These
include:
(i)
altering
its
solubility,
(ii)
mineralization
of
organic
phosphate
compounds
into
inorganic
phosphates,
and
(iii)
oxidation
and
reduction
of
phosphorus
compound.
Of
these,
mobilization
and
immobilization
are
the
most
important.
Describes
the
simplified
phosphate
cycle
as
it
occurs
in
nature.
The
phosphate
requirement
of
plants
is
met
by
the
uptake
of
phosphate
ions
which
are
then
utilized
for
the
synthesis
of
organic
phosphates
within
the
cell.
By
this,
a
fraction
of
the
phosphate
gets
immobilized.
Upon
the
death
of
the
plants,
the
organic
phosphate
is
rapidly
released
by
enzymatic
hydrolysis.In
many
instances,
phosphate
becomes
a
limiting
factor
for
plant
growth
because
much
of
it
in
the
soil
is
bound
as
insoluble
calcium,
iron
or
aluminium
phosphates.
The
availability
of
phosphates
therefore
depends
on
the
degree
of
solubilization
of
insoluble
phosphates
by
various
organic
and
inorganic
acids
produced
by
the
microorganisms.
Several
soil
organisms,
particularly
the
fungi
are
known
to
produce
substantial
amounts
of
these
acids
and
there
by
solubilize
insoluble
phosphates
and
make
it
available
to
the
plants.
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