Plasticity Index of Vesicular Horizons.

Vesicular (V) horizons are common surface horizons of arid and semiarid regions characterized by their predominance of vesicular pores. Vesicular horizons play a critical role in surface hydrology and dust emissions in the landscapes where they occur. This study was conducted to determine if the Atterberg limits influence the development of porosity in the V horizon. The liquid limit and plastic limit of V horizons were measured in the lab to determine the plasticity index (PI) of V horizon samples collected from the Mojave, Sonoran, and Great Basin deserts. The ability to form vesicular pores was assessed in by calculating the Vesicular Horizon Index (VHI) of V horizons formed from crushed and sieved soil material exposed to field conditions for one year. Statistical analysis shows PI to have a significant positive correlation with VHI when analyzed in combination with precipitation data from the field sites. After conducting a multiple regression analysis on VHI in relation to number of precipitation events (PE) and PI, VHI= -0.114 + 0.496(PI) + 0.684(PE), with an adjusted R-square of 0.67 and P-values of 0.033 for PI and 0.018 for PE. These results suggest that soil material with higher PI values is more susceptible to the formation of vesicular pores.