09v..- -QOMM—“-o“\!0-.

SEASONAL VARIABILITY OF pH AND LIME .
REQUIREMENT IN SEVERAL SOUTHERN MICHIGAN ‘
SOILS WHEN MEASURED IN DIFFERENT WAYS

Thesis for the Degree of M. S.
MICHIGAN STATE UNIVERSITY
JOHNNIE B. COLLINS
1967

 

 

IIIIIIIII IIZIIIIIILIIIII II III I I III; I III I L ,3 R .4 R y

Michigal, Statc
University

 

SEASONAL VARIABILITY OF pH AND
LIME REQUIREKEKT IN SEVERAL
SOUTHERN MICHIGAN SOILS WHEN

MEASURED IN DIFFEREN WAYS

By

Johnnie B. Collins

A Thesis
Submitted to
- Michigan State University
in partial fulfillment of the requirements
for the degree of
Master of Science

Department of Soil Science

i967

' LIZ-U

.— : -u.‘—

 

 

ABSTRACT

SEASONAL VARIABILITY 0F pH AND
LIME REQUIREMENT IN SEVERAL
SOUTHERN MICHIGAN SOILS WHEN

MEASURED IN DIFFERENT WAYS
By

Johnnie B. Collins

The variability of soil pH and lime requirement was
investigated from May through September. 1966. at nineteen
soil sites representing thirteen southern Michigan soil series.
The experimental errors in pH determinations were also
studied.

To be reasonably certain of a significant difference
between individual soil pH measurements a variation greater
than 10.3 pH is necessary. However. when mean soil pH values
of a representative number of observations are compared. dif-
fgrenoes greater than 30.15 pH unit are likely significant.

On the average. during the wetter portion of the sea-
son. the air dry and oven dry soil pH values (measured in
water) were approximately 0.5 and 0.8 pH unit lower. respec-
tively. than the corresponding field moist pH values. How-
ever. during the drier portion of the season. differences
between the average pH values measured at the three moisture
conditions were less than 0.1 pH unit and non-significant.

‘Ihere were also no significant differences between the averages

of the air dry and oven dry soil pH values measured during
the season.

The field moist soil pH values measured in water showed
the maximum seasonal variability and the air dry soil pH's
measured in 1.0NKCl showed the least seasonal variability.
The field moist pH's measured in water showed a maximum var-
iation of 1.6 pH units and an average variation of 0.8 pH
unit during the season. Similarly. the air dry soil pH's
measured in 1.0NKC1 showed a maximum variation of 1.0 pH
unit and an average variation of less than 0.2 pH unit during
the season.

The field moist soil pH values measured in water were
positively and highly correlated‘with organic matter content.
This is probably due to the combined effect of the relation-
ships of organic matter content to field moisture content.
and field moisture content to electrical conductivity. The
seasonal variability of the air dry pH's measured in water
were negatively and highly correlated with electrical conduc-
tivity of the samples. Most of the soil sites exhibited no
seasonal variability of air dry pH's when measured in 1.0NK01.
This indicates that soluble salts are probably responsible
for most of the observed seasonal variations in soil pH values.

On the average. the 0.01hCaCl2 and 1.0NKCl salt solu-
tions lowered the air dry soil pH's measured in water approx-
imately 0.6 and 1.0 pH unit. respectively.

Regardless of method of determination. seasonal varia-

bility of lime requirement was observed on eleven of the

nineteen so
the eleven
earlier pan

shoued a 1

nineteen soil sites. Using air dry samples. only four of
the eleven sites exhibited a lime requirement during the
earlier part of the season. but each of the eleven sites

showed a lime requirement during mid-summer.

SEASONAL VARIABILITY OF pH AND
LIME REQUIREMENT IN SEVERAL
SOUTHERN MICHIGAN SOILS WHEN

MEASURED IN DIFFERENT WAIS

By
Johnnie B. Collins

AN ABSTRACT OF A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE

Department of Soil Science

1967

.H

.env

'-n¢

Fr...

.2.

ACI-Il-I C L'fLEDGI-IEI-I T

Sincere gratitude is expressed to Dr. E. P. Nhiteside.
the author's major professor. for introducing the author to
the problem studied herein. His infinite patience. under-
standing. unfailing guidance and constant supervision have

been very much appreciated.

-——.-—_ 9. a,
.-

The author wishes to thank Dr. C. E. Cress. Mrs. N.
Galuzzi and Dr. E. C. Doll for their guidance in preparing
data for the computer and interpreting the same. He is N
also indebted to staff members of the Soil Testing Labor-
atory. especially to hr. 0. Pierce. for the use of instru-
ments.

His sincere appreciation goes to Dr. B. G. Ellis. Dr.

H. D. Foth. Dr. R. E. Lucas. Dr. J. C. Shickluna and Mr. R.
White for helpful suggestions during the course of this in-
vestigation.

Many thanks are extended to professors and fellow
graduate students of the Soil Science Department for pro-
viding a wonderful environment in which to conduct this
study.

The writer gratefully acknowledges the Graduate
ASSisrtantship provided him by Michigan State University en-

ablidrg him to pursue and complete this study.

ii

 

Tv-I

tn

TABLE OF CONTEB

INTRODUCTIOIq O O O O O O O O 0
LITERATURE REVIEW . . . . . .

Introduction . . . . .

Seasonal Variations of soil pH
Causes of seasonal variations in soil pH

Influence of salt content
Influence of drying, moisture content

TS

of sample or rainfall

Influence of soil water ratio
Influence of CO2 pressure in the atmos-

phere. e e e e o 0

Influence of plants and relation of pH

to base saturation

Influence of absorbed aluminum .
Influence of organic matter.

Influence of time interval between
preparation and pH measurements

Comparison of various colorimetric methods

for pH measurements . .

Accuracy of glass electrode measurements

EXPERIMENTAL PROCEDURE . . . .

Location of sites . . . .
Collection of samples .
Preparation of samples

PHETHODS OF ANALYSIS . . . . .

Soil reaction . . . . . .
Cation exchange capacity.

Total exchangeable metallic

Electrical conductivity .
Organic matter content .
Lime requirement . . . .

-REK3ULTS AND DISCUSSION . . . .

Evaluation of the experimental errors in the
measurement of soil pH with the glass

eleCtrOde o e e e e e 0

iii

0 O O O O O

eeemee

Page

\TU‘I 4? two) \O H

10
IO
11
ll

ll
12

15
15
18
19
20
20
20
21
21
21

22

22

Variability of pH measurements made
on standard laboratory check samples
during the season . . . . . . . . . .
Effects of different operators and
different pH meters on the variabil—
ity of the pH's of five air dry soil
samples 0 o o o o o o o o o o o o o o
Reproducibility of soil pH measurements
made in H20, in 0.01MCaC12 and in
1.0NKC1 by one operator using one pH
meter on the same day . . . . . . . .
Variability of soil pH values measured

in 0.01MCaCl with one pH meter by one

operator on wo different dates . . .
Variability of field moist pH values

within each of the nineteen soil sites

Summary . . . . . . . . . . . . . . . .

