13 - Factors of soil formation: time

Summary

The factors of parent material, climate, topography and organisms are tangible and can be seen and/or touched. By contrast, time is intangible and progressive as the others interact with each other (Fig. 13.1). Time is presented within the Newtonian philosophy which deals with absolute time and space considered as a world framework. Alternatively time can itself be considered as an infinite and ever-increasing universe in which the other factors interact to produce an infinite number of soils, or more precisely soil horizons, the infinite composites of which comprise soils. Perhaps within this context there should be a consideration of the energy in soils (Blum, 1997). There are four main sources of energy – gravity, mineral energy, solar and capillarity (anti-gravity). All processes in soils are dependent upon energy; for example translocation is largely dependent on gravity, while climatic change is largely dependent upon variations of solar radiation.

Climate is not constant and may change to induce different processes, or there may be a change in vegetation as a result of human activity, natural successions or events such as fire. Thus although the progression through time is uninterrupted, the processes may change, leading to a different situation which will show a combination of the properties acquired by the first progression with the imprint of the new properties acquired by the new set of processes. The result will depend upon the strength of the two or more sets of properties.