contact area.
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Ancillary Experiments soil forward
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Conclusions � The longitudinal so
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Bibliography 10 BIBLIOGRAPHY Aboaba
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Bibliography Defossez, P., Richard,
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Bibliography Gregory, A.S.; Whalley
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Bibliography Lamande, M., Schjonnin
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Bibliography Seig, D., 1985. Soil C
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Appendix 11 APPENDIX Ph.D. Thesis D
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Appendix Figure 32: VCL sample at t
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Appendix comparison at the deepest
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Appendix Estimated Pressure (kPa) 2
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Appendix 11.1.1.2.1 SOCOMO One of t
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Appendix by Seig (1985) who showed
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Appendix Soil water content 15 % an
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Appendix Adapting critical state so
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Appendix density is obtained by add
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Appendix Table 5: Values of constan
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Appendix choice of a concentration
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Appendix 11.1.3.1 Dense/Hard and Lo
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Appendix 11.1.3.2 Stratified Soil C
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Appendix To summarize the ability t
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Appendix In the following the predi
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Appendix concentration factor of 4,
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Appendix 11.1.5.1 Confining Pressur
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Appendix Figure 24. The VCL created
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Appendix Rel. Density 2 1,9 1,8 1,7
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Appendix relation of � 1 to � 2
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Appendix Rel. Density 2 1,9 1,8 1,7
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Appendix Rel. Density 1,7 1,68 1,66
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Appendix Depth (mm) 0,0 100,0 200,0
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Appendix Figure 42: Plate in cookin
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Appendix � z � � �� k c p
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Appendix Table 8: n and k depending
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Appendix to the plate sinkage equat
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Appendix with a slight deviation fr
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Appendix Table 12: DBD values for a
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