Influence of moisture conditions and sus-
pending media on seasonal variability of
SOilpHvalueS..............

Influence of moisture condition on sea-
sonal variability of soil pH values
measured in water and in 0.01MCaC12
with the glass electrode . . . . .

Comparison of the variability of the
air dry pH‘s of soil samples collect-
ed from May through September when
measured in H O, in 0.01MCaC12 and in
1.0NKC1 with %he glass electrode . .

Comparison of the seasonal variability
of field moist and air dry soil pH
values measured with the Truog kit
and with the glass electrode . . . .

summaryooooooooooooooo.

Several Factors influencing the seasonal
variability of soil pH values . . . . . .
Seasonal variability of lime requirement . .
iSUMMARY AND CONCLUSIONS . . . . . . . . . . . . .
LIST OF REFEREIJCES O O O O O O O O O O O O O O 0

APPENDIX 0 O O O O O O O I O O 0 O O O O O O O 0

iv

Page

22

26

28

3o
33

33

34

37

39
41

#2
48

51

56
63

 

 

I
is 9. m.

o

O

o

o

o c

C a C

o . c o

u u o o

u o o o

a a o a

o c o o

u a o n

o o a o

o o 1 a

a o o c 9

a o o a u

o o u o c o

a o u a o o

c n o w o c p

LIST OF TABLES

Table

l.
2.

7.

8A.

8B.

11).

Location Of pIOtS O O I O O O O O O O O O O 0

Texture, degree of erosion, percent slope,
direction of lepe. crOp or vegetation and
natural drainage of the 19 sites used in
this study . . . . . . . . . . . . . . . . .

"Known pH values" and variability of pH
measurements made on standard laboratory
check samples from May to October . . . . .

Analysis of variance for a three way analysis
(5 soils, 3 Operators, 3 suspending media) .

Summary of the variability in the pH's of five
air dry soil samples measured in water, in
OoOlD’ICflClZ and in loONKCl o o o o o o o o 0

Variations in the pH's of the composite and

single core samples collected in the initial.

sampling or eaCh plot. 0 o o o o o o o o o 0

Soil reaction measured at three moisture con—
ditions and in several suspending media for
each site on each sampling date . . . . . .

Field moisture percentage, total exchangeable
metallic cations, electrical conductivity
and organic matter content measured during
the season'for each soil site. . . . . . . .

Cation exchange capacity of each site, and the
base saturation percentages and exchange
acidities of each site determined during the
seasonoooooooooooooo00000

Significant simple correlations between sea-
sonal variability of soil pH and field
moisture percentage, base saturation per-
centage, electrical conductivity and or-
ganic matter content . . . . . . . . . . . .

Seasonal variability of lime requirement
(Tons/acre) determined by the pH plus tex-
ture, S.M.P. buffer and exchange acidity'
methods as determined on air dry samples
from 11 of the sites representing 9 soils. .

Page

16

17

27

29

32

63

64

65

46

66

K!

v-27. F."- '
, _-

 

2.

 

Va

Se

LIST OF FIGURES

FIGURE Page

1. Variability of pH measurements made on sev-
eral standard laboratory check samples
from May through OCtOber e e o e o e o o e 0 2n

2. Comparison of pH values of all the air dry
samples from the 19 sites measured in
0.01MCaC12 on two dates 0 e o o e o e e o e 31

3. Average pH's of ten soil sites measured at
three moisture conditions and in two sus-
pending media from May through September . . 36

h. Variability of air dry pH's of ten soil sites
measured in three suspending media from May
throughSeptember 000.00.000.00 38

5. Comparison of average field moist and air dry
pH values of nineteen soil sites measured with
the Truog kit and in water with the glass
electrode from June through September . . . #0

6. Variability of the air dry pH's of five soil
sites measured during the season . . . . . . an

7. Seasonal variability of average lime require-
ment determined by three methods . . . . . . 50

vi

Perhaps
medium for 1
A activity". *3
1
are closely I
Detemf

Operations u

 

of son pfi v
Sideration C
measured p};
the soil in
11011 of the

This.

in °rder 1
WNW 01
teen Site
”88151.
am to 9.1
of 8011 1
In
differEr
Wire 00:
field 1m

mints.

INTRODUCTION

Perhaps the most important chemical test of a soil as
a medium for plant growth is its pH value or "hydrogen ion
activity“. The solubility and availability of many nutrients
are closely related to soil pH.

Determination of pH is one of the easiest and quickest
operations used in soil chemical analysis. However, the use
of soil pH values as expressions of acidity involve the con-
sideration of several factors: In the first place. does the
measured pH value give a true expression of the acidity of
the soil in the field? Secondly, how variable is the reac-
tion of the soil in the field throughout the year? Thirdly,
how do the magnitudes of seasonal variations compare to the
experimental errors encountered in pH determinations.

This study was conducted from May to September, 1966,
in.order to investigate: the seasonal variability of the
acidity of the plow layers of thirteen soil series at nine-
teen sites in Southern Michigan, to observe several of the
INJssible factors influencing the apparent seasonal variations,
EHM1 to evaluate the experimental errors in the determinations
01‘ soil pH.

In evaluating the experimental errors, the effects of
different operators. different pH meters and different times
were considered. Consideration was given to the effect of
fielxi moist, air dry and oven dry samples on the pH measure-

ments. Also, the pH's of the air dry samples collected during

 

the season 1
LONKCI sob
two salt 30'
was also g1
at the f 011
media: fie
water and 1

T0 ‘m
tion, elee
saturation
W of to

In a
tent was d
McLean-Sm

8011 text:

the season were measured in water. in 0.01MCaC12 and in
1.0NKCl solutions in order to determine the effects of the
two salt solutions on the pH measurements.- Special attention
was also given to the variability of soil pH values measured
at the following moisture conditions and in two suspending
media: field moist in water and in 0.01MCaClz; air dry in
water and in 0.01MCaC12; and oven dry in water and in 0.01MCaC12.

To help understand the seasonal variation in soil reac-
tion, electrical conductivity (or salt content), percent base
saturation. field moisture content, and organic matter con—
tent of the soil samples were investigated.

In addition, the seasonal variation of the lime require-
ment was determined and compared by the following methods:
McLean-Shoemaker—Pratt buffer, exchange acidity, and pH plus

soil texture.

