Using a standard reductive perturbation theory, a Zakharov-Kuznnetsov (ZK) equation is derived in an inhomogeneous dusty plasma comprised of negatively charged dust grains of equal radii, Boltzmann distributed electrons and positive ions. The effects of dust thermal pressure, dust charge variation, dust-neutral collision, and the external magnetic field are taken into account. Either compressive or rarefective solitons are shown to exist depending on the critical value of the phase velocity which in turn, depends on the dust temperature and pressure. An analytic soliton solution is obtained and discussed. The behaviors of the soliton amplitude, width, and the Mach number are investigated numerically for different plasma parameters.