Physical and empirical models for estimation of specific surface area of soils

Abstract

The specific surface area of soil (SSA) is crucial for the interaction of ions and water molecules with the soil particles. Therefore, many physical and chemical properties of soil are determined by its total specific surface area. Measurement of SSA is time-consuming and laborious; therefore, its estimation by a physical or an empirical model is preferred. The objectives of this investigation were: (i) To estimate the SSA of soils from the south of the Islamic Republic (IR) of Iran by considering spherical and cylindrical models for soil particles (physical model), and (ii) to develop a multivariate pedo-transfer function to estimate SSA based on the geometric mean (d_g) and the standard deviation (σ_g) of the diameter of soil particles (empirical model). The results indicate that the physical model is superior to the multivariate pedo-transfer function in estimation of SSA. However, a power pedo-transfer function for is superior to the physical model and the multivariate pedo-transfer function for the estimation of SSA.

Keywords:

• pedo-transfer function
• geometric mean
• geometric standard deviation
• specific surface area

Acknowledgements

This research was supported in part by Grant no. 87-GR-AGR-42 of Shiraz University Research Council and the Center of Excellence for On-Farm Water Management.