 

m— ww—
m

2
"v
-—-——a

pH i
the hydrog
my be di‘
electrode
colorimet'
9.31.1“. or
in Platin
“Inf. of
QIECtI‘Ode
up to 8. 5
and hydro
Ution. I
tion that
aluminum
or the so
hitable

change 1:1

It ‘
“153,59,

“031 the I

consider a‘:

LITERATURE REVIEW
Introduction

pH is commonly defined as the negative logarithm of
the hydrogen ion activity. Methods for determining soil pH
may be divided into two groups: electrometric (hydrogen
electrode, quinhydrone electrode and glass electrode) and
colorimetric. The hydrogen electrode (5.25) measures the
e.m.f. of the equilibrium between gaseous hydrogen dispersed
in platinum black and hydrogen ions in solution against the
e.m.f. of a standard calomel half cell. The quinhydrone
electrode (5) is based on the principle that for pH values
‘up to 8.5. the oxidation-reduction potential between quinone
and hydroquinone depends on the hydrogen ion activity in sol-
'ution. The glass electrode (30) evolved from the observa-
tion that the potential between membranes of certain low-
aluminum glasses and a solution is closely related to the pH
of the solution. The colorimetric methods (22) makes use of
suitable dyes or acid-base indicators, the colors of which

Change with the hydrogen ion activity.
Seasonal;iagiations of Soil pH

It has frequently been observed (6.7.9.18.31.33.37,#1.
“5.53.59.75.78.79,82,87) that pH values of soil samples taken
from the same site at different times during the year show

considersmde variations. Studies of seasonal variation in

-3...

 

soil react
ical test

micronutri
is also on
tion Syste

at the fa:

l/‘x

soil reaction are of much practical importance where this chem-
ical test is used to determine the fertilizer (particularly
micronutrients) and lime requirement of soils. Soil reaction
is also one of the criteria used in the new soil classifica-
tion system (7th Approximation) to classify certain soils

at the family level, and it has very commonly been a criterion
for differentiation among soil series. Therefore. an inves-

tigation of seasonal variations in soil reaction should be

very useful.

Causes of seasonal Variations in_pH

Many investigations (6.7.9.18,31,#3,44,h5,53,78,79,82)
have also been conducted in an attempt to ascertain why soil
reaction fluctuates during the year, and to determine the mag-
:nitude of the apparent variation. A large number of inves-
tigators (18,h3,h#,53,78,82) have reported an increase in soil
acidity during the summer months. In some instances (#3,#4,
78) a.variation during the year of as much as 1.0 pH unit has

been reported.

Lrflgence of salt content

JBaNer (6) attributed the increase in soil acidity dur-
ing tkue summer months to the accumulation of soluble salts.
Others (33,53,59,66,87) have reported similar findings.
Puri,I§t2 a1. (59) and Schofield, et. a1. (66) pointed out
that "natural none-saline" soils contain varying amounts of

Salts: aund that soil pH is altered appreciably in the presence

 

 

of even 3
that a c'::
contact t
tamed by

it? from

of even small quantities of neutral salts. Yuan (87) found
that a change in pH resulted when the soil was brought into
contact with a salt solution, and that the change was accom-
panied by the liberation of exchangeable and hydrolytic acid-
ity from exchangeable hydrogen and aluminum. As pointed out
by Olson (53), probably one of the important factors respon—
sible for an increase in acidity during the late spring or
early summer is the relative high concentration of salts in
the soil solution following the application of fertilizers.
This conclusion is contrary to the results of Bell. et2 al.

(7) who found that fertilizers had no effect on seasonal

changes in soil pH.

Influence of drying, moisture content of samples or rainfall

 

The effects of drying and moisture content on variation
Of‘soil reaction.have been the subjects of many investigations
(3,6,16,19,28,4l,51.52.64). Olson (53) determined the acidity
CH1 the same sample but at different moisture contents, and
(Hancluded that soil moisture may have an appreciable effect
CHI soil pH. Chapman, et. a1. (19) found that at moisture
Cinntents corresponding to the moisture equivalent, stable
ireadings may be obtained provided the electrodes are well
covered with the moist soil. They also found that constant
euui consistent readings may be obtained with the soil at or

Heal? the "sticky point," and that differences in moisture

content in this general range had but little effect on the

 

.- . ,
ik’hn sue e ..

Slass elec
and that t
are charac

3028.

(13315 he.
alkaline

(3) Tepor
011 and

at 10001:.
”Home:
dry p3 VE
1°“? p3
dry gimp.

Variable

pH values. McGeorge (51) employed the spear type electrode
and concluded that it yields values that truly reflect the
acidity under any and all growing conditions, and that the
readings are accurate and can be closely duplicated. Davis
(28) pointed out that attempts to measure soil pH with the
glass electrode below the moisture equivalent are undesirable
and that there is no acceptable evidence that air dry soils
are characteristically more acid or more alkaline than moist
soils.

Burgess (16) pointed out that both air drying and oven
drying had little or no effect on acid soils but that drying
talkaline soils rendered them somewhat less alkaline. Arrhenius
(:3) reported the effect of drying on the pH of an alkaline
£3011 and found that neither air drying nor drying in an oven
sat lOO°F brought about any change in pH values. Huberty (41)
cwonducted an experiment to determine the suitability of oven
clrw'pH values as expressions of soil acidity. He obtained
lxower pH values with the oven dry samples than with the air
(irw'samples and observed that the oven dry pH's were no more
variable than the air dry pH's.

Rost (64) et. a1. studied 14% soils develOped from
glacial and loessial materials and found that all but one
beBCame more acid upon air drying. Therefore. they concluded
tfluit the only reliable indication of conditions existing in
the :field are obtained when pH's are determined on field moist

Samples 0

 

Severe
fluctuations
Van Der Pea;
alternating
that the tr:
1315 wet 2r:
0f “Sh arr;
deserted Si
filament
Pi ‘mit {‘01
8.0151 soils‘
mt Ulrika
tion: and

rainfall w

Several investigators (6.53.82) have related seasonal
fluctuations in soil pH values to variations in rainfall.
Van Der Paauw (82) attributed fluctuations in soil pH to
alternating periods of low and high rainfall. He observed
that the trend of pH corresponds fairly closely to alternat-
ing wet and dry periods: it gradually increases in periods
of high and decreases in periods of low rainfall. Baver (6)
observed similar trends in soil pH at the Ohio Agricultural
Experiment Station and he reported variations of 0.6 to 0.7
pH unit for alkaline soils and as much as 0.9 pH unit for
acid soils. Olson (53) observed no effect of rainfall on pH
but indicated that if factors such as temperature, evapora-
tion, and others could be kept constant it is possible that

rainfall would have a decided influence on soil acidity.

Influence of soil water ratio

 

There has been little agreement among different inves-
ti4§ators (2, 10.19.35.4l,50,57,65,70.76) as to the prOper
1%It10 of soil to water that should be uSed in preparation of
the: soil suspension for pH measurements. Several investigators
(159.41.76) agree that the increase in pH upon dilution from
the! "sticky point" to a soil-to-water ratio of 1:5 may be
Over 1.0 pH unit. '

Pierre (5?) found that the hydrogen activity of some
Soilds were not affected by changing the soil-water ratio from

1:2 tn) 1:50. Further, those soils that showed a change in pH

no longer set
were leached
nlticant the
varying fro:
no consiste:
soils using
varied from
on 1:]. as 5
Chang
be depende:
Arrhenius
With 3 mm
33ml 801]
1.500 Wert
i“Crease,
for soil-
found the
ratios be
On
that a S
1930, th
5°Clety
rattic as
a 1:1 I‘a
vanOus

(1:1) 84”.

