DEPARTMENT OF SOILS MIMEO REPORT NO. 58-3

METHODS OF ANALYSIS USED IN SOIL TESTING

by

Herman L. Breland

Department of Soils
Florida Agricultural Experiment Stations
Gainesville, Florida

November 6, 1957

TABLE OF CONTENTS

Page

Recording 1

Sample Preparation 1

Soil Texture Determination 1-2

Organic Matter Determination 2

pH Determination 2-3

Extracting Solution 3

Extracting the Nutrients from the Soil Sample 3

Calcium Determination 4

Calcium Standard Curve 5

Magnesium Determination 6

Magnesium Standard Curves 7-8

Potassium Determination 9

Potassium Standard Curve 10

Phosphorus Determination 11

Phosphorus Standard Curve 12

Nitrate Nitrogen Determination 13

Water Soluble Salts, Determination of 13

Sodium Determination 14

Chloride Determination 15-16

Copper Determination 17

Limestone Calcium Carbonate Equivalent 18

Limestone Calcium and Magnesium Determination 19-20

Definitions 21

Calculations 22-24

Factors 25

-1-

Department of Soils
Agricultural Experiment Station
University of Florida

METHODS OF ANALYSIS USED IN THE SOIL TESTING LABORATORY

Herman L. Breland
Assistant Soils Chemist

Recording

All samples, whether received by mail or brought into the laboratory,
should have a Soil Sample Information card filled out for them. As the samples
are received in the laboratory each one is assigned a number and the date it was
received is stamped on the Soil Sample Information card. The samples are referred
to by number only while they are in the laboratory. After the analyses have been
completed the data are entered on the original Soil Sampling Information card and
returned to the office for the recommendations to be made.

Sample Preparation

The samples should be properly taken and dried when received in the
laboratory. If, however, the samples come in wet it will be necessary to allow
them to air dry completely in open pans before sieving. All samples are then
passed through a 2 mm sieve, mixed thoroughly and stored in the numbered one-
half pound paper bags. The samples are then placed numerically in trays before
going to the laboratory for analysis. Each tray holds 50 samples in 5 rows of
10 samples each. After the samples have been analyzed they are stored until it
is felt that they will no longer be needed before they are discarded.

Texture

The texture is determined by feeling of the soil. That is, the soil
is rubbed between the fingers to determine the relative proportions of the various
size particles of individual soil grains in a mass of soil. Considerable skill
and experience is required for consistent and accurate determinations, because
mineral particles may vary in size from those easily discernible with the unaided
eye to those below the range of ultramicroscope.

-2-

The characteristics of some of the more important textural grades found
i Florida which may be readily recognized by feel are listed below:

General Name

Sandy soils

Loamy soils

Clayey soil

Organic soils

Marl soils

Limestone

Textural Class Name

sand
fine sand
very fine sand
loamy sands

1. sandy loam
2. sandy clay loam

1. sandy clay

1. peats
2. mucks

1. sandy marl
2. silty marl

Symbol

s
fs
vfs
ls

sl
scl

so

P
m

sma
si ma

1. chiefly calcium carbonate
or calcium and magnesium carbonate

Organic Matter

The organic matter content of the soil is determined visually by color
it is a fairly reliable indicator of the organic matter content. Dark colored
'il usually contains more organic matter than the light colored soil. The
)proximate amount is indicated as high, medium, low and very low.

pH

Buffer Solution pH 7.0 Weigh 3.3910 grams of citric acid (C6H807)
*3.7090 grams of citric acid (i-cH07.H20) and 23.3844 grams of disodium phos-
ate (Na2HPO4) or 58.9913 grams of disodium phosphate (Na2HPO4.12H20) dissolve
d dilute to one liter with distilled water.

Buffer Solution pH 4.0 Weigh 11.8060 grams of citric acid (C6H807)
12.9131 grams of citric acid (C6H807*H20) and 10.9h68 grams of disodium
osphate (Na2HPO4) or 27.6152 grams of disodium phosphate (Na2HP04.12H20),
ssolve and dilute to one liter with distilled water.

To preserve the above buffer solutions add about 0.1% of toluene.

-3-

Procedure for making the determination Measure out a 50 ml beaker full
of air-dry soil, place in a 150 ml beaker, add 100 ml of distilled water and stir
thoroughly. Allow to stand at least one hour (two hours for peats and mucks),
stir again and immediately determine the pH by means of a potentiometer and glass
electrode.

Extracting Solution

Ammonium acetate (pH 4.8) is used as the extracting solution. This is
made by adding 1271 ml of cone. acetic acid to 8 to 10 liters of distilled water
and mixing well, then adding 860 ml of concentrated ammonium hydroxide, make to
a volume of 18 liters and mix well. The pH of this solution should be h.8.

Extracting the Soil Sample

Weigh out 5.00 grams of air-dry soil on a Torsion balance and place in
the extracting flask. Add 25 ml of the ammonium acetate (pH h.8) extracting
solution, shake on a reciprocating shaker for 30 minutes, then filter through
11 cm filter paper (Whatman No. 5) into a filter funnel.

The clear filtrate contains the easily extractable plant nutrients and
is used for making the following determinations: calcium, magnesium, phosphorus,
potassium and nitrates.

