Single value soil properties A study of the significance of certain soil constants

Numerous attempts have been made to devise an experimental method that, applied to a variety or a series of soils, enables them to be placed in an order closely reflecting their field behaviour or their most important physical characteristics. They are called “single-value” determinations as they endeavour to specify the soil by a single number, in distinction to the group of figures obtained, for example, from a mechanical analysis. A number of these methods are discussed in the present paper which contains an account of a detailed investigation on 39 soils of certain single value determinations.

The methods selected for study were chosen because (i) they required only simple apparatus, and (ii) they appeared to be related to some distinct soil characteristic.

The list of measurements was as follows:

Percentage of clay.

Moisture content of soil in equilibrium with atmosphere of 50 per cent, relative humidity (the ordinary “air-dry moisture content” which was also determined, is close to this value).