ESTIMACIÓN DEL CONTENIDO DE HUMEDAD DEL SUELO MEDIANTE EL EMPLEO DE FUNCIONES DE PEDOTRANSFERENCIA (Soil water content estimation using pedotransfer functions)

During recent year an important number of pedotransfer functions (PFs) with the capacity to estimate soil water content based on easily measured physical and chemical soil properties have been published. In view of their relatively scarce use in Chile, a study was conducted to evaluated five of the most used PFs in an Inceptisol, a Vertisol and three Alfisols of central Chile. The water retention curves were determined experimentally and fitted to a van Genuchten function. The results using the PFs point out that the functions based only on texture, organic matter and bulk density do not allow estimations of the water retention properties with an acceptable level of precision for the selected soils. These PFs showed mean errors between +0.16 and +0.19, and mean relative errors between +106 and +310%. The accuracy of the estimations was progressively improved by including one (1500 kPa) or two (33 and 1500 kPa) known values of the water retention curve in the regression. Thus, the PF which include water content at 33 and 1500 kPa showed mean and mean relative errors in the range of -0.03 to +0.05 and -2 to +83%, respectively, and a R 2 coefficient equal to 0.86. Even though the results obtained are not detailed enough to conclude about the predictive accuracy of the PFs for Chilean soils, they appear to be an interesting alternative, allowing easier field measurements when characterizing soils, and also indicate the necessity to carry out more research concerning the behavior of the PFs under different soil conditions in the country