-4-

Calcium

Standard Solutions Weigh 2.4973 grams of oven dry calcium carbonate
(CaCO3) C.P. grade, and dilute to one liter with ammonium acetate (pH 4.8).* This
solution will contain 1000 parts per million of calcium. This stock solution is
then used to make standard solutions of the following concentrations: 0, 50, 100,
150, 200, 300 and 400 parts per million.

Instrument and Settings Used The Beckman Model B Flame Spectrophoto-
meter with the acetylene-oxygen burner assembly (No. 4030 medium bore) is used for
the calcium determination. The burner consumes about 8 cu. ft. of oxygen and
5 cu. ft. of acetylene per hour. The instrument settings are as follows:

1. Oxygen Tank 30 psi; control panel pressure designated
on burner tag, usually 10 psi.
2. Acetylene Tank 15 psi; control panel 5 to 8 psi.
3. Sensitivity switch 4
4. Wavelength 622 mu
5. Slit width 3 to 5 mm
6. Phototube red sensitive, with 10,000 megohm resistor.

Procedure for making the determination The standard solutions should
be run through the flame and the values obtained as percent transmission plotted
on the ordinate (vertical axis) corresponding to the known concentration of the
standards on the abscissa (horizontal axis) of coordinate (10 x 10) graph paper.

The concentration of the unknown samples can now be determined by read-
ing the concentration of calcium in parts per million from the abscissa when per
cent transmission is plotted on the graph. The calculations are then as follows:

ppm Ca X dilution factor X factor Ca to CaO X 2 (2,000,000 lbs/A
parts per million ) = Ibs/A CaO
ppm Ca X 5 X 1.3992 X 2 = lbs/A. CaO.
ppm Ca X 13.99 = lbs/A. CaO.

A standard curve for calcium, instrument settings and a table of
converted values are given in Figure 1.

* Add a few drops of 1.0 N HC1 to dissolve the GaC03 before diluting to volume.

lO-5-
Fig. 1 STANDARD CURVE FOR CALOIUM /
Instrument Beckman Model B Spectrophotometer
SOxygen 12 psi
90- Acetylene 5 psi
Sensitivity 4
Phototube Red
Resistor 10,000 megohm
Wavelength 622 mu
Slit 3.6 mm /
80

/

70-

% T /Ca CaO CaO
%T Lbs/A T Lbs/A % T-Lbs/A
60 1 0 34 1451 67 3241
2 46 35 1497 68 3308
3 -91 36 1545 69 3375
/ 4 137 37 1592 70 3442
5 182 38 1640 71 3509
/ 6 227 39 1687 72 3576
50 7 272 40 1735 73 3643
/ 8- 316 41 1785 74 3711
/ 9 361 42 1836 75 3778
/ 1 406 43 1886 76 3845
/ 11 448 U4 1936 77 3912
/ 12 490 45 1987 78 3979
-40 13 532 46 2040 79 4047
/ 14 574 7 2093 80 -11ll4
/ 15 616 48 2146 81 4187
/ 16 658 49 2200 82 4259
17 700 50 2253 83 4332
3-/ 18 742 51 2306 84 4405
/ 19 784 52 2359 85 4477
/ 20 826 .33 212 86 4550
21 871- 54 2466 87 4623
22 915 55 2519 88 4695
23 960 56 2575 89 4768
20 24 1004 57 2631 90 4841
/ 25 1049 58 2687 91 4916
26 1093 59 2743 92 4992
27 1138 60 2799 93 5067
28 1183 61 2860 94 5143
29 1228 62 2922 95 5218
10- 30 1273 63 2983 96 5294
31 1317 64 3045 97 5369
32 1362 65 3106 98 5445
33 1407 66 3173 99 5520
/ 100 5596
50 100 200 400
Ca ppm

Magnesium

Standard Solutions Weigh 1.6579 grams of oven dry magnesium oxide (MgO),
C.P. grade, and dilute to one liter with ammonium acetate (pH h.8). This solution
will contain 1000 parts per million of magnesium. This stock solution is then used
to make standard solutions of the following concentrations: 0, 2, 6, 10, 20, 30,
ho, 50, 70, 100, 150 and 200 parts per million.

Instrument and Settings Used The Beckman Model DU Flame Spectrophoto-
meter with Photomultiplier attachment and hydrogen-oxygen burner assembly (No. h020,
medium bore) is used for the magnesium determination. The burner consumes about
8 cu. ft. of oxygen and 20 cu. ft. of hydrogen per hour. The instrument settings
are as follows:

1, Oxygen Tank 20 psi; control panel pressure designated
on burner tag, usually 10 psi.
2. Hydrogen Tank 10; control panel 5
3. Wavelength 285.2 mu
h. Slit width 0.05 0.09 mm
5. Sensitivity 5 turns clockwise from counterclockwise limit.
6, Phototube Blue sensitive (knob pulled out)
7. Phototube load resistor position 2 (22 megohm)
8. Filter slide Blank (slide pushed in)
9. Sensitivity (photomultiplier) Full
10. Zero Suppression (Photomultiplier) Off (1 when used)

Procedure for Making the Determination The standard solutions should
be run through the flame and the values obtained as percent transmission plotted
on the ordinate (vertical axis) corresponding to the known concentration of the
standard plotted on the abscissa (horizontal axis) of coordinate (10 x 10) graph
paper.

