In this paper, a numerical formulation for solving the transmission line equations for a bare wire buried in a dispersive soil is derived. The formulation is developed using the finite-difference time-domain (FDTD) method, including the frequency-dependent nature of the soil electrical parameters. The soil electrical parameters are rigorously represented through the soil model proposed by Alipio and Visacro. It is shown that the results obtained with the proposed formulations are in good agreement with experimental results. In addition, the results show an excellent agreement with a reference solution of the transmission line equations first obtained in the frequency domain and, later transformed back into the time domain using the numerical inverse Laplace transform.