Wednesday, 5 April 2017

LABORATORY TESTING PROCEDURE FOR SOIL & WATER SAMPLE ANALYSIS

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(FOR OFFICIAL USE ONLY)
GOVERNMENT OF MAHARASHTRA
WATER RESOURCES DEPARTMENT
DIRECTORATE OF
IRRIGATION RESEARCH & DEVELOPMENT, PUNE
LABORATORY TESTING PROCEDURE
FOR SOIL & WATER SAMPLE ANALYSIS
SUPERINTENDING ENGINEER & DIRECTOR
IRRIGATION RESEARCH AND DEVELOPMENT, PUNE - 411 001.
ISO 9001 : 2000 CERTIFIED
2009
DOCUMENT NO. SSD/GL.01
1
LABORATORY TESTING PROCEDURE FOR
SOIL & WATER SAMPLE ANALYSIS
CONTENTS
Sr. N0.
Name of Test
Page No.
A.
Soil Sample Registration & Preparation in the
Laboratory for Analysis
3
B.
Soil Sample Analysis
5
I.
Physical Tests
5
1
Determination of Soil Texture –
International Pipette Method (Mechanical Analysis)
5
2
Determination of Saturation Moisture Percentage
(Water Holding Capacity)
12
3
Determination of Bulk Density -
1) Weighing bottle method
2) Clod method
3) Core method
14
4
Determination of Hydraulic Conductivity of Soil -
1) Constant head method
2) Falling head method
20
5
Determination of Soil Moisture Content
1) Gravimetric method
2) Infrared moisture meter method
27
II.
Chemical Tests
31
1
Soil Reaction (pH)
31
2
Measurement of Electrical Conductivity (EC)
35
3
Determination of Organic Carbon -
1) Walkely & Black Method
2) UV spectrophotometer method
38
4
Determination of Calcium Carbonate (CaCO3) Free Lime
1) Acid neutralization method
2) Schrotus apparatus method
45
5
Determination of Nitrogen -
Alkaline Permanganate Method
51
6
Determination of Phosphorous – Olsen’s Method.
56
2
Sr. N0.
Name of Test
Page No.
7
Determination of Potassium on Flame Photometer
61
8
Determination of Sodium on Flame Photometer
66
9
Determination of Calcium & Magnesium – EDTA
Titrimetric Method
71
10
Determination of Cation Exchange Capacity
1) Ammonium Saturation Method
2) Sodium Saturation Method
76
C.
Reclamation of Problematic Soil
85
1
Determination of Gypsum Requirement of Soil
85
D.
Water Sample Analysis
88
1
Determination of pH
88
2
Determination of Electrical Conductivity (EC)
90
3
Determination of Carbonates & Bicarbonates
93
4
Determination of Calcium & Magnesium -
EDTA Titrimetric Method
96
5
Determination of Sodium on Flame Photometer
101
6
Determination of Chloride
104
7
Determination of Sulphate on Spectrophotometer
107
E
Appendices
110
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A. SOIL SAMPLE REGISTRATION & PREPARATION
IN THE LABORATORY FOR ANALYSIS
Registration of Samples :
1.
The soil samples are received in the Sample Receiving Cell, where
the condition and quantity of the samples are examined and
acknowledgement slip is issued to the person delivering the sample.
2.
The entry of soil sample is taken in the Sample Register (office) as
per the relevant particulars furnished in the Register. Lab. No. is
given to each sample.
3.
Test required and expected date of reporting and other details along
with the sample is then transferred to analysis.
Soil Sample Preparation for Analysis :
1.
The collected soil samples are homogeneously mixed and left to
attain equilibrium with air for 2 hours in the trays / paper dishes.
2.
If the samples are dry there is no need to keep the samples in the
oven. It can be directly taken for further testing.
3.
If the soil samples are wet, samples are dried in the oven at 25oC for
2 hours or more (depending upon the wetness of the sample). If
samples found sticky even after drying, then the temperature may be
raised by 2 to 5oC, but in any case it should not exceed 35oC.
4.
After drying the soil, clods are crushed gently and grounded with the
help of wooden pestle and mortar. Gravel, soft chalk, limestone,
stones and concretions should be removed from the samples.
5.
The soils are passed through 2.0 mm and 0.5 mm stainless steel
sieve. The sufficient quantity of sieved soil sample is kept in plastic
bag labeled with permanent ink marker (IC No. along with the sieve
size 2.0 mm / 0.5 mm).
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6.
The plant residues, gravel, and other materials retained on the sieve
may be discarded.
7.
If the gravel content is substantial, the percent of the sample (W/W)
may be recorded.
8.
After the analysis of samples, the results are reviewed by the Higher
Authority and entered in appropriate register.
9.
The test reports should be signed by the authorized person.
Reviewing of Soil Samples :
1.
After the completion of the analysis, the remaining samples are
stored in the sampling room.
2.
The advisory soil samples having test results not in normal range
are retained for one month after sending the test results.
3.
The samples are retained to recheck the test results, if any query is
raised.
4.
The soil samples of research studies are retained depending on the
objective of the investigation of the project.
Reference Documents :
Jackson, M. L., 1967, Handling Soil Samples in the Laboratory, in soil
“Chemical Analysis”, Prentice Hall of India Pvt. Ltd., New Delhi, 2, 30-37.
Singh, Dhyan, Chhonkar, P. K. and Pande, R. N., 1999, Soil Testing in Soil,
Plant, Water Analysis, Methods Manual IARI, ICAR, New Delhi, 1, 1-6.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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B. SOIL SAMPLE ANALYSIS
I. PHYSICAL TESTS
1.
DETERMINATION OF SOIL TEXTURE - INTERNATIONAL
PIPETTE METHOD (MECHANICAL ANALYSIS)
Purpose :
The process of determining the amount of individual size separates
of soil below 2 mm in diameter i.e. sand, silt and clay called particle
size analysis. Particle size distribution has an important influence on
soil permeability or water intake rate, water storage capacity ability
to aggregate, crushing and the chemical makeup of the soil. The
value of land, land use capability and soil management practices are
largely determined by the texture.
The size limits for different fractions according to International
system of classification is as follows – ISSS.
a)
Gravel
Greater than 2 mm diameter
b)
Coarse Sand
2.0 to 0.2 mm diameter
c)
Fine Sand
0.2 to 0.02 mm diameter
d)
Silt
0.02 to 0.002 mm diameter
e)
Clay
Less than 0.002 mm diameter
The size limits for different fractions are also classified according to
CSSC, USDA.
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CSSC
USDA
ISSS
Fine clay
Clay
Clay
Coarse clay
Fine silt
Silt
Silt
Medium silt
Coarse silt
Fine sand
Very fine sand
Very fine sand
Fine sand
Fine sand
Medium sand
Medium sand
Coarse sand
Coarse sand
Coarse sand
Very coarse sand Very coarse sand
Gravel
Fine gravel
Gravel
Coarse gravel
Cobbles
Cobbles
Stones
Fig. 1 : A comparison of particle size limits in 3 systems of particle size.
Particle
size
in mm
0.0002
0.002
0.006
0.02
0.06
0.1
0.3
0.5
1.0
2.0
10.0
80
Sieve
size
300
270
200
140
60
40
20
10
0.5 in.
0.75 in.
3 in.
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Principle :
Mechanical analysis of soils consists of essentially two distinct
operations.
i) Dispersion of the soil
ii) Determination of particle size distribution by sedimentation
(by Stokes Law)
Apparatus :
i)
Shaking machine
ii)
1000 ml measuring stoppered glass cylinder
iii)
Thermometer
iv)
Pipette
v)
Stirrer
vi)
Stop watch
vii) Oven
viii) Physical balance
ix)
500 ml plastic bottle.
x)
Sieve (2, 0.2, and 0.02 mm)
xi)
China dishes
Reagents :
i)
Sodium hexa-meta phosphate [NaPO3]6
ii)
Sodium carbonate (Na2CO3)
iii)
Dispersing reagent - Take 33 gm of Sodium Hexameta-
phosphate and add 7 gm of Sodium carbonate and make the
volume 1 litre with distilled water.
Procedure :
i)
For determination of soil texture, take 50 gm of air dry soil
(passed through 2 mm sieve) in 500 ml bottle.
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ii)
Add 100 ml above dispersion solution in 50 gm soil in 500 ml
plastic bottle.
iii)
Shake a set of sample bottles at regular intervals for half an
hour on shaking machine for preparing homogeneous
solution.
iv)
Transfer above soil sample solution transferred to 1000 ml
glass measuring cylinder and make solution 1000 ml by
adding water.
v)
As per International approved system, shake the sample
solution for 30 sec. Depending on the solution temperature
and sedimentation chart, first pipetting is done with 50 ml
pipette at 10 cm depth. In first pipetting, 50 ml solution sucked
and transferred in 60 ml china dish. This sample solution
contains mixed of clay and silt particles.
vi)
Depending on the solution temperature and sedimentation
chart, second pipetting is done with 50 ml pipette at 10 cm
depth. In second pipetting 50 ml solution sucked and
transferred in 60 ml china dish. This solution contains clay
particles in soil sample.
vii) Transfer remaining soil solution in 1 lit. measuring cylinder by
using 0.02 mm sieve and wash the material through the sieve
using jet of water. Sand particles on sieve are collected in
china dish.
viii) Transfer pipetted solution in 3 dishes and dry overnight in an
oven at 105oC, Cool in a desiccators and weigh quickly.
ix)
The weight of fine sand determined by deducting the weight
of clay, silt and coarse sand particle from 100.
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Setting time for Silt and Clay, 10 cm depth
At different temperatures (Sedimentation Time Chart)
Temperature
oC
I – Pipetting Time
Upper limit of silt
(0.02 mm Dia.) min-Sec.
II – Pipetting Time
Upper limit of Clay
(0.002 mm Dia.) Hrs.-Min.
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
5-30
5-20
5-10
5-00
5-00
4-48
4-40
4-30
4-30
4-20
4-15
4-10
4-05
4-00
3-55
3-50
3-45
3-40
3-35
9-05
8-50
8-35
8-25
8-10
8-00
7-50
7-40
7-25
7-15
7-07
6-55
6-45
6-40
6-30
6-20
6-15
6-10
5-55
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Calculations :
Coarse Sand (A gm) x 2 = ………..……..% Coarse sand
In 50 gm soil sample
A gm Coarse sand
100 gm soil sample
A gm x 2 …… Coarse sand (I)
In 1000 ml sample solution
50 gm soil
In 50 ml sample solution
2.5 gm soil
In 2.5 gm sample
B gm …… (Clay + Silt)
In 100 gm sample
(B x 100) / 2.5 = B x 40 gm … (Clay + Silt)
In 2.5 gm sample
C gm …… (clay)
100 gm sample
C x 40 gm …… (clay)
(II)
% Silt = (B x 40) – (C x 40)
(III)
% Coarse sand = ---------
(1)
% Clay = -----------
(2)
% Silt = -----------
(3)
% Fine sand = 100 – (1) + (2) + (3)
Reference Documents :
Singh, Dhyan, Chhonkar, P. K. and Pande, R. N., 1999, Soil Testing
in Soil, Plant, Water Analysis, Methods Manual IARI, ICAR, New
Delhi, 1, 6-11.
Kadam, J. R., Shinde P. B., 2005, Practical Manual on Soil Physics
– A method manual, Department of Agricultural Chemistry and Soil
Science, P.G.I., Rahuri, P-8.
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Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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2. DETERMINATION OF SATURATION MOISTURE
PERCENTAGE (WATER HOLDING CAPACITY)
Purpose :
The determination of water holding capacity in soils is important as it
gives an idea of the capacity of soil to hold water for the use by
crops. The light soils which do not hold such water require more
frequent irrigations than heavy clay soils, well decomposed organic
matter increases the water holding capacity. Exchangeable sodium
and type of clay mineral also have a marked effect on water holding
capacity.
Water holding capacity of soils is useful for selection of soils for
irrigability classification. It also helps for comparing other properties
of soils.
Apparatus : 1)
Physical balance
2)
Perforated dish or circular brass boxes
3)
Enamel tray.
4)
Sieve (2 mm)
5)
Filter paper
Procedure :
1)
Crush air-dry soil and pass through 2 mm sieve.
2)
Place round filter paper and fix it to the internal perforated
floor of the dish. The weight of the dish and filter paper is
noted. The dish is then filled with soil by tapping the dish
briskly & making plane the top of soil and find out its weight.
3)
Place the set of perforated dishes in enamel tray. Pour the
water in enamel tray at half of height of dish. Water may rise
in dish through perforated bottom and moist the soil to its
capacity. Keep it for 5 to 6 hours in water.
4)
Take the dishes and place it on a filter paper sheet, so that
the excess of water may drain away from the pores within half
an hour. The dish containing moist soil is weighted and the
weight is noted.
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Observations :
1)
Weight of empty dish + filter paper
-
a gms.
2)
Weight of empty dish + filter paper
-
b gms.
+ air dry soil
3)
Weight of empty dish + filter paper
-
c gms.
+ wet soil
Calculations :
Saturation Moisture % =
x 100
=
x 100
Reference Documents :
Soil Testing Procedure Manual 2008, Marathwada Agricultural
University, Parbhani, P-22.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
(c – a) – (b – a)
(b – a)
(c – a) – (b – a)
(b – a)
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3. DETERMINATION OF BULK DENSITY -
Purpose :
The bulk density varies indirectly with total pore space present in the
soil and gives a good estimate of porosity of soil. Bulk density is of
great importance than particle density in understanding the physical
condition of soil.
Soil bulk density is defined as the ratio of the mass of the oven dry
soil to its bulk volume.
Method of determination :
Different methods are available for bulk density determination which
differ how the soil sample is obtained and its volume is determined
such as core, clod and excavation methods. There are other
methods for the determination of bulk density where different
principles are employed, for example, radiation method. Commonly
used methods are weighing bottle, core and clod method.
1.
Weighing bottle method :
Principle :
The mass of the soil is determined by weighing the oven dry soil
sample. The soil in small amounts, say 5-6 gm., is placed in a
container which is tapped 15-20 times on a table be letting it fall from
a height of about 2-3 cm. This tapping is assumed to produce the
same packing as occurring naturally in the field, even though this
assumption is not strictly correct. The volume of this packed soil will
be equal to the volume of the container. Bulk density is calculated
from the mass and volume of the soil.
Apparatus :
A weighing bottle (50 ml), balance and a burette of 50 ml capacity.
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Procedure :
Weigh an empty 50 ml bottle. Fill the bottle with oven dry soil upto
the brim by tapping and weigh it. Empty the bottle and determine its
exact volume using burette.
Observations & Calculations :
Mass of empty bottle
= M1 gm.
Mass of bottle + soil
= M2 gm.
Mass of the soil
= (M2 – M1) gm.
Volume of water filling the bottle = V cm3.
Bulk density
= (M2 – M1) / V gm.cm-3 or Mg. m-3
2. Clod Method :
Principle :
A few pieces of soil clods are oven dried, weighed and coated with a
water repellent substance (rubber solution) just enough to check the
water entry into them. A number of such clod pieces are placed
inside a graduated cylinder filled with water and the volume of water
displaced by them is noted. Knowing the dry weight of the soil and
its volume, the bulk density is calculated. The clod must be
sufficiently stable to cohere during coating, weighing and handling.
Apparatus and Reagents :
Crepe rubber or smoke sheets, benzene, toluene, electric stirrer,
wide mouthed container, a thin wire mesh, 250 ml. Graduated
cylinder, weighing balance and oven.
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Procedure :
Method of preparation of rubber solution :
Weigh 50 gm rubber sheets. Cut them into smaller pieces and soak
in toluene (rubber to toluene ratio is kept at 1:5 by weight). Keep the
mixture overnight in a tight container. Next day add benzene (440-
500 ml) and stir the contents thoroughly with the help of electric
stirrer so that swollen rubber pieces are shattered and
homogeneous solution is obtained. Dilute this solution with benzene
to achieve concentration of 1:30 by weight. Instead of benzene,
toluene can also be used for dilution but the benzene has the
advantage that it dries rapidly when applied over the soil clod.
Instead of rubber solution we can also use paraffin wax.
Coating Procedure :
Take a soil clod, oven dry it and note its weight. Wrap the clod in a
thin wire mesh, dip in the rubber solution placed in wide mouthed
container. Remove it momentarily. Repeat the process 3-4 times.
Volume Measurement :
Take a 250 ml graduated cylinder containing 150 ml of water. Put
the coated soil clod into the cylinder and note the volume of water
displaced by the clod. The volume of the displaced water will be
equal to the volume of the clod.
Observations & Calculations :
Mass of oven dry clod
= M gm.
Volume of water in the cylinder
= V1 cm3
Volume of water + Clod in the cylinder = V2 cm3
Volume of the clod
= (V2 – V1) cm3
Bulk density of the clod
= M / (V2 – V1) gm.cm3
or Mg.m-3
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3.
Core Method :
This is a field method for bulk density determination.
Principle :
In this method a cylindrical metal sampler or core of known volume
is driven into the ground to the desired depth and carefully removed
to preserve a known volume of sample as it existed in situ. This core
sample is dried at 105oC and weighed. Bulk density is the oven dried
mass divided by volume of the sample. The core method is usually
unsatisfactory if gravels are present in the soil.
Apparatus :
A core sampler, sharp knife, a tray, moisture boxes and oven.
Procedure :
Drive the sample into either a vertical or horizontal soil surface far
enough to fill the sample but not to compress the soil in the confined
space. Carefully remove the sampler and its contents. Trim the soil
extending beyond the sampler with a sharp knife. The soil sample
volume is the same as the volume of the sampler or the core.
Transfer the wet soil to a tray and weight it. Take a portion of the
sample in a moisture box, weigh and place it in an oven at 105oC for
about 24 hours and weigh it again.
Observation & Calculations :
Mass of wet bulk soil sample
= M1 gm.
Mass of the moisture box
= M2 gm.
Mass of moisture box + wet soil
= M3 gm.
Mass of moisture box + oven dry soil = M4 gm.
Mass of wet soil
= (M3 – M2) gm.
Mass of oven dry soil
= (M4 – M2) gm.
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Oven dry mass of bulk soil sample
= (M4 – M2) M1 / (M3 – M2) gm or
say = M5 gm.
Volume of bulk sample / core sampler = V cm3 or πr2h cm3
Where r is the radius in cm. and
h is the height of the core in cm.
Bulk density
= M5 / V gm.cm3
Precautions :
Core samples should not be taken in too wet or too dry condition of
the soil. In wet soils, the friction along the sides of the sampler and
vibrations due to hammering are likely to result in viscous flow of the
soil and thus, compression of the sample. When this occurs, the
sample obtained is unrepresentative, being more dense than the soil
in situ. Compression may occur even in dry soils if they are very
loose. Also, hammering the sampler into dry soil often shatters the
sample and makes it loose.
Ratings :
Textural Class
Bulk Density
Pore Space (%)
Sandy Soil
1.6
40
Loam
1.4
47
Silt Loam
1.3
50
Clay
1.1
58
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Reference Documents :
Kadam, J. R., Shinde P. B., 2005, Practical Manual on Soil Physics
– A method manual, Department of Agricultural Chemistry and Soil
Science, P.G.I., Rahuri, P-24.
