CHAPTER 4: METHODS AND METHODOLOGY
Himachal Pradesh is a northern state in India, nestled in the western Himalayas. It shares
borders with Jammu & Kashmir to the north, Punjab to the west, Haryana to the south, and
Uttarakhand to the southeast. Shimla, the state’s capital experiences majorly two types of soil
– loamy soil and alluvial soils in the river valleys. On the other hand, the state experiences six
main types of soil – Alluvial soil, Mountain soil, Laterite soil, Brown Forest soil, Black soil,
Sandy soil.
4.1 Materials Required
Waterproof marking pen, Beakers(250ml, 500ml), Droppers, Measuring
cylinder(10ml,500ml,1000ml), Glass rod, Burette, Conical flask, Density gradient column,
Whatmann filter paper, Sieve, Munsell colour chart. Pipette, Burette, Glass slide, Compound
Microscope, Calorimeter
0.2 N Acetic Acid (CH3COOH), 0.25 N Ammonium Nitrate (NH4NO3), 0.015 N
Ammonium Fluoride (NH4F), 0.013 N Nitric Acid (HNO3), 0.001 M EDTA
(Ethylenediaminetetraacetic acid), Deionized water, calibrated conductivity meter and cell,
Standard buffer solution, Hydrochloric acid(HCl), Barium Chloride Solutions, Ammonium
Hydroxide, Sodium Hydroxide, Phenolphthalein indicator, Sulphuric Acid, Potassium
Sulphate, Copper Sulphate, Sodium Bicarbonate Solution, Molybdate-Ascorbic Acid Reagent
were used for sample preparation and analytical purposes.
4.2 Sample Preparation
Each soil sample was air dried under shade to remove moisture. Then the samples were
sieved using 2mm sieve to remove unwanted materials like roots, large stones, leaves, etc.
Sieved samples were stored in plastic zip-bags and labelled accordingly.
4.3 Sample Analysis
Different methods were used for the analysis of the soil samples. In physical examination,
soil colour determination was done by referring and comparing the colour of samples, both in
dry and wet conditions, with the Munsell colour chart. Wet soil samples were taken for
measuring soil consistency through physically touching and feeling the soil grains; and the
density cylinder method was used for measuring the density of the soil. Soil pH was
determined with the help of pH strips and electrical conductivity was measured using cell. In
chemical examination, total soluble sulphate in soil was determined by titration method,
Calcium level test was determined by Mehlich III Extractant method, Salinity test was
performed with the help of electrical conductivity, nitrogen and phosphorus level was
determined by Kjeldahl method and Olsen method respectively.
Soil colour was determined with the help of Munsell colour chart, both in dry and wet
conditions. Soil density was measured by Cylinder method in which a cylindrical ring was
used to collect an undisturbed soil sample of known volume. The soil sample was dried
completely in an oven and weighed to determine its mass. The density was calculated by
dividing the dry mass of the soil by its volume.
Soil pH was determined by using the pH strips in which the soil samples were allowed to air
dry, then crushed it to pass through a 2 mm sieve to ensure a uniform particle size. Weighed
out 10g of soil sample into a beaker and added distilled water in it to create a slurry and
mixed thoroughly for 30 minutes. Let the slurry settled for 10 minutes and took the pH
measurement.
To determine electrical conductivity, a 20 g of collected soil was weighed out into a 150 ml
plastic jar and 100 ml distilled water was added to it. Lid of jar was packed tightly and stirred
continuously for 5 minutes. Then it was kept overnight and stirred again. Allowed to set for
15 minutes and strained sample into clean measuring cup and electrical conductivity readings
were taken.
In determination of total soluble sulphate in soil, took exactly 10 grams of oven dried soil
sample and transferred the soil sample in to the beaker and added 50 ml of water. Stirred
well, allowed to decant, filter, wash on a filter paper with small quantity of water and made
the filtrate to 100 ml. Pipette out 10 ml of water extract in to a conical flask, made it slightly
acidic by adding concentrated Hydrochloric acid and heated to boiling. While boiling added
Barium Chloride solution (N14) from the burette till the precipitation was complete and
Barium Chloride solution was in light excess. Neutralized the solution with ammonium
hydroxide and titrated the excess of Barium Chloride against Potassium Chromate
solution (NI 4). A brick red colour was obtained when a drop of Silver Nitrate was added to a
drop of the chromate solution. Sulphates as Sodium Sulphate was calculated, percent by mass
= 0.0177 x 100(N/4 barium chloride actually used for perceptibly Sulphate).
To perform the salinity test of the soil samples, weighed 50 g of soil sample in a beaker and
added 100 ml of distilled water in 1:2 soil-water ratio method. Stirred and let it stand to 30
minutes and filtered the mixture to obtain a clear solution. Measured the electrical
conductivity(EC) of the filtrate using a calibrated EC meter. EC < 2 dS/m refers non saline
and EC > 8 dS/m refers highly saline.
To determine nitrogen content by Kjeldahl method, weighed 1 g of air-dried, ground soil and
added catalyst mixture (K₂SO₄ + CuSO₄) and 10 ml of concentrated H₂SO₄. Heated the
mixture until the solution became clear. Cooled the digested sample, diluted with water,
added NaOH to make the solution alkaline. Distilled the released ammonia (NH₃) into a
known volume of Boric acid solution. Titrated the collected ammonia using Hydrochloric
acid, used a methyl red as indicator and calculated the nitrogen content from the volume of
acid used.
To determine phosphorus content by Olsen method, weighed 2.5 g of air-dried, sieved soil,
added 50 mL of Olsen’s extractant (0.5 M NaHCO₃, pH 8.5) and shaken for 30 minutes.
Filtered the suspension using filter paper to obtain a clear extract. Took an aliquot of the
filtrate and added ammonium molybdate and ascorbic acid reagents to develop blue colour
(molybdenum blue complex). The intensity of the blue colour is measured using a
colorimeter at a specific wavelength of 880 nm. The phosphorus concentration is determined
by comparing the colour intensity with known standards.
