Evaluation of Soil Water Characteristics Models Under Zero Tillage and Conventional Tillage Treatments
J. Y. Diiwu
R. P. Rudra
W. T. Dickinson
G. J. Wall
AbstractThe effect of tillage and soil horizon on the performance of three soil water characteristics models, the 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 analyzed. Variabilities in model parameters were found to be significant at 5 percent significance level. the model predictions were more reliable for conventional tillage treatment than for zero 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 percent of variability of soil water characteristics, yet no one model pave a best theoretical representation of soil water characteristics in both the A and B horizons over the entire field. Sensitivity analyses on the van Genuchten parameters indicated that ζ is a more sensitive parameter than a in both the A and B horizons for zero tillage and conventional tillage treatments.
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