This study aimed to develop models to estimate the two physical-hydric soil attributes, drainable porosity (PD) and water holding capacity (CTA), based on easily and quickly measured physical attributes (particle-size distribution, water dispersible clay, total porosity, bulk density and particle density). Disturbed and undisturbed soil samples were collected in the Ribeirão Marcela watershed, from the of 0-15 cm layer, in grids of 240 x 240 and 60 x 60 m, totaling 165 sample points. Linear multiple regression was applied, using variables that combined the different attributes with each other and the coefficients of variables estimated by the Least-Squares Estimation, using the software SAS. The models for CTA and PD presented good statistical qualities, with high coefficients of determination, low estimate error and, statistical significance of estimated parameters. These results suggest that these models might be used for projects in the Ribeirão Marcela watershed, which is representative of the Oxisols domain in the Alto Rio Grande region. They further provide region-specific technical information for agricultural and environmental projects and above all, for the parameterization of the hydrosedimentological simulation models in development.
drainable porosity; water holding capacity; Oxisols