-8-

no longer showed such differences after the soluble salts

were leached out. Sharp and Hoagland (25) reported no sig-
nificant differences in the pH's of soils at soil-water ratios
varying from 1:2 to 1:500. GilleSpie and Hurst (35) found

no consistent differences in the hydrOgen ion activity of
soils using soil-water ratios of 1:1 and 1:2. His results
varied from a minus 0.15 to a plus 0.25 of a pH unit, based
on 1:1 as a standard.

Changes in soil pH with different soil—water ratios may
be dependent on organic matter content, as pointed out by
Arrhenius (2). This investigator found but little change
with a humus rich soil, but a change of 0.9 pH unit with a
sandy soil (low in organic matter), when ratios of 1:2.5 and
1:500 were compared. McGeorge (50) pointed out that the
increase in soil pH with different dilutions is most rapid
:for soil-water ratios below 1:10. Likewise. Bradfield (10)

:found that the increase in pH is most rapid for soil-water

ratios below 1:8.

0n the basis of the above reports it became apparent
tkuat a standard soil-water ratio was needed. Therefore, in
19.30. the soil reaction committee of the International
Society of Soil Science (38) adapted a 1:2{5,,soil-w'ater
raizio as the standard. However. several states have adepted
a 1.:1 ratio (55), and various investigators have adopted
V8”Pious ratios.' The procedures used here for pH's in water

(1:1) and in 0.01MCaC12(1:2) are those recommended Jointly by

 

 

the America”.
“testing and

malysls Par

Influence of

Severe
effect of it
and that it
the atmosp‘o
7.0. Real
tlvlty of t
by lncreasl
t° ten per:
soils is sj
m that w,
nent Chang
‘50“ dioxid
of “1108.11

arithm of

pa °r Suc':
Partial p:
or the Dr:

1
.n wtiter.

Tee
“wiles.

the American Society of Agronomy and the American Society of
Testing and Materials in Agronomy No. 9, Methods of Soil

Analysis Part 2. 1965.

Influence of 002_pressure in the atmosphere

Several investigators (39.57.61.85) agree that the
effect of increased carbon dioxide is to decrease soil pH,
and that its effect at the partial pressure prevailing in
the atmosphere is very small in soils having pH values below
7.0. Hoagland, et, a1. (39) found that the hydrogen ion ac-
tivity of the suspension of acid soils is not markedly affected
by increasing the carbon dioxide content of the suspension up
to ten percent, but that the acidity of a slightly aklaline
soils is slightly increased by such treatment. They pointed
out that when the original conditions are restored no perma-
nent change in soil reaction could be attributed to the car-
bon dioxide. Whitney and Gardner (85) found that the pH
01’ calcareous soils is a straight-line function of the log-
arithm of the carbon dioxide pressure and concluded that the
PH of such soils, measured after equilibration with known
PaJVtial pressures of 002, should give a better indication
of the probable pH range in the field than the pH measured
in Water. In the U.S. salinity laboratory (61). the pH
measurements are ordinarily made after equilibration of the
s°11With the carbon dioxide pressure of the atmosphere,

regalxiless of the soil to water ratio used.

 

Influence o

It he.
changes in
cotiller dur
tween pH at
vestlgatior
relations‘n
fair-1y con
widely bet
Saturation
latlons‘n'l;
“65311558 t
of the so]
kaolimti
of the co
latlonshi

It
2"),(10’46

hen Con-

-10-

Influence of plants and relation of pH to base saturation

It has been reported that plants may influence seasonal
changes in soil reaction by removing bases from the exchange
complex during the growing season (75). Relationships be-
tween pH and base saturation have been the subject of many in-
vestigations (48,#9,58,72). Morgan (52) pointed out that the
relationship between pH and percent base saturation may be
fairly constant within a soil type. but that it may vary
widely between soil types. Mehlich (H8,h9) studied the base
saturation and pH relationships and concluded that this re-
lationship is almost solely influenced by the nature of the
exchange complex. For montmorillonitic soils base saturation
of the complex at pH 7.0 is practically complete; whereas for
ikaolinitic soils at the same pH value only 50 to 80 percent
of the colloids are base saturated. The base saturation re-
lationships are very useful in classifying soils in the new

soil classification system (7th Approximation).

Influence of absorbed aluminum

It has been reported by several investigators (13.20,
2&,40,#6.62.63,67.70,80,83) that in very acid soils aluminum
«contributes to soil acidity. 0n the breakdown of clay, alum-
1num.contributes to soil acidity. 0n the breakdown of clay,
EiLuminum is released and absorbed on the exchange complex.
The hydrolysis of aluminum results in the formation of
hydIWIxy-aluminum ions and hydrogen ions, thereby increasing

the apparent soil acidity.

 

niluence <

Seve:
studied to.
soils in r
eluded the
Orsmic ac

Slightly :

T 9‘ H

in: iueRCe

\
mi
3.8

mum?) t)“:

Values he

-11-

Influence of organic matter

Several investigators (1.12.15.34.68,69.7u,8h) have
studied the organic matter content and organic acids of
soils in relation to variations in soil reaction. They con-
cluded that the organic matter acts as a buffer. whereas the
organic acids accumulated underanaerobic conditions may

slightly influence soil acidity.

Influence of time interval between preparation and pH measurements
The time interval between preparing the suspension and
.making the determination in relation to changes in soil pH
‘values has been the subject of several investigations (4,29.
_SO). Working with alkaline soils, McGeorge (50) concluded
tunat the pH decreases with an increase in the time interval.
(Zontrary to the above. Bailey (A) used boiled distilled
vmater, a 1:2 and l:# soil-water ratio, field moist and air
(irw'samples. and concluded that the pH of the suSpension was
rust affected by the length of time the water was in contact
trith the soil sample. Bailey's conclusion was substantially

1J1 agreement with the results of Dean and Walker (29).
Skunparisons of Various colorimetric methods for pH measurements

At the present time. the colorimetric method for pH de-
'terndnation is primarily confined to field test kits. Mason
.Et.efl4 (47) compared several pH fieldldts based on their cost,
accuracy and adaptability for rapid use. They found that the

reproducibility of pH values as indicated by the several field

0T»:- ' - —- —-

 

lun—

kits were

Operator,

as aqueou
however,

on reasur
31‘. attet;
thus mini

(:29 8.201:

D
',h-

-12-

kits were influenced by the following: (1) experience of
Operator, (2) purity of chemicals and prOper adjustment of
pH, (3) cleanliness, (4) contamination, (5) and manipulation
of soil extract. In moSt colorimetric techniques. the pH of
an aqueous soil extract is usually measured. Woodruff (8h),
liowever, has recently prOposed a colorimetric method based
¢Dn measurement of the pH of a 0.01MCa012 extract of soil in
zan attempt to fix the salt concentration of the soil and
'thus minimize the variation in soil pH due to fluctuation in

“the amount of soluble salts.
Accuracy of glass electrode measurements

At present. the glass electrode is the most extensive—
13r used electrometric method for pH determinations. It is
stuxndard equipment in most laboratories and it may be line
ox"battery Operated.