Soil Testing Procedure Manual 2008, Marathwada Agricultural
University, Parbhani, P-30.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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4. DETERMINATION OF HYDRAULIC CONDUCTIVITY OF SOIL
Purpose :
The saturated hydraulic conductivity is a measure of readiness with
which a saturated soil transmits water through its body and is
expressed as length per unit time. Hydraulic conductivity is of a
considerable importance for irrigation, drainage and evaporation
studies. It depends upon properties of water / fluid and on the
porosity, pore size distribution and continuity of soil pores. It is
generally assumed to be a constant physical property of a soil for
any given positioning the field at any given time varying only with
respect to water content or water potential. Since viscosity and
density of water passing through the soil affect the hydraulic
conductivity, this soil property varies for different quality of waters.
The hydraulic conductivity of soil varies from 0.001 cm/hr in a fine
clay to over 25.0 cm/hr. on coarse sand.
There are several methods for determining the saturated hydraulic
conductivity in the laboratory and in the field. In principle the
hydraulic conductivity of soil is calculated from Darcy’s Law after
measuring the soil water flux and hydraulic gradient.
1.
Constant Water Head Method :
Principle :
When a constant head of water is maintained (Fig. 1) on one end of
saturated column of soil of length L cm, the volume of water Q cm3,
percolating through the other end per unit cross-sectional area A
cm2 of the soil column per unit time t minute, is directly proportional
to the hydraulic gradient (∆H/L) over the length of the soil. Thus ,
Q / At = - Ks ∆H / L
…. (1)
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Fig. 1 : Darcy’s Experimental Arrangement
According to Darcy’s Law the proportionality constant Ks in equation
(1) is the saturated hydraulic conductivity of the soil. The symbol H
stands for the total head, which is the sum of hydraulic head (h) and
the gravity head (z) at any point in the soil column. The difference of
H at the top and the bottom of soil column divided by the length of
the column gives the hydraulic or the total head gradient. Thus,
Htop
=
htop + Ztop
…. (2)
Hbottom
=
hbottom + Zbottom
…. (3)
∆H
=
htop - Hbottom
=
(htop + Ztop) – (hbottom + Zbottom) …. (4)
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Apparatus :
Brass permeameters of 7 cm inner diameter and 10 cm length with
the perforated bottoms (the dimensions of permeameters can vary
but smaller diameter causes more error due to wall effect), a stand
for supporting the permeameter, a water reservoir with an
arrangement for maintaining a constant head over the soil column, a
stop watch, graduated cylinders and measuring rods.
Procedure :
1. Place a filter paper disc on the screen of the permeameter.
2. Take 200 gm of 2 mm sieved air dry soil.
3. Dump the entire sample in one lot into the permeameter and
pack it by tapping the permeameter 15 to 20 times on a
wooden block from a height of 2 to 3 cm.
4. Place the filter paper disc on the top of the soil.
5. Place the permeameter in a tray filled with water, keeping the
water level slightly above the bottom of the sample and allow
it to soak overnight (14 –16 hrs) or longer till fully wet at the
surface.
6. Raise the water level in the tray to coincide with the top of the
soil in the permeameter for complete saturation.
7. Place the permeameter on the stand and start the siphon to
maintain a constant head (2 – 3 cm) on the top of the soil (do
not allow the water to flow over the top of the permeameter).
8. Keep at least 4 to 6 replications (if different students are using
the same soil, then their data can be used as replicates).
9. Note down the time when the water head on soil sample
becomes constant and a steady flow is obtained.
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10. Collect the percolate in a graduated cylinder and measure the
volume at pre-decided interval of time.
11. Record a few consecutive readings till the flux becomes
constant and measure the exact water head on the soil and
then discontinue the experiment. Measure the length of soil
column with the measuring scale.
Observations & Calculations :
Diameter of the permeameter
= d cm
Cross sectional area of the permeameter= A cm2
Depth of water above the soil
= h cm.
Length of soil column
= L cm
Time for which percolate collected
= T min.
Volume of percolate collected
= Q cm3 or ml
Hydraulic gradient
= (L + h) / L
Saturated hydraulic conductivity
= QL / At (L + h) cm./min
2.
Falling head method :
Principle :
In this method, drop in water level in a narrow tube is measure
instead of flow. This method is better adopted for slowly permeable
soils.
Suppose in a small time ‘dt’, there is drop of ‘dh’ height of water in a
narrow tube of cross sectional area ‘a’ inverted over a saturated soil
whose cross sectional area ‘A’ and length ‘L’.
The flux ‘dq’ in time ‘dt’ will be –
dq
=
a.dh
…. (1)
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In terms of Darcy’s Law,
dq
=
- K.A.dt (h/L)
…. (2)
from equations (1) and (2),
K.A.dt (h/L) =
- a.dh or dt = - a.(dh/h) L/K.A
Integrating between t1, h1 and t2, h2 gives
K
=
(aL/At) ln (h1/h2)
Apparatus :
Special apparatus (Fig….) consists of a galvanized iron cylinder (40
cm in length and 30 cm in diameter) with a conical top to which a
vertical glass tube of small diameter is attached.
Fig. : Falling head permeameter
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Procedure :
1. Push the cylinder into the soil to a depth for which
determination is to be made and assemble the whole
apparatus.
2. Wet the sample from below by water supply through a three
way stop cock and lower porous plate.
3. Fill the space above the sample by introducing water with
pipette or syringe at the top of the sample until it overflows.
4. Record the time for water level to fall from h1 to h2. make
additional 2 – 3 such measurements.
Observations and Calculations :
Diameter of stand pipe
= d cm
Cross sectional area of stand pipe
= a cm2
Length of the sample
= L cm
Diameter of the sample
= D cm
Cross sectional area of the sample (A) = π r2 cm2
Initial hydraulic head
= h1 cm
Final hydraulic head
= h2 cm
Time taken for change in head
= t sec
Saturated hydraulic conductivity
= (al / At) ln (h1/h2) cm./s
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Hydraulic conductivity ratings :
Rating
Ks (cm./hr)
Very slow
< 0.125
Slow
0.125 – 0.50
Moderately slow
0.50 – 2.0
Moderate
2.0 – 6.25
Moderately rapid
6.25 – 12.5
Rapid
12.5 – 25.0
Very rapid
> 25.0
Reference Documents :
Kadam, J. R., Shinde P. B., 2005, Practical Manual on Soil Physics
– A method manual, Department of Agricultural Chemistry and Soil
Science, P.G.I., Rahuri, P-59.
Soil Testing Procedure Manual 2008, Marathwada Agricultural
University, Parbhani, P-35.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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5.
DETERMINATION OF SOIL MOISTURE CONTENT
Purpose :
There are numerous methods available for the determination of soil
water content. These methods can be divided into two categories i.e.
the direct and indirect methods.
In direct method, the amount of water present in a given soil is
directly determined whereas in indirect methods, a soil property or
some reaction products relating to soil water content is determined.
In other words, a calibration curve indicating the relation of the soil
properties and soil water content is first prepared and then used for
the estimation of water content.
1. Gravimetric Method (Direct Method) :
Gravimetric method is the simplest and most widely used direct
method. It is frequently used for the calibration of other indirect
methods.
Principle :
Disturbed or undisturbed wet soil samples are weighed, dried to
constant weight in an oven at 105oC and reweighed. From these
measurements, the water content on dry mass basis is calculated. It
can be expressed on a volume basis by multiplying it with the bulk
density.
Apparatus :
A sampling tool – auger, Soil cores or some other suitable device,
Moisture box, oven and a desiccators with an active desiccant
(calcium chloride).
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Procedure :
1. Place the moist soil sample in a moisture box and weight it
immediately.
2. Place the box with lid off in an oven (105oC) and dry the soil to
a constant weight.
3. Remove the sample from the oven, replacing the lid, and place
the box in the desiccators until it is cool.
4. Weigh it and also determine the mass of the empty moisture
box. Determine the mass of the moisture.
Observations :
Mass of empty moisture box
= M1 gm.
Mass of moisture box + Moist soil
= M2 gm.
Mass of moisture box + oven dry soil = M3 gm.
Calculations :
Mass of water in the soil
= (M2 – M3) gm.
Mass of the oven dry soil
= (M3 – M1) g.
Percentage moisture content on
dry mass basis (θg)
= (M2 – M3) 100 / (M3 – M1)
Percentage moisture content on
volume basis (θv)
= (θg) x Db / Dw
Where Db is the bulk density of soil & Dw is the density of water
2 . Infra Red Moisture Meter Method (Direct Method) :
This method is the simplest and quick method. It gives moisture
content on wet weight basis. This method is useful for determining
moisture content in soils which are hygroscopic.
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Principle :
Wet soil samples are dried in Infra Red Moisture meter under
exposure to infra red radiation. The balance scale of meter is divided
directly in moisture percentages from 0 to 100% with least count of
0.2%
Apparatus : Infra red moisture meter with all accessories.
Procedure :
1. Turn the scale lamp ON by means of toggle switch.
2. Turn the scale adjusting knob and rotate scale until 100% mark
coincides with the index
3. Move the pointer to index by turning pointer adjusting knob in opposite
direction to the direction pointer must move to coincide with index.
4. Rotate scale until 0% mark coincides with index.
5. Raise the lamp housing and carefully distribute wet soil on sample pan
until pointer returns to index. This weight of material corresponds to 100
divisions of the scale.
6. Lower the lamp housing and turn the infra red lamp ON.
7. Set proper drying temperature by adjusting auto transformer control.
8. Rotate the scale by scale adjusting knob until pointer returns to index.
Read the percentage of moisture lost. (P)
Observations :
Percentage moisture on wet weight basis
= P
Calculations :
Percentage moisture on dry weight basis = 100P/100-P
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Reference Documents :
Kadam, J. R., Shinde P. B., 2005, Practical Manual on Soil Physics
– A method manual, Department of Agricultural Chemistry and Soil
Science, P.G.I., Rahuri, P-29.
Soil Testing Procedure Manual 2008, Marathwada Agricultural
University, Parbhani, P-22.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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II. CHEMICAL TESTS
1.
SOIL REACTION (pH)
Purpose :
The determination of pH in soil is important as it plays a great role in
availability of nutrients to plants. This determination can be done
more accurately in the laboratory by electrometric method.
pH determination is useful for soil classification on the basis of
acidity or alkalinity.
Principle :
The electrometric determination of pH by a pH meter is based on
measuring the e.m.f. (milivolts) of a pH cell both a reference buffer
and then with a test solution. The change in the potential difference
at 25oC for 1 pH unit is 59.1 mV. The pH of a soil is a measure of the
hydrogen or hydroxyl ion activity of the soil – water system. It
indicated whether the soil is acidic, neutral or alkaline in reaction. By
shaking a certain amount of soil with a certain amount of liquid, soil
suspension is brought in equilibrium with a supernatant solution. In
the supernatant solution the pH is measured potentiometrically on a
direct reading pH meter using a glass electrode with a saturated KCl
– calomel reference electrode.
Reagents :
i)
Standard buffer solutions : Dissolve one commercially
available buffer tablet each of pH 4.0, 7.0 and 9.2 in freshly
prepared distilled water separately and make up the volume
to 100 ml. Prepare the fresh solution every week as these
solutions are unstable. Alternatively the buffer solutions can
be prepared in the laboratory as given below.
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ii)
0.05 M Potassium hydrogen phthalate (KHC3H4O4, Mol. Wt.
204.22) : Dissolve 10.21 gm AR grade potassium hydrogen
phthalate in warm water and making volume to 1 L. This gives
a pH of 4.00 at 25oC and can be used as standard buffer.
iii)
Buffer solution pH 6.86 : Potassium dihydrogen phosphate +
Disodium hydrogen phosphate, each 0.025 M – Dissolve 3.40
gm of potassium dihydrogen orthophosphate and 4.45 gm
disodium hydrogen orthophosphate dihydrate (Sorenson’s
salt – Na2HPO4.2H2O) to 1 L in distilled water.
iv)
Buffer solution pH 9.2 : Dissolve 3.81 gm sodium tetraborate
(A.R.) in water and dilute to 1000 ml.
Apparatus :
i)
pH meter with glass electrodes
ii)
Thermometer
iii)
Glass beaker (100 ml)
iv)
Glass rod
Procedure :
1) Weigh 20 gm of 2.0 mm air dry soil into a beaker. Add 50 ml
of distilled water and stir with a glass rod thoroughly for about
5 minutes and keep for half an hour.
2) In the mean time turn the pH meter ON, allow it to warm up
for 15 minutes. Standardize the glass electrode using
standard buffer of pH = 7 and calibrate with the buffer pH = 4
or pH = 9.2.
3) Dip the electrodes in the beakers containing the soil water
suspension with constant stirring.
4) While recording pH, switch the pH meter to pH reading, wait
30 seconds and record the pH value to the nearest 0.1 unit.
Put the pH meter in standby mode immediately after
recording.
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5) Remove the electrodes from soil suspension and clean the
electrodes with distilled water.
6) Rinse the electrodes after each determination and carefully
blot them dry with filter paper before the next determination.
Standardize the glass electrodes after every 10
determinations.
7) Dip the electrodes in distilled water, when not in use and
ensure that the reference electrode always contains saturated
potassium chloride solution in contact with solid potassium
chloride crystals.
8) Three to four drops of toluene are added in standard buffer
solutions to prevent growth of mould.
Ratings :
< 4.5
Extremely Acidic
4.6 to 5.2
Strongly Acidic
5.3 to 6.0
Moderately Acidic
6.1 to 6.5
Slightly Acidic
6.6 to 7.0
Neutral
7.1 to 7.5
Slightly Alkaline
7.6 to 8.3
Moderately Alkaline
8.4 to 9
Strongly Alkaline
> 9
Extremely Alkaline
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Reference Documents :
Davis, J. and Freitas F., 1970, In Physical & Chemical Methods of
Soil & Water Analysis, FAO of United Nations, Rome, Soil Bulletin,
10, III-1 : 65-67.
Singh, Dhyan, Chhonkar, P.K. and Pande R.N., 1999, Soil Reaction
in Soil, Plant, Water analysis Method Manual, IARI, ICAR, New
Delhi, 1 : 4.2 (b) 11-13.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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2.
Measurement of Electrical Conductivity (EC) in Soil
Purpose :
Salted soils are classified on the basis of two criteria, one is on the
basis of total soluble salt (TSS) content and another is
exchangeable sodium percentage (ESP) or more recently sodium
Absorption ration (SAR). Ions in water conduct electrical current,
therefore electrical conductivity is fast, simple method of estimating
amount of total soluble salt (TSS) in soil sample. Electrical
conductivity is expressed in dS/m.
Principle :
The electrical conductivity of water extract of soil gives a measure
of soluble salt content of the soil. Pure water is very poor conductor
of electric current, whereas water containing the dissolved salts in
soil conducts current approximately in proportion to the amount of
soluble salts present. Based on this fact, the measurement of
electrical conductivity of an extract gives a satisfactory indication of
the total concentration of ionized constituents. The conductivity of
the soil is the specific conductivity at 25oC of water extract obtained
from a soil and water mixture of a definite ration. It is measured on a
conductivity meter and normally reported in dS/m or milimhos/cm
and the value gives information on the total amount of the soluble
salts present in soil, i.e. on the degree of salinity.
Apparatus :
1)
Digital conductivity meter
2)
Conductivity cell.
3)
Glass beaker (100 ml)
4)
Glass rod
Reagent :
0.01N Potassium chloride solution : Dry a small quantity of A.R.
grade Potassium chloride at 60oC for 2 hours. Weigh 0.7456 gm of it
and dissolve in freshly prepared distilled water and make to one litre.
This solution gives and electrical conductivity of 1411.8 x 10-3 i.e.
1.41 dS/m at 25oC.
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Procedure :
i)
Calibrate the conductivity cell with the help of standard KCL
solution and determine the cell constant.
ii)
The soil water suspension of 20 gm : 50 ml ratio prepared for
the determination of pH can also be used for conductivity
measurements. After recording the pH, allow the soil water
suspension in the beaker to settle for additional half an hour
(the total intermittently shaking period is 1 hr.)
iii)
After the calibration dip the conductivity cell in the
supernatant liquid of the soil water suspension. Read the
conductivity of test solution in proper conductance range,
iv)
Remove the cell from soil suspension, clean with distilled
water and dip into a beaker of distilled water. EC is expressed
as dS.m–1
v)
Dip the conductivity cell in distilled water when not in use.
vi)
Record the temperature of soil water suspension during the
test. (See Appendix-9).
Calculations :
The cell constant K is given by
Cell constant (K) =
ECe25 = ECT x K x ft
Where ECe25 is the conductivity of the extract at 25oC.
Known conductivity of 0.01 N KCL
Conductivity of 0.01 N KCL measured
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Ratings : EC in dS.m–1
0 to 1
Good soil
1 to2
poor seed emergence
2 to 4
Harmful to some crops, e.g. Pulses.
Above 4
Harmful to most of crops.
Reference :
Davis, J. and Freitas F., 1970, In Physical & Chemical Methods of Soil & Water
Analysis, FAO of United Nations, Rome, Soil Bulletin, 10, III-1 : 68-70.
Singh, Dhyan, Chhankar, P.K. and Pande R.N., 1999, Electrical Conductivity in
Soil, Water analysis Method Manual, IARI, ICAR, New Delhi, 1 : 4.2 (b) 14-16.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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3. DETERMINATION OF ORGANIC CARBON IN SOIL :
Purpose :
Besides its value as a source of plant nutrients, organic matter has a
favourable effect upon soil physical properties. Organic matter also
contains the informable effective of exchangeable sodium on soils.
The determination of organic carbon in soil serves indirectly as
measure of available nitrogen. The organic matter content of a
typically well drained mineral soil is low varying from 1 to 6% by
weight in the top soil and even less in the subsoil. The influence of
organic matter (OM) on soil properties and consequently on plant
growth is far greater even though the percentage of organic matter
(OM) is less in the soil.
1. Walkley and Black Method :
Principle :
Organic carbon is oxidized with potassium dichromate in the
presence of concentrated sulphuric acid. Potassium dichromate
produces nascent oxygen, which combines with the carbon of
organic matter to produce CO2. The excess volume of K2Cr2O7 is
titrated against the standard solution of ferrous ammonium sulphate
in presence of H3PO4, using ferroin to detect the first appearance of
unoxidised ferrous iron and thus volume of K2Cr2O7 can be found
out which is actually required to oxidize organic carbon.
