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This program is developed to predict the major ion, B composition, electrical conductivity (EC) and osmotic pressure (OP) of a soil solution at a desired water content based on the known ion composition at another water content.

The major uses of the model are envisioned as:
Obtaining a predicted saturation extract composition, EC and OP based on analysis of a 1:1, 1:2 or 1:5 soil water extract.
Correction of the soil water extract data for gypsiferous soils when calibrating field electromagnetic or electrical resistivity surveys for salinity.
Calculating UNSATCHEM or other chemical transport model input soil water concentrations at a specific pressure head (and thus water content) based on analyses of soil extracts.
Basis of the model

The program is based on the chemical routines used in the UNSATCHEM model (Suarez and Simunek, 1996, 1997). It considers major ions, boron, and the chemical processes of cation exchange, precipitation-dissolution of calcite and gypsum, and boron adsorption using the constant capacitance model.

The model can be run in batch mode or in individual cases with display to the screen.

Dataset Info

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U.S. Salinity Laboratory
Product Type
United States Department of Agriculture
Contact Name
Suarez, Donald
Contact Email
Public Access Level
Primary Article

Suarez, D., & Šimůnek, J. (1997). UNSATCHEM: Unsaturated Water and Solute Transport Model with Equilibrium and Kinetic Chemistry. Soil Science Society Of America Journal, 61(6), 1633.

AgID: 1426744
Funding Source(s)
Agricultural Research Service
Program Code
005:037 - Department of Agriculture - Research and Education
Bureau Code
005:18 - Agricultural Research Service
Modified Date
Release Date
Ag Data Commons Keywords: 
  • Agroecosystems & Environment
  • Water
  • Agroecosystems & Environment
ISO Topic(s):