EVALUATION OF A SIMULATOR MODEL FOR PREDICTING SOIL-WATER CHARACTERISTICS OF SELECTED AGMCULTURAL FIELDS

Abstract

The ability of the Soil Water Characteribtics-Hydraulic Calculator (SWC-HPC) model in predicting soi-water agricultural fields in Zaria, Nigeria, was tested and rep< >rted in this study. The goal was to establish the predictability and reliability of the nodel, and hence, its use in determining water characteristics of soils in the stud/ area. Forty soil samples collected from four irrigation sites were used in the valuation. The soils particle size distribution (specifically, percent clay and sand) and organic matter contents were inputted into the model to simulate soil moistur; status at saturation, field capacity and wilting point, soil bulk density and saturated hydraulic conductivity. The model outputs were statistically compared with observed parameters from laboratory tests using root mean square error (RMSE), c< ^efficient of variation (CV), modeling efficiency (EF) and coefficient of residual mass (CRM). The model accurately simulated the observed bulk densities of the soil tested, satisfactorily simulated soil moisture content at field capacity, and mot lerately simulated moisture content at saturation and wilting point. The model lowever, poorly simulated saturated hydraulic conductivity of the soils tested. The SWC-HPC may therefore be used only to simulate soil bulk densities and moistui e status at saturation, field capacity and wilting point in the study locations.