The concentration of the unknown samples can now be determined by read-
ing the concentration of magnesium in parts per million from the abscissa when
percent transmission is plotted on the graph. The calculations are then as
follows:

ppm Mg x dilution factor x factor Mg to MgO x 2 (2,000,000 lbs/A "
parts per million) = lbs/A of MgO.

ppm Mg x 5 x 1.6579 x 2 = Ibs/A MgO

ppm Mg x 16.58 = lbs/A MgO

Two standard curves for magnesium, instrument settings and table of
converted values are given in Figures 2 and 3.

100-

90

80-

Oxygen 10 psi
Hydrogen 5 psi

Fig. 2 STANDARD CURVE FOR MAGNESIUM

Instrument Beckman DU Spectrophotometer
Phototube Multiplier tube (blue)
Sensitivity 5 turns ccw
Wavelength 285.2 mu
Photomultiplier Full
Zero suppression 1
Resistor 2 (22 megohm)
Sli +. nr no0 Ii

//

/
/

/

/

//

6,6 1 20 4o

//
//

MgO M
/% T iLbs/A % T Lb
0 00 0 3 3
0-0 34-2
1 -8 35-3
2 -17 36 3
3 25 37- 3
4 33 38 -3
5 32 39- 3
6 50 40 -
7 59 41 -
8 67 42 4
9 -76 43 -45
10 84 44 b
11 90 45 L
12 -98 46 5
13 107 47 5
14 115 48 5
15 124 49 5
16 133 50 5
17 142 51 -6
18 151 52 6
19 161 53 6
20 170 5 '6
21 180 55 7
22 191 56 7
23 201 57 7
24 211 58 7
25 222 59 8
26 233 60 8
27 244 61 8
28 255 62 9
29 267 63 9
30 278 64 1
31 290 65 1
32 301 66 1
33 313

60

100

Mg ppm

;go0
Is/A

124
36
51
65
80
994
09
.26
42
9
.75
.92
10
30
:49
68
'87
11
ill
36
60
85
09
'39
'69
'99
28
,58
)94
29
65
,000
036
085

~7

604.

4ot

30-

204

10o

MgO
Lbs/A

1135
1185
1234
1284
1344
1403
1463
1523
1583
1647
1712
1777
1841
1906
1972
2039
2105
2171
2238
2309
2381
2453
2525
2597
2668
2740
2812
2884
2956
3027
3099
3171
3243
3316

% T
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100

60- 1p,00-- _

S'200

I

__ I

, '

-8-
Fig 3 STANDARD CURVE FOR MAGIESIUM

Instrument Beckman DU Spectrophotometer
Phototube Multiplier tube (blue)

Sensitivity 5 turns ccw.
Wavelength 285.2 mu
Photomultiplier Full
Zero Suppression Off
Resistor 2 (22 megohm)
Slit 0.093 mm
Oxygen 10 psi.
Hydrogen 5 psi.

7
/
/
/
/
/
,~1

70-

/

MgO
- Lbs/A

% T

41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70

0
12
25
37
50
66
83
100
117
133
150
166
183
199
216
239
262
285
309
332
353
373
394
415
440
464
498
531
564
597

MgO
% T Lbs/A

71 634
72 671
73 725
74 779
75 833
76 887
77 949
78 1011
79 1082
80 1152
81 1237
82 1322
83 1406
84 1491
85 1575
86 1678
87 1781
88 1884
89 1987
90 2089
91 2202
92 2315
93 2427
94 2540
95 2653
96 2785
97 2918
98 3051
99 3183
100 3316

301 1 I
06 20

I0 60 -80 10-0 120
4o 60 80 i00 120

Mg ppm

100-

80-

I

7

150

200

L I

Potassium

Standard Solutions Weigh 1.9069 grams of oven dry potassium chloride
(KC1), C.P. grade, and dilute to one liter, with ammonium acetate (pH 4.8). This
solution will contain 1000 parts per million of potassium. This stock solution is
then used to make standard solutions of the following concentrations: 0, 5, 10,
15, 20, 30, 40, 50, and 60 parts per million.

Instrument and Settings Used The Beckman Model B Flame Spectrophoto-
meter with the acetylene-oxygen burner assembly (No 4030 medium bore) is used for
the potassium determination. The burner consumes about 8 cu. ft. of oxygen and
5 cu. ft. of acetylene per hour. The instrument settings are as follows:

1. Oxygen tank 30 psi; control panel pressure designated
on turner tag, usually 10 psi.
2. Acetylene tank 15 psi; control panel 5 psi.
3. Sensitivity switch 4
4. Wavelength 768 mu
5. Slit width 2 to 4 mm
6. Phototube Red sensitive, with 10,000 megohm resistor

Procedure for Making the Determination The standard solutions should
be run through the flame and the values obtained as percent transmission plotted
on the ordinate (vertical axis) corresponding to the known concentration of the
standard plotted on the abscissa (horizontal axis) of coordinate (10 x 10) graph
paper.

The concentration of the unknown samples can now be determined by read-
ing the concentration of potassium in parts per million from the abscissa when
percent transmission is plotted on the graph. The calculations are then as
follows:

ppm K x dilution factor x factor K to K20 x 2 (2,000,000 Ibs/A
f parts per million) = Ibs/A K20

ppm K x 5 x 1.2046 x 2 = Ibs/A K20

ppm K x 12.05 = lbs/A K20

A standard curve for potassium, instrument settings and a table of
converted values are given in Figure 4.

