The relations existing between the soil and its water content: A Résumé of the Subject

In any systematic account of the work done on the moisture in soil and its behaviour under varying conditions, it is necessary to keep constantly in mind that the underlying hypotheses have been profoundly modified in recent years. When physical methods were first applied to the examination of soils, the results were interpreted on the obvious hypothesis that the soil could be regarded as composed of mineral particles of varying shapes and sizes, over the surfaces of which the water was distributed in a thin film. The movements of the film water and its average thickness at any time, under the varying meteorological and soil influences, could be predicted more or Jess completely from known physical principles such as surface tension, etc. Similarly, the concentration of the plant nutrients in the soil moisture was considered mainly as a matter of solubility in, and diffusion within, this moisture. The foundation of the subject of soil physics was laid upon these lines in the early 19th century by Davy and Schübler.