Abstract

The end-over-end shaking technique has been widely used to provide a measure of soil dispersibility. However, results are dependent on the specific methodology employed. This paper investigates the effect of various physical parameters on the dispersion produced using an end-over-end shaking technique. Significant (P < 0·05) increases in the percentages of clay (D₂) and silt+clay (D₂₀) particles dispersed as a proportion of the total soil weight were observed with increasing period of shaking, suspension concentration, container size, and air-gap above the suspension. However, differences due to suspension temperature and soil texture were either relatively minor or insignificant (P > 0·05). To enable better comparison of results from different workers, the following methodology for end-over-end shaking studies is proposed as a standard. The soil sample should be air-dried and crushed to pass through a 2-mm sieve. The air-dried equivalent of 50 g oven-dried soil should then be immersed in 1 L double-deionised water at 20°C within a 1·425-L cylinder (70 mm internal diameter) and shaken end-over-end at 20 rpm for 30 min before measuring the amount of dispersed <2 and <20 µm material produced. The amount of dispersed material should be expressed as a proportion of the total soil material.