100-

901

804

70-

/
/
/

/ l1
/ 2
/ 3
14

6
/ 7
/ 8

/
/

/
/
/

/

% T
26
27
28
/ 29
30
31
32
K20 33
- Lbs/A 34
35
- 0 36
- 7 37
- 14 38
- 22 39
- 29 40
S36 41
- 42 42
- 49 43
- 56 44
- 63 45
- 70 46
- 77 47
- 84 48
- 91 49
-98 50
- 105 51
- 112 52
- 119 53
- 126 54
- 133 55
- 140 56
- 146 57
- 153 58
- 160 59
- 166 60

K20
- Lbs/A

173
180
186
193
200
207
214
220
228
235
2142
248
255
262
269
276
282
289
296
303
310
317
324
331
338
345
352
359
366
373
380
387
394
402
409

/

K20
% T Lbs/A

61 416
62 423
63 430
64 438
65 445
66 452
67 460
68 467
69 475
70 482
71 490
72 497
73 505
74 512
75 520
76 528
"77 536
78 544
79 552
80 560
81 568
82 576
83 584
84 593
85 600
86 609
87 617
88 625
89 633
90 640
91 649
92 658
93 666
94 674
95 683
96 691
97 699
98 707
99 716
100 723

50 -, 60

K ppm
K ppm

-10-
Fig. 4 STANDARD CURVE FOR POTASSIUM

Instrument Beckman Model B Spectrophotometer
Oxygen 12 psi
Acetylene 5 psi
Sensitivity 4
Phototube Red
Resistor 10,000 megohm
Wavelength 768 mu
Slit 0.1 mm

601

I

-11-

Phosphorus
Standard Solutions and Reagents Weigh 0.4356 gram of oven dry monobasic
potassium phosphate (KH2PO.), C.P, grade, and dilute to one liter with distilled
water. This solution contains 100 parts per million of phosphorus. Transfer 50 ml
of this solution, quantitatively to a 1000 ml volumetric flask, and make to volume
with distilled water. This solution contains 5 parts per million of phosphorus.

Ammonium molybdate sulfuric acid solution is made by dissolving 25.00
grams of ammonium molybdate ((NH4)6Mo7024.hH20), C.P. grade, in 200 ml of distilled
water heated to 600C. Filter if needed. 'ihen dilute 280 ml of arsenic and phos-
phorus free concentrated sulfuric acid (H2SO4) (Approx. 36 N) to 800 ml (add acid
to water). After both solutions have cooled, add the ammonium molybdate solution
slowly, with stirring, to the sulfuric acid solution. After this solution has
cooled to room temperature, make up to exactly 1000 ml with distilled water. This
is a 10 N sulfuric acid solution containing 2.5 grams of ammonium molybdate per
100 ml of solution.

Stannous Chloride solution is made by dissolving 25 grams of stannous
chloride (SnC12.2H20) in concentrated hydrochloric acid (HC1) and making to a
volume of 100 ml. with concentrated HC1. A dilute solution of stannous chloride
is made each day by taking 5 ml of the stock solution and 5 ml of concentrated
HC1 and diluting to 200 ml with distilled water.

Instrument Used The Bausch and Lomb, Spectronic 20 colorimeter with a
red filter, IP40 phototube and a wavelength of 700 mu, is used for the phosphorus
determination. The number 33-20-30, one inch, test tube adapter that will accept
the 25 x 150 mm test tube, graduated at 50 ml, is used in the instrument.

Procedure for Making the Determination Transfer suitable aliquots of
the 5 ppm phosphorus standard solution to the calibrated test tubes to give final
concentrations of 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7 ppm of phosphorus when
made to a final volume of 50 ml. Add 5 ml ammonium acetate (pH 4.8) and then
distilled water to make a volume of about 25 to 30 ml and mix well. Then add 5 ml
*of the ammonium molybdate solution and mix well. Finally, add 0.5 ml of the dilute
stannous chloride solution, make to a volume of 50 ml with distilled water and mix
well. Let stand at least 10 minutes before reading the percent transmission on the
colorimeter. The values (percent transmission) obtained should be plotted on the
ordinate (vertical axis) corresponding to the concentration of the standards on the
abscissa (horizontal axis). Use semi-logarithmic, 1 cycle x 10 to the inch graph
paper.

The concentration of the unknown samples can then be determined by
pipetting 5 ml of the unknown solution into a 25 x 150 ml test tube, graduated at
50 ml, and proceed as described above for the standard solutions. The amount of
phosphorus in the solution can then be determined by reading the phosphorus con-
centration from the graph in ppm on the abscissa (horizontal axis) that corresponds
to the percent transmission obtained on the ordinate (vertical axis). The calcu-
lations are then as follows:

ppm P x dilution factor x factor P to P205 x 2 (2,000,000 lbs/A
f parts per million) = lbs/A P205
ppm P x (5 x 10) x 2,2912 x 2 = lbs/A P205
ppm P x 229.12 = Ibs/A P205
A standard curve for phosphqrus, instrument settings, and a table of
converted values are given in Figure 5.

