  We investigate the hadronic two-body decay modes of the scalar-isoscalar
$f_0(1370)$, $f_0(1500)$ and $f_0(1710)$ states as resulting from the mixture
of the lowest lying scalar glueball with the isoscalar states of the ground
state $^3P_0$ $Q\bar Q$ nonet. In the decay analysis we take into account the
direct coupling of the quarkonia and glueball components of the $f_0$ states to
the quarkonia components of the two-meson final state with the decay dynamics
inspired by the strong coupling limit of QCD. We calculate partial decay widths
for the $f_0$ states in the proposed three-state mixing schemes and discuss
their compatibility with the observed decay features. Finally, we determine the
glueball-quarkonia content of the $f_0$ states from a detailed fit to
experimental decay data of $f_0(1500)$ and give predictions for the partial
decay widths of $f_0(1370)$ and $f_0(1710)$, providing thus a sensitive test of
the proposed mixing scheme.
