  We study the zero temperature phase diagram of the disordered spin-1
Bose-Hubbard model in a 2-dimensional square lattice. To this aim, we use a
mean field Gutzwiller ansatz and a probabilistic mean field perturbation
theory. The spin interaction induces two different regimes corresponding to a
ferromagnetic and antiferromagnetic order. In the ferromagnetic case, the
introduction of disorder reproduces analogous features of the disordered scalar
Bose-Hubbard model, consisting in the formation of a Bose glass phase between
Mott insulator lobes. In the antiferromagnetic regime the phase diagram differs
more from the scalar case. Disorder in the chemical potential can lead to the
disappearance of Mott insulator lobes with odd integer filling factor and, for
sufficiently strong spin coupling, to Bose glass of singlets between even
filling Mott insulator lobes. Disorder in the spinor coupling parameter results
in the appearance of a Bose glass phase only between the n and n+1 lobes for n
odd. Disorder in the scalar Hubbard interaction inhibits Mott insulator regions
for occupation larger than a critical value.
