  We study the ground state of the disordered Bose-Hubbard model for spin-1
particles by means of the stochastic mean-field theory. This approach enables
the determination of the probability distributions of various physical
quantities, such as the superfluid order parameter, the average site occupation
number, the standard deviation of the occupation per site and the square of the
spin operator per site. We show how a stochastic method, previously used in the
study of localization, can be flexibly used to solve the relevant equations
with great accuracy. We have determined the phase diagram, which exhibits three
phases: the polar superfluid, the Mott insulating and the Bose glass. A
complete characterization of the physical properties of these phases has been
established.
