Agriculture Reference
In-Depth Information
Figure
9.10.
White spots in field show where soil sample was taken.
desired pH. Soils with pH above 7.5 can be acidified by the addition of sulfur to bring
the pH down to that needed for the crop to be grown.
Organic matter (OM), cation exchange capacity (CEC), percent base saturation,
(%BS), and all other important characteristics used to make recommendations about
the amount and types of fertilizer needed are given in the soil analysis report. Although
nitrogen level is not given, knowledge of general soil nitrogen levels and previous
cropping are used to modify nitrogen recommendations based on crop needs for
maximum production.
Fixed nitrogen, that is, nitrogen combined with other elements (not elemental
nitrogen as occurs in air), can occur in a number of different forms in soil and changes
rapidly, is highly labile, is easily lost, and thus its concentration changes rapidly over
time. For this reason it is not generally profitable to do a nitrogen analysis. However,
in
some
lower
rainfall
areas
it
is
useful
to
analyze
the
soil
profile
for
nitrogen
compounds and
take
their
availability
into
consideration
when making
fertilizer recommendations.
Phosphate and potassium soil analysis are straightforward and are very important
in making fertilizer recommendations. Local conditions, the crop being grown, and soil
conditions will dictate the amounts and types of these fertilizers needed.
T A B L E 9.5. Soil Fertility Report
Buffer
pH
Percent
OM
Percent
B S
Other
b
Sample No.
pH
CEC
N
P
K
Ca
Mg
a
AR25a
5.5
6.0
1.1
12
75
12
150
3520
290
a
AR30b
AR10c
6.3
6.7
0.5
9
80
15
200
4250
300
a
Nitrogen may be reported in many forms.
b
Other might be any of the micronutrients or other components.
