This document provides instructions for preparing a soil sample and determining the soil pH using a pH meter. It describes collecting a soil sample from 15 cm below the surface, drying the sample, grinding and sieving it to obtain particles smaller than 2 mm. It recommends mixing 5 grams of the processed soil sample with 50 ml of distilled water to make a solution in a 1:10 proportion for pH testing. The solution is stirred and allowed to settle before filtering and measuring the pH using a pH meter probe placed directly in the filtered soil solution. Maintaining proper procedures in collecting, preparing and testing the soil sample ensures accurate pH results.

1. Preparation of soil sample and
Determination of Soil Reaction (pH) with
the help of a pH Meter
UG Geography Honours CBCS Syllabus
Part of GEO-A-CC-4-10-P: Soil and Bio-Geography Lab:
30 marks, 2 Credits
Study Material: Part I
Dr. Sarada Mandal
Associate professor in Geography
Prabhu Jagatbandhu College
Courtesy: Post Graduate Students of Prabhu Jagatbandhu College

2. Step 1: Collect the soil sample:
Theoretical consideration http://agritech.tnau.ac.in/agriculture/agri_soil_sampling.html
Soil testing is an essential component of soil resource
management. Each sample collected must be a true
representative of the area being sampled. In case of
agricultural studies, ‘Utility of the results’ obtained from the
laboratory analysis depends on the sampling precision.
Hence, collection of large number of samples is advisable so
that sample of desired size can be obtained by sub-sampling.
In general, sampling is done at the rate of one sample for
every two hectare area. For soil survey work, samples are
collected from a soil profile representative to the soil of the
surrounding area.

3. Procedure of soil collection
(For students)
Materials required for soil
collection
1. Spade or auger
(screw or tube or
post hole type
2. Khurpi
3. Sampling bags
4. Plastic tray
Ref.
http://agritech.tna
u.ac.in/agriculture/
agri_soil_sampling.
html
Methodology:
• Select the sample spot
• Remove the surface litter
• Make a ‘V’ shaped cut with a spade to a
depth of 15 cm in the sampling spot or
Drive the auger to a plough depth of 15
cm and draw the soil sample
• Collect soils using khurpi
• Mix the sample in a plastic tray thoroughly
• Remove foreign materials like roots,
stones, pebbles and gravels
• Collect the sample in a clean zip lock cloth
or polythene bag
• Label the bag with required information

4. Collection of Soil Sample by the student
Removing soil litter, Collecting soil
sample from the V cut zone
Putting the soil sample and the
label in a bag
http://agritech.tnau.ac.in/agriculture/agri_soil_
sampling.html
Place: Spot A at Prabhu
Jagatbandhu College
Campus
Date: 17th April, 2019
Time: 12 noon

5. Step 2: Dry the sample
• Assign the sample number and enter it in the
laboratory soil sample register.
• Some people like to air dry the sample first by
spreading on a clean sheet of paper after breaking
the large lumps, if present under shade then put it
into the oven at 105-110 degree Celsius for 24
hours to a constant weight. Heat applied at this
temperature is effective in evaporating water held
in soil pores and on soil surface, however organic
matter is not lost from the soil.
http://agritech.tnau.ac.in/agriculture/agri_soil_sampli
ng.html

7. Is it correct to say that -Air dried soil samples
have a constant pH value for a long time? Kumari
Priyanka at Researchgate
• Peter Finke : Certainly nor in all cases will the
pH remain constant when a soil sample is
dried. It depends on the storage. Imagine
that the air-dried soil contains some
ammonium. This will nitrify and produce
acidity unless maybe the sample is dried and
kept frozen. Decay of organic matter may
also change the amount of free protons in
the sample.

8. Why the soil sample should be dried?
• If soil remain wet, we may
get skewed result. pH of
water is 7. pH of the soil
sample may be acidic. So
wet soil can show the
result more alkaline.
• So set the oven at 110
degree Celsius
• Keep the collected soil in
the oven overnight,

9. Preparation of soil sample:
Step 2, 3, 4 and 5
2. Put the soil at oven, 3. Powder the
dried sample by Mortar and pestle
4. Sieve the sample by ordinary
Steiner and 5. weigh 5 gram of soil

10. Preparation of soil sample continued
• Sieve the soil material through 2 mm sieve.
• Repeat powdering and sieving until only materials
of ≤2 mm (no soil or clod) are left on the sieve.
• Collect the material passing through the sieve and
store in a clean glass container (preferably a
borosilicate glass beaker) with proper labeling for
laboratory analysis.
http://agritech.tnau.ac.in/agriculture/agri_soil_sampli
ng.html

11. What should be the ideal proportion of
solute and solvent?
• Solute = Soil, Solvent = Distilled water
• Mix the 5 gram of soil with 50 ml of distilled water
in a glass beaker. Now the proportion of solution
becomes 1: 10
• We can mix this 5 gram of soil with increased
volume of distilled water up to 250 ml. It means
that proportion of solute and solvent could be up to
1:50
• The result will be the same.

12. Why 5 gram, not less?
• If we mix 1 gram of soil with 10 ml of distilled water,
the proportion will be 1:10. Suppose at the time of
weighing the 1 gram of soil, 0.1 gram error occurred
due to manual or instrumental error. Therefore the
result will show 10% error.
• 0.1 gram weighing error on 5 gram of soil will show
the result with 2% error.

13. Why 5 gram, not more?
• If we take amount of soil more than 5
gram, the amount of distilled water will
also be increased for maintaining the
proportion.
• If volume of solution increases, filtering
becomes difficult and it takes more time.

14. Preparation of final soil solution
• After making the solution
• Stir the mixture in a circular way (a glass rod may be
used or the beaker itself should be moved in a circular
way)for 2 minutes and then keep it in rest for 2
minutes.
• Repeat the process for 7-8 times within at least 30
minutes.
• In this process the H+ ions which were adhered to the
soil particles will become free in the solution
• Now filter the solution with a funnel, filter paper and
conical flask

15. Preparation of final soil solution
Measure 50 ml of distilled water , Mix the water
with soil, Fold the filter paper and put it in the
funnel, put the funnel on the conical flask
Slowly filter
the solution

16. Dip the probe of the pH meter into the soil
solution and wait for a while, until the
digital display gives a steady reading

17. • For detail
discussion and
thorough concept,
please consult the
standardized soil
quality
determination
procedure by ISO