Fig. 2. Effect of sodium adsorption ratio (SAR) and prewetting rate (PWR) on aggregate-size distribution of three soils ((a) Malibu, (b) Millox, and (c) Mokelumne) with different clay mineralogy. The figure shows the proportion of aggregates that remained on the group of size 1 to 2 mm after prewetting at 2 or 30 mm h^–1 and sieved according to the aggregate stability procedure (the error bar indicates the standard error of the mean).