An improved method of presenting comparisons of soil compaction effects below wheel ruts

Abstract Conventional methods of evaluating compaction effects by comparing soil properties at fixed depths below the undisturbed surface can be difficult to interpret, or even misleading, where wheels produce ruts of different depths. A method is described in which bulk density measurements are used to trace vertical soil movement due to compaction. This allows comparisons between treatments to be made on soil elements which derive from the same depth in the undisturbed profile, irrespective of their depths in the compacted profiles. The problems associated with different rut depths and with differential soil movement are thereby eliminated. The method is also extended to the presentation of other soil mechanical properties. An experiment to verify the calculated soil displacement by introducing chalk markers into a prepared soil is briefly described. New ways of displaying bulk density data are also suggested, both in graphical form and in more qualitative ways which attempt to display soil displacement and density changes in a single diagram with more visual impact.