Description of the subject: Pedotransfer functions are based on the search for mathematical relationships allowing the water properties of soils to be deduced from known or easily measurable characteristics of the soils.

Objective: This work aims to establish pedotransfer functions (FPTs) at eight levels of soil water retention potential on a north–south transect from Algiers to Djelfa (Algiers, Mitidja, Médéa, Djelfa).

Methods: The measurements and analyses were carried out on a set of 38 soil samples representing the main soils of Algeria (vertisols, fersiallitic soils, calcimagnesic soils, less evolved soils). The importance of the contribution of various soil variables with respect to water retention is estimated by the values ​​of the determination and correlation coefficients. The level of reliability of the established pedotransfer functions was estimated using 20 test samples from the studied soils.

Results: The main results obtained showed that clay, organic matter and fine silt, and coarse silt and total limestone are the factors that contribute the most to the water retention of soils, including at low potentials (-1600 kPa). In addition, it emerges from this study that reworking of the ground provoked an increase in porosity, essentially structural, in spite of small variations in its values. Validation of the pedotransfer functions indicates that the biases of the predictions are low, thus reflecting a good quality estimate of the water contents.

Conclusion: The results of this research show once again the importance that should be given to understanding the water functioning of soils in the Mediterranean environment. The results obtained for this study, covering a very large space and a wide range of Algerian soils, deal with a diversity of soils with different parental materials, located under several bioclimatic floors and with varied occupations.

We highlight several interesting results in particular on the soil factors to take into consideration for the calculation of the equations.