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Soil Management

Sodic Soils and Their Management

Landscape of salt mines during a break in production in rainy season.

Alan Blaylock, Ph.D.

Sodic soils, occurring mainly in arid and semi-arid regions, are especially challenging to manage. They may result from high water tables and/or poor-quality irrigation water. High exchangeable sodium in the soil creates undesirable physical properties, such as poor structure, crusting, clay dispersion, poor infiltration, and poor aeration. These soils also exhibit high pH, typically greater than 8.5. Soil sodicity refers to the amount of sodium held on soil cation exchange sites.

It is typically expressed either as the percentage of the soil cation exchange capacity filled with sodium ions (exchangeable sodium percentage or ESP), or as a ratio comparing exchangeable sodium to exchangeable calcium plus magnesium (sodium adsorption ratio or SAR). Sodic-soil reclamation typically requires large additions of soluble calcium amendments, such as gypsum, or addition of acids to dissolve calcium carbonate in the soil and increase calcium in the soil solution. Dr. James Walworth, University of Arizona explores the relationship between soil salinity, soil sodicity, and soil physical properties and how to manage these difficult soils. Download the report here.

Dr. James Walworth, Department of Soil, Water and Environmental Science, University of Arizona, Tucson, Arizona, jlw1@email.arizona.edu. Western Nutrient Management Conference. 2019. Vol. 13. Pg. 21. Reno, NV.