The reproducibility of pH values with the glass elec-
tnxxie has been the subject of several investigations (19,23,
25.5#.55,59,60,66). Chapman, et. a1. (19) found that read-
ings with the glass electrode were stable. constant and con-
sistent at moisture contents corresponding to the moisture
equivalent and/or the sticky point; providing the electrodes
Were well covered with the moist soil and there was good
contact. They reported a maximum variation of 0.08 pH unit
With a loam soil, and a range of O.# pH unit with a clay loam

soil at the above moisture content.

 

EOE!
a
me uS‘ia“
lower 210*

'4
Pu Values

F1
(D
p)
'1

'A

-13-

However, soil pH measurements with the glass electrode
are usually made in dilute suspensions rather than at the
lower moisture contents. Coleman, et. a1. (25) observed that
ij values obtained for a stirred soil suSpension was lower
than that of the supernatant liquid and that the pH value
Ineasured when the electrodes were pressed into the sediments
*were still lower. He concluded that the measured e.m.f. which
is interpreted in terms of pH includes two terms, the activity
«of hydrogen ions and a junction potential, and that potentio-
Inetric measurements of the pH of soil suspensions or pastes
czannot be entirely attributed to soil acidity. For twelve
CLifferent soils they reported that the pH of the suspensions
were 0.1 to 0.9 pH units lower and the pH of the sediments
wexre 0.5 to 1.7 pH units lower, than the pH of the supernatant
liquid.

Peech. et. al. (55) pointed out that the error due to
the: junction potential when both the glass and calomel elec-
trmxies are immersed in the flocculated soil suspension should
not exceed 0.25 pH unit. They indicated that the error may
be avoided in flocculated soil suspensions by placing the
salt bridge or the conventional type calomel electrode in the
Clear supernatant liquid and the glass electrode in the sedi-
ments or partly settled suspension.

Schofield. et. al. (66) preposed the measurement of pH
in a 0.01MCa012 solution.) They indicated that the error due
to the Junction potential could thus be minimized because

8°11 suspensions are flocculated in 0.01MCaClZ. Also. they

 

 

pointed on
ution over
equivalent
solution c
tent. Th:
indepeme
Saline so
Cla
pmential
the clear
the 9ND]
ionic Sat:
Mar.
Ea-
sonal Va

(59). 1

immem

-14-

pointed out that the pH in 0.01MCaC12 is independent of dil-
ution over a wide range, and that 0.01MCa012 is approximately
equivalent to the total electrolyte concentration of the soil
solution of a non—saline soil at optimum field moisture con-
tent. Therefore the observed pH in 0.01MCa012 should be
:1ndependent of the initial amount of salts present in non-
saline soils.

Clark (23) found that the errors due to the junction
1>otential were not eliminated by placing the K01 bridge in
1:he clear supernatant liquid. However, he indicated that
tune errors are essentially eliminated by insuring that the
icnnic strength of the salt in solution is less than 0.005
molar.

Many European workers have attempted to minimize sea-
scnial variations in soil pH values by measuring pH in IN KCl
(59). They have indicated that pH values in lN KCl are less
influenced by changes in biological and meteorological condi-
tions and thus reflect a.more intrinsic characteristic of the
soil than the soil pH measured in water, as is commonly done

in the United States.

were mine]
{Laughton
drainage .
M811 to p
Sal{files m
tion of 6

“2112889 ’

Lhfi
zaps. F]
vll‘e, n?

Tin)

-15-

EXPERIMENTAL PROCEDURE

Location of Sites

 

This study was initiated in May, 1966, using thirteen
soil series and nineteen sites. All of the series and sites
were mineral soils except one which was an organic soil
(Houghton muck).l The texture of the surface, and the natural
drainage of the soils varied from clay loam to sand and from
well to poorly drained, reSpectively. The pH's of air dry
samples measured in water varied from 5.2 to 8.0. The loca-
tion of each site is given in Table l, and the texture, natural
drainage, degree of erosion, percent lepe, direction of slope,
vegetation or crop, and area studied at each site are given in
Table 2.

The general soil areas were located by the use of soil
maps. From these areas. plots with uniform t0pography, tex-
ture, natural drainage, vegetation or crop, color of surface
and pH were selected. The sites selected were not close to
gravel roads, dead furrows, lime or manure piles, or burned

muck areas.

\0 Q
hELOC

1" 1 D r‘
“E“ g

(f' *1]

Tab]. 6 l c

Ceresco No. 1
Ceresco No. 2
Colwood No. l
Colwood No. 2
Chelsea*
Hillsdale No. l
Hillsdale No. 2
Houghton
Lapeer

Nekoosa No. l
Nekoosa No. 2
Oakville

Pewamo No. l
Pewamo No. 2
Plainfield
Spinks No. l
Spinks No. 2

St. Clair

 

-15-

Location of plots

County
Clinton
Ingham
Ingham
Clinton
Clinton
Clinton
Ingham
Ingham
Clinton
Ingham
Clinton
Clinton
Ingham
Clinton
Clinton
Shiawassee
Ingham
Clinton

Clinton

 

“Formerly called Graycalm.

to Northern Michigan

Two.

-.

 

Hatertown
Meridian

Meridian

U3
SD

.th

(15

ath
Victor
Leslie
Meridian
Bath
Meridian
Bath
Bath
Meridian
Watertown
Eagle
Woodhull
Meridian
Bath

Dallas

Graycalm is now restricted

Table'l. Continued

Erectional Section, Sectionl Township ard Range
NE %, sw 3 NW % Sec. 6. T5N, 33w
RN 3, NW i, NW i, Sec. 36, TQM, BIN

rs i, NE 1. NE 1. Sec. 35. Tux, Bid

7*
54
WP
'7‘
o]

Sec. 22. TEN, le

If .1
E3
NJ

E3
'r t
o
H
‘ 4
[41
.t 'u
u
1'“
”up.
.

See. 23. TSN, le

SE %. Kw i, sw ;, Sec. 31, T36N, RlN
NE 1. SE ;. NW i, Sec. 24, TlN, Riv
sw i, RE i, 5v i, Sec. 30, Tux, Riv
NE i, Ne g. NE 2, Sec. in, T5N, Riv
sw i. 54 i, NE &, Sec. 19. Thu, 32w
KB }, RE i. N? 1. Sec. 22, T5N, le
SE i. SE ;. sq 3. Sec. 2n, T5N. , Riv
hi 3, Lw {. DE ;, Sec. 22. Tun, Rlfl
L4 2, NW &, *w 1, Sec. 6. T5K, 33w
sw ;, Sb %, YE ;. Sec. 1, T5N, Run

U)
[*1
N"
(I)
re

h.-
.5":
2..