Reaction : 2K2Cr2O7 + 8H2SO4
2K2SO4 + 2Cr2 (SO4)3 + 8H2O + 6O
3C + 6O
3CO2
(Mol. wt. of K2Cr2O7 = 294.212,
Eq. wt. of K2Cr2O7 = 294.212/6 = 49.03)
2 K2Cr2O7 = 3C, K2Cr2O7 = 3C/2 OR
49.03 g K2Cr2O7 = 12C/4 = 3.0 g C
As 1000 cc (N) K2Cr2O7 = 3.0 g C
1 cc (N) K2Cr2O7 = 3 g C / 1000 = 0.003 g C
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Apparatus :
1. Conical flask – 500 ml
2. Pipettes – 2 ml, 10 ml, & 20 ml capacity
3. Burette – 50 ml capacity
4. Volumetric measuring flask – 2 Nos. (1 Lit. capacity)
5. Reagent bottles.
6. Asbestos sheet
Reagents :
1. 1 N potassium dichromate : Dissolve 49.04 AR grade K2Cr2O7
(dry) in distilled water and make up the volume to one litre.
2. Concentrated sulphuric acid (Sp. Gravity 1.84, 96%) : If the soil
contains chloride, then 1.25% silver sulphate may be added in
H2SO4.
3. Orthophosphoric acid (Sp. Gravity 1.75, 85%)
4. Sodium Fluoride (chemically pure)
5. 0.5 N Ferrous ammonium sulphate – Dissolve 196.0 gm of AR
grade Ferrous ammonium sulphate in distilled water, add 20 ml of
concentrated H2SO4 and make volume to one litre. The ferrous
ammonium sulphate should be from a fresh lot and light green in
colour.
6. Ferroin indicator
Procedure :
1.
Weigh 1 gm. of 0.5 mm sieved soil into dry 500 ml conical flask.
Add 10 ml of K2Cr2O7 into the flask with pipette and swirl.
2.
Add rapidly with a burette 20 ml conc. H2SO4 and swirl gently
until soil and reagents are mixed then more vigorously for one
minute.
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3.
Allow the reaction to proceed for 30 min on asbestos sheet to
avoid burning of table due to release of intense heat due to
reaction of sulphuric acid.
4.
Add slowly 200 ml of distilled water, 10 ml of concentrated
orthophosphoric acid and add about 0.2 gm NaF (one small
teaspoon) and allow the sample to stand for 1.5 hrs. The titration
end point is clear in a cooled solution.
5.
Just before titration add 1 ml ferroin indicator into the conical
flask. Titrate the excess K2Cr2O7 with 0.5 N ferrous ammonium
sulphate till the colour flashes from yellowish green to greenish
and finally brownish red at the end point.
6.
Simultaneously blank test is run without soil.
Observation Table :
Sr.
No.
Lab.
No.
Blank
reading (B)
Burette
reading (S)
Difference
(B – S)
%
Organic
carbon
%
Organic
matter
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Calculations :
% Organic carbon = (B – S) x N x 0.003 x
Where, B = ml of std. 0.5 N ferrous ammonium sulphate required for blank.
S = ml of std. 0.5 N ferrous ammonium sulphate required for soil sample.
N = Normality of std. ferrous ammonium sulphate (0.5N)
The correction factor 1.3 is multiplied as according to Walkley and Black method
only estimated 77% carbon (av. Value).
The result can be converted to corrected total organic carbon by multiplying the
factor 100/77 = 1.3
Soil organic matter contains (58%) of organic carbon, the percentage of organic
carbon multiplied by 100/58 = 1.724 which gives the percentage of organic matter
i.e.
Organic matter = Organic Carbon x 1.724
2.
UV Spectrophotometer Method :
Apparatus :
1. UV spectrophotometer
2. Volumetric flask
Reagents :
1. 1N potassium dichromate : Dissolve 49.04 AR grade K2Cr2O7
(dry) in distilled water and make up the volume to one litre.
2. 97% conc. Sulphuric acid
100
Wt. of soil (oven dry)
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Procedure :
Preparation of Standard Curve :
Take 1 gm sucrose and add to it 1000 ml distilled water. From this solution take 0,
1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 ml in 100 ml flask and add 10 ml potassium
dichromate and 20 ml sulphuric acid. Shake well and allow the mixture to cool on
asbestos sheet, Make the volume of each solution to 100 ml with distilled water
and observe optical densities at 660 nm. wavelength. Prepare standard curve and
calculate factor F.
Sucrose
Sol. Ml
Sucrose
ppm
Carbon
ppm
Carbon %
O. D.
Reading
Carbon %
for 1 O. D.
Blank
0
0
0
1
10
4.2
0.04
5
50
21
0.21
10
100
42
0.42
15
150
63
0.63
20
200
84
0.84
25
250
105
1.05
30
300
126
1.26
35
350
147
1.47
40
400
168
1.68
45
450
189
1.89
50
500
210
2.10
Total
X
Factor F = X/11
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Determination of Organic Carbon
Sieve the soil sample with 1 mm sieve and take 1 gm of sieved soil
sample in 100 ml flask. Add to it 10 ml potassium dichromate and 20
ml sulphuric acid, shake well and allow it to cool on asbestos sheet.
Make the volume to 100 ml with distilled water and keep it overnight.
Measure optical density at 660 nm wavelength on
spectrophotometer.
Organic Carbon % = Optical density x Factor F
Ratings :
% Organic carbon
1)
Less than 0.20
Very low
2)
0.21 to 0.40
Low
3)
0.41 to 0.60
Moderate
4)
0.61 to 0.80
Moderately high
5)
0.81 to 1.0
High
6)
More than 1.0
Very high
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Reference Documents :
1)
Singh, Dhyan, Chhonkar, P.K. and Pande R.N., 1999, Soil
Organic Carbon in “Soil, plant, water Analysis” A methods
manual, Indian Agricultural Research Institute, Indian Council
of Agricultural Research, New Delhi, 1.4.6 : 19-19.
2)
Page, A.L., Miller, R.H. and Keeny, D.R. 1982, Organic
Carbon in Methods of Soil Analysis, Chemical &
Microbiological properties, American Society of Agronomy,
Inc, Soil Science Society of America, Inc, Madison, Wilconsin,
USA, 9(2) : 570-571.
3)
Soil & Water Analysis Methods – Soil Survey & Analysis
dept., Commissionorate of agriculture, Maharashtra State,
Pune-5, P. 5-7.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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4. DETERMINATION OF CALCIUM CARBONATE (FREE LIME) IN SOIL :
Purpose :
Alkaline earth carbonates that occur in significant amounts in soils
consist of calcite, dolomite and possibly magnesite and occur
commonly in the silt size fraction. These influence the texture of the
soil when present in appreciable amounts. These are important
constituents of alkali soils, they constitute a potential source of
calcium and magnesium. Lime aids in preserving soil structure and
may serve as a source of calcium in the reclamation of alkali soil.
Zonal soils of arid regions usually contains accumulation of lime at
some point in the profile. Calcareous soil contains an accumulation
of calcium and magnesium carbonated in varying proportions
throughout the soil profile.
In calcareous soils if CaCO3 is present in problematic amount
improvement may be done by drainage of sub-soil for breaking the
hard pan formed due to CaCO3 accumulation at lower depth and
leaching. Acid forming substances like S, FeSO4, Al2(SO4)3 may also
used followed by leaching.
1. Acid Neutralization Method :
Principle :
Soil is treated with an excess of standard hydrochloric acid,
destroying carbonates. The amount of excess acid is determined by
titration with standard sodium hydroxide, after separation from the
soil by filtration or centrifugation. The acid dissolves a certain
amount of iron and aluminium from oxides and soil materials and
these metals are precipitated as hydroxides when the pH rises
towards the end of the filtration with alkali. The amount of acid
destroyed in dissolving the metals is equivalent to the amount of
alkali used to precipitate., their hydroxides, so no error arises from
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this source. However, acid is lost by reaction with primary minerals.
Alkaline soils of high pH also destroy some acid through
neutralization by sodium carbonate.
Apparatus :
1)
Glass beaker 100 ml.
2)
Conical glass flask 250 ml.
3)
Glass funnel
4)
Volumetric flask (100 ml)
5)
Erlenmeyer flask (150 ml)
Reagents :
1)
Hydrochloric acid (1N) : Dissolve 89 ml of conc. HCL in
distilled water and make upto 1 lit.
2)
Hydrochloric acid (0.2N) : Take 25 ml of 1N HCL and dilute it
to 100 ml.
3)
Sodium hydroxide (0.2N) : Dissolve 8.0 gm of sodium
hydroxide in distilled water and make up the volume upto
1000 ml.
4)
Potassium hydrogen phthalate (0.2N) : Dissolve 4.084 gm of
KHP in distilled water and make up the volume upto 100 ml.
Procedure :
1)
The preliminary tests are carried out on the soil to establish a
rough idea of the amount. Of carbonate present from the
degree of effervescence with dilute acid.
2)
Based on the degree of effervescence the soil is taken for
analysis as per the following table.
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Degree of effervescence
Wt. of air dry soil (g)
(W)
No effervescence
10.0 to 20.0
Moderate
5.0
Fairly vigorous
2.0
Vigorous to very vigorous
1.0
3)
Transfer (W) g air dried soil of 0.5 mm sieve to a 250 ml
plastic conical flask and carefully add 25 ml of 1N HCl down
from the side of the flask. Cover with a watch glass and allow
standing for 1 hour, swirling occasionally to mix the contents.
4)
Then transfer the mixture quantitatively to a 100 ml volumetric
flask and make up the volume with distilled water and mix.
Filter through a dry filter paper into a dry flask.
5)
Transfer 20 ml. of the clear liquid to a 150 ml Erlenmeyer
flask. Add a little distilled water and bring just to the boil. Cool
for a minute.
6)
Add about 6 – 10 drops of bromothymol blue and titrate hot
with 0.2N NaOH until the blue colour persists for 30 sec.
7)
Rub the blank simultaneously (Blank is made by taking 25 ml
1N HCL in 100 ml volumetric flask and diluting with distilled
water upto mark. 20 ml of this solution is taken as a blank for
titration with 0.2N NaOH.)
8)
Titrate 10 ml of 0.2N NaOH with 0.2N KHP using
phenolphthalein and determine the factor of NaOH.
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Observation Table :
Sr.
No.
Lab.
No.
Blank
Reading
Burette
(Sample)
Reading
Difference
Std. HCl
in ml.
% CaCO3
Calculations :
Let W be the moisture corrected weight of the soil in gm.
‘T’ is the volume in ml of the titration with 0.2 N sodium hydroxide.
Since 20 ml of liquid, after reaction with soil contains excess acid
equivalent to “T” ml of 0.2N NaOH, so 100 ml contains T ml of 1N
excess acid.
Thus, the acid neutralized in reaction with the soil is (Blank – T) ml
of 1N.
Thus W gm soil contains 0.05 (Blank – T) gm calcium carbonate.
CaCO3 % in soil =
x F
Where,
F = factor of 0.2N NaOH and
W = wt. of air dry soil after correcting the moisture percentage.
5 (Blank - T)
W
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F =
This may be reported as an apparent CaCO3 % or as a neutralizing
value.
2. Schrotus Apparatus Method :
Apparatus
Glass Beaker, Conical Flask, Glass Funnel, Erlenmeyer Flask
Reagents
3 N Hydrochloric acid
Procedure
Pipette 10 ml of hydrochloric acid into 50 ml Erlenmeyer flask.
Weigh the Erlenmeyer flask with cork stopper. Transfer 1 to 10 gm
of soil to the flask. After effervescence has largely subsided make
the stopper loose and swirl the flask. The reaction is usually
complete in two hours. Displace the carbon dioxide in the flask with
air and weigh the flask with stopper.
Calculations
Wt. of CO2 lost = (Initial wt. of flask + acid + soil) – ( Final wt. of flask
+ acid + soil)
Ratings :
% CaCO3
1)
Less than 1
Low
2)
1 – 5
Medium
3)
5 – 10
High
4)
10 – 15
Very high
Exact normality of NaOH
0.2
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Reference Documents :
Dewis J. and Freitas F., 1970. calcium carbonate – Acid
neutralization in Physical and Chemical Methods of Soil and Water
Analysis. Food and Agricultural Organization of the United Nations,
Rome, Italy, III.2-2, P. 71-72.
Diagnosis and improvement of saline & alkaline soils – United States
Salinity Laboratory Staff, Agricultural Handbook No. 60, United State
Dept. of Agriculture, P. 105.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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5. DETERMINATION OF NITROGEN –
(ALKALINE PERMANGNATE METHOD)
Purpose :
Soil nitrogen occurs largely in the organic form (97-99%). The
availability of N is associated with the activity of micro-organisms
which develops the organic matter (NH4-N and NO3-N). The
nitrification rate of a soil is measure of the rate of release of
available nitrogen from the organic matter in the soil.
A discrete fraction of the soil organic nitrogen is attacked by KMnO4
and that this fraction was most readily susceptible to biological
mineralization. This forms the basis for determination of available
nitrogen by alkaline permanganate method (Subbiah and Asija,
1856).
Principle :
The organic matter in the soil is oxidized by KMnO4 in presence of
NaOH. The ammonia released during oxidation is absorbed in boric
acid to convert the ammonia to ammonium borate. The ammonium
borate formed is titrated with standard H2SO4. From the volume of
standard H2SO4 required for the reaction with ammonium borate, the
N is calculated.
Apparatus :
1)
100 ml conical flask
2)
Funnels, filtration stands
3)
100 ml volumetric flask
4)
Beaker
5)
One lit. round bottom flask
6)
Distillation unit (Kheldhal Digestion Unit)
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Reagents :
1) Potassium permanganate, KMnO4 (0.32%) : Dissolve 3.2 g of
potassium permanganate in 1 lit distilled water with the
intermittent shaking till it is completely dissolved. Store in
amber coloured bottle and in the dark
2) Sodium hydroxide solution, NaOH (92.5%) : Dissolve 25 g of
pure sodium hydroxide pellets in one lit. distilled water.
3) Boric Acid H3BO3 (2%) : Dissolve 20 g boric acid of AR grade
in 800 ml distilled water by heating the content. Cool it and
dilute to 1000 ml volume.
4) Mixed indicator - Bromocresol green + Methyl red : Weigh out
separately 99 mg of Bromocresol green and 66 mg of well
powdered methyl red and dissolve them together in 100 ml
ethyl alcohol.
5) Working Boric Acid solution : Add 20 ml of the mixed indicator
to one lit. of 2% boric acid solution and adjust the pH to 5.0
after shaking, or add 0.1N NaOH continuously until the
solution assumes reddish purple tingeuine red colour.
6) Standard sulphuric acid, H2SO4 (0.02N) : Standardise the
H2SO4 solution using standard NaOH. NaOH be standardised
against 0.02N H2C2O4 or 0.02N potassium pthalate.
7) Liquid paraffin
8) Glass beads
Procedure :
1)
Transfer 20 g of sieved soil into 1lit. round bottom flask.
2)
Add little distilled water with the help of jet in such a way that
the particles of soil do not remain stuck to the sides of the
flask.
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3)
Add 2 to 3 glass beads to present bumping and 1 ml of liquid
paraffin to prevent frothing.
4)
Add 100 ml of potassium permanganate and 100 ml of
sodium hydroxide solution to the flask (both the solutions
should be prepared fresh).
5)
Distill and collect the distillate in a beaker containing 20 ml of
boric acid working solution.
6)
Collect approximately 150 ml of distillate.
7)
Titrate the distillate with standard H2SO4 0.02N till the colour
changes from green to red and record the burette reading.
8)
Carry out blank without soil.
Observations :
1)
Weight of soil sample taken
=
20 g
2)
Volume of standard H2SO4 required for
=
... A ml
soil sample
3)
Volume of standard H2SO4 required for
=
... B ml
blank sample
4)
Normality of H2SO4
=
0.02N
Calculations :
N% = (A – B) x Normality of H2SO4
x Equi. Wt. of N
x
x
N% = (A – B) x Normality of H2SO4 0.02N x Equi. Wt. of N (14)
x
x
100 g_______
Wt. of soil sample
1_______________
100 to convert N mg into g
100 g________
Wt. of soil sample g
1_______________
100 to convert N mg into g
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N% = (A – B) x Normality of H2SO4 x 0.014
x
Available N kg/ha = N% x
OR
Available N kg/ha = (A – B) x N x 0.014 x
N = Normality of H2SO4. (See Appendix-2).
Ratings :
Nitrogen
Kg/ha
Very low
< 140
Low
140 – 280
Medium
281 – 420
Moderately High
421 – 560
High
562 – 700
Very High
> 701
100 g___
Wt. of soil (g)
2240000
100
2240000____
Wt. of soil sample g
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Reference Documents :
1)
Black, C.A. 1965, Methods of Soil Analysis, Part-2, American
Society of Agronomy, INC. Soil Society of America, Madison,
Wisconsin, USA.
2)
Birch, H.F., 1960, Ibid, 12, 81.
3)
Nelson, D.W. and J.M. Bremner, 1972. Preservation of soil
samples for inorganic nitrogen analysis, Agron. J., 64 : 196 –
199.
4)
Page, A.L. 1983 (Ed.), The Methods of Soil Analysis, Part-2,
American Society of Agronomy, INC. Soil Society of America,
Madison, Wisconsin, USA.
5)
Perur, N.G., C.K. Subramaniam G.R., Muhr and H.E. ray,
1973, Soil Fertility Evaluation to serve Indian Farmers,
Mysore Dept. of Agri., Mysore University of Agricultural
Sciences, U.S. Agency for International Development,
Bangalore, India.
6)
Somwansi, R.B., B.D. Tamboli, V.M. Patil, D.B. Bhakare and
P.P Kadu, 1994, twenty Five years of research on soil test
crop response correlation studies in Maharashtra. 1968 – 93,
MPKV Res. Publ. No. 14.
7)
Subbaiah, B.V. and G.L. Asija, 1956, A Rapid Procedure for
the Estimation of Available Nitrogen in soils. Curr. Sci., 25 :
259 – 260.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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6. DETERMINATION OF PHOPHOROUS IN SOIL :
(OLSEN’S METHOD)
Purpose :
Next to nitrogen, phosphorous is most critical essential element in
influencing plant growth & production throughout the world. Among
the more significant functions & qualities of plants on which
phosphorous has an important effect are –
1)
Photosynthesis
2)
Nitrogen fixation
3)
Crop maturation – flowering and fruiting including seed
formation
4)
Root development
5)
Protein synthesis
Thus, it is essential to calculate the available phosphorous present
in the soil.
It is determined by Olsen’s Method.
Principle :
Under neutral to alkaline soil conditions, Olsen’s P (0.5 M NaHCO3
solution at pH 8.5) is the most widely used extractant for estimation
of available phosphorous in soil. The reagent is designated to
control the ionic activity of calcium through the solubility product of
CaCO3 in case of neutral and calcareous soil. In this process the
most effective form of “P” is extracted from the phosphates of Fe, Al
& Ca present in different type of soils. The extracted phosphorous is
measured calorimetrically.
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Apparatus :
1)
Conical flask – 150 ml.
2)
Funnel
3)
Pipettes
4)
Volumetric flask – 25 ml.
5)
Reagent bottles
6)
Spectrophotometer
Reagents :
1)
0.5M NaHCO3
– Dissolve 42.0 gm of P-free sodium
bicarbonate in about 500 ml of hot distilled water and dilute to
1 litre. Adjust the pH to 8.5 using dilute NaOH or dilute HCL.
Prepare fresh solution before use.
