Description of the subject: Watersheds of northern Algeria are frequently exposed to water erosion where its consequences are recorded in upstream and downstream of these vulnerable areas. Objectives: We carried out this study in a watershed in northern Algeria with the aim of testing an agroforestry system for its ability to improve the hydraulic conductivity of unsaturated soil by measuring the infiltration speed of water in this soil. Method: Using a mini-disk infiltrometer, we measured, in different points from upstream to downstream of the study area, the volume of water infiltrated into the soil at regular time intervals, and this before and after three years of the installation of the agroforestry system. Results: The difference in hydraulic conductivities between 2022 and 2019 differs from one measurement point to another in the study area. It oscillates between -1,6 × 10-5 cm/s considered as the lowest difference, and 6,33 × 10-5 cm/s considered as the highest difference. Generally, there has been a remarkable increase in the hydraulic conductivity of the majority of measurement points which is from 25% to 150%. Conclusions: Improving hydraulic conductivity thanks to the installed agroforestry system will allow sloping soils to infiltrate the maximum amount of water circulating on the surface during heavy rains, which will therefore minimize the probability of the concentration of surface runoff along the slope.