Soil Shrinkage Characteristics as Affected by Solution Composition and Mineral Contents

ABSTRACT

Soil-shrinkage characteristics affect fluid transport and soil mechanical properties, with broad implications for environmental flows, crop production, and civil engineering designs. We quantified mild-saline-solutions effects on soil shrinkage curves and developed pedotransfer functions to predict curve parameters. Seven soil and soil mixes were equilibrated with solutions of 0.5-to-8 dS m⁻¹ and 0-to-20 sodium adsorption ratios (SAR). Saturated paste rods were dried; water contents and isotropic shrinkage measured. Texture affected shape-forming factors when clay and smectite contents were >260 and 140 g kg⁻¹, respectively. Solutions ≥2 dS m⁻¹ affected the coefficient of linear extensibility for smectitic soils containing clay ≥300 g kg⁻¹. Solution SAR affected only the highest clay content (530 g kg⁻¹) and mixed mineralogy soils. However, the solution salinity levels were not high enough to affect shape factors of the shrinkage curves. Pedotransfer functions successfully described soil shrinkage with root-mean-squared-errors 1 to 4 magnitudes lower than the highest measured values.

KEYWORDS:

• Clay mineralogy
• pedotransfer function
• salinity
• sodium adsorption ratio

Acknowledgements

The authors thank Radu Carcoana and Kevin Horsager for their expert technical assistance during the laboratory analysis. This work is supported by the USDA National Institute of Food and Agriculture Hatch project 1005366.