2)
Activated Charcoal – wash pure activated charcoal or
commercially available Darco G-60 with acid to make P-free,
even if having traces of P.
3)
Ammonium Paramolybdate [(NH4)6 MO7 O24 4H2O] – Dissolve
12.0 gm of ammonium paramolybdate in 250 ml of distilled
water to get solution ‘A’. Prepare solution ‘B’ by dissolving
0.2908 gm of potassium antimony tartarate (KsbO . C4H4O6)
in 100 ml of distilled water. Prepare one litre of 5N H2SO4 (14
ml of concentrated H2SO4 diluted to 1 lit.) and add solutions
“A” and “B” to it. Mix thoroughly and make the volume to 2 lit
with distilled water. Store in amber coloured bottle in dark and
cool compartment. (Reagent C).
4)
Ascorbic Acid Solution – Dissolve 1.056 gm of ascorbic acid
in 200 ml of molybdate tartarate solution (reagent C) and mix
well. This ascorbic acid (reagent D) should be prepared as
required because it does not keep more than 24 hrs.
5)
P - nitrophenol indicator – Dissolve 0.5 gm of p-nitrophenol in
100 ml of distilled water to get approximately 5N H2SO4.
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6)
Standard P Solution (Stock Solution) – Analytical grade (AR)
KH2PO4 is dried in an oven at 60oC for one hour and after
cooling in desiccator, weigh 0.4393 gm and dissolve in about
500 ml distilled water (shake the content until the salt
dissolves.) Add 25 ml of approximately 7N H2SO4 & make the
volume to 1 lit. Add 5 drops of toluene to diminish microbial
activity. This gives 100 ppm stock solution of P (100 mg/ml).
7)
P solution (5 ppm) – Pipette out 5 ml of stock solution of P
and make up the volume to 1 lit with distilled water. This
solution contains 5 mg P/ml (i.e. 5 ppm solution).
8)
Hydrochloric Acid (0.02 N) – Dilute 1.8 ml of concentrated
HCl to 1 lit.
9)
Standardization of sodium hydroxide (NaOH) – Pipette out 10
ml of 0.02 potassium hydrogen pthalate in a 250 ml conical
flask. Add 3 drops of phenolphthalein indicator. The end point
is appearance of pale permanent pink colour.
Procedure :
1)
Weight 2.5 gm of soil sample in 150 ml plastic conical flask,
add pinch (0.3 gm) of phosphate free activated charcoal AR
grade. Add 50 ml of Olsen reagent and shake for 20 minutes
exactly on platform type shaker at 180 rpm.
2)
Filter the contents immediately through filter paper. Transfer 5
ml of aliquot into 25 ml volumetric flask.
3)
Pipette out 5 ml of filtrate into 25 ml volumetric flask. Add 4 ml
of the freshly prepared ascorbic acid and ammonium
molybdate solution. Shake well and keep it for 30 minutes
then make the volume.
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4)
Prepare the standard curve using 0, 1, 2, 3, 4 & 5 ml of 5 ppm
standard P solution into 25 ml volumetric flask and develop
the colour using the same procedure as above. The
corresponding P concentration will be 0, 0.2, 0.4, 0.6, 0.8 & 1
ppm.
5)
Measure the absorbance and colour intensity at 882 nm after
half an hour.
6)
Run a blank method sample with the extracting solution.
Observation Table :
Sr. No. Lab. No.
Reading on
Spectrometer
P (ppm)
P ( kg/ha.
Calculation :
P (ppm) =
Where,
GR – Concentration of P in analysed sample. (read from std. curve)
P (kg/ha) = P (ppm) x 2.24 (See Appendix-7).
GR x 50 x 5
Corrected Ht. Of Soil
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Rating –
Phosphorous (kg/ha)
1)
Very low
-
< 7
2)
Low
-
7 – 13
3)
Medium
-
13 – 22
4)
Moderately high
-
22 – 28
5)
High
-
28 – 35
6)
Very high
-
> 35
Reference Documents :
Dewis J and Freitas F, 1970, Ammonium fluoride – Hydrochloric acid
and Extraction.
Olsen S. R. and Sommers L. E. 1982, Phosphorous in method of
soil analysis, Part-2, Chemical and microbiological properties –
Agronomy monograph number 9 (2nd Ed.)
American Society of Agronomy, Inc, Soil Science Society of
America, Inc, Madison, Wisconsin, USA, 24 : 421 – 422.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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7. DETERMINATION OF POTASSIUM ON FLAME PHOTOMETER :
Purpose :
Next to nitrogen and phosphorous, potassium is the most critical
essential element in influencing plant growth and production
throughout the world. Potassium plays essential role in plants. It is
an activator for dozens of enzymes responsible for plant process.
Potassium is essential for photosynthesis, for protein synthesis, for
starch formation and for translocation of sugars. Also it exerts a
balancing effect on the effects of both nitrogen and phosphorous.
Thus, it is essential to calculate the available potassium present in
soil. Purpose of potassium determination is to determine available
potassium content in given soil.
Principle :
When a solution of the metallic salt is atomized into a non luminous
flame, electrical K atoms get excited and emit light when come to
ground state. The light emitted is filtered through a glass filter which
allows light to definite wavelength of that element, 766.5 nm for K, to
pass. The light falls on photocell emitting electrons generating an
electric current. This current is measured on the galvanometer and
is proportional to the concentration of metal element present in
solution atomized.
Reaction :
Soil-K + NH4OAC ==== Soil-NH4 + K+ + Acetate
Apparatus :
1) 100 ml Conical flask
2) Funnels, filtration stands
3) 100 ml volumetric flasks
4) Flame photometer
5) 50 ml volumetric flasks
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Reagents :
1) Neutral normal ammonium acetate solution – Take 58 ml of
glacial acetic acid in 500 ml volumetric flask. Also take 71 ml
of concentrated ammonium hydroxide solution in another 500
ml volumetric flask. Dilute both the solutions with distilled
water upto the 2/3 volume and mix both in 1 lit. flask then
adjust pH to 7.0 and finally make up the volume to 1 lit. For
bringing pH of solution to 7, add dilute acetic acid or
ammonium hydroxide, or dissolve 77 gm/lit. NH4OAC and
adjust pH to 7 by acetic acid or ammonium hydroxide.
2) Standard potassium stock solution (100 μg K / ml) – Dissolve
1.908 gm chemically pure KCl in distilled water, make up the
volume to 1 L. This solution contains 1000 μg / ml of K. It
serves as standard stock solution. Also prepare secondary
stock solution of 100 μg K / ml from this primary stock solution
by taking 10 ml and making 100 ml volume.
3) Working solution – Pipette 0, 0.5, 1, 2, 4, 6, 8 and 10 ml of
100 μg K / ml solution in 100 ml volume flask separately and
make up the volume with NH4OAC solution. This gives 0, 0.5,
1, 2, 4, 6, 8 and 10 μg / ml respectively.
Observation Table :
Sr. No.
Lab. Sample
No.
Reading on flame
photometer for potassium
Potassium
in ppm
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Precautions while handling flame photometer :
1) All the necessary safety precautions meeting the appropriate
specifications for use of LPG burner should be strictly
followed.
2) Never view the flame from the top of the chimney. It should
be viewed from the round viewing indicator provided on the
front side.
3) Ensure air is flowing through the burner before LPG is
allowed in to the burner and lighting it.
4) Always start the air compressor first and then the LPG gas to
avoid inadequate air and gas accumulation.
5) While switching off, turn off the LPG gas supply first. After the
flame goes off, switch off the compressor.
6) Inadequate air and more fuel would result in accumulation of
fuel gas, which will cause flame to appear above the chimney
and burn the chamber.
7) Ensure that all the end clamps are tight and that there is no
leakage. The leakage can be checked using soap solution at
the nozzle end.
Procedure :
1) Add 25 ml of NH4OACextracting solution to a conical flask
containing 5 gm air dry soil sample.
2) Shake on a reciprocating shaker at 200 to 220 oscillations per
minute for 5 min and filter.
3) Determine potassium as indicated in preparation of standard
curve, dilute if necessary.
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Calculation :
K (ppm) = Reading from graph μg K / ml in extract (R) x 5 x Dilution Factor (Df)
K (kg/ha) =
x
x
x
x
x
x
x Dilution Factor (Df)
K (kg/ha) = R x (25/5) x (1000/1) x (1/1000) x (1/1000) x (1/1000) x (2240000/1)
= R x 5 x 2.24 x Dilution Factor (Df)
K2O+ (kg/ha) = R x 11.20 x 1.2
To convert K to K2O multiplied by 1.2 and
to covert K2O to K multiply by 0.83.
Ratings :
Potassium (K) – kg/ha
Very low
Low
Moderate
Moderately high
High
Very high
Less than 120
121 – 180
181 – 240
241 – 300
301 – 360
Above 360
Reading from graph μg
K / ml in extract (R)
Aliquot used 25 ml
Soil used 5 g
1 Kg soil 1000 g
1
1
1000 to convert μg into mg
1
1000 to convert mg to g
1
1000 to convert gm into kg
Wt. of soil 2240000 kg/ha
1
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Reference Documents :
Ghosh A. B. and Bajaj J.C., Finanul Hasan and Dhyan Singh, 1983, Soil and
water testing methods, Laboratory Manual, P. 21-22 (ICAR Publication)
Knudsen D and G. A. Peterson, 1982, Lithium, Sodium and Potassium, P. 225 to
246, In A.L. Page (Ed.) Methods of Soil Analysis. Agronomy Monogram No. 9,
American Society of Agronomy, Inc. Soil Sci. Soc. Of America Inc. Publisher
Madison WB Consin, USA.
Somawanshi R. B., Tamboli B.D., Patil Y. M. and Kadu P. P., 1994, twenty Five
years of Research on soil test Crop Response Studies in Maharashtra. 1968 –
1993, M.P.K.V. Res. Publ. No. 14.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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8. DETERMINATION OF SODIUM ON FLAME PHOTOMETER :
Purpose :
Sodium affects the permeability of soil by causing swelling and
dispersion of clay particles and clogging the soil pores. It may also
the cause injury to crops specifically sensitive to sodium such as fruit
crops. An alkali soil also called sodic soil contain sufficient
exchangeable sodium to cause soil dispersion and increase the pH
thereby adversely affecting both the physical and nutritional
properties of the soil with consequent reduction in crop growth
significantly or entire.
Principle :
Available sodium includes exchangeable sodium and water soluble
sodium. Exchangeable sodium in soils varies from trace amounts to
a large portion of the exchange capacity depending on the soil
environment. Likewise water soluble sodium varies dramatically
depending on soil salinity level. Even though soils may have high
sodium saturations, the actual quantity of exchangeable sodium
compared with the total soil sodium content is generally small. The
exchangeable sodium in soils is determined by extracting with
neutral 1.0N ammonium acetate and then subtracting the water
soluble sodium. The correction for water soluble sodium is negligible
in many soils of the humid regions but is often important in the soils
of dry regions. The sodium is estimated by flame photometer.
Apparatus :
1) Flame Photometer
2) Beaker – 250 ml, 100 ml.
3) Volumetric measuring flask – 50 ml capacity
4) Measuring flask – 1 lit capacity.
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Reagents :
1) 1 N Ammonium Acetate - Dissolve 77.08 gm of ammonium
acetate in distilled water and make the volume to 1 lit. Adjust
the pH to 7.0 with glacial acetic acid or ammonia solution.
2) Standard Sodium Solution –
i)
Dissolve 2.542 gm of dried NaCl (AR at 110oC for 1 hr)
in distilled water and make the volume to 1 lit. i.e. 1000
ppm Na solution. 10 ml of 1000 ppm solution was
diluted to 100 ml. The concentration of the sodium is
100 ppm.
ii)
Take 2, 4, 6, 8 and 10 ml of 100 ppm Na solution in
separate 100 ml volumetric flask and make up volume
with distilled water. Thus 2, 4, 6, 8 and 10 ppm Na
solutions are maintained and readings are taken on the
flame photometer.
Precautions while handling flame photometer :
1) All the necessary safety precautions meeting the appropriate
specifications for use of LPG burner should be strictly
followed.
2) Never view the flame from the top of the chimney. It should
be viewed from the round viewing indicator provided on the
front side.
3) Ensure air is flowing through the burner before LPG is
allowed in to the burner and lighting it.
4) Always start the air compressor first and then the LPG gas to
avoid inadequate air and gas accumulation.
5) While switching off, turn off the LPG gas supply first. After the
flame goes off, switch off the compressor.
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6) Inadequate air and more fuel would result in accumulation of
fuel gas, which will cause flame to appear above the chimney
and burn the chamber.
7) Ensure that all the end clamps are tight and that there is no
leakage. The leakage can be checked using soap solution at
the nozzle end.
Procedure :
1)
Weigh 5 g of 2 mm sieved soil sample in 250 ml plastic
conical flask.
2)
Add 25 ml of the neutral 1N ammonium acetate solution and
shake for 30 minutes on mechanical shaker at 110 rpm. Filter
through whatman No. 1 filter paper.
3)
Take the readings on flame photometer.
4)
Feed the working standard solution and prepare a standard
curve.
5)
If the sample reading is not found within the standard reading
range in that case the appropriate dilution of the filtrate may
be made to bring the reading within standard range.
Observation Table :
Sr. No.
Lab.
Sample No.
Reading on flame photometer
for sodium
Sodium in ppm
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Calculation :
Na (ppm) =
x Dilution factor (Df)
=
x Dilution factor (Df)
= GR x 5 x Dilution factor (Df)
Where GR stands for concentration of Na obtained from the flame
photometer
ESP and SAR is calculated on the basis of sodium and Ca + Mg values.
SAR = Na+ / √(Ca+++Mg++)/2 Na+ , Ca++, Mg++ in meq/lit
ESP = 100(-0.0126+0.01475SAR) / (1-(-0.0126+0.01475SAR))
Rating :
Name of Soil
Sodium Adsorption Ratio
(SAR)
Exchangeable Sodium
Percentage (ESP)
Saline Soils
Alkali or Sodic Soils
Saline Alkali Soils
Degraded Alkali Soils
< 13
> 13
> 13
> 13
< 15
> 15
> 15
> 15
Salinity & Alkalinity Appraisal
Type of Soil
pH
EC dS/m
ESP %
Saline
< 8.5
> 4
< 15
Saline Alkali
> 8.5
> 4
> 15
Alkali
> 8.5
< 4
> 15
GR x Vol. of extractant
Corrected wt. of the soil
GR x 100
20
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Reference Documents :
Knudsen D., Peterson G. A. and Pratt P. F. 1982, Lithium, sodium
and potassium in methods of soil analysis – Chemical and
microbiological properties, 2nd edition of American Society of
Agronomy, Inc and Soil Science Society of America Inc., Madison,
Wisconsin, USA, Number 9 (Part-2), 13:238-241.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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9. DETERMINATION OF CALCIUM AND MAGNESIUM :
(E.D.T.A. TITRIMETRIC METHOD BY EL MAHI, et.al. (1987))
Purpose :
Calcium and Magnesium ions serve as plant nutrients in cation exchange capacity
of soils calcium and magnesium forms the predominant exchangeable base,
constituting 60 to 80% of total exchangeable cations.
Calcium clay and magnesium clay possesses excellent physical conditions. It
develops good crumb structure by virtue of the flocculation and aggregation of
primary particles allow free movement of water without stagnation and contains
sufficient air for the proper aeration of plant roots. Such a soil is highly productive
it supplies necessary plant nutrients.
Principle :
The method is based on the fact that ca, Mg and number of other ions from stable
complexes with versene (Ethylene diamine tetra acetic acid disodium salt) at
different pH and Sn, Cu, Mn, Zn may interfere in the determination of calcium and
Magnesium if present in appropriate amounts. Their interference is prevented by
use of 2% Nac N solution.
Apparatus :
1)
1 litre flaks
2)
Porcelain dishes 3” to 4” diameter
3)
Burette of 50 ml capacity
4)
Pipette of 5 ml and 10 ml.
5)
Beaker of 100 ml.
6)
Centrifuge tubes / polythene shaking bottle.
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Reagents :
1)
Standard Ca solution, 0.01 N : Weigh 0.05 gm CaCo3 and
dissolve in 10 ml of 2N HCl. Heat till the solution boils and
CO2 is completely driven off. Cool and make the volume
accurately to 1 litre.
2)
EDTA Solution : Dissolve 2 gm disodium EDTA in distilled
water and make the volume 1 litre. Standardize against
standard Ca Solution.
3)
NH4Cl – NH4OH buffer solution : Dissolve 67.5 gm NH4Cl in
570 ml of concentrated NH4OH solution and make 1 litre
volume.
4)
NaOH 10% : Add 10 gm NaOH to 90 ml distilled water.
5)
NH2OH.HCL : Dissolve 5 gm hydroxylamine hydrochloride in
100 ml of distilled water.
6)
K4Fe(CN)6 : Dissolve 4 gm potassium ferrocyanide in 100 ml
of distilled water.
7)
Triethanolamine : TEA.
8)
EBT : Dissolve 0.2 gm Erichrome black T in 50 ml of
methanol.
9)
Calcon indicator : Dissolve 20 mg calcon in 50 ml methanol.
10) Neutral normal ammonium acetate solution – Take 58 ml of
glacial acetic acid in 500 ml volumetric flask. Also take 71 ml
of concentrated ammonium hydroxide solution in another 500
ml volumetric flask. Dilute both the solutions with distilled
water upto the 2/3 volume and mix both in 1 lit. flask then
adjust pH to 7.0 and finally make up the volume to 1 lit. For
bringing pH of solution to 7, add dilute acetic acid or
ammonium hydroxide, or dissolve 77 gm/lit. NH4OAC and
adjust pH to 7 by acetic acid or ammonium hydroxide.
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Procedure :
Extraction :
1)
Weigh 2 – 4 gm of soil sample (2mm sieved) in conical flask
or polythene shaking bottle or 100 ml centrifuge tubes.
2)
Add 30 ml of NH4OAc and shake for 5 min and decant.
3)
Then add 30 ml of 0.5N HCl to each sample and agitate the
contents, shake for 5 min. in a upright loosened position.
4)
Then filter the solution using whatman No. 1 filter paper.
Collect the filtrate.
Estimation of Ca & Mg (determination of ca & Mg together) :
1)
Pipette out 20 ml of the filtrate into a 150 ml conical flask.
2)
Add 50 ml distilled water.
3)
Add 10-15 ml NH4Cl – NH4OH buffer solution and add 10
drops each of NH2OH.HCL, K4Fe(CN)6, TEA and EBT
indicator.
4)
Titrate with standard EDTA to permanent blue colour.
Determination of Calcium alone :
1) Pipette out 5 or 10 ml extract, add 10 drops each of
NH2OH.HCL, K4Fe(CN)6 and TEA and enough of 10% NaOH
to raise pH to 12.
2) Add 5 drops of calcon indicator.
3) Titrate against standard EDTA. The end point is the change
of colour from red to blue.
The value obtained from Ca plus Mg and Ca alone are used to
calculate the Ca and Mg in the soil samples respectively.
