The nonlinear regression model parameters were estimated from the experimental data by using the method of least squares. The results of least squares fitting of equation 6 to the experimental data are c1 = 36.746; c2 = 31.736; c3 = 26.687; c4 = 0.437; d1 = 0.295; d2 = 0.158; d3 = 0.081; d4 = 0.003. Fig. 6 compares predicted and measured infiltration rate values for different soil gypsum contents, sprinkler application rates and the number of irrigations. Generally, there is a good agreement between the model and the measured infiltration rate values. Moreover, the difference between measured and predicted values was not significant at P < 0.05. Thus, the model could be successfully used to predict the infiltration rate for gypsifereous soils under the studied sprinkler application rates and irrigation number.