Tillage and Heterogeneity Effects on the Performance of Soil Water Characteristic Models

Abstract

Abstract The effect of tillage and soil horizon on the performance of three soil water characteristic models (Hutson and Cass, van Genuchten, and Verma and Brusaert models) was investigated. The impact of field-scale heterogeneity on the estimated parameters of the models was also analysed. Variabilities in model parameters were found to be significant at 5% significance level. The model predictions were more reliable for conventional tillage treatment than for no tillage treatment. For both tillage treatments all the models performed equally well for the A horizon, while the van Genuchten model was the best choice for the B horizon. All the models accounted for over 97% of variability of soil water characteristics, yet no one model gave a best theoretical representation of soil water characteristics in both the A and B horizons over the entire field. Precision analyses on the van Genuchten parameters indicated that α gives more precise estimates of soil water characteristic than η in both the A and B horizons for no tillage and conventional tillage treatments.