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Observation Table :
A)
For Ca determination :
Sr. No.
Lab. Sample No.
Burette reading
Ca meq/lit.
B)
For Ca + Mg determination :
Sr. No.
Lab. Sample No.
Burette reading
Ca + Mg meq/lit.
Calculations :
Meq (Ca + Mg) or Ca/100 gm
=
Meq (Mg) = Meq (Ca + Mg) – Meq (Ca)
ml. of EDTA required x Normality of EDTA (0.01) x vol. made 100 ml x 100
sample taken for titration (ml) x Weight of soil in gm.
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Reference Documents :
Devis J. and Freitas, 1970, Calcium plus Magnesium and Calcium in
Physical and Chemical Methods of Soil & Water Analysis, Food and
Agriculture Organization of the United Nations, Rome, Italy, Soil
Bulletin – 10 : 212-217.
Nelson R.E., 1982, Carbonate and Gypsum, In A. L. Page (Ed.).
Methods of Soil Analysis, Part-2. Agronomy 9 : 181-197. American
Society of Agronomy Ins. Soil Science Society of America Inc.,
Madison Wisconsin.
Somwanshi et.al., (1999), Analysis of Plants, Irrigation Water and
Soils, MPKV, Rahuri, P. 225-228.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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10. DETERMINATION OF CATION EXCHANGE CAPACITY IN SOIL
Purpose :
The Cation Exchange Capacity (CEC) is the capacity of soil to hold
an exchangeable cations. The higher the CEC of soil, the more
cations it can retain. Soil differ in their capacities to hold
exchangeable K+ and other cations. The cations exchange capacity
depends on amount and kind of clay and organic matter present.
High clay soil can hold more exchangeable cations than a low clay
soils. CEC also increases as organic matter increases. Clay mineral
usually range from 10 to 150 meq./100g. In CEC values organic
matter ranges from 200 to 400 meq/100g. So the kind and amount of
clay an organic matter content greatly influence the CEC of soil.
Cation exchange is an important reaction in soil fertility in causing
and correcting soil acidity and basisity.
1. Ammonium Saturation Method :
Principle :
1.
The cation exchange capacity (CEC) determination involves
measuring of total quantity of negative charges per unit
weight of the soil which are neutralize by the exchangeable
cations. It is defined as the capacity of the soils to adsorb the
sum total of exchangeable cations expressed as
milliequivalents per 100.0 gm of soil or C mol (P+)/kg of soil
on oven dry basis.
Clay particles and organic matter carry negative charges over
their surface due to which they adsorb positively charged
particles (cations). There are different types of cations e.g.
H+, Ca++, K+, NH4
+, Mg++ etc. These cations can replace each
other depending upon their concentration (mass action) and
replacing power. The replacement of cations by one another
is known as cation exchange. The order of replacing power of
some cations are given below –
H+ > Ca++ . Mg++ > K+ > NH4
+ > Na+ > Si++++
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2.
The CEC of different colloids are as follows –
Inorganic Colloid (average 8 to 100 me/100 gm soil)
Kaolinite
3 to 15 me/100 gm soil
Halloysite 2H2O
5 to 10 me/100 gm soil
Illite
10 to 40 me/100 gm soil
Chlorite
10 to 40 me/100 gm soil
Sepionite, Attapulgite,
20 to 40 me/100 gm soil
Polygorstite
Halloysite 4H2O
40 to 50 me/100 gm soil
Montmorillonite
80 to 150 me/100 gm soil
Vermiculite
100 to 150 me/100 gm soil
Organic colloid :
Humus
150-300 me/100 of material
3.
Soil is treated with 1(N) ammonium acetate at pH 7.0 to
saturate colloidal complex and the excess salt is removed
with methanol / ethanol (60%). Then the ammonium ion is
displaced with potassium by titrating with 10% potassium
chloride at pH 2.5 and finally the ammonia is measured by
distillation from alkaline solution, absorption in hydrochloric
acid and titration with standard acid.
Reagents :
1) Ammonium Acetate, 1N, pH 7.0 + 0.1 : Dissolve 77.08 gm of
ammonium acetate in distilled water and makeup the volume
to one litre. Adjust the pH at 7 with ammonia or acetic acid.
2) Potassium Chloride (10%, pH 2.5 + 0.1) : Dissolve 10 gm of
potassium chloride in distilled water and make up the volume
to 100 ml. Adjust the pH at 2.5 with 1N HCl.
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3) Methanol or ethanol, 60% : Dilute 60 ml methanol with
distilled water and make up the volume to 100 ml.
4) Sodium hydroxide, 40% : Dissolve 400 gm NaOH in water in
a 1 litre volumetric flask. Let it cooled and make it upto the
mark.
5) Methyl red : Dissolve 0.1 gm methyl red in 100 ml ethanol
(98%).
6) Hydrochloric acid (0.02N) : Take 1.8 ml of concentrated HCl
in one litre volumetric flask and make the volume with distilled
water.
Procedure :
1) Weigh 10.0 gm of 5 mm sieved air dried soil sample into 500
ml plastic conical flask. Add 250 ml of neutral ammonium
acetate solution.
2) Shake the contents on mechanical shaker at 110 rpm for an
hour and keep it over night. Next day again shake it for 1
hour.
3) Filter the contents through Whatman No. 1 filter paper
receiving the filtrate in a 250 ml volumetric flask.
4) Transfer the soil completely on the filter paper and continue to
leach the soil with the neutral solution (using 20-25 ml at a
time).
5) Allowing the leachate to drain completely before fresh aliquot
is added. If it is not enough add some ammonium acetate to
make up the mark. The solution is now ready for
determination of individual cations.
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6) The residue left on the filter paper is intended for the
determination of cation exchange capacity of soil. Wash the
leached soil with 60% methanol or ethanol to remove the
excess ammonia. Each time 10 ml of alcohol in interval is
added, draining between each addition is necessary.
Nessler’s reagent does the test of ammonia. If Nessler’s
reagent is not available the test of ammonia is done by HCl.
7) Collect the leachable washing of ethanol / methanol in watch
glass and add few drops of concentrated HCl if it fumes that
indicates presence of ammonia otherwise not. After washing,
the soil is leached with acidified potassium chloride (10%, pH
= 2.5+0.1) and the extract is collected finally in a 250 ml
volumetric flask.
8) 25–30 ml of KCl solution is added. Each time draining
between each addition is necessary. The volume is adjusted
to the mark by the replacing solution of KCl. It is shaken to
make the concentration solution homogeneous.
9) Transfer 20 ml of KCl leachate and 10 ml of distilled water in
a Gerhardt tube, add 10 ml of 40% NaOH and distilled into 20
ml of HCl (0.02N) containing 6 drops of methyl red indicator.
The approximate distillate is collected about 150 – 200 ml.
Titrate the solution until the yellow colour appears with 0.02N
NaOH.
10) The changes from red to yellow, the end point being taken at
the first appearance of the yellow colour. 20 ml of 10% KCl
solution is distilled in the same manner for blank.
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Calculations :
Let D = The weight of oven dry soil in the weight of air dry soil
taken for analysis.
V = The total volume of the final solution containing the
ammonium ion.
T = The volume of standard acid (0.02N) used for titrating the
ammonia nitrogen after correction for the blank.
N = Normality of standard acid 0.02N
If 20 ml of ammonium solution is distilled,
V ml contains
milliequivalents =
Thus, Cation exchange capcity =
meq/100 gm of soil.
If 10 ml ammonium solution is distilled,
Cation exchange capacity =
meq/100 gm of soil.
Notes :
The ammonium acetate method is suitable for neutral and
non-calcareous soils, since displacement of hydrogen ions
from acid soils may be incomplete. The extraction with
ammonium acetate is also a reliable method for determination
of CEC of acid soils if it is combined with another method for
measurement of exchange acidity. The exchangeable
calcium, magnesium, sodium, potassium and manganese are
determined in the ammonium acetate extract and exchange
acidity (exchangeable hydrogen plus exchangeable
aluminium), is determined with 1N KCl or barium chloride
triethanolamine. The sum of all the exchangeable cations
then gives a good estimate of CEC.
0.01 T V
20 D
1 T V
2000
NTV x 100
20 D
NTV x 100
10 D
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To ensure that the saturating cation displaces all the
exchangeable cations, it is advisable to use on an average 25
parts of solution to 1 part of soil. Sandy soils low in exchange
capacity may be extracted satisfactorily at a ration less than
this, but on the other hand clay soils particularly organic ones,
may need to be treated at a ratio of 40:1 or 50:1 for accurate
results. Similarly consideration apply to the replacement
process.
For heavy clay soils it is better to take 5.0 gm of soil for
analysis.
After washing do not allow the soil to dry out as this may
cause less of absorbed ammonia.
Take the soil sample for analysis after sieving with 0.5 mm
sieve.
The Nessler’s reagent is prepared by dissolving 45.5 gm of
mercuric iodide and 35.0 gm of potassium iodide (Kl) in a few
ml. of water.
HgI2 + 2 KI
K2HgI4
The solution is transferred into a 1 litre volumetric flask. Then
112.0 gm of KOH is added and the volume is brought to
about 800 ml. The solution is mixed well, cooled and diluted
to 1 litre with water. The solution is allowed to stand for few
days and the clear supernant liquid (Nesslers’ reagent) is
decanted off into amber coloured bottle for use.
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2 . Sodium Saturation Method ( Bower et. al. ) :
Reagents :
1)
1 N Sodium Acetate - Dissolve 136 gm of sodium acetate in
distilled water and transfer solution to 1 litre volumetric flask. Make
the volume to 1 litre with distilled water. Add few drops of acetic acid
or few pellets of NaOH to adjust the pH to 8.2
2)
1 N Ammonium Acetate – Dissolve 77 gm of ammonium acetate
in distilled water and make the volume to 1 litre in volumetric flask.
Adjust the pH to 7.0
3)
99% Isopropyl Alcohol
4)
1000 ppm Na Solution – Transfer 2.541 gm of pure dry NaCl
equivalent to 1 gm Na in to 1 litre volumetric flask. Add distilled
water and mix the contents by shaking
5)
250 ppm Na Solution – Transfer 25 ml of 1000 ppm Na solution
in to 100 ml flask and dilute the solution with distilled water up to 100
ml mark.
6)
0 to 20 ppm Na Solution – Transfer 0,2,4,6,8 ml of 250 ppm Na
solution in separate 100 ml volumetric flasks. Add 1 N ammonium
acetate (pH 7.0) to each flask to make the volume to 100 ml mark for
obtaining 0,5,10,15 and 20 ppm Na solution. Add few drops of butyl
alcohol in each flask to improve spraying property of the solution.
Procedure :
1) Preparation of Standard Curve for Sodium – Prepare standard
curve as per procedure given in test for sodium
2) Preparation of Soil Extract for CEC Determination – Weigh 6 gm
of coarse textured or 4.5 gm of medium or fine textured soil passing
through 2 mm sieve in to 50 ml centrifuge tubes. Add 33 ml of 1 N
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sodium acetate (pH 8.2) and triturate with a glass rod for 5 minutes
and centrifuge the tubes at 2000 to 2440 rpm for 10 minutes or till
supertanant liquid becomes clear, placing the tubes opposite to each
other. Decant supertanant liquid. Repeat the procedure twice to
complete the process of saturation of the exchange complex with
sodium. Wash the soil saturated with sodium in identical manner
with three 33 ml 99% isopropyl alcohol washings. This will remove
soluble sodium acetate in soil without causing any hydrolysis of
exchangeable sodium.
3)
Determine the concentration of sodium in CEC extract as per
procedure given for determination of sodium.
Calculations :
Meq of Na / litre in CEC extract = ppm Na in CEC undiluted extract / Eq. Wt. of Na
Meq of Na / 100 gm of soil
= Meq of Na / litre in CEC extract x 100
10 x Soil in gm taken for preparation of CEC extract
CEC of Soil = meq of Na / 100 gm soil
Ratings :
Result
Low
Medium
High
Very High
CEC meq/100 g
or
C mole (P+)/kg.
Less than 10
10 - 25
25 - 45
More than 45
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Reference Documents :
Devis J. and Freitas, 1970, Cation Exchange Capacity, Physical and
Chemical Methods of Soil & Water Analysis, Food and Agriculture
Organization of the United Nations, Rome, Italy, Soil Bulletin – 10 :
94-130.
P. C. Jaiswal, 2003, Soil, Plant and Water Analysis, Kalyani
Publishers, p 123-126
Soil Testing Manual of B.Sc.(agri.) 2007, Marathwada Agricultural
University, Parbhani, P. 33.
Notes on Soil Science, DIRD, Pune, 2008, P. 196.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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C. RECLAMATION OF PROBLEMATIC SOIL
1. DETERMINATION OF GYPSUM REQUIREMENT OF SOIL
Principle :
Gypsum requirement of alkali soils can be determined by treating
the soil with known amount of excess saturated gypsum solution,
and then estimating the unreacted or unutilized amount by versenate
titration method as suggested by Schoonover (1952). Though, Ca
can be estimated by other methods also but the versene titration is
more suitable.
Instrument : Mechanical shaker.
Reagents :
Saturated gypsum solution : Add 5 g of chemically pure
CaSO4.2H2O to one litre of distilled water. Shake vigorously for 10
min. using a mechanical shaker and filter through Whatman No. 1
paper.
0.01N CaCl2 solution : Dissolve exactly 0.5 g of AR grade CaCO3
powder in about 10 ml of 1:3 diluted HCl. When completely
dissolved, transfer to 1 litre volumetric flask and dilute to the mark
with distilled water. CaCl2 salt being highly hygroscopic should not
be used.
0.01N Versenate solution : Dissolve 2.0 g of pure EDTA-disodium
salt and 0.05 g of magnesium chloride (AR) in about 50 ml of water
and dilute to 1 litre. Titrate a portion of this against 0.01N CaCl2
solution to standardize.
Erichrome black T indicator : Dissolve 0.5 g of EBT dye and 4.5 g
of hydroxylamine hydrochloride in 100 ml of 95% ethanol. Store in a
stoppered bottle or flask.
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Ammonium hydroxide - ammonium chloride buffer : Dissolve
67.5 g of pure ammonium chloride in 570 ml of conc. ammonia
solution and dilute to 1 litre. Adjust the pH at 10 using dil. HCl or dil.
NH4OH.
Procedure :
1.
Weigh 5 g of air dry soil in 250 ml conical flask.
2.
Add 100 ml of the saturated gypsum solution. Firmly put a
rubber stopper and shake for 5 minutes.
3.
Filter the contents through Whatman No. 1 filter paper. Entire
quantity needs to be filtered.
4.
Transfer 5 ml aliquot of the clear filtrate into a 100 or 150 ml
porcelain dish.
5.
Add 1 ml of the ammonium hydroxide – ammonium chloride
buffer solution and 2 to 3 drops of Erichrome black T
indicator.
6.
Take 0.01N versenate solution in a 50 ml burette and titrate
the contents in the dish until the wine red colour starts
changing to sky blue.
7.
Run a blank using 5 ml of the saturated gypsum solution in
place of sample aliquot.
Calculation :
Ca or Ca+Mg (me/L) in the aliquot = 2 V
Where, V stands for volume of versenate solution used.
Since, 1 litre extract = 50 g soil (5 g soil to 100 ml)
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Ca retained (or Ca requirement) in me/100 g soil
= [2V for added gypsum solution – 2V for filtrate] x 2 ….. (A)
Gypsum requirement of soil in tons per hectare
upto 30 cm soil depth
= A x 3.852
Apply correlation depending on purity of gypsum.
Reference Documents :
Singh, Dhyan, Chhonkar, P.K. and Pande R.N., 1999, Assessment
of Irrigation Water Quality in “Soil, Plant, Water Analysis” - A
methods manual, Indian Agricultural Research Institute, Indian
Council of Agricultural Research, New Delhi, 3 : 48-50.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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D. WATER SAMPLE ANALYSIS
1.
DETERMINATION OF pH
Principle :
The determination of pH of water sample is based on the same
principle as mentioned in section of pH determination of soil.
Apparatus :
i)
pH meter with glass electrodes
iii)
Thermometer
Reagents :
Standard buffer solution – Dissolve one commercially available
buffer tablet each of pH 4.0, 7.0 and 9.2 in freshly prepared distilled
water separately and make up the volume to 100 ml. Prepare the
fresh solution every week as these solutions do not keep for long.
Three to four drops of toluene are added in standard buffer solutions
to prevent growth of mould.
Procedure :
1)
Turn the pH meter ON and allow it to warm for 15 minutes.
2)
Standardize the glass electrode using standard buffer of pH
7.0 and calibrate with the buffer pH = 4 or pH = 9.2.
3)
Take 50 ml of filtered water sample in 10 ml beaker and
immerse the glass and calomel electrodes or combined
electrode of the pH meter. Never allow the lower portion of
glass electrodes to touch the bottom of the beaker.
4)
While recording pH, switch the pH meter to pH reading, wait
for 30 seconds and record the pH value to the nearest 0.1
unit. Put the pH meter in stand by mode immediately after
recording.
5)
Remove the electrodes after each determination and carefully
blot them dry with filter paper before the next determination.
Standardize the glass electrodes after every ten
determinations.
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6)
Keep the electrodes in distilled water, when not in use and
ensure that the reference electrode always contains saturated
potassium chloride solution in contact with solid potassium
chloride crystals.
Based on pH values, neutral water can be divided into 3 classes –
1) Those, which contain carbonates, with or without
bicarbonates, do not have free carbonic acids. The pH value
of these waters are always above 8.0.
2) Those, which contain no carbonates but contain bicarbonates
and carbonic acid, the pH values of these waters range from
4.5 to 8.0. Most of neutral waters fall under this category. The
pH value of neutral water usually lie between 6.5 and 7.5.
3) Those which contain free acid in addition to carbonic acid, do
not contain carbonates or bicarbonates. The pH value of
these water is 4.5 or below 4.5.
Reference Documents :
Devis J. and Freitas, 1970, Analysis of Water and Water Extracts,
Physical and Chemical Methods of Soil & Water Analysis, Food and
Agriculture Organization of the United Nations, Rome, Italy, Soil
Bulletin – 10 : 208.
Singh, Dhyan, Chhonkar, P.K. and Pande R.N., 1999, Assessment
of Irrigation Water Quality in “Soil, Plant, Water Analysis” - A
methods manual, Indian Agricultural Research Institute, Indian
Council of Agricultural Research, New Delhi, 3 : 73-74.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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2.
DETERMINATION OF ELECTRICAL CONDUCTIVITY (EC) :
Principle :
The determination of electrical conductivity of water sample is based
on the same principle as mentioned in section under measurement
of electrical conductivity in soil.
Apparatus :
i)
EC meter
ii)
Thermometer
Reagent :
0.01N Potassium chloride solution : Dry a small quantity of A.R.
grade Potassium chloride at 60oC for 2 hours. Weigh 0.7456 gm of it
and dissolve in freshly prepared distilled water and make to one litre.
This solution gives and electrical conductivity of 1411.8 x 10-3 i.e.
1.41 dS/m at 25oC.
