Characterization of the Microstructural Properties of Saline-Alkali Soils in the Yellow River Delta, China

Studies on the microstructure of saline-alkali soil are imperative for understanding its physical properties and for remediating saline-alkali land. We investigated the microstructural characteristics of saline-alkali soils sampled at different depths in the Yellow River Delta, China. Particle size distribution (PSD), X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM) were used to analyze the soil samples. Based on the average saturated hydraulic conductivity, the sub-surface soil belonged to the micro-permeable or extremely micro-permeable water classes. The proportions of clay (<0.002mm) and clay minerals (mainly illite, kaolinite, and chlorite) were 9.43–14.13% and 12.25%, respectively; therefore, they are not aprimary factor contributing to the soils’ poor permeability. The porosity of the local saline-alkali soil was only 19.55–34.90%, and these pores consisted mainly of micropores (0.1 ≤ d < 2 μm) and ultra-micropores (d < 0.1 μm). The saline-alkali soil was composed of compact lamellar structures and micro-fissures, and soil particles were connected by cement. The findings of this study improve our understanding of the micro-characteristics of saline-alkali soil in the Yellow River Delta, China, and provide atheoretical basis for remediating saline-alkali land.