Influence of slaking on the size distributions of water-stable aggregates

Wet sieving is a common practice used to treat soil samples before analyses. However, slaking might occur during wet sieving, and this significantly affects analytical accuracy. To minimize side effects caused by slaking, we treated soils with ethanol and investigated the resulting efficiencies. Soil aggregates from the black soil zone of northeast China were selected as the study objects. In combination with Yoder's traditional wet-sieving method, ethanol-soaked aggregates were exposed to air under three different conditions (no exposure, brief exposure, and long-term exposure) to assess whether slaking could be eliminated during wet sieving and to clarify whether slaking would reoccur when ethanol-soaked aggregates were exposed to air. The results showed that soaking aggregates in ethanol fully eliminated the entrapped air and that the slaking effect was completely prevented during wet sieving. Compared with Yoder's wet-sieving method, ethanol soaking increased the mass percentages of aggregates sized >2 and 2-1 mm by 51.06 and 3.67%, respectively. Regardless of whether the sample was exposed to air, patterns of the size distributions of ethanol-soaked aggregates remained unchanged after wet sieving. When ethanol-soaked aggregates were briefly exposed to air, there was no apparent slaking effect. Nevertheless, because the aggregates were soaked in ethanol, the internal structure of the aggregates was reinforced and the aggregates were not evidently dispersed and broken despite slight slaking during wet sieving. These findings provide a reference for studying water-stable aggregates and improving measurement accuracies.

Automated summary

Wet sieving is a common practice used to treat soil samples before analyses. Slaking during wet sieving can significantly affect analytical accuracy, but treating soils with ethanol can eliminate slaking and improve measurement accuracies. Ethanol soaking of soil aggregates increases the mass percentages of larger aggregates and maintains the size distribution patterns of ethanol-soaked aggregates after wet sieving. The internal structure of the ethanol-soaked aggregates is reinforced, preventing significant dispersion and breaking during wet sieving.