Quantitative Pedological Studies on Soils Derived From Silurian Mudstones

Summary Considerable variations in the apparent density of the fine earth fraction were recorded in stony soils in Cwmcadian, Merionethshire. A highly significant relationship between fine earth apparent density and stone content was observed which was not caused by disturbance during sampling. The relationship could be predicted by assuming that the bulk volume of a stony soil approximates to the sum of the self‐packing volumes of the separated stone and fine earth components. It is suggested that in natural soils there is a similar relationship between soil apparent density and organic matter content, namely that the bulk volume of a soil containing organic matter approximates to the summed self‐packing volumes of the mineral and organic components.