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Soil compaction and soil tillage - studies in agricultural soil mechanics

Keller, Thomas (2004). Soil compaction and soil tillage - studies in agricultural soil mechanics. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae. Agraria, 1401-6249 ; 489
ISBN 91-576-6769-1
[Doctoral thesis]

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This thesis deals with various aspects of soil compaction due to agricultural field traffic, the draught force requirement of tillage implements and soil structures produced by tillage. Several field experiments were carried out to study the mechanical impact of agricultural machines. It was shown that the stress interaction from the different wheels in dual and tandem wheel configurations is small and these wheels can be considered separate wheels with regard to soil stress. Hence, soil stress is not related to either axle load or total vehicle load. At high wheel load, tyre inflation pressure affected subsoil stresses. The maximum stress at the soil-tyre interface was greater than the tyre inflation pressure. Furthermore, the distribution of stress beneath tyres and rubber belts was highly non-uniform. This was shown to have a great influence on stress propagation in soil. Therefore, with regard to soil compaction modelling, a uniform stress distribution (as often used) is too poor an approximation of the real stress distribution and can result in underestimation of soil compaction. A model for predicting the distribution of stress below tyres using readily-available tyre parameters is proposed. With a more realistic approximation of the stress distribution at the soil surface, simulated stresses generally agreed well with measured stresses. Both field and laboratory measurements rejected the concept of precompression stress as a distinct threshold value between reversible and irreversible compressive strain. Irreversible strain was measured at applied stresses that were lower than the precompression stress. The precompression stress was dependent on the nature of the compression test and the method of analysis. The draught requirement of tillage implements could be related to shear vane strength for specific soil-implement combinations. Draught force and aggregate size distribution produced by tillage were strongly affected by soil water content, with the optimum tillage results being produced at water contents close to the water content at the inflection point of the water retention curve. Specific draught was calculated for comparison of the tillage efficiency of different implements. The chisel plough often worked below its critical depth, which strongly increased the energy requirement without any benefit in terms of soil break-up. Therefore, the specific draught was higher for the chisel plough compared with the disc harrow and the mouldboard plough.

Authors/Creators:Keller, Thomas
Title:Soil compaction and soil tillage - studies in agricultural soil mechanics
Series Name/Journal:Acta Universitatis Agriculturae Sueciae. Agraria
Year of publishing :2004
Number of Pages:75
ALLI. Arvidsson, J. & Keller, T. 2004. Soil precompression stress. I. A survey of Swedish arable soils. Soil & Tillage Research 77(1), 85-95. II. Keller, T., Arvidsson, J., Dawidowski, J.B. & Koolen, A.J. 2004. Soil precompression stress. II. A comparison of different compaction tests and stress-displacement behaviour of the soil during wheeling. Soil & Tillage Research 77(1), 97-108. III. Keller, T., Trautner, A. & Arvidsson, J., 2002. Stress distribution and soil displacement under a rubber-tracked and a wheeled tractor during ploughing, both on-land and within furrows. Soil & Tillage Research 68(1), 39-47. IV. Keller, T. & Arvidsson, J., 2004. Technical solutions to reduce the risk of subsoil compaction: Effects of dual wheels, tandem wheels and tyre inflation pressure on stress propagation in soil. Special issue of Soil & Tillage Research on Soil Physical Quality. In press V. Keller, T. A model for prediction of the contact area and the distribution of vertical stress below agricultural tyres from readily-available tyre parameters. Submitted to Biosystems Engineering VI. Keller, T., Défossez, P., Weisskopf, P., Arvidsson, J. & Richard, G. SoilFlex: A model for prediction of soil stresses and soil compaction due to agricultural field traffic including a synthesis of analytical approaches. Manuscript VII. Arvidsson, J., Keller, T. & Gustafsson, K., 2004. Specific draught for mouldboard plough, chisel plough and disc harrow at different water contents. Special issue of Soil & Tillage Research on Soil Physical Quality. In press VIII. Keller, T., Arvidsson, J. & Dexter, A.R. Soil structures produced by tillage as affected by soil water content and the physical quality of soil. Manuscript
Place of Publication:Uppsala
ISBN for printed version:91-576-6769-1
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F07 Soil cultivation
N Machinery and buildings > N20 Agricultural machinery and equipment
Subjects:Not in use, please see Agris categories
Agrovoc terms:soil structural units, models, stress, soil compaction, soil strength, soil water, tillage, vehicles
Keywords:aggregates, draught force, model, precompression stress, soil compaction, soil displacement, soil strength, soil stress, soil water, tillage
Permanent URL:
ID Code:673
Department:(NL, NJ) > Dept. of Soil Sciences (until 081001)
Deposited By: Thomas Keller
Deposited On:17 Nov 2004 00:00
Metadata Last Modified:02 Dec 2014 10:06

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