4:. IL:

Sec. 20, T7N. 313

See. 30, TAN, RIM

m
2,
NH
H
(4
[=1
er
Ce
2.
wk

SE %. SE ;. :3 1, Sec. 2n, T5N, BIN

See. 4, T7N, Raw

0)
hi
we
U)
H
,z In
03
2:
if

3011 Site

HA

I

~-\

1..
3

3

\1 &"

‘
V..E§tc:

,-

N

.n .i AM
fi- A;
W,. .1;
‘1‘ ‘ q
nun Pad

‘
,L
.J

.‘

*‘
.0

\

V. 1- \v I A h
3

o O 0 mm .c:
6 Z . .. .m .r
hu. ‘Cu C. W .e
m K x . 2.
V

f Di '1

b

t ‘ ' '\ t
‘ C O I

a ‘ .ru
a
.I 1‘ ¥Un
H: «‘0
I

Table 2.

Soil Site

 

Blount

Ceresco No
Ceresco No
Colwood No
Colwood No

Chelsea

-17-

Texture, degree of erosion, percent slope,

direction of lepe, crop or vegetation and

natural drainage of the 19 sites used in
the study.

Hillsdale No.

Hillsdale
Houghton
Lapeer
Nekoosa No
Nekoosa No
Oakville
Pewamo No.
Pewamo No.
Plainfield
Spinks No.
Spinks No.

St. Clair

 

J

H

 

Texture Degree of
(Surface) Erosion
(1)
Clay Loam Slight
(0)
. 1 Sandy Loam None
(0)
. 2 Sandy Loam none
(1)
. 1 Loam Slight
(1)
. 2 Loam Slight
(1)
Sand Slight
(1)
Sandy Loam Sli‘ht
(1
No. Sandy Loam Slight
(0
Iviuck None
(1)
Sandy Loam Slight
(1)
. 1 Sand Slight
(1)
. 2 Sand Slight
(1)
Sand Slight
(l)
1 Clay Loam Slight
(1)
2 Clay Loam Slight
2
Sand moderate
(l)
1 Loamy Sand Slight
(l)
2 Loamy Sand Sliwht
1
Clay Loam Slight

0 “cl

(3
(b

:1»

wk

b Is-
as

d"

\

bl b»:
(vi

(U I D> l
131'. a;

53' I
6"

:1» I be I b:-
o'k (N ‘65; 654.

U" l tr! I
655‘

\
0“

{r-

\ :}
0“

a»:
mv mv (NV O\v‘(\) v N V (\Vf‘o V_(\) V‘h) V (\J VmVG\V N VN VN V N V (\3 VI\) V

6K

m
‘ek

(D
‘64.

cfk

("H I m

wAWA‘wAwAOAOAw/xOAOAOAOAWAwr-‘OAOAOAOAOAOA

"ex

I i c ' C
i N . I f . I. -
LP: a.“ m. «r . . 5 v
v .u 4 .fi ,
£1 .5 A . J. ‘4 ”A
‘L «O . .. .‘J. WV RU
.I . N4 Aw ~\.U 3AM fib

441w . 1.11.06. . .I.,-
1Fir§1

A.

4’ u I

. v .+ i. . .
«A . A s a
. 0 3
Aug AD 1.)

301‘.“

Direction

of Slang
Southern
Southern
Southern
South Western
Southern
South Western
South western
Southern
Southern
Southern
South western
Southern
South western
South western
Southern
South western
South western
Southern

Southern

Table 2.

CrOp or
Vegetation

 

Corn
Grass
Grass
Grass
Grass
Grass
Alfalfa
Grass
Sod
Grass
Grass
Grass
Pasture
Corn
Alfalfa
Grass
Alfalfa
Corn

Alfalfa

Cont inued

Natural
Draina;§
Imperfect*
Imperfect
Imperfect
Poor
Poor
Well
well
Well
Poor
Nell
Imperfect
Imperfect
well
Poor
Poor
Well
Well
Well
Well

 

Area of Plot

 

to
50
5o
30
to
100
60
to
100
to
no
30
30
100
100
30
so
so
no

ft.
ft.
ft.
ft.
ft.
ft.
ft.
ft.
ft.
ft.
ft.
ft.
ft.
ft.
ft.
ft.
ft.
ft.

ft.

50 ft.
50 ft.
60 ft.
so ft.
50 ft.
100 ft.
so ft.
60 ft.
zoo ft.
50 ft.
100 ft.
100 ft.
80 ft.
zoo ft.
zoo ft.
70 ft.
80 ft.
’40 ft.
60 ft.

* "Imperfectly drained" and "somewhat poorly drained" are
synonymous expressions of the natural drainage conditions

of a soil.

___,-,__.,_,..-. .. .

 

 

-18-

Collection of samples

Uniformity of the pH at each site was ascertained by the
variability of pH among six individual cores and a composite
sample which consisted of 20 cores. The six individual cores
were 3 inches in diameter and extended to a depth of 6 to 8
inches (the plow depth). The 20 cores of the composite sample
were one inch in diameter and extended to a depth of 6 to 8
inches. The six cores were collected by dividing each plot
into six equal parts and taking a core from the center of
each of the six parts. The 20 cores of the composite sample
for each site were taken according to Extension Bulletin E-498
of the Cooperative Extension Service of Michigan State Univer—
sity (2}). Two sub-samples were taken from each of the six
individual cores and from the composite sample, and the pH's
were determined with the glass electrode in a 1:1 soil-
water suspension, Table 3.

After the sites or plots were located and established,
the plow layer or upper 6 to 8 inches of each-plot was sampled
about the fifteenth of each month. Ten of the sites were
sampled from May through September the other sites were sampled
from June through September. One composite sample was collected
from each plot each month in the same way the first composite

sample of each plot was collected.

=19.-
Preparation of samples

The composite samples were well mixed in a plastic
pail. After uniform mixing, a sub-sample was taken from the
original sample of each site and placed in a plastic bag.
After the sub-sample from each site was brought into the lab-
oratory, part of it was refrigerated at about 40°F. until
the field moist pH's could be determined and the remainder
was placed on a laboratory bench and allowed to air dry. The
samples were covered with wrapping paper, while air drying,
in order to prevent contamination by dust particles. Deter-
minations of pH on the air dry samples were made after three
or four weeks of air drying. The pH of the field moist sam-
ples were determined from one to three days after collection
of the samples. A portion of the field moist sample from
each plot was dried in an oven for 2h hours, at approximately
100-1100F, and the pH's of these oven dried samples were also

determined.

-20-

METHODS OF ANALYSIS

All samples were crushed and sieved through a two mill-

imeter screen prior to analysis, and all determinations were

run in duplicate, except where otherwise indicated.

