22-5 Interactive Effects of Soil Salinity and Texture on Soil Water Retention and Plant-Available Water in Dryland Agroecosystems

Session: Advances in characterizing groundwater, surface water, and their interactions (Posters)

Presenting Author:

Authors:

Abstract:

Soil salinization is a major concern in many dryland agroecosystems around the world and is one of the major factors contributing to global food insecurity. Although several studies have investigated the effects of salinity on crop productivity, soil health, and infiltration, less attention has been given to how salinity alters soil water retention and to the combined influence of osmotic and matric potentials on plant-available water, and salinity management through the application of biochar has been proposed as a method to reduce soil salinity. However, the hydrologic properties of salt-affected soils with different textures and compositions modified by biochar have not been thoroughly studied. To address this knowledge gap, we used an experimental methodology to add different salinity levels to soils (0.30 - 8.0 dSm-1) to determine the water retention functions in the laboratory, and to investigate water retention properties for three salinity-affected agriculturally important soils from the High Plains of Texas, USA. The water retention experimental data was fitted to an existing water retention model, and the fitting parameters were used to describe changes in soil physical properties due to the concentration of salts and biochar. We used the integral water capacity approach to assess the effect of salt-related osmotic pressure in the soil solution on water availability for plant uptake. This model accommodates an inflection point and is well-defined at both the saturated end (saturation) and the dry end (permanent wilting point), eliminating the challenges in accurately determining residual water content in dry saline soils for fitting commonly used water retention models. Our results indicate that salinity affected both matric and osmotic potentials, shifting the plant-available water range, with the magnitude of these shifts dependent on salt concentration and soil texture, resulting in sandy soil showing the largest increase in moisture content at the wilting point and the greatest proportional loss of plant-available water (PAW), sandy loam showing an intermediate response, and clay soil showing the smallest change. Biochar amendment reduced salinity in the pore-water and enhanced plant water availability in salt-affected soils, depending on the soil texture. Biochar-amended saline soils exhibited increased integral water capacity—reflecting the total volume of water that can be retained and released to plants—indicating that biochar alleviates combined osmotic and matric stress.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2, 2026

© Copyright 2026 The Geological Society of America (GSA), all rights reserved.