Fonctions de pédotransfert pour les vertisols de la plaine de la Mitidja (Algérie) : recherche de paramètres les plus pertinents pour la rétention en eau

Soil pedotransfer function for the vertisols of the Mitidja plain (Algeria): search for most suitable parameters for water retention. This work aims at establishing pedotransfer functions at two water potential levels, to predict the water retention properties of vertisols in the Mitidja plain. The measurements and analyses were performed on a set of 154 horizons from 50 profiles of the study area. The importance of the contribution of different soil variables versus water retention is estimated by the values of the coefficients of determination and correlation. The level of reliability of pedotransfer functions was estimated by testing 20 samples from the same soil. The main results obtained show that the clay content, organic matter and fine silt (2 to 20 μm) are the factors that contribute most to the water retention of soils including at low potential (-1,600 kPa). The cationic exchange capacity appears to be a poor estimator of water retention properties when it is substituted for clay and organic matter. Moreover, before stratificating, porosity expressed by bulk density contributes to water retention at average potential (-100 kPa) despite the small differences in values. Validation of pedotransfer functions indicates that the bias predictions are low, thus reflecting then a good quality estimation of water contents.