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United States Department of Agriculture

Agricultural Research Service

Title: Average concentration of soluble salts in leached soils inferred from the convective-dispersive equation

item Mikayilsoy, Fariz
item Pachepsky, Yakov

Submitted to: Irrigation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/27/2009
Publication Date: 1/1/2010
Publication URL:
Citation: Mikayilsoy, F., Pachepsky, Y.A. 2010. Average concentration of soluble salts in leached soils inferred from the convective-dispersive equation. Irrigation Science. 28(5):431-434.

Interpretive Summary: As water infiltrates through soil, different parts of the soil water move with different velocities. Consequently, chemicals found in the soil water (solutes) also move with different velocities. This phenomenon is referred to as solute dispersivity. To characterize the dispersivity of soil profiles at the field scale, it is desirable to use changes in total chemical mass in the whole soil profile rather than chemical content in individual soil layers. We obtained the analytical solution of the dispersive transport model in soils, and developed software to fit this solution to field data to obtain soil dispersivity parameter. Results of this work will benefit practitioners concerned with parameterizing and predicting solute leaching from soils.

Technical Abstract: The convective-dispersive, or advective-dispersive, or CDE, equation has long been the model of choice for solute transport in soils. Using the total mass of soluble salts in soil profile to evaluate changes in salinity due to irrigation can be beneficial when the spatial variability of soil salinity at selected depth intervals is often smaller than the spatial variability of soil salinity in the layer encompassing these depth intervals, and when soil salinity is evaluated with electric conductivity measurements that allow one to obtain average soil salinity values for soil profiles rather than salinity at a specific depth. The objective of this work was to present analytical solutions of the CDE that express the average soluble salt content in soil profile as the function of time, water flux, and solute dispersion parameter. The solutions are developed for both semiinfinite and finite domain and implemented in a computer code in FORTRAN. An example of using these solutions to develop a nomogram for dispersion coefficient estimation is presented. In cases when the application of the CDE is justified, the analysis of the salt leaching process based on the average concentrations of salts in soil profile can provide useful estimates of the salt dispersion parameter that can be used in land evaluation and soil reclamation in areas with salt-affected soils..

Last Modified: 06/27/2017
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