-12-
Fig. 5 STANDARD CURVE FOR PHOSPHORUS

I100

90

P205
- Lbs/A

- 26
- 25
- 24
- 23
- 22
- 21
- 19
- 18
- 17
- 16
- 15
- 14
- 13
- 12
- 11
- 10
-9
-8
-7
-7
-6
-5
-4
-3
-2
-2
-1
-0

P ppm

0.4

0.3

Instrument Bausch and Lomb, Spectronic
20 Colorimeter.
Phototube 1 Ph0
Wavelength 700 mu (with red filter)
Test tube adapter 1 inch

P2o
Lbs/A

160
155
150
145
141
136
132
129
125
122
118
115
111
108
10k
101
99
96
94
91
89
86
8k
81
79
77
75
73
71
69

% T

15
16
17
18
30 19
20
21
22
23
24
25
26
27
28
20 29
30
31
32
33
34
35
36
37
38
39
4o
41
42
43
kk

P205
- Lbs/A

- 67
- 65
- 64
- 62
- 60
- 58
- 56
- 55
- 53
- 52
- 50
- 49
- 47
- 46
-.44
- 43
- 42
- O40
- 39
- 38
- 36
- 35
- 34
- 32
- 31
- 30
- 29
- 27

% T

45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72

% T

73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100

UO.

0.1

0. V

J1o ^ '^1 _ ____

k

-13-

Nitrate Nitrogen
Standard solutions and reagents Weigh 1.3709 gm of oven dried sodium
nitrate (NaN03), C.P. grade, and dilute to one liter with ammonium acetate (pH 4.8).
This solution contains 1000 parts per million of nitrate nitrogen (NO3). Transfer
quantitatively 4, 13 and 44 ml of the stock solution into 200 ml volumetric flasks
and make to volume with ammonium acetate (pH 4.8). The solutions will contain 20,
65 and 220 parts per million of nitrate nitrogen respectively.

Diphenylamine Dissolve 0.20 gram of diphenylamine in 100 ml of concen-
trated sulfuric acid, at a temperature not to exceed 20oC. The resulting solution
should have no trace of bluish color. It should also remain colorless when four
drops of the solution are added to one drop of distilled water on a spot plate.

Procedure for Making the Determination Transfer one drop of the standard
to a spot plate, add four drops of diphenylamine solution, let stand for two minutes
stir with glass rod and note intensity of the resulting blue color. The unknown
soil extracts are run in the same way and the color is compared with that of the
standards. The results are reported as low, medium or high.

Water Soluble Salts

Instrument Used Solu-Bridge, Type RD-15, reading specific conductance
from 10 to 1000 mhos x 10-5.

Procedure for Making the Determination Place 50.00 grams of air-dried,
sieved, soil and 100 ml of distilled water into a 250 ml beaker, stir and allow to
stand overnight. (A wider ratio may have to be used for organic soils). Filter a
suitable aliquot of the soil extract into a 100 ml graduate cylinder and measure
the temperature with a thermometer. Set the "temperature" dial on the Solu-Bridge
to correspond with the measured temperature. Then insert the cell into the
solution to be tested and rotate the "concentration" dial until the black segment
of the cathode ray tube reaches its widest opening.

The specific conductance of the extract, in Mhos x 10-5, must then be
multiplied by the dilution factor. Since the relationship between specific con-
ductance and salt concentration varies with the chemical nature of the salt a
calibration curve using standard solutions should be made for the salts in question.
The concentration of soluble salts in parts per million can also be obtained
directly by multiplying the specific conductance in Mhos x 10-5 (at 250C) by 7.

-14-

Sodium
Standard Solutions Weigh 2.5418 grams of oven dry sodium chloride(NaCI)
C.P. grade, and dilute to one liter. This solution will contain 1000 parts per
million of sodium. This stock solution is then used to make standard solutions of
the following concentrations: 0, 20, 40, 80, 120, 160, 200, 280 and 560 parts per
million of sodium.

Instrument & Settings Used The Beckman Model B Flame Spectrophotometer
with the acetylene-oxygen burner assembly (No 4030, medium bore) is used for the
calcium determination. The burner consumes about 8 cu. ft. of oxygen and 5 cu. ft.
of acetylene per hour. The instrument settings are as follows:

1. Oxygen Tank 30 psi; control panel pressure designated
on burner tag, usually 10 psi,
2. Acetylene Tank 15 psi; control panel 4-5 psi.
3. Sensitivity switch 4
4. Wavelength 589 mu
5. Slit width 3 to 5 mm
6. Phototube Blue sensitive, with 10,000 megohm resistor.

Procedure for Making the Determination The standard solutions should
be run through the flame and the values obtained as percent transmission plotted
on the ordinate (vertical axis) corresponding to the known concentration of the
standard plotted on the abscissa (horizontal axis) of coordinate (10 x 10) graph
paper.

The concentration of the unknown samples can now be determined by read-
ing the concentration of sodium in parts per million from the abscissa when per-
cent transmission is plotted on the graph,

ppm Na X dilution factor = ppm Na

ppm Na X 5 = ppm Na

ppm Na X 2 = lbs/A Na

Chloride

Standard Solutions and Reagents -

Potassium Chromate, 1 M Dissolve 19.42 grams of K2CrO4 in distilled
water and dilute to 1 liter.

Silver nitrate, 0.1 N Weigh 16.988 grams of C.P. AgN03, dissolve in
water and dilute to one liter. (3 drops of conc. HN03 should be added to prevent
the formation of deposits).

