Date of Award:


Document Type:


Degree Name:

Doctor of Philosophy (PhD)


Biological and Irrigation Engineering


Lyman S. Willardson


The purpose of this study was to develop a model to predict water extraction patterns and therefore salt distribution patterns in a one dimensional homogeneous soil profile for a specified root distribution .

Water extraction was simulated as a function of the total potential and the root density at any level of the profile.

Salt redistribution caused by irrigation was simulated by assuming a partial and proportional displacement of the water in each soil layer.

A computer program was written for the model in Fortran language and implemented on the Vax. To evaluate the performance of the model, test studies were carried out in the laboratory using two lysimeters and wheat as a crop.

A neutron probe and the four-probe electrode method were used to follow the change in the soil moisture and the salinity in the profile during the growing season. Comparisons were made between the measured and simulated values of water content and salinity. Application of the model results and recommendations for further research were suggested to improve the performance of the model.