Procedure :
1) Calibrate the conductivity cell with the help of standard KCL
solution and determine the cell constant.
2) Dip the conductivity cell assembly in water sample taken in a 50
or 100 ml beaker and record the conductivity. If the value is too
low, change the adjustment accordingly. Record the temperature
of water during the test.
3) Observed values of EC are multiplied by the cell constant
(usually given on conductivity cell) and a temperature factor to
express results at 25oC.
4) Remove the cell from soil suspension, clean with distilled water
and dip into a beaker of distilled water. EC is expressed as dS/m.
5) Keep the conductivity cell in distilled water when not in use.
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Calculations :
The cell constant K is given by
Cell constant (K) =
ECw25 = ECT x K x ft
Where,
ECw25 is the conductivity of the water at 25oC.
ECT is apparent conductivity of water as measured.
K is the cell constant
Ft is temperature correction factor. (See Annexure No. 9).
• The EC values can either be used as such categorizing the water on
salinity basis or may be used to get the concentration as given
below –
• Salt concentration (mg/L) = EC in dS.m
–1 at 25oC x 640
• Salt concentration in me/L (approx) = EC in dS.m
–1 at 25oC x 10
Note :
• Even if the scale is marked to read directly, it is necessary to check /
calibrate the instrument with the standard KCl solution.
• Now a day, the temperature correction factor is provided in the
instrument itself. Measure the temperature of the solution.
Known conductivity of 0.01 N KCL
Conductivity of 0.01 N KCL measured
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• Depending on ECw values, irrigation waters are classified in
following classes –
Class
Low
salinity C1
Medium
salinity C2
High
salinity C3
Very high
salinity C4
ECw in dS.m–1
< 025
0.25 to 0.75 0.75 to 2.25
> 2.25
Reference Documents :
Singh, Dhyan, Chhonkar, P.K. and Pande R.N., 1999, Assessment
of Irrigation Water Quality in “Soil, Plant, Water Analysis” - A
methods manual, Indian Agricultural Research Institute, Indian
Council of Agricultural Research, New Delhi, 3 : 74-75.
Diagnosis and improvement of saline & alkali soils – United States
Salinity Laboratory Staff, Agricultural Handbook No. 60, United
States of Agriculture, P. 79-81.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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3.
DETERMINATION OF CARBONATES AND BICARBONATES
Principle :
Carbonate and bicarbonate ions in the sample can be determined by
titrating it with against standard sulphuric acid (H2SO4) using
phenolphthalein and methyl orange as indicators. Addition of
phenolphthalein gives pink red colour in the presence of carbonates
and titration with H2SO4 converts these CO3
- into HCO3
- and
decolourises the red colour as shown below –
2 Na2CO3 + H2SO4
2 NaHCO3 + Na2SO4
Thus the carbonates neutralization is only half way. These
carbonates along with the already present ones are then determined
by continuing the titration using methyl orange indicator which gives
yellow colour in presence of bicarbonates. On complete
neutralization of bicarbonates the yellow colour will change to red.
2 NaHCO3 + H2SO4
Na2SO4 + 2 H2O + 2 CO2
Obviously the bicarbonate titre value will be less if carbonates were
not present. (absence of pink colour). In such a situation, either the
same aliquot is used for bicarbonate titration or a fresh sample is
analyzed for this. If carbonates are present and neutralized, the
volume of H2SO4 used in the first phase (carbonate titration) is to be
doubled to get the actual volume needed for complete neutralization
of the carbonates.
Reagents :
1) Saturated H2SO4 (0.01N) : Carefully add 2.8 ml of conc.
H2SO4 to one litre volumetric flask and dilute to one litre with
distilled water, the strength will be approximately 0.1N H2SO4.
Dilute 100 ml of this solution to 1 litre to obtain 0.01N H2SO4.
Standardize it against primary standard, Na2CO3.
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2) Standard Na2CO3 (0.01N) : Dissolve 5.3 gm of A.R. grade
Na2CO3 in one litre volumetric flask with distilled water, the
strength will be 0.1N Na2CO3. Dilute 100 ml of this solution to
get 0.01N. This may be used for standardization of 0.01N
H2SO4.
3) Phenolphthalein (0.25%) : Dissolve 25 gm of pure
Phenolphthalein powder in 100 ml of 60% ethyl alcohol.
4) Methyl Orange (0.50%) : Dissolve 0.5 gm of dry methyl
orange powder in 100 ml of 95.0% ethyl alcohol.
Procedure :
1) Transfer 25 ml of water sample to a 150 ml conical flask. Add
2-3 drops of Phenolphthalein.
2) If pink red colour appears, titrate it against standard H2SO4 till
colour disappears. The burette reading (volume used) is
designated as Y ml.
3) To this colourless solution or in original sample (25 ml) add 2-
3 drops of methyl orange. This will develop the yellow colour.
4) Again titrate with standard H2SO4 till colour changes from
yellow to rosy red. Record the volume of H2SO4 as Z ml. This
volume corresponds to initial carbonate changed to
bicarbonates plus initial bicarbonates present in irrigation
water.
5) Run a blank (25 ml distilled water) and subtract from the titre
value to avoid error due to any impurity of chemicals.
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Calculations :
a)
Carbonates (milliequivalents / litre) CO3
2 (me/L)
=
b)
Bicarbonates (milliequivalents / litre) HCO3
- (me/L)
=
Here Y is the burette reading (ml of H2SO4) after phenolphthalein is
neutralized and Z is the final burette reading (total volume of H2SO4)
after methyl orange.
Reference Documents :
Singh, Dhyan, Chhonkar, P.K. and Pande R.N., 1999, Assessment
of Irrigation Water Quality in “Soil, Plant, Water Analysis” - A
methods manual, Indian Agricultural Research Institute, Indian
Council of Agricultural Research, New Delhi, 3 : 76-78.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
2 ( Y – B) x Normality of H2SO4 x 1000
Sample in ml.
(Z – B) – 2 (Y – B) x Normality of H2SO4 x 1000
Sample in ml.
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4.
DETERMINATION OF CALCIUM AND MAGNESIUM
(EDTA TITRIMETRIC METHOD) :
Principle :
The extent of sodium hazard in irrigation water is determined in
terms of the sodium concentration in relation to the two useful
divalent cations namely Ca++ and Mg++. The most common method
of calcium and magnesium determination in irrigation water is by
complexometric titration using sodium salt of ethylene-diamine tetra
acetic acid. (EDTA).
Ethylene diamine tetra acetic acid (EDTA) form soluble complexes
with calcium and magnesium ions at an optimum pH of 10.0 and
thus removing them from solution without precipitation. The reaction
is stoichiometric and essentially instantaneous at temperature near
60oC and the complex formed are very stable. At the same pH the
dye erichrome blue-black B has a turquoise blue colour in the
absence of calcium and magnesium ions but forms red compounds
with them which are less stable than the EDTA-Ca and EDTA-Mg
complexes. The formation of Ca and Mg complexes at pH 10.0 is
achieved by using ammonium hydroxide-ammonium chloride buffer.
A number of polyvalent ions are preferably complexed by EDTA as
these are less dissociated than those of Ca and Mg and thus
included in the titration. Fortunately, the concentration of such
interfering metals e.g. Fe, Cu, Pb, Cd, Zn, Co and Mn is quite low
and negligible in most waters and can be ignored. However, the
interference, if high, can be prevented by using 2% solution of NaCl.
If the sample is made strongly alkaline (pH about 12.0), magnesium
is selectively precipitated as magnesium hydroxide. At the same pH
Patton and Reeder’s indicator / ammonium purpurate (murexide)
forms a red compound with calcium ions but is not affected by
magnesium present as magnesium hydroxide. If EDTA is then
closely added, the calcium ions are gradually transferred from the
dye complex to the more stable EDTA complex until when all have
been transferred, the liquid acquired a pure turquoise blue colour.
The reaction is virtually instantaneous at normal room temperature.
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Reagents :
1)
Standard Calcium Chloride Solution (0.01N) : Dissolve
exactly 0.5005 gm of A.R. grade CaCO3 (dried at 150oC) in
minimum (about 10 ml) of 0.2N HCl (AR). Boil gently to expel
the CO2. Cool and neutralize the excess acid with ammonia
(pH near 5.0). Then make the volume accurately to 1 litre.
This solution is for standardizing EDTA.
2)
EDTA 0.01N :
Dry the disodium salt of EDTA
(Na2H2C10H12O8N2.2H2O) at 80oC for about 2 hrs and cool in
a desiccator. Dissolve 1.8613 in one litre of distilled water.
3)
Ammonium Hydroxide – Ammonium Chloride Buffer (pH
10.0) : Dissolve 67.5 gm of ammonium chloride (NH4Cl) in
200 ml of distilled water. Add 570 ml of concentrated
ammonium hydroxide (NH4OH) and dilute the solution to a
volume of 1 litre with distilled water and adjust the pH at 10.0.
4)
Erichrome Black T Indicator : Homogenize 0.2 gm of EBT
in 50 gm of KCl or NaCl. Erichrome blue-black – B, 0.5% in
ethanol. Dissolve 0.5 gm Erichrome blue-black – B in 100 ml
of 95% of ethanol.
5)
Standard Magnesium Chloride (0.01N) : Dissolve 1.0165
gm magnesium chloride (MgCl2,6H2O) in distilled water and
make up the volume to 1 litre with distilled water. Standardize
by titration with 0.01N EDTA and dilute to 0.01N exactly.
6)
Sodium Hydroxide (10%) : Dissolve 10 gm of NaOH in 100
ml of distilled water.
7)
Patton’s and Reeder’s Indicator (HHSNN Indicator) : Mix
1.0 gm of HHSNN intimately with 100 gm anhydrous sodium
sulphate. Store in a dark bottle away from light. If Patton’s
and Reeder’s indicator is not available, Murexide indicator
may be used.
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8)
Murexide Indicator : Take 0.2 gm of murexide (also known
as ammonium purpurate) and mix it with 40 gm of powdered
potassium sulphate. This indicator is kept in powdered form
as it goes oxidized in the solution form.
Procedure for Ca + Mg :
1)
Take 25 ml of sample in 100 ml of conical flask and dilute the
content by adding about 25 ml of distilled water.
2)
Add 4 ml of NH4Cl + NH4OH buffer (see note). Warm to about
60oC (see note).
3)
Add a pinch of EBT indicator and titrate with 0.01 N EDTA to
a pure turquoise blue without any traces of red. This titre
value may be considered as “A”.
4)
Before carrying out a batch of determinations, titrate 20 ml
0.01N magnesium chloride with 0.01N EDTA in order to
check the EDTA concentration and provide a pure blue
standard for use in the subsequent titration.
Procedure for Calcium (Ca++) :
1)
Take 10 ml water sample in 100 ml of conical flask and dilute
the content by adding about 25 ml of distilled water.
2)
Add approximately 5 ml of 10% NaOH solution to raise the pH
to 12.0. warm to about 60oC.
3)
Add a pinch of HHSNN indicator mixture or Murexide
indicator and titrate with 0.01N EDTA to a pure turquoise blue
without any traces of red. This titre value may be considered
as “B”.
4)
Before carrying out a batch of determinations, titrate 20 ml
0.01N calcium chloride. (A little 0.01N Magnesium chloride
may be added) with 0.01N EDTA in order to check the EDTA
concentration.
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Calculations :
Ca2+ + Mg2+ milli equivalents per litre (me/L) of water
=
=
(1 ml of o.o1N EDTA = 0.01 me of Ca or Ca+Mg or Mg in given
aliquote).
Ca2+ (me/L)
=
=
Mg2+ (me/L)
=
me / L (Ca2+ + Mg2+) – me / L (Ca2+)
Notes :
Erichrome blue – black B is stable in solution for some weeks,
whereas erichrome black T must be used in solid form to give
good colours.
Erichrome blue – black B is sodium 1 – (1-hydroxy = 2-
naphthylazo) – 2 – naphthol – 4 – Sulphonate; erichrome
black T contains a nitro group in addition and is sodium 1 – (1
– hydroxy – 2 – naphthylazo) – 6 – nitro – 2 – naphthol – 4 –
sulphonate.
ml of EDTA x Normality of EDTA x 1000
water sample (ml)
A (titre value) x 0.01 N x 1000
water sample (ml)
ml of EDTA x Normality of EDTA x 1000
water sample (ml)
B (titre value) x 0.01 N x 1000
water sample (ml)
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Add 5 ml of buffer to 50 ml water and read the pH, which
should be 10.0 + 0.1. Adjust the volume of buffer in sample to
bring the pH 10.0
Preliminary tests with about 50 ml water the time of heating to
bring the volume of water to near 60oC (say about 2 minutes).
In routine work, time is more convenient than temperature
measurement for determination.
The HHSNN colour sometimes tends to fade rather quickly
and a permanent blue standard cannot normally be used for
matching. If HHSNN is not available, murexide may be used
although the colour change is much less satisfactory.
Atomic absorption spectrophotometry may be used to
determine calcium and magnesium separately, if the
equipment is available.
Reference Documents :
Page A. L., Miller R.H., and Keeney D.R., 1982, calcium and
Magnesium by EDTA titrimetry in Method of Soil Analysis, Chemical
& microbiological properties, 2nd ed., American Society of Agronomy,
Ins and Soil Science Society of America, Inc, Madison, Wisconsin,
USA, 9(2) : 252-256.
Devis J. and Freitas, 1970, Calcium plus Magnesium, Physical and
Chemical Methods of Soil & Water Analysis, Food and Agriculture
Organization of the United Nations, Rome, Italy, Soil Bulletin – 10 :
212-215.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
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5.
DETERMINATION OF SODIUM ON FLAME PHOTOMETER :
Principle :
Irrigation water may have two types of hazards viz. salinity and
sodium hazard. The latter is expressed as the residual sodium
carbonate (RSC) and sodium adsorption ratio (SAR). Sodium
constitutes 50% or more of cations of saline and sodic water. The
content of sodium may be quite high in saline water with EC greater
than 1 ms/cm, and containing relatively less amount of Ca+2 and
Mg+2.
At higher levels, it also exerts a toxic effect on plant growth.
Therefore determination of sodium in irrigation water is very
important for predicting its harmful effect on soil and crops and
judging the suitability of water for irrigation. The concentration of
sodium in water sample is determined by flame photometer.
Reagents :
Standard Stock Solution (100 me Na / L) : Dissolve 5.845 gm of
AR grade dried NaCl in water and make the volume to 1 litre with
distilled water.
Working Standard Solution of Na : Dilute 5, 10, 15, 20, 30, 40 &
50 ml portions of the stock solution (containing 100 me Na / L) to
100 ml in volumetric flasks to get working standards of 5, 10, 15, 20,
30, 40 & 50 me Na / L concentrations.
Procedure :
1)
Filter a portion of the water sample if suspended material is
visible. Filtration is desirable as it prevents chocking of the
capillary tune of the flame photometer.
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2)
Take the working standard solutions and record the flame
photometer reading against each, after sterling zero with
distilled water and 100 with highest concentration i.e. 50 me
Na / L.
3)
Feed the test sample and record the reading.
4)
Draw a standard curve by plotting the readings against Na
concentrations.
Calculations :
1)
Na concentration in water (me/L) is directly obtained from X-
axis against reading.
2)
Residual Sodium carbonate (RSC) : The residual sodium
carbonate may be calculated by subtracting the quantity of
Ca2+
+ Mg2+
from the sum total of carbonates and
bicarbonates determined separately in a given sample and
expressed in me/L. Thus,
RSC = [ CO3
= + HCO3
- ] – [ Ca++ + Mg++ ]
3)
Sodium Adsorption ratio (SAR) : Sodium adsorption ratio is
calculated using the formula –
SAR =
4)
Quality of irrigation water is judged by RSC as under -
Class
1
2
3
RSC meq/litre
< 1.25
1.25 to 2.5
> 2.5
Interpretation
Safe
Marginal
Unsuitable
Na+
Ca++ + Mg++
2
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Note :
When water sample contains lower Na (meq/L), prepare the
standard range as 1, 2, 4, 6, 8 and 10 meq/L from stock solution
(100 me Na / L)
Reference Documents :
Singh, Dhyan, Chhonkar, P.K. and Pande R.N., 1999, Assessment
of Irrigation Water Quality in “Soil, Plant, Water Analysis” - A
methods manual, Indian Agricultural Research Institute, Indian
Council of Agricultural Research, New Delhi, 3 : 78-79.
Diagnosis and improvement of saline & alkali soils – United States
Salinity Laboratory Staff, Agricultural Handbook No. 60, United
States of Agriculture, P. 79-81.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
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6
DETERMINATION OF CHLORIDE :
Principle :
Chlorides being highly soluble are present in water but the amounts
is often very low in natural water. However, their contents may be
appreciable when the electrical conductivity is high. The
determination of chloride is easily made by AgNO3 titration (Mohr’s
titration) method in which silver reacts with chloride forming while
AgCl precipitate in the presence of sulphuric acid. When all the
chlorides are precipitated, potassium chromate (the indicator used)
shows the brick red colour at the end point due to the formation of
silver chromate. The reaction involved are as follows –
AgNO3 + Cl-
AgCl + NO3
(white ppt.)
K2Cr2O4 + 2 AgNO3
Ag2Cr4
+ 2 KNO3
(Brickish red ppt)
Initially the Cl- ions are precipitated as AgCl and dark brick red
precipitate of Ag2CrO4 starts just after the precipitation of AgCl is
over.
The optimum acidity for the reaction is about pH 3.0 since the
amount of carbonates and bicarbonates present is known from
determinations. This optimum pH or one near it may easily be
obtained by adding a calculated volume of standard sulphuric acid.
Reagents :
1)
Standard sodium chloride solution (0.02N) : Dry AR grade
NaCl in oven at 80oC for one hour and dissolved 1.170 g in
distilled water and make up the volume to one litre.
2)
Standard Silver Nitrate Solution (0.02N) : Dissolve 3.40 g
AgNO3 in distilled water and make up the volume to one litre.
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3)
Potassium Chromate Indicator (5%) : Dissolve 5.0 g of
K2CrO4 in 100 ml of distilled water.
Procedure :
1)
Transfer 25 ml of water sample to a 150 ml of conical flask.
2)
Add 0.01N H2SO4 with methyl orange to neutralize the
amount of carbonate and bicarbonate and provide 1 ml in
excess.
3)
Add 5-6 drops of potassium chromate indicator making it dark
yellow.
4)
Titrate the contents against 0.02N AgNO3 solution with
continuous stirring till the first brick red tinge appears. Note
the volume of the AgNO3 required (ml.)
5)
Run a blank of 25 ml of distilled water and subtract from the
titre value to avoid error due to any impurity of chemicals.
6)
Determine the normality of AgNO3 by standardizing it against
NaCl solution.
Calculation :
Chloride (meq/lit.) =
Where N = Calculated normality of AgNO3,
B = Blank Titre value
Notes :
1)
After appearance of white AgCl precipitate, add AgNO3 drop
wise to get exact start of red precipitation.
2)
Always store silver nitrate in dark amber coloured bottle.