To standardize the AgNO3 solution, weigh out duplicate samples of pure,
oven dried, sodium chloride of such size as to be equivalent to 30-35ml of the AgNO3
solution. This can be calculated as follows:

wt NaCl = ml AgNO3 x N AgN03 x mol. wt. NaCl
1000
= 30 x 0.1 x 58,457
1000
0.1754 or 0.2000 gm. NaCl

Dissolve the NaC1 in about 50 ml of distilled water and titrate with the
AgN03 solution to be standardized.

The normality of the AgN03 can then be determined as follows:

N AgNO3 = wt NaCl x % Purity NaC1
ml AgN03 x eq. wt. AgN03
1000

Store the AgNO3 solution in a dark bottle and keep out of strong light.

Calcium Carbonate C.P.
Calcium Hydroxide, C.P.

Nitric Acid 0.1 N Measure out 6.5 ml of cone. HN03 and dilute to one
liter with distilled water. This solution will be approximately 0,1 N.

Sodium Hydroxide 0.1 N Weigh out 4.0 grams of C.P. grade NaOH, dissolve
in distilled water and dilute to one liter. This solution will be approximately
0.1 N.

Phenolphthalein Indicator Solution Dissolve 0.05 gm phenolphthalein in
.0 ml of ethyl alcohol and dilute to 100 ml with boiled, distilled water.

Procedure for Making the Determination Place 50 gms of air-dried,
sieved, soil and 100 ml of distilled water into a 250 ml beaker (a wider soil-
solution ratio may be used for organic soils). Allow to stand for at least 4 hours
or overnight, with frequent stirring (if the suspension is turbid and highly de-
Llocculated 2 gms. of calcium hydroxide may be added). Filter, and transfer a
suitable aliquot, usually 50 ml. of the leachate, into a 125 ml erlenmeyer flask.

i

-16-

Chloride (Cont'd.)

The solution should be made basic with 0.1 N NaOH using phenolphthalein
as an indicator (pink color), and then titrate with 0.1 N HN03 until solution is
about neutral in reaction (colorless). Then add small amounts of solid calcium
carbonate until a slight excess remains undissolved (appreciable acidity prevents
the formation of red silver chromate which indicates the end-point and basic
solutions precipitate silver oxide). Add 6 drops of the M K2Cr04 indicator
solution and titrate until the solution assumes a definitely brownish-red hue.
A white porcelain background will aid in detecting the end point. Calculate the
percentage of chloride as follows:

ppm Cl = ml AgN03 x N AgNO3 x mol. wt. Cl
1000 x dilution factor x 10,000
wt. sample

i

-17-

Copper
Reagents

Hydrochloric Acid leaching solution, 1 N Dilute 8 ml concentrated HC1
to 100 ml with distilled water (5 drops of a wetting agent added to the solution
will give better leaching action on some soils).

Carbamate Reagent Weigh 16 grams of disodium ethylenediamine
tetraacetate (diNaEDTA) and 0.250 grams of sodium diethyldithiocarbamate. Then
dissolve it in 80 ml of ammonium citrate solution (made by dissolving 22 grams of
ammonium citrate in 130 ml of concentrated ammonium hydroxide and diluting to one
liter with distilled water) and dilute to 100 ml with distilled water.

Procedure for Making the Determination Place about 2 grams of air-
dried, sieved, soil (approx. teaspoonful) in a cone-shaped mound on a 9 to 12.5
cm filter paper. Make a small depression in the top of the soil cone. Then add
the 1 N HC1 leaching solution dropwise until the solution penetrates the soil
mass and spreads out on the filter paper about 1/8 inch beyond the edge of the
soil cone. This will require approximately 20 drops of the solution.

The filter paper should then be folded over and the carbamate solution
applied to the moist filter paper with a medicine dropper. The intensity of the
brown color formed is directly proportional to the copper content of the soil.
Compare the intensity of the brown color with the standard color chart given in
Bulletin 544, and report as pounds of copper per acre.

-18-

Limestone
(Calcium Carbonate Equivalent)

Standard Solutions and Reagents -

Methyl Orange Indicator Solution Weigh 0.10 gram of methyl orange,
dissolve in distilled water, and make to a volume of 100 ml.

Phenolphthalein Indicator Dissolve 0.05 gm. phenolphthalein in 50 ml
ethyl alcohol and dilute to 100 ml with, boiled, distilled water.

Hydrochloric acid solution, 0.5 N Dilute 41.7 ml of concentrated
hydrochloric acid to one liter with distilled water. To standardize the acid,
weigh out two separate portions of pure sodium carbonate of sufficient size to
require a titration of 30 to 35 ml of the acid. This can be calculated as follows:

wt. Na2C03 = ml of acid x N of acid x 106.00 (mol. wt. Na2CO3)
2 x 1000
= 30 x 0.5 x 0.053

= 0.7950 or 0.8000 gn.

