The monitoring probe (1) comprises: a FR-4 substrate (2) with two faces; two copper tracks (3) arranged on one of the faces of the substrate (2), with an electrical contact terminal (7) on the outside of the probe (1); a conductive region (6) with reference electrode functions, with an electrical contact terminal (8) on the outside of the probe (1), occupying the entire other face of the substrate (2); a passivating material layer (5) partially covering the copper tracks (3) and leaving two free zones (12, 13) of said tracks (3) uncovered, one of said free zones (12) corresponding to the electrical contact terminal (7) of the two copper tracks (3); and two ISE sensor elements (4) that are sensitive to at least one of the parameters of interest to be monitored in the ground, and arranged in the other of the free zones (13) of the two copper tracks (3).