(V – B) x N x 1000
sample (ml)
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Reference Documents :
Devis J. and Freitas, 1970, Calcium plus Magnesium, Physical and
Chemical Methods of Soil & Water Analysis, Food and Agriculture
Organization of the United Nations, Rome, Italy, Soil Bulletin – 10 :
231-232.
Jackson M.L., 1967, Chloride Determination, in Soil Chemical
Analysis, Prentice hall of India Pvt. Ltd., New Delhi, 10:261-263.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
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Master copy
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7.
DETERMINATION OF SULPHATE ON SPECTROPHOTOMETER
(CHESNIN AND YIEN)
Principle :
The traces of sulphate occur universally in all types of waters. Its
content may be appreciable in most saline water showing EC
greater than a dS/m (25oC). Sulphate can be determined
turbidimetrically.
The sulphate content is determined by the extent of turbidity created
by precipitated barium Sulphate suspension. Barium chloride is
added to ensure fine and stable suspension of BaSO4 at a pH of
about 4.8. It also eliminates the interface of phosphate and silicate.
Fine suspension of BaSO4 is stabilized by Gum Acacia and the
degree of turbidity measured by Turbidimeter or Spectrophotometer.
Reagents :
1)
Barium Chloride Crystals (AR grade) : Pure BaCl2 crystals
ground to pass through 0.5 mm sieve but retained on a 0.25
mm sieve.
2)
Gum Acacia (stabilizing reagent) : Dissolve 0.25 g of gum
acacia in 100 ml of distilled water. Keep overnight and filter.
3)
Sodium Acetic Acid Buffer : Dissolve 100 g of pure sodium
acetate in 200 ml of distilled water. Add 31 ml of glacial acetic
acid and make volume to one litre. The solution pH should be
4.8.
4)
Standard Sulphate Stalk Solution : 10 me/L of SO4
-S :
Dissolve 0.870 g of AR grade potassium sulphate (K2SO4) in
about 800 ml of S free distilled water and adjust the volume to
one litre. The strength of solution will be 10me/L of SO4
-S.
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Preparation of Standard Curve :
1)
Take 25 ml volumetric flask, add 0.0, 1.0, 2.0, 4.0, 6.0, 8.0
and 10.0 ml of 10 me/L of SO4
-S (for obtaining a
concentration of SO4
-S 0.0, 0.4, 0.8, 1.6, 2.4, 3.2 and 4.0
me/L
2)
Add 7.5 ml of sodium acetate acetic acid buffer to maintain
the pH around 4.8, Add 2.0 ml of gum acacia and 1 g BaCl2
crystals and shake well. Make the volume of 25 ml mark by
adding distilled water. Invert the flask several times.
3)
Measure the turbidity after 30 minutes with
Spectrophotometer at 490 nm wavelength.
4)
From this standard curve SO4
-S content in the water is
determined.
Procedure :
1)
Pipette out 10 ml of water sample in the 25 ml of volumetric
flask.
2)
Add 7.5 ml sodium acetate acetic acid buffer to maintain the
pH around 4.8. Add 2 ml of gum acacia and 1.0 g BaCl2
crystals and shake well.
3)
Make the volume to 25 ml mark with distilled water, invert the
flask several times and measure the turbidity after 30 minutes
with spectrophotometer at 499 nm wavelength.
4)
If the water has EC > 1.0 dS/m, dilute it with distilled water to
bring the electrical conductivity around 1.0 dS/m.
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Calculation :
SO4- =
Where GR = SO4 (me/L) concentration from the standard curve. If
the dilution of the sample is done, the dilution factor may be taken
into account.
Notes :
Buffer solutions should be prepared very carefully so that it gives pH
of 4.8.
BaCl2 should be added as a solid crystal to the sulphate solution.
Reference Documents :
Singh, Dhyan, Chhonkar, P.K. and Pande R.N., 1999, Assessment
of Irrigation Water Quality in “Soil, Plant, Water Analysis” - A
methods manual, Indian Agricultural Research Institute, Indian
Council of Agricultural Research, New Delhi.
Diagnosis and improvement of saline & alkali soils – United States
Salinity Laboratory Staff, Agricultural Handbook No. 60, United
States of Agriculture.
Reference : ISO 9001 – 2000
Clause No. : 7.5.1
D. R. Pawar
Soil Survey Officer
Er. K. M. Shah
CEO / SE & Director
Prepared by
Approved by
Controlled Copy
Master copy
GR x 25
sample (ml)
110
E. APPENDICES
LIST OF APPENDICES
SECTION - A :
APPENDIX –1
International Atomic Weights
APPENDIX –2
Normality, Specific Gravity and Percent by weight of
Acids and Ammonia Reagent in the Laboratory
APPENDIX –3
Approximate pH values of some acid and alkali
APPENDIX –4
Preparation of 1000 ppm solutions of different elements
APPENDIX –5
List of the chemicals that serve as primary standard for
the respective reactions with their equivalent weights
APPENDIX –6
Preparation of Standard Solutions
APPENDIX – 7
Some Important Conversion Factors
APPENDIX – 8
Conversion factors for different elements
APPENDIX – 9
EC reading according to temperature
APPENDIX – 10 Some Indicator plants of nutrient deficiency
APPENDIX – 11 Instrument settings for flame atomic absorption analysis
APPENDIX – 12 Terminology
SECTION - B :
APPENDIX –1
General safe laboratory operation procedures
1.
General safe procedures
2.
Bases
3.
Acids
4.
Flammables & Combustibles
5.
Compressed gas cylinders
111
SECTION - A
APPENDIX - 1 : International Atomic Weights
Element
Symbol
At. Wt.
Element
Symbol
At. Wt.
Aluminium
Al
26.97
Neon
Ne
20.18
Antimony
Sb
121.76
Nickel
Ni
58.69
Argon
A
39.94
Arsenic
As
74.91
Columbium
Cb
92.91
Barium
Ba
137.36
Nitrogen
N
14
Beryllium
Be
9.02
Osmium
Os
190
Bismuth
Bi
209
Oxygen
O
16
Boron
B
10.92
Baltadium
Pd
106.7
Bromine
Br
79.92
Phosphorus
P
30.98
Cadmium
Cd
112.41
Platinum
Pt
195.23
Caesium
Cs
132.91
Potassium
K
39.09
Calcium
Ca
40.08
Praseodymium
Pr
140.92
Carbon
C
12.01
Protoactinium
Pa
231
Cerium
Ce
140.13
Radium
Ra
226.05
Chlorine
Cl
35.46
Radon
Rn
222
Chromium
Cr
52.01
Rhenjum
Re
186.31
Cobalt
Co
58.94
Rhodium
Rh
102.91
Copper
Cu
63.57
Rubidium
Rb
85.46
Disprosium
Dy
162.46
Ruthenium
Ru
101.7
Erbium
Er
167.2
Samarium
Sm
150.43
Europium
Eu
152
Scandium
Sc
45.1
Fluorine
F
19
Selenium
Se
78.96
Gadolinium
Gd
156.9
Silicon
Si
28.06
Gallium
Ga
69.72
Silver
Ag
107.88
Germanium
Ge
72.6
Sodium
Na
23
Gold
Au
197.2
Strontium
Sr
87.63
Hafnium
Hf
178.6
Sulphur
S
32.07
Helium
He
4
Tantalum
Ta
180.88
Holmium
Ho
163.5
Tellurium
Te
127.61
Hydrogen
H
1.01
Terbium
Tb
159.2
Indium
In
114.76
Thallium
Tl
204.39
Iodine
I
126.92
Thorium
Th
232.12
Iridium
Ir
193.1
Thulium
Tm
169.4
Iron
Fe
55.84
Tin
Sn
118.7
Kripton
Kr
83.7
Titanium
Ti
47.9
Lanthanum
La
138.92
Tungsten
W
183.92
Lead
Pb
207.21
Uranium
U
238.07
Lithium
Li
6.94
Vandadium
V
50.95
Lutesium
Lu
175
Xenon
Xe
131.3
Magnesium
Mg
24.32
Ytterbium
Yd
173.04
Manganese
Mn
54.93
Yttrium
Y
88.92
Mercury
Hg
200.61
Zinc
Zn
65.38
Molybdenum
Mo
95.95
Zirconium
Zr
91.22
112
APPENDIX –2
Normality, Specific Gravity and Percent by weight of Acids and Ammonia
Reagent in the Laboratory
Sr.
No.
Reagent
Normality
N*
Specific
gravity
ml required to
make 1 litre of
1N solution
1
Acetic acid glacial
17.4
1.05
58 ml
2
Hydrochloric acid Conc.
11.8
1.18
89 ml
3
Nitric acid Conc.
16
1.42
63 ml
4
Sulphuric acid Conc.
41.1
1.69
23 ml
5
Phosphoric acid Conc.
36
1.84
28 ml
6
Perchloric acid
11.6
1.66
86 ml
7
Ammonium Hydroxide Conc.
14.3
0.9
71 ml
8
Phosphoric acid
41.1
1.69
23 ml
N* = Normality approximate
Note : To prepare a diluted reagent from a concentrated one use the expression
V1 = V2 x N2 / N1
Where -
V1 – Vol. of the conc. reagent required
V2 – Vol. of the diluted reagent
N1 – Normality of the conc. reagent
N2 – Normality of the diluted reagent
APPENDIX –3
Approximate pH values of some acid and alkali
Substance
Normality
pH
Substance
Normality
pH
HCl
1
0.1
0.01
0.001
0.1
1.07
2.02
3.01
NaOH
1
0.1
0.01
0.001
14.05
14.07
12.12
11.13
Acetic acid
1
0.1
0.01
0.001
2.37
2.87
3.37
3.87
NH4OH
1
0.1
0.01
0.001
11.6
11.1
10.6
10.1
H2SO4
0.1
1.2
Oxalic acid
0.1
1.6
113
APPENDIX –4
Preparation of 1000 ppm solutions of different elements
Sr.
No.
Elements
Quantity of salt to be dissolved in 1000 ml distilled water
1
Nitrogen
4.719 g of (NH4)2SO4 Ammonium sulphate
2.140 g urea CO(NH2) 2
2
Phosphorus
4.390 g of KH2PO4 Pot. Dihydrogen phosphate
5.555 g of CaHPO4.2H2O, Dicalcium phosphate dihydrate
14.31 g of single superphosphate containing 6.986% P
3
Potassium
1.906 g Potassium chloride (Muriate of potash) KCl
4
Zinc (Zn)
4.398 g Zinc sulphate ZnSO4.7H2O
5
Manganese
(Mn)
3.609 g Manganese chloride, MnCl2.2H2O
3.077 g Manganese sulphate MnSO4.H2O
6
Copper (Cu)
3.929 g Copper sulphate CuSO4.5H2O
7
Iron (Fe)
4.978 g FeSO4.7H2O, Ferrous sulphate
7.021 g (NH4)2.Fe(SO4)2.6H2O of Ferrous ammonium sulphate
8
Molybdenum
12.139 g Ammo. Molybdate (NH4)6Mo7O24.4H2O
2.521 g of Sodium molybdate Na2Mo O4.2H2O
9
Boron
5.720 g Boric acid H3BO3
* Add 15 ml of conc. sulphuric acid in solution and then make volume to 1 litre.
114
APPENDIX –5
List of the chemicals that serve as primary standard for the respective
reactions with their equivalent weights
Sr. No.
Name
Formula
Eq. wt.
I.
1
2
3
4
5
6
7
8
Acidimetry and alkalimetry
Sodium carbonate
Borax
Potassium hydrogen pthalate
Potassium bi-iodate
Sulphamic acid
Sucinic acid
Benzic acid
Furoic acid
Na2CO3
Na2B4O7.10H2O
KHC8H4O4
KH(IO3) 2
NH2 SO2 OH
H2C4O4
HC7H5O2
HC3H3O2
52.99
190.72
204.22
389.95
97.09
59.04
122.12
112.08
II.
9
10
Precipitation reactions
Sodium chloride
Potassium chloride
NaCl
KCl
58.44
74.54
III.
11
12
13
14
15
16
Oxidation-Reduction
Potassium dichromate
Potassium bromate
Potassium bi-iodate
Iodine
Sodium oxalate
Oxalic acid
K2Cr2O7
KBrO3
KH(IO3) 2
I2
Na2C2O4
H2C2O4.2H2O
49.04
27.84
389.95
126.92
134.02
63.034
Note : Such of the hydrated salts that do not efforence on drying such as borax, oxalic
acid, have been experimentally found to be satisfactory, are known as “secondary
standards”.
115
APPENDIX –6
Preparation of Standard Solutions
To prepare 1 litre of 0.1 N or N/10 Solution
(approx.)
Standardize with
1
2
3
Sulphuric acid
Dilute 3.0 ml of conc. 36N acid to 1 lit.
Hydrochloric acid
Dilute 10 ml of conc. 16N acid to 1 lit.
Nitric acid
Dilute 6.3 ml of conc. 12N acid to 1 lit.
1
2
Sodium carbonate (N/10)
For this weigh exactly 5.29 g of A.R.
grade dry sodium carbonate and
dissolve in water and make up to 1
litre. OR
Borax solution (N/10)
Weigh exactly 1.907 g of pure A.R.
grade borax Na2B4O7.10H2O and
dissolve in water & make upto 100 ml.
4
5
Sodium hydroxide
4.0 g to be dissolved in water and
make upto 1 lit.
Potassium hydroxide
Dissolve 5.7 to 6.0 g of Potassium
hydroxide in water and make up to
1 lit.
1 Potassium Hydrogen pthalate (N/10)
Dissolve accurately 5.1 g Potassium
hydrogen pthalate (A.R.grade) in water
and make up to 250 ml.
Succinic acid (N/10)
Weigh 5.9 g of succinic acid (A.R.) to
be dissolved in water and make up to
1 lit.
6
Silver nitrate
Dissolve accurately 16.989 g
crystallized (A.R.) silver nitrate in
water and make up to 1 lit.
0.25 g of pure iron, 2 g of NaHCO3 and
20 ml of 5N H2SO4
7
Potassium permanganate
about 3.25 g Potassium permanganate
to be dissolved in water and make up
to 1 lit.
Oxalic acid
1.574 pure oxalic acid to be dissolved
in water and make upto 250 ml, makes
0.1N (N/10)
Sodium oxalate
1.67 pure sodium oxalate dissolve in
water and make upto 1 lit,
makes 0.01 N.
116
APPENDIX –6 (Cont.)
Preparation of Standard Solutions
Sr.
No.
Reagent
Quantity of reagent requires to prepare solution of
known concentration
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
1N HCl
0.5N HCl
5N H2SO4
0.1N H2SO4
0.2N H2SO4
0.01N
0.1N Pot. Acid pthalate
0.25N NaOH
0.1N NaOH
4N NaOH
0.02N AgNO3
0.1N KCl
0.1N NaCl
100 ppm P solution
1000 ppm K solution
100 meq Na
0.01N EDTA
87.5 ml conc. HCl / litre
44 ml per litre
140 ml conc. H2SO4 per litre
2.8 ml H2SO4 per litre
5.6 ml H2SO4 per litre
100 ml of 0.1N H2SO4 per litre
5.1 g pure oven dried Pot. Acid pthalate in 250 ml
distilled water.
10 g NaOH per litre
4 g NaOH per litre
160 g NaOH per litre
3.4 g AgNO3 per litre
0.7456 g KCl per litre
5.845 g NaCl per litre
0.439 g Potassium hydrogen orthophosphate (A.R.
grade) per litre
1.907 g KCl (A.R. grade) per litre
5.845 g NaCl per litre
2.0 g disodium dihydrogen EDTA + 0.05 g MgCl2 6H2O
per litre
117
APPENDIX –6 (Cont.)
Preparation and Standardization of Solutions
Normal solution : A normal solution contains 1 g equivalent weight of solute in a
litre of the solution.
To prepare 1000 ml (1 litre) of 0.1N solution
(approximately)
Standardize with
Sodium Hydroxide
4.0 g to be dissolved in water and make up to 1
litre
Potassium Hydroxide
Dissolve 5.7 to 6.0 g of potassium hydroxide in
water and make up to 1 litre.
Potassium Hydrogen Pthalate (0.1N)
Dissolve accurately 5.q g of potassium
hydrogen pthalate (A.R.grade) in water and
make up to 250 ml.
Succinic acid (0.1N)
Weigh 5.9 g of succinic acid (A.R. grade) to be
dissolved in water to make up to 1 litre.
Silver Nitrate
Dissolve accurately 16.989 g crystallized (A.R.)
silver nitrate in water & make up to 1 litre.
NaCl sodium chloride (0.1N)
Weigh 5.486 g of sodium chloride (A.R. grade)
and dissolve in water to make up to 1 litre.
Sulphuric Acid
Dilute 2.8 ml of conc. 36N sulphuric acid to 1 lit.
(36N x ? ml = 0.1 N x 1000) = 2.8 ml OR
considering the gram equivalent wt., purity and
sp. Gravity of the H2SO4, dilute calculated
amount of H2SO4 in distilled water and make
up to 1 litre.
Hydrochloric Acid
Dilute 8.33 ml of conc. 12.0 N hydrochloric acid
to 1 litre of distilled water.
(12N x ? ml = 0.1 N x 1000) = 8.33 ml
Nitric Acid
Dilute 6.3 ml of conc. 16N nitric acid to 1 litre of
distilled water.
Sodium Carbonate (0.1N)
For this weigh exactly 5.29 g of A.R. grade dry
sodium carbonate and dissolve in water and
make upto 1 litre.
118
APPENDIX – 7
Some Important Conversion Factors
To covert column-1
to column-2, multiply
by the factor
Column-1
Column-2
To covert column-2
to column-1, multiply
by the factor
0.892
220.2
2.205
1.094
0.394
2.29
1.20
1.39
1.66
2.24
0.10
0.0001
22.4
10.00
(9.0/5.0 oC) + 32
Kg/ha.
Quintal
Kg
Meter
cm.
P
K
Ca
Mg
ppm
g/kg
ppm
mg/100 g
mg/100 g
oC
lb/acre
lbs
lb
yard
inch
P2O5
K2O
CaO
MgO
Kg/ha
Percent
Percent
Kg/ha
ppm
oF
1.121
0.00454
0.454
0.914
2.540
0.437
0.830
0.715
0.602
0.446
10.0
10000.0
0.0446
0.10
(5.0/9.0 (oF – 32)
ppm
=
miliequivalent per litre x eq.wt.
meq. Per litre
=
microgram per ml or mg per litre
meq.
=
ppm / equivalent weight
1 N solution
=
gram equivalent weight / litre
mg / 100 g
=
ppm x 0.1
119
APPENDIX – 8
Conversion factors for different elements
1.
P2O5
x
0.44 =
P
2.
K2O
x
0.83 =
K
3.
P
x
2.29 =
P2O5
4.
K
x
1.20 =
K2O
5.
N
x
1.22 =
NH3
6.
Ca
x
1.40 =
CaO
7.
CaO
x
0.71 =
Ca
8.
Mg
x
1.67 =
MgO
9.