Dissolve the sodium carbonate in about 100 ml of distilled water, add
one or two drops of methyl orange indicator solution and titrate with the acid
until the solution color changes from yellow to pink. Calculate the normality
of the acid as follows:

N HCI = wt. Na2CO3 x % Purity Na2CO3
ml HCI x 106,00 (mol. wt. Na2C03)
2 x 1000

Sodium Hydroxide Solution, 0.5 N weigh 20.00 grams of sodium hydroxide,
C.P. grade, dissolve in boiled distilled water and dilute to one liter. The
solution can now be standardized by pipetting duplicate O0 ml samples into 200 ml
erlenmeyer flasks, then adding 2 drops of methyl orange indicator solution, and
titrating with the standard acid until the color of the solution turns from yellow
to pink. The normality of the sodium hydroxide solution can be calculated as follows:

N NaOH x ml NaOH = N HCI x ml HC1

Procedure for Making the Determination Grind the limestone samples in a
porcelain mortar so that it will all pass a 60 mesh sieve, mix thoroughly, and dry
at 1050 C. Weigh 0.5000 gram samples of oven dried material in duplicate and place
in 250 ml beakers. (Always include samples of pure calcium carbonate as checks)
Add 50 ml of 0.5 N HC1, cover beaker with a watch-glass and heat slowly just to
boiling on hot plate. Cool, filter and titrate the excess acid with 0.5 N NaOH
solution, using phenolphthalein as the indicator. Carry out a blank determination
to obtain the titer of hydrochloric acid. Report results as percentage of calcium
carbonate equivalent (C.C.E.). The calculations are as follows:

% CC.E. = Actual N HC1 x 50 ml HC1) Actual N NaOH N
,5 0.5 N H01 0. N NaOH x l Na
x 100 (mol. wt. CaC03) x 100
2 x 1000

S 0,5t N HC1 50 ml H' Actual N NaOH ml 5
0 NHl / ( 0.5 N NaO naH

-19-

Limestone

(Calcium and Magnesium)

Standard Solutions and Reagents -

Ammonium Hydroxide Concentrated
Hydrochloric acid Concentrated
Sulfuric acid 18 N (1 to 1 dilution)
Ammonium chloride C.P.
Oxalic acid, 10% (10 gms oxalic acid diluted to 100 ml with
distilled water)
Brom Cresol Green Grind 0.1 gm of the indicator in a mortar
with 14.3 ml. .01 N NaOH and dilute to
250 ml. with distilled water.
Potassium Permanganate, 0.2 N Weigh 6.32 gms. of KMnO4
crystals, dissolve in and make to one liter with distilled water.(A normal solution
of KMnO4 will contain 1/5 mole of KMnOh because the atom of Mn loses 5 positive
charges in changing from a valence of + 7 to +2, This would give
158.03 mol. wt. KMnOh x 0.2 = 6.32 gm.) Boil the solution 10-15 minutes, allow to
5-
stand over night, or longer, and filter through asbestos. (Asbestos felt on top of
glass wool in an ordinary funnel is satisfactory. Do not allow the solution to
come in contact with rubber as it will cause the formation of Mn02 and a KMnOh
solution containing MnO2 is unstable.) The KMnOh solution can be standardized by
weighing duplicate sodium oxlate (Na2C204) samples of sufficient size to require
40-45 ml titration of KMnO4. This can be calculated as follows:

wt. Na2C204 = 40 ml KMnO4 x 0.2 N KMnO4 x 134.01 (mol. wt. Na2C204
2 x 1000
= 40 ml KMnO4 = 0.5360 or 0.5000 gm.
Dry the Na2C204 at 1050C, weigh 0.5000 gm of the material and place in a-
600 ml beaker. Add 250 ml of diluted H2SO4 (5 ml concentrated H2SO4 + 95 ml H20),
previously boiled for 10-15 minutes, and cooled to 2700. Stir until the oxlate has
dissolved. Add about 30-35 ml of the 0.2 N KMnOh solution slowly while stirring.
Let stand until pink color disappears. Heat to 55-60oC and complete the titration
by adding KMnO4 until a faint pink color persists for 30 seconds. Store in a dark
colored bottle. The calculations are as follows:

N KMnO4 = wt. Na2C204 x % Purity Na2C204
ml KMnOL x 158.03 (mol. wt. KMnO4)
2 x 1000

Procedure for Making the Determination Make the solution from the above
determination slightly acid by adding 1 ml of cone. HC1. Then add 5 gms of ammonium
chloride and 10 ml of 10% oxalic acid. Heat to boiling, add 3 drops of brom-cresol
green and then add ammonia, slowly with constant stirring, until the solution turns
permanently bluish-green. Digest on hot plate, not boiling, for an hour. Add a
little more 10% oxalic acid to make sure that the precipitation is complete. Allow
to settle for 4 hours, or overnight, and then filter through a fine grained filter
paper into a beaker. Wash the filter paper with hot water until all trace of
chlorine is removed. (This can be checked by adding AgNO3 to a small amount of the
solution.) Replace the beaker with a clean dry one, puncture the filter paper and
wash the precipitate into the beaker with hot water. Add sufficient water to the
beaker to make a volume of about 100 mls and then add 10 ml 1-1 H2SO4.

-20-

Limestone (Calcium and Magnesium) (Con'd.)

