Effect of salinity on soil structure and soil hydraulic characteristics

Abstract

Revealing the influences of soil salinity on soil structure and hydraulic properties contributes to understanding the mechanism of salinity restraining rehabilitation of saline sodic soil in coastal area. After being passed through a 1 mm sieve, silt loam and silty clay were irrigated with saline water to achieve different soil salinities to highlight the effect of irrigation salinity on aggregate formation from primary particles. Three irrigation events with different saline water were conducted in the same 2 mo interval in soil columns; the soil columns were subjected to natural evaporation during the interval. The soil salinity, soil structure, soil–water characteristic curve, and saturated hydraulic conductivity (Ks) results were determined after the end of the third drying subprocess. The results showed that the proportion of water-stable macroaggregates (0.25–2 mm) in the silt loam and silty clay increased as the soil salt content (SSC) increased. Under the same matric suction, the retention capacity and plant-available water capacity (PAWC) of the silt loam first increased and then decreased, with the SSC increasing to a maximum of approximately 14.5 g kg−1. The retention capacity of the silty clay increased with the SSC, whereas the PAWC decreased with the SSC. The Ksof the silt loam increased with SSC. This study reveals the effects of soil salinity on aggregate formation from primary particles in wetting–drying cycles and describes the corresponding changes in hydraulic properties, which influence the rehabilitation of saline sodic soils in coastal areas.