  We consider the amplitude modulation of low-frequency, long wavelength
electrostatic drift wave packets in a nonuniform magnetoplasma with the effects
of equilibrium density, electron temperature and magnetic field
inhomogeneities. The dynamics of the modulated drift wave packet is governed by
a nonlinear Schr\"odinger equation. The latter is used to study the
modulational instability of a Stoke's wave train to a small longitudinal
perturbation. It is shown that the drift wave packet is stable (unstable)
against the modulation when the drift wave number lies in $0< k < 1/\sqrt{2}$
$(1/\sqrt{2}<k<1)$. Thus, the modulated drift wave packet can propagate in the
form of bright and dark envelope solitons or as a drift wave rogon.
