ACCURATE SOIL SAMPLING

 Accurate sampling is absolutely
critical to a successful soirl
management plan as all
recommendations are based on
the samples submitted to labs.
SELECTING SAMPLE AREAS
The actual size of the sample area
is determined by certain factors.
Areas that differ in any of the
following must be sampled
separately:
Soil type, previous cropping,
previous lime or fertilizer
applications, slope, drainage
For example……eleven samples
have been taken from the area
Where very large areas of land are
uniform, divide the land into areas
that would be treated as a unit
(i.e. one field), and sample these
areas individually.
One sample should not represent
more than one field, as individual
fields will have had different
treatments in the past. Large
fields can be divided for sampling
purposes into two or three
smaller sections
Sampling depth Depth of sampling
is critical because tillage and
nutrient mobility in the soil can
influence nutrient levels in
different soil zones. Sampling
depth depends on the crop,
cultural practices, tillage depth
and the nutrients to be analyzed.
Plant roots, biological activity and
nutrient levels occur mainly in the
surface layers (0-25 cm) hence
most of the soil samples are
collected within this layer. For tree
crops, samples from 30 – 50 cm
can also be collected.
Sampling Procedure One sample
should consist of between 20 - 30
cores taken from the set area. It is
recommended that the cores be
taken from the area in a zigzag
pattern as shown in the field
ONCE IN THE FIELD CARRY OUT
SAMPLING AS FOLLOWS:
1) Divide your field into areas
which have the same soil type,
color, slope, fertilizer and crop
history.
2) Scrape away surface litter and
crop residues and sample the
whole core from the true soil
surface to 25 cm depth
3) Take between 20-30 cores from
each uniform soil area. Place each
core in a bucket and mix them
thoroughly once you have taken
all the cores.
4) Fill the soil sample bag half full
(500g) from this mixed
representative sample.
5) Several different tools such as a
soil sampling tube, soil auger, or
spade may be used in taking soil
samples. Label the bag carefully
with you company name, farm
name, field name, sample depth
and crop to be grown.
6) Avoid taking samples from
areas such as lime piles, fertilizer
spills, gate areas, livestock
congregation areas, poorly
drained areas, dead furrows,
fertilizer bands, old fence rows, or
any other unusual areas.
7) Do not use galvanized, soft
steel or brass equipment if trace
metal analyses are desired.
Sample handling and dispatch to
lab If possible soil samples that
are moist should be air dried on
site away from dust
contamination and not in direct
sunlight.