MgO
x
0.60 =
Mg
10. S
x
3.00 =
SO4
11. SO4
x
0.33 =
S
12. HNO3
x
0.22 =
N
13. H3PO4
x
0.32 =
P
14. Ca3(PO4) x
0.20 =
P
15. KCl
x
0.52 =
K
16. K2SO4
x
0.45 =
K
17. CaCO3
x
0.40 =
Ca
18. CaCO4
x
0.29 =
Ca
19. MgCO3
x
0.28 =
Mg
20. MgSO4
x
0.20 =
Mg
21. H2SO4
x
0.33 =
S
22. CaSO4
x
0.24 =
S
23. Na
x
2.305 =
Na2CO3
120
APPENDIX – 9
EC reading according to temperature
Temp.
EC
Temp.
EC
Temp.
EC
20.0
20.2
20.4
20.6
20.8
21.0
21.2
21.4
21.6
21.8
22.0
22.2
22.4
22.6
22.8
23.0
23.2
23.4
23.6
23.8
24.0
24.2
24.4
24.6
24.8
25.0
1.276
1.281
1.287
1.292
1.298
1.303
1.309
1.314
1.320
1.325
1.331
1.336
1.342
1.347
1.353
1.358
1.364
1.369
1.375
1.380
1.386
1.391
1.397
1.402
1.408
1.413
25.2
25.4
25.6
26.8
26.0
26.2
26.4
26.6
26.8
27.0
27.2
27.4
27.6
27.8
28.0
28.2
28.4
28.6
28.8
29.0
29.2
29.4
29.6
29.8
30.0
1.4185
1.4240
1.4294
1.4349
1.4404
1.4459
1.4514
1.4569
1.4623
1.4678
1.4733
1.4788
1.4843
1.4898
1.4952
1.5007
1.5062
1.5117
1.5172
1.5226
1.5281
1.5336
1.5391
1.5446
1.5501
30.2
30.4
30.6
30.8
31.0
31.2
31.4
31.6
31.8
32.0
32.2
32.4
32.6
32.8
33.0
33.2
33.4
33.6
33.8
34.0
34.2
34.4
34.6
34.8
35.0
1.556
1.561
1.567
1572
1.577
1.583
1.588
1.594
1.599
1.605
1.610
1.616
1.621
1.627
1.632
1.639
1.643
1.649
1.654
1.660
1.665
1.671
1.676
1.682
1.687
121
APPENDIX – 10
Some Indicator plants of nutrient deficiency
Nutrient
Indicator Plants
N
P
K
Ca
Mg
S
Fe
Zn
Mn
Cu
B
Cl
Mo
Maize, cereal (small grain), mustard, apple, citrus.
Maize, barley, lettuce, tomato.
Potato, lucern, beans, tobacco, cucurbits, cotton,
tomato, maize.
Lucern, other legume crops.
Potato, cauliflower.
Lucern, raya.
Sorghum, barley, citrus, peach.
Maize, onion, citrus, peach.
Apple, cherry, citrus, maize, oats, pea, radish, wheat.
Apple, citrus, barley, maize, lettuce, oats, onion,
tobacco, tomato,
Lucern, turnip, cauliflower, apple, peach.
Lettuce.
Cauliflower, other Brassica sp., citrus, legumes, oats, spinach.
122
APPENDIX – 11
Instrument settings for flame atomic absorption analysis
Element Line
(nm)
Slit
width
(nm)
Working
range
(μg m/L)
Sensitivity
(μg m/L)
Lamp
current
(mA)
Flame type
Al
Al
Ca
Ca
Cd
Co
Cr
Cr
Cu
Cu
Fe
Fe
K
Mg
Mg
Mn
Mn
Mo
Ni
Ni
Pb
Se
Si
Zn
309.3
396.2
422.7
422.7
228.8
240.7
357.9
425.4
324.7
217.9
248.3
372.0
766.5
285.2
202.6
279.5
403.1
313.3
232.0
352.4
283.3
196.1
251.6
213.9
0.5
0.5
0.5
0.5
0.5
0.2
0.2
0.2
0.5
0.2
0.2
0.2
0.5
0.5
1.0
0.2
0.2
0.2
0.2
0.5
0.5
1.0
0.2
0.5
25-135
25-110
1-4
1-10
0.5-5
1-20
2-20
7-40
1-20
7.5-30
2-20
20-40
1-10
0.1-2
5-20
1-10
7-27
10-50
2-20
6-30
4-40
45-185
20-200
0.5-5
1.0
1.0
0.02
0.09
0.03
0.2
0.2
0.5
0.1
0.2
0.1
0.5
0.01
0.01
0.1
0.06
0.2
0.8
0.2
0.2
0.2
1.0
2.0
0.03
10.0
10.0
10.0
10.0
3.0
6.0
6.0
6.0
3.0
3.0
7.0
7.0
6.0
3.0
3.0
5.0
5.0
7.0
4.0
4.0
5.0
10.0
15.0
5.0
N2O-C2H2 (Red.)
N2O-C2H2 (Red.)
N2O-C2H2 (Oxi.)
Air- C2H2 (Sto.)
Air- C2H2 (Oxi.)
Air- C2H2 (Oxi.)
Air- C2H2 (Red.)
Air- C2H2 (Red.)
Air- C2H2 (Oxi.)
Air- C2H2 (Oxi.)
Air- C2H2 (Oxi.)
Air- C2H2 (Oxi.)
Air- C2H2 (Oxi.)
Air- C2H2 (Oxi.)
Air- C2H2 (Oxi.)
Air- C2H2 (Sto.)
Air- C2H2 (Sto.)
N2O- C2H2 (Red.)
Air- C2H2 (Oxi.)
Air- C2H2 (Oxi.)
Air- C2H2 (Oxi.)
N2O- C2H2 (Sto.)
N2O- C2H2 (Red.)
Air- C2H2 (Oxi.)
123
APPENDIX – 12
Terminology
Standard Solution :
The solution of accurately known strength (or concentration) is called standard solution. It
contains a definite number of gram equivalent or gram moles per litre of solution. Strength
of a solution refers to the weigh of a solute dissolved in a unit weight of the solution. It can
be expressed in many ways as follows –
Normal Solution and Normality : A normal solution is one which contain 1 gram
equivalent (eq.wt. in grams) of the active reagent, dissolved in 1 litre of the solution.
Normality is the number of gram equivalent of the substance, dissolved in 1 litre of the
solution. If the number of gram equivalent is 1, it is expressed as 1 N. If the number is
1/10, 1/100 or 1/1000 then it is designated as 0.1 N (decinormal), 0.01 N (centinormal) or
0.001 N (millinormal) solution respectively.
Normality = (No. of gram eq. of solute) / (No. of litre of solution)
Molar Solution and Molarity : A molar solution is one which contain a gram of molecular
weight of the solute dissolved in 1 litre of solution. It is denoted by M. Whereas, molarity
is the number of gram molecules of the substance dissolved in 1 litre of the solution.
Molal Solution : A molal solution is the one which contain a number of gram molecules
of the solute dissolved in 100 g of water.
Percentage composition by weight : The concentration is expressed in terms of the
gram of solute per 100 g of solution. e.g. 10% KCl solution is prepared by dissolved 10 g
of the salt in 90 g of water.
Percentage composition by volume : The concentration is expressed in terms of
volume of the solute and solvent. e.g. 25 g of solution of methanol is prepared by mixing
25 ml of methanol with 80 ml of water.
Parts per million (ppm) : The concentration is expressed in terms of grams of solute per
million millilitres of solution or milligrams of solute per litre of the solution. Thus a solution
containing 10 mg / litre of solute or 10 microgram of solute per millilitre or solution is 10
ppm solution.
Milli equivalent per litre : A solution containing milli (1/1000) g equivalent of substance
in a litre of the solution is expressed as meq/litre.
Titration : titration is defined as the process of determining the volume of a substance
required to just complete the reaction with a known amount of other substance. The
quantitative analysis carried out by titration is known as titrimetric analysis.
a) Titrant : The solution of accurately known strength used in titration is called titrant.
b) Titrate : The substance (in solution) to be determined by titration is called titrate.
124
SECTION - B
GENERAL SAFE LABORATORY OPERATION PROCEDURES
1. GENERAL SAFETY PROCEDURES
Inform yourself :
❖ Consult the material safety data sheets (MSDS) to learn the hazards of each
chemical. (MSDS can be obtained from chemical suppliers).
❖ It is highly recommended that all supervisors, employees, students and volunteers
get Workplace Hazardous Materials Information System (WHMIS) certification.
This system informs workers of commonly used warning labels and symbols for
chemicals and other agents used in the workplace.
❖ Follow all policies, regulations and safety procedures (municipal, provincial/state
and federal) detailed for your workplace.
❖ Verify that the appropriate personal protection equipment (PPE) is available and
used as prescribed.
❖ Special attention is required if there are any level 4 hazards listed on the
chemical’s National Fire Protection Association (NFPA) label regarding health
(blue), fire (red) or reactivity (yellow). Level 4 hazards indicate extreme hazard
potential. Special training or safety requirements must be attained before handling
these chemicals.
Label chemical bottles and containers when received and opened, as per WHMIS
guidelines. Most chemicals have a shelf life. Some of these chemicals may
become unsafe and/or unstable after expired date.
Ensure that there is an adequate supply of the reagents before starting any
procedure.
Do not carry glass bottles only by the finger-ring on the neck of the bottle. This
ring is meant to help grip bottle when pouring its contents. Transport the bottle
using both hands or use an appropriate rubber / plastic bottle holder.
Store chemicals in an appropriate location as directed in MSDS. Pay special
attention to non-compatible chemicals, shelf life and ventilation. Make sure
chemicals are properly labeled and an accurate chemical inventory is kept.
125
2. BASES
General characteristics and precautions :
❖ Bases are caustic and some have low surface tensions, making them difficult to
wash off.
❖ Eye contact : causes severe eye burns. May cause irreversible eye injury.
❖ Skin contact : causes skin burns. May cause deep, penetrating ulcers of the skin.
❖ Ingestion : causes gastrointestinal tract burns. May cause perforation of the
digestive tract.
❖ Bases and acids should be stored separately due to incompatibilities (i.e.
potentially violent reaction).
❖ Strong bases include the following : LiOH (Lithium Hydroxide), NaOH (Sodium
Hydroxide), KOH (Potassium Hydroxide), RbOH (Rubidium Hydroxide) and CsOH
(Cesium Hydroxide).
Unique hazards :
Ammonium Hydroxide :
❖ Volatile : Produces ammonia fumes which are pungent and toxic. This chemical
must be used in a fume hood.
Sodium Hydroxide, Lithium Hydroxide and Potassium Hydroxide :
❖ Substances are hygroscopic (i.e. absorb water from the atmosphere).
❖ Must be stored in plastic bottles since these bases can fuse glass.
❖ These bases are exothermic when dissolved / diluted with water. LiOH may boil if
10 M stock solution is made, NaOH & KOH will heat up significantly. There is a
small risk of skin burns.
Sodium Hypochlorite (Bleach) :
❖ Toxic if ingested in sufficient quantities.
❖ Avoid skin contact as this can cause irritation.
❖ Avoid inhaling excessive quantities of vapour.
❖ Strong oxidizer : This chemical has several incompatibilities (i.e. acids, ammonia
based compounds, hydrogen peroxide and flammables).
3. ACIDS
General characteristics and precautions :
Most acids are volatile and produce acidic fumes.
Corrosive to most metals, this reaction can form explosive hydrogen gas.
126
❖ Eye contact : causes severe eye burns. May cause irreversible eye injury.
❖ Skin contact : causes skin burns. May cause deep, penetrating ulcers of the skin.
❖ Ingestion : causes gastrointestinal tract burns. May cause perforation of the
digestive tract. Does not include vomiting.
❖ Inhalation : may be fatal if inhaled. Effects may be delayed. May cause irritation of
the respiratory tract with burning pain in the nose and throat, coughing, wheezing,
shortness of breath and pulmonary edema.
❖ Chronic effects : repeated inhalation may cause chronic bronchitis.
❖ Reacts exothermically with water, sometimes violently. Always add acid to water
when making up solutions.
❖ Store acids and bases separately.
❖ Strong acids include : HCl (Hydrochloric acid), HNO3
(Nitric acid), H2SO4
(Sulphuric acid), HBr (Hydrobromic acid), HI (Hydroiodic acid) and HCIO4
(Perchloric acid).
Unique Hazards :
Acetic Acid :
❖ Highly volatile, strong pungent, vinegar-like odour.
❖ Flammable in its concentrated form (i.e. glacial).
Hydrochloric acid :
❖ Volatile : Releases toxic chlorine gas, vapours are visible in high humidity.
Nitric acid :
❖ Strong oxidizer : Reacts violently with some chemicals.
❖ Volatile : vapours are visible, especially in high humidity.
Sulphuric acid :
❖ Hygroscopic : Absorbs moisture from the air. Keep tightly sealed.
❖ Strong inorganic acid. Mists containing sulphuric acid may cause cancer.
❖ Sulphuric acid reacts vigorously, violently or explosively with many organic and
inorganic chemicals and with water.
Formic acid :
Flash point is 69oC. Both liquid and vapour are combustible.
Strong reducing agent. : fire and explosion risk if in contact with oxidizing agents.
Keep refrigerated (store below 4oC)
Lachrymator (i.e. a substance that produces the flow of tears).
127
Hydrofluoric acid :
Poison, extremely hazardous liquid and vapour. Special safety training
recommended.
Neutralizing HF gel (2.5% calcium gluconate gel) must be kept on your person
both at and away from the workplace. A person’s reaction to exposure may be
delayed by 8 h or longer, depending on the concentration of the acid. Fluoride
ions readily penetrate skin, causing deep tissue and bone damage and can be
fatal. Any exposure requires hospital care, even after neutralizing gel application.
Hydrofluoric acid must be stored in plastic bottles, since HF can dissolve glass.
4. FLAMMABLES AND COMBUSTIBLES
General characteristics and precautions :
These substances can result in a fire or explosion if in contact with a heat or
ignition source.
Most flammables are volatile and considered to be toxic. Many flammable
solvents affect the central nervous system.
To avoid potential contact with ignition sources, it is important to determine
whether fumes are lighter or heavier than air (e.g. chloroform is heavier than air,
while natural gases are lighter than air).
Some flammables can become unstable through time due to peroxide formation,
resulting in auto ignition (e.g. diethyl ether, tetrahydrofuran).
Safety Precautions :
Store in a vented cabinet or room.
Store away from ignition, heat or oxidizer sources (including sunlight and room
heaters).
If flammables need to be stored cold, they must be stored in a fridge which has
been specifically designed by the manufacturer to be suitable for the storage of
flammables. The fridge must be labeled as such.
Reduce routine handling of large volumes of flammable or combustible materials
by dispensing into smaller WHMIS-labeled containers. Ensure that metal
containers are grounded to prevent static discharge.
Dispense and use flammable or combustible materials in properly working fume
hoods or well ventilated areas. Certification of fume hoods is often mandatory to
ensure that adequate airflow is available for safe working conditions.
128
Do not use the laboratory as a storage place. Return all containers to the volatile
materials storage facility.
Store flammables separately from other chemicals. It is especially important to
store flammables separately from oxidizers.
5. COMPRESSED GAS CYLINDERS
General Characteristics and Precautions :
Some gases support combustion (e.g. oxygen).
Some gases are flammable (e.g. acetylene, hydrogen, propane).
Some gases are asphyxiants (e.g. carbon dioxide, carbon monoxide).
All gases (except air and oxygen) can displace breathable air if they are
exhausted in to non vented, closed areas.
Incorrect use of pressure regulators can cause fires or explosions.
High temperatures can cause a buildup of pressure in cylinders.
Safety Precautions :
Label all cylinders clearly. Do not use a cylinder it its contents cannot be
unequivocally identified.
Keep all unused cylinders well sealed.
Use appropriate PPE while handling cylinders.
Ventilate storage areas.
Secure cylinders individually by using chains or straps.
Do not store cylinders near open flame or heat source.
Ground all flammable gas cylinders.
Oxygen tanks : Ensure all surfaces on the tank and regulator are absolutely free
of grease or any other lubricant.
Transportation of Gas Cylinders :
The appropriate cap must be in place.
Person(s) transporting the cylinder should wear gloves and safety shoes or boots
(steel-toed or equivalent).
Prior to transport : Ensure that suitable tie-down chains or straps are available
immediately upon arrival at the destination place.
Use freight elevators (where available) to transport cylinders.
Person(s) transporting compressed gases in vehicles often requires specific (and
mandatory) training and licensing.
129
Reference Documents :
Singh, Dhyan, Chhonkar, P.K. and Pande R.N., 1999, Assessment of Irrigation
Water Quality in “Soil, Plant, Water Analysis” - A methods manual, Indian
Agricultural Research Institute, Indian Council of Agricultural Research, New
Delhi.
Analysis of Plants, Irrigation Water & Soils (MPKV, Rahuri Manual) by R.B.
Somwanshi, P.P. Kadu, B.D. Tamboli, B.D. Bhakre.
Methods of Soil & Water Analysis, laboratory Manual, PKV, Akola, M.N. Patil, S.K.
Thakare.
Laboratory Manual by National Bureau of Soil Survey & Land Use Planning,
Nagpur.
Soil & Water Analysis Methods, Soil Survey & Analysis Department,
Commissionorate of agriculture, Maharashtra State, Pune-5.
Soil Sampling & Method of Analysis – 2nd Edition, Canedian Society of Soil
Science – 2008.
130
PREFACE
This un-priced laboratory manual is expected to serve as a source of
information on laboratory testing procedure for soil and water sample analysis.
The technical information has been collected from several books,
authorized manuals from agricultural universities, agricultural departments of
Maharashtra State, National Bureau of Soil Science (NBSS), Nagpur, IARI, ICAR,
New Delhi.
The information in this manual is exclusively written for the use of technical
staff engaged in doing soil classification, soil survey work, laboratory testing of soil
and water samples, Diagnosis of problematic soils in command area and allied
research work, in the Directorate of Irrigation Research & Development, Pune.
I sincerely acknowledge the help received from several authors and
researchers in the form of their published literature.
Er. K. M. Shah
Superintending Engineer & Director
Directorate of Irrigation Research &
Development, Pune
Date : 14/05/2009
Place : Pune
131
PREPARED BY :
1) D. R. Pawar
Soil Survey Officer,
Soil Survey Division,
Pune-37.
2) D. B. Randhe
Dy. Soil Survey Officer,
Soil Survey Division,
Pune-37.
3) Dr. Mehraj Shaikh (S.S.A.)
4) Smt. A. K. Korde (S.S.A.)
5) K. A. Shinde (R.A.)
6) Miss. M. P. Yadav (R.A.)
7) Miss. A. E. Chavan (R.A.)
8) Miss. V. M. Sapkale (R.A.)
SPECIAL THANKS :
1) D. R. Joshi
Asst. Engineer (II)
2) S. M. Amrutkar
Retd. Soil Scientist
3) H. Mulani
Soil Scientist
APPROVED BY :
Er. K. M. Shah
Superintending Engineer & Director
Directorate of Irrigation Research
& Development, Pune.
132
NOTES
133

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