Soil reaction

The hydrogen ion activity was determined with a Beckman

Zeromatic pH meter and with the Hellige-Truog colorimetric kit

at the following moisture statuses: field moist, air dry,

and oven dry.

All pH measurements made with the glass electrode were
on samples with the soil water ratios as indicated, on a weight

basis. Glass electrode pH's of the oven dry and field moist

samples were measured in a 1:1 soil -H20 suspension and in a

1:2 soil - 0.01MCaCl2 suspension. The hydrogen ion activities

of the air dry samples were also measured in a 1:2 soil -

IUWKCl suspension, in addition to the above two suspensions.

{Noe suspensions were each allowed to equilibrate for fifteen

mixnxtes with several intermittent stirrings.
Cation exchange capacity

The cation exchange capacities were determined by sat-
urating the exchange complex with sodium ions (1N NaAc, at':.pH8.2)
and replacing the sodium ion with ammonium ions (1N NHuAc)

(443). The sodium in dilute solution was determined with a

 

Colezar

I 0f soil

l-il

.—

electri¢
PEech (

an the

-21-

Coleman flame photometer, and expressed as m.e./100 grams

of soil.

Total exchangeable metallic cations

The total exchangeable bases were determined by the

titration method as described by Bray and Willhite (42).
Electrical conductivity

The total soluble salt content was estimated by the
electrical conductivity method as described by Greweling and
Peach (36). A Solu—Bridge soil tester (Model RD—l5) was used

and the specific conductance was expressed as mhos x 10‘5/cm.
Organic matter content

Total organic matter was determined by the ignition and

'weight loss method as described by Mitchell (#2).
Lime requirement

Lime requirement was evaluated by the following three

methods:

1. Shoemaker, et. al.. buffer method (73).

2. pH - Texture method (77). ,

3. Exchange acidity - determined by difference be—
tween cation exchange capacity and total exchange-
able metahlic cations.

The lime requirements as determined by the above three

me thods were compared .

'J_

 

We"? at r'
with. «m: - -

-22-
RESULTS AND DISCUSSION

Evaluation of the errors encountered in the

measurements of soilqu with the glass electrode

To evaluate the errors in soil pH measurements with the
glass electrode, consideration was given to: (l) the varia-
bility of the pH's of several standard laboratory check sam-
ples measured repeatedly during the period of this study,

(2) the effects of different operators, different pH meters
and different times on the pH's of five air dry soil samples,

and the reproducibility of soil pH measurements made on these

air dry samples: in water, in 0.01MCaC12 and in 1.0NKC1,

(3) the variations in duplicate pH measurements made on com-
posite field moist samples from each of the 19 sites, com-
‘pared to the variability of duplicate measurements made on
six core samples from each of these sites.

‘Variability of pH measurements made on standard laboratggy
check samples during the season

pH values of the check samples used in this investiga-
‘tion.were each measured several times during this study from
bury to October and approximately on the same dates that the
Ifli’s of the nineteen soil sites were measured. In addition,
these pH measurements were not always made by the same 0p-

erator and the measurements were not always made with the

samuang meter on the different dates.

-23-

Variability of pH values measured during this study
for each of three of the standard check samples are illus—
trated in Figure 1. Check sample No. 1 has the highest
pH value and it showed the least variability. pH values
of this check sample fluctuated only 0.1 pH unit from time
to time during this study. The maximum and minimum pH
values for each of the other two check samples were observ—
ed during the earlier and latter part of this study, re-
spectively, Figure 1. Differences between the maximum and
minimum pH values for each check sample were 0.3 pH unit
or less. Variations of the pH's of the other three check
samples were comparable and similar to the variations, as
illustrated in Figure l, of check samples number 2 and 6.

The standard deviations of the means for the indi-
vidual check samples ranged from a low of 0.07 to a high
of 0.22 pH unit (Table 3). The combined standard error
of the difference between the "known mean pH values and
the measured mean pH values was i 0.075. Twice this value
will Judge significance at the 0.05 probability level. By
this criterion none of the measured mean pH values of the
check samples differed significantly from their known pH
'values. However, it is interesting that all the observed
means were less than the known values: on the average this
ciifference was 0.09 pH unit. It is concluded that differ-

ences between mean soil pH values of a group of represen-

-24-

Figure 1. Variability of pH measurements made on
several air dry standard laboratory
check samples from May through October.

'L7r °--w ° °
\/ Sample
. o NoJ

'16-

 

6.|'

613- , “////
Sampm
No6

519"

:E:
C‘- 5.8 - .___.

SJ /////>
5.0- ° . \\\\\ Sampm
.\\\\\ N012

4.9’

 

 

IWT

0—0

4.8-

 

J I I 4

May June July Aug Sept Oct
Time

-25-

Table 3. "Known pH Values" and variability of pH
measurements made on standard laboratory
check samples from May to October, 1966.

 

Number
Sample "Known mean of pH Means and standard
Number pH Values" measur- deviations of pH
ments measurements
1 7.75 13 7.68 i 0.07
2 5.05 12 4.94 i.0-17
3 6.0 10 5.94 i.0°22
4 5.9 10 5.75 i 0.17
5 5.7 9 5.68 i_0.l6
6 6.05 5 5.90 i 0.14

-26-

tative observations may be significant when the differences
are greater than 3; 0.15 pH unit.

Effects Of different Operators and different pH meters on
the variability of the_pH's of :five air dry soil samples

The pH's Of one air dry sample from each of five of
the nineteen soil sites used in this study were measured
repeatedly to evaluate various possible sources of exper-
imental errors in the pH measurements. The textures of these
five seaples ranged from loamy sand to clay loam, and their
reaction, measured in water. ranged from a pH value of
6.0 to a pH value Of 7.4.

Three Operators measured the pH's of the five soil
samples with one pH meter on the same day in the following
suspending media: water, 0.01MCa012 and 1.0NKC1. A three 1
way analysis of variance (5 soils. 3 Operators. and 3 sus-
pending media) was performed on the data: soils and media
were considered fixed and Operators random in that analysis,
Table 4. Significant differences were found for all main
effects and a soil by media interaction. Table 4. There-
fore. the variability Of soil pH measurements made by dif-

ferent Operators must be considered in studies Of this

type.

-27..

Table 4. Analysis of variance for a three way
analysis (5 soils, 3 Operators, 3 sus-
pending media).

 

 

 

Source of Degrees of Means
Variance Freedom Squared_
Soil 4 1.96**
Operator 2 0.13**
Soil X Operator 8 0.01
Suspending media 2 3.62**
Soil X Suspending Media 8 0.04*
Operator X Suspending 4 0.01
Media
Error 16 . 0.01

** Significant at probability less than 0.01

'* Significant at probability less than 0.05

 

 

The pH's of the five soil samples were measured in
the three suspending media by one Operator using two dif-
ferent pH meters on the same day. The maximum average dif-
ference between the two pH meters was 0.06 pH unit, Table 5.
This is not a significant difference. Thus it appears that
variations in pH measurements made under these conditions
with the different pH meters are not important.
Reproducibility of soiltpH measurements made in 320,
in 0.0130381; andwin 1.01KCl by one operator usipg
one_pH meter on the same day.