Titrate at 70-80oC with 0.2 N KMnO4 until a purple color is obtained
and then place the filter paper in the beaker and finish the titration. The
calculations are as follows:

100 (mol. wt. CaC03)
(1) % CaCO3 = ml KMnO), x 0.2 N KMnOh x !x 1000 x 100
0.5 gm (wt. sample)
% CaC03 = ml KMnOj x 2

(2) % MgCO3 = % C.C.E. % CaC03 x 84.33 (mol. wt. MgCO3)
100.09 (mol. wt. CaC03)

% MgC03 = % C.C.E. % CaC03 x .8425

-21-

Definitions

Valence That property of an element which determines how many atoms of any other
kind it can hold in combination or can displace in a reaction.

a, Univalent elements H, Na, K, Ag, Cl, Br, I.

b. Bivalent elements Ca, Ba, Mg, Zn, Hg, Fe, S, 0.

c. Trivalent elements Al, Bi, As, Fe, N, P.

d. Quadrivalent elements Sn, C, Si, S.

e. Pentavalent elements N, P, As, Sb.

Acids Are substances whose molecules ionize in water solution to give the
hydrogen ion from their constituent elements. The strength of an acid
is proportional to the concentration of hydrogen ions present.

Bases Are substances which ionize in water to give the hydroxyl ion from their
constituent elements. The strength of the base is proportional to the
concentration of hydroxyl ions.

Molality- Number of moles of solute in 1000 grams of solvent.

Molarity- Number of moles of solute in one liter of solution.

Normal Concentration of one gram equivalent per liter.

i

-22-

Calculations

Acids

Hydrochloric Acid HC1

= 1.008
= 35.457
36-465

Normality Cone. HC1 = Specific Gravity X Percent Purity X 1000
Equivalent weight

Cone. HC1

= 1.90 x 0.38 x 1000
36.465

Cone. HC1 = 12.80 N

1 NHC1 = IN
S 2.80 N

1 NHC1

0 0.0781 ml Cone. HC1 to dilute to 1 ml,

or X ml Cone HC1 : 12.80 N
12.80 x = 1000
78.125 ml

HC1 = 1000 ml : 1 N HCI

cone. HC1 diluted to 1 liter

Nitric Acid HN03

H = 1.008
N = 14.008
0 = 16.000

1.008

48.000
63,01o

Normality Cone. HNO3

mol. wt. HNO3

S Specific Gravity x percent purity x 1000
Equivalent weight

= 1.42 x 0.70 x 1000
63.016

= 15.7738

IN HNO3

1
15.1738

- 0.0633963 ml cone. HI03 diluted to 1 ml.

or x ml cone. HN03 x 15.7738 = 1000 ml x 1 N
15.7738 x 1000
1 N HN03 = 63.3963 ml cone. HN03 diluted to 1 liter.

-23-

Calculations

Bases
Ammonium Hydroxide NH4OH

N = 14.008 N = 14.008
H = 1,008 HS = 5.o04
0 = 16.000 0 = 16.000
35.048 mol. wt. NH4OH

Normality Cone. NH4OH = Specific gravity x percent purity NHOH
Equivalent weight X 1000

= 0.90 x 0.58 x 1000
35.0o8

a 14.8939
1 N NH4OH 1 = 0.0671416 ml cone. NH40H diluted to 1 liter
14.8939 or
X ml x 14.8939 = 1000 ml x 1 N
14.8939 X 1000
1 N NH4OH = 67.1416 ml diluted to 1 liter

Sodium Hydroxide NaOH
Na = 22.997
0 = 16.000
H = 1.008
40.005 mol. wt NaOH

Normal solution = 1 gram equivalent weight of the substance per liter of
solution.
1 N NaOH = 40.005 grams per liter of solution.

0.1 N NaOH = 4.005 grams per liter of solution.

1/14 or 0,0714 N = 2.8575 grams per liter of solution.

-24-

Acids (Continued)

Sulfuric Acid H2SO4

H = 1.0080 H2 = 2.016
S = 32,006 S a 32.066
0 = 16.000 04 = 64.000
100.082 mol. wt. II2SO

Normality Cone. H2S04 = Specific Gravity x Percent Purity x 1000
Equivalent weight
S= 1.84 x .96 x 1000
100,082 2

= 35.2990

1 N H2S04

1 N 11280k

= 1 = 0.01564 ml conc. H2SO4 diluted to 1 ml
35.2990
or x ml cone. H2SO4 : 35.2990 N = 1000 ml : 1 N

= 15.64 ml cone. H2SO4 diluted to 1 liter.

Percent = parts per million 10,000

Pounds per acre six inches = percent x 20.000
= parts per million x 2

Parts per million = milligrams per kilogram
= pounds per one-half acre
= milligrams per liter

1000 parts per million = 1 milligram per milliter

Grams per milliter = specific gravity x percent purity

Milliequivalents = equivalent weight Y 1000

1, CaCo3
Ca

= 100,090 = 2.4973
40.80

Ca x 2.4973 = CaC03

2. Ca
5aCO3

= 40,080
100090

= 0.4004

CaC03 x 0.UOOL4 Ca

3. K20 = 94.192 = 1.20%
K2 78.192

K x 1.204 = K20

U. K2
K20

= 78.192 = 0.8300
94.192

K20 x 0.8300 = K

5. P205
P2

a 141.96 = 2.2911
61.96

P x 2.2911 = P205

6. P2
P205

= 61.96
141.96

= 0.4365

P205 x 0.4365 = P

7, Mgo = 40.32
Mg 21.32

Mg x 1.6579 = MgO

- 24.32
0T32

- 1.6579

MgO x 0.6032 = Mg

Factors

8, Mg
MgO

= 0.6032