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Chemical Characteristics Of Soil Revision: (Steps On How Floccule…
Chemical Characteristics Of Soil Revision:
Steps On How
Floccule Formation
Occurs:
The colloids are linked together by polarisedwater to form a floccule.
Cations are adsorbed onto the surface of soil colloids.
1.Chemical reactions form negative charges on soil colloids.
Floccules trap larger particles such as sand to form aggregates.
How Is
Cation Exchange
Best Described?
Cation exchange is best described as the
ability of a soil
to
attract, retain
and
release cations.
What Is
Sandy Loam
?
Sandy loam is the
soil texture
that has the
lowest cation exchange capacity
.
What Does
pH Measure
?
pH measures the
concentration of the hydrogen
in a
solution
.
The
Four Factors
That
Affect Cation Exchange Capacity (CEC)
:
Clay Content:
Soils with a
high
clay content will have a
higher
CEC than those with a
low
clay content.
Soil Texture:
Soils with a
fine texture
have a
higher
CEC.
Humus Content:
Humus has the
highest
CEC value as
colloidal humus has high quantities
of
negative charges
which make it
suitable
for cation exchange. It can be up to
30 times more effective
at cation exchange than
clay
.
pH:
Fewer
cations are available at
lower pH levels
, particularly when pH is
lower than 5.0.
Cation exchange levels can be
maintained
or
raised
by
liming
, which
increases
the amount of
Ca2+
cations available for exchange. Also, as pH increases the number of
negative charges on soil colloids increase
, leading to
greater
CEC.
The Effects That A pH
Outside The Range Of 5.5 - 8.5 On A Crop
Are:
A
very low
or very
high
pH can
reduce
the
availability of nutrients to plants
and when
essential
nutrients are
unavailable
to plants,
growth rates
are
limited
, and
yields
are
reduced
.
Certain
ions
may become
abundant
in the soil, to the point where they are at
toxic levels
.
The
activity
of some
microorganisms
may
decrease
because of
unsuitable environmental conditions.