Performance of Saxton and Rawls Pedotransfer Functions for Estimating Soil Water Properties in the Cap Bon Region-Northern Tunisia

Appropriate land use and management requires a good knowledge about the main hydraulic properties of the soil, in particular soil moisture at field capacity (FC), permanent wilting point (PWP), and water holding capacity (HC). In the absence of direct measurements, these characteristics could be estimated from data on texture and organic matter content, using pedotransfer functions (PTFs). In this study, FC, PWP, and HC of predominant soil types in Cap Bon (Vertisols, Cambisols, and Calcisols), are estimated using Saxton and Rawls (Soil Sci Soc Am J 70:1569-1578, 2006) PTFs and complete sets of soil analysis data. Results show that when all soil samples (61) are taken together, obtained estimations were well correlated with measured values for FC (R 2 = 0.72) and PWP (R 2 = 0.72). Similar correlations were observed for Cambisols and Calcisols taken separately (R 2 = 0.65-0.70.); but there was an overestimation of FC and PWP for Vertisols (percentage of clay > 50%). However, relatively weak relationships were observed between estimated and measured values for HC in all cases (R 2 = 0.15). PTFs seem appropriate to be used in combination with remote sensing methods for generation of soil FC and PWP maps needed in irrigation and agriculture efficient management.