  If the sparticles are relatively heavy (a few TeV) while the Higgs sector is
not so heavy ($m_A$ is not so large), the Higgs boson Yukawa couplings can
harbor sizable quantum effects of sparticles and these large residual effects
may play a special role in probing supersymmetry at foreseeable colliders. In
this work, focusing on the supersymmetric QCD effects in the hbb coupling (h is
the lightest CP-even Higgs boson), we give a comparative study for the two
popular supersymmetric models: the MSSM and NMSSM. While for both models the
supersymmetric QCD can leave over large residual quantum effects in hbb
coupling, the NMSSM can allow for a much broader region of such effects. Since
these residual effects can be over 20% for the hbb coupling (and thus over 40%
for the ratio $Br(h->bb)/Br(h->\tau \tau)), future measurements may unravel the
effects of heavy sparticles or even distinguish the two models.
