Collection, processing and storage of
representative soil Samples
By
Dr Narender K Sankhyan
Principal Scientist, Department of Soil
Science,
CSK Himachal Pradesh Krishi
Vishavavidyalaya, Palampur (H.P.)
The soil testing is comprised of
four consecutive steps:
Collect a representative soil sample
from the field.
Determine the quantity of plant
available nutrient in soil sample (soil
test).
Interpret the soil test results (soil test
calibration).
Estimate the quantity of nutrient
required by the crop (nutrient
recommendation
Soil Sampling
The most critical aspect of soil testing is
obtaining a soil sample that is
representative of the field.
A useful soil testing service starts with the
collection of representative soil samples. A
soil sample must be taken at the right time
and in the right way. The tools used, the
area sampled, the depth and the correct mix
of the sample, the information provided, and
packaging all influence quality of the soil
test data.
Sampling time
Take soil samples well before sowing of the crop
or establishing a new orchard.
For agricultural crops, the best time of sampling
is when the field is free of crops.
For horticultural crops, the best time to collect a
soil sample is during autumn.
As a general rule, it is best to go for soil sampling
a couple of weeks prior to the start of any
seedbed preparation.
In case of perennial crops like forage and fruit
tress, soil sampling should be done prior to the
beginning of a new flush of growth.
Sampling Units
Divide the area into
sampling units based on
visual observations on
crop growth, appearance
of the soil, soil colour,
field slope, past crop
management practices
like manuring, fertilization
techniques and cropping
pattern etc. Collect one
composite sample from
each block or unit.
Sampling for fertilizers’
recommendation
Step 1. First remove the litter from the
surface by scraping it away at each spot
selected for soil sampling.
Step 2. If probe auger/specially designed
soil sampling tubes are available, then take
about 15-20 surface soil samples (0-15 cm)
from each block (sampling unit) of about ½
acre area in a random zig-zag manner as
shown in figure 2. Avoid sampling near
houses, roads, bunds, channels, marshy
spots, trees, recently fertilized area,
compost pits, any other abnormal spots and
other non representative locations. Collect
these in a clean dry container or cloth sheet.
Sampling for fertilizers’
recommendation
Step 3. If a khurpi or a kassi
(spade) is used, first dig a ‘V’
shaped hole (15-20 cm) and take
out the soil-slice (like bread-slice)
of ½ inch thickness from one of
the exposed surface
Sampling for fertilizers’
recommendation
Step 4a. Mix the soil sample collected in
step 2 or 3 thoroughly on a clean piece of
cloth or polythene sheet.
Step 4b.Level it and divide into four quarters
with the help of finger or wooden stick
Step 4c. Discard the soil in the opposite
quarters.
Sampling for fertilizers’
recommendation
Step 5. Mix rest of the soil and
continue quartering till about ½ kg of
representative soil is obtained. Dry
the sample in shade and fill in the
cloth or polythene bag. Label the
sample as shown in figure 5. The soil
sample is now ready for
submitting/sending to the soil testing
laboratory for its analysis.
Sampling for fertilizers’
recommendation
Step 6. If the sample is to be
analyzed for micronutrient(s), a
stainless steel probe auger must
be used. In case, stainless steel
probe auger is not available, then
stainless steel khurpi could be
used for drawing the soil sample.
Sampling for Horticultural
Crops
Roots of horticultural crops
penetrate deep into the soil profile
and the success of plantations
depends upon the fertility status of
sub-soil layers. So the method of
collecting samples for horticultural
crops is different from agricultural
crops.
Sampling for Horticultural
Crops
Step 1. Dig a pit to a maximum of
150 cm depth (as shown in figure
6) or till one gets hard pan/bed
rock or water table. Make one side
of this pit vertical for soil sampling.
Step 2. Mark the vertical side of the
pit at 15, 30, 60, 90, 120 and 150
cm depth from the surface.
Sampling for Horticultural
Crops
Step 3. Hold a bucket or container at 150
cm mark and collect about half kg of soil-
slice of ½ inch thickness from 120 - 150 cm
depth and transfer the sample to a storage
bag marking it: Sample 6 (120-150 cm).
Step 4. In the same way collect the
samples from preceding upper layers i.e. 90
– 120, 60 – 90, 30 – 60, 15 – 30 and 0 – 15
cm depths. Mark sample number with
corresponding depth on each sample. For
example sample collected from 90 – 120 cm
depth would be SAMPLE No. 5 and the one
from 60 – 90 cm depth SAMPLE No. 4.
Sampling for Horticultural
Crops
Step 5. Put one
INFORMATION LABEL inside
each bag and tie one to the
sampling bag.
Step 6. Send the soil sample
to the nearest soil testing
laboratory.
Precautions
(i). While sampling soil at different depths in a soil
profile or sampling pit, care must be taken to
start sampling from the last layer so as to avoid
mixing of soil from the upper layers with the soil
of lower layers.
(ii) In case there is hard pan within 150 cm depth
from the soil surface, its depth and thickness
must be recorded, because the recommendations
for orchard establishment would depend upon
effective soil depth and its nutritional status.
(iii) Similarly, if water table is shallow, its depth
must also be recorded
Information to be sent with the soil
sample
Name and address of the farmer.
Khasra number or any other identity that
identifies the field (or Soil sample).
Availability of irrigation facilities.
Upland/Medium land/Lowland.
Depth of soil sample.
Information of the previous crop before
soil sample collection:
Name and variety of the crop.
Dose of organic manure, if applied.
Dose of fertilizers, if applied.
Yield.
Information of the crop that will be
grown.
Name and variety of the crop.
Season (kharif/rabi).
Problem(s), if any in the sampling area
(like water logging problem, low yields,
low response to added inputs, stunted
growth of plantation crops etc.).
Date of sample collection.
Signature of the farmer/sample collector
Address
Thanks
