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International Journal of Soil Science
  Year: 2013 | Volume: 8 | Issue: 2 | Page No.: 58-67
DOI: 10.3923/ijss.2013.58.67
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Evaluation of SOILWAT Model for Predicting Soil Water Characteristics in Southwestern Nigeria

A.I. Oyeogbe and K.O. Oluwasemire

Investigations of soil water potential and its variability with soil characteristics are necessary for studying water availability for plants, plant water stress, infiltration, irrigation scheduling, drainage and water conductivity. However, measurements of soil water characteristics are difficult, costly and time consuming. A modified version of the SOILWAT model (2006) of the soil water characteristics was adapted to 50 (replicated thrice) soil samples collected at depths 0-60 cm from upper, middle and lower slopes in 12 dug profile pits in 5 states of Southwestern Nigeria. Samples were assessed for their physical, hydrological and chemical parameters in the laboratory and compared with the simulated values obtained with the SOILWAT model. Coefficient of determination (R2) as a goodness-of-fit index of agreement and the Root Mean Square Error (RMSE) were computed. The soils textural class varied from Sand, Sandy loam, Loamy sand and Sandy clay loam. There was good agreement between the measured and simulated bulk density for Sandy loam texture class (R2 = 0.722; RMSE = 0.476), saturated moisture content (R2 = 0.544; RMSE = 30.135), field capacity (R2 = 0.770; RMSE = 86.877) and available water content (R2 = 0.547; RMSE = 0.940) at p<0.05 probability level. However, a poor fit was observed for saturated hydraulic conductivity and permanent wilting point. SOILWAT had a fairly good prediction of bulk density for a Sand texture class (R2 = 0.460, p<0.05, RMSE = 0.476) but a poor fit for saturated hydraulic conductivity, saturated moisture content, field capacity, permanent wilting point and available water content. However, it had the smallest RMSE when compared to the other texture class.
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How to cite this article:

A.I. Oyeogbe and K.O. Oluwasemire, 2013. Evaluation of SOILWAT Model for Predicting Soil Water Characteristics in Southwestern Nigeria. International Journal of Soil Science, 8: 58-67.

DOI: 10.3923/ijss.2013.58.67






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