One operator employed the same pH meter and made ten
pH measurements on each of the five soil samples at hourly
intervals on one day. On the average the standard deviations
of the measurements made in water, in 0.01MCaClZ and in
1.0NKC1 were :0.08, :0.07. and i0.08 pH unit respectively.
‘Table 5. It is concluded that there are no significant dif-
ferences in the reproducibility of soil pH values measured
in the three suspending media. This conclusion is con-
trary to the prOposal of Schofield et. al. (66) who indicated
that soil pH measurements made on air dry samples in 0.01MCaC12
are more reproducible than measurements made in water. How-
ever, the possibility remains that seasonal variations in
3011 Pfii's may be less in 0.OlI'=ICaCl2 than in water even though

:individlial determinations are no more reproducible.

Table 5. Summary of the variability in the pH's
of five air dry soil samples measured
in water, in 0.01KCaCl2 and in 1.01KC1.

Suspending Hedia

 

Standard deviation(s)

Standard error of
the mean (SE)

Kean pH for
each gperator

 

O\O\O\
O\\J\CO
(DOC

(1)
(2)
(3) .

10.11 pH unit

10.03 pH unit

Bean pH Of
each meter

10.04 pH unit

10.01 pH unit

 

0.01MCaC12

Standard deviation(s)

Standard error of the
mean (S?)

(l) 6.44
(2) 6.22
(3) 6-30

10.12 pH unit

10.03 pH unit

10.03 pH unit

10.01 pH unit

 

1.0NK01

Standard deviation(s)

Standard error of the
mean (Sr)

(1) 5.74
(2) 5.62
(3) 5.78

10.08 pH unit

10.02 pH unit

10.04 pH unit

10.01 pH unit

Table 5.

Continued

Fean, standard deviation(s) and standard error

13;) of the mean of ten replicationsfor each of 5 soils

 

 

Dean pH S SE

(1) 6.20 10.08 pH unit 10.025 pH unit
(2) 7.36 10.05 pH unit 10.016 pH unit
(3) 6.95 10.09 pH unit 10.028 p1 unit
(4) 6.20 10.09 pH unit 10.028 pH unit
(5) 6.61 10.07 pH unit 10.022 p3 unit
(1) 5.79 i0.09 pH unit 10.028 pH unit
(2) 6.97 :0.06 pH unit 10.019 pH unit
(3) 6.67 10.05 pH unit 10.016 pH unit
(4) 5.78 10.08 pH unit 10.025 pH unit
(5) 6.30 10.08 pH unit 10.025 pH unit
(1) 5.40 10.08 pH unit 10.025 pH unit
(2) 6.70 10.08 pH unit 10.025 pH unit
(3) 6.20 10.09 pH unit 10.028 pH unit
(4) 5.28 10.03 pH unit 10.025 pH unit
(5) 5.75 10.06 pH Unit 10.019 pH unit

 

-30-

Variability of soilka values measured in 0.01MCaCl2 with
one pH meter by one Operator on two different dates.

The pH's of all theeflrdry samples from each of the
nineteen soil sites used in this study were measured in
0.01MCaC12 on two different dates. The regression of March
21 values on April 13 values was calculated (Figure 2):

y = 0.04 + 0.99x. The standard error of the estimates
equals 0.15 pH unit. To Judge what may be a real difference

between soil pH measurements, twice the standard error of

the estimate was employed or 0.30 pH units. This will judge

significance at approximately the 0.05 probability level.

Variability of field moist pH values within each of
the nineteen soil sites.

pH values of the first composite sample collected and

each of the six single core samples collected from 1/6 of

each plot are presented in Table 6. These pH values were

zneasured in water with one pH meter. by one operator on the

snmne day. The determination standard deviation for the sites

ranged from a low of 0.096 to a high of 0.169 pH unit, and
kar the combined analysis it was 0.138 pH unit. Thus we con-
olluie that the determination variability is consistent from

site to site. The individual F statistics for testing the

variability among cores within each plot were all non-sig-

nificant. In fact, the F tests deviated only slightly from

31.0. From this we can conclude that the variability in the

pH measurements of a particular soil site is due mainly to

determination rather than to sampling.

 

pH (ApnII3,I967)

 

-31-

 

Figure 2. Comparison of pH values of all the air
dry samples from the 19 sites measured
in 0.01MCa012 on two dates.
oé’
. ' Q
'75 .§® (g?
)(/////
/ ‘3
- ‘\
7.0 o / oo//Q'
y° %/
/.,o a.
oo / x6 9
(3.5 V / /:a/.
/°/4f 3'0
0/ / /
6.()" ,/: .39,/
o/o 00/ A o
/e/ /é
/ :2
5.5 - 4";
//;;;/ y=004+wi99(X)
/ 9/5/ °
// '9 , :i: '
5.0 _ / / S 0.|5pH unit
00 /
/o o”! /o
flat/O'l/
4. 5 ' / o 0;"
1 / /
1 /
4 O I l 1 1 L l J
4.5 5.0 5.5 6.0 6.5 7.0 7.5

pH (March 2|, I967)

Table 6. Variations in the pH's of the composite
and single core samples collected in the
initial sampling of each plot

Field hoist pH values - 1:1 SoilnHQO Ratio, py Weight

 

Composite Single Cores (3 in. in diameter)
Soil Site 14mgi? §§Od§2§iiéry Ko.l No.2 Ko.3 9—
Blount 7.0 7.2 7.2 7.0 7.1 6.9 7.2 7.0
Ceresco No.1 7.9 8.1 8.0 8.2 8.0 7.8 8.2 8.0
Ceresco NO.2 7.9 7.7 8.0 8.1 7.6 7.8 8.0 7.8
Colwood No.1 8.0 8.2 8.2 8.2 8.0 8.3 8.0 8.2
Colwood No.2 8.0 7.8 7.6 7.8 7.9 7.6 7.8 7.8
Chelsea 5.8 5.6 5.9 5.6 5.6 5.6 5.8 5.6
Hillsdale No.1 6.7 6.9 6.5 6.7 6.6 6.7 6.6 6.8
Hillsdale No.2 6.2 6.2 6.3 6.0 6.2 6.4 6.3 6.1
Houghton 6.9 7.0 7.1 7.1 7.1 6.9 7.2 7.0
Laper 7.4 7.4 7.3 7.3 7.3 7.5 7.3 7.4
Nekoosa No.1 6.8 7.0 6.9 6.7 6.9 7.2 6.8 ’.8
Nekoosa No.2 7.7 7.9 7.6 7.8 7.9 7.7 7.7 7.6
Oakville 6.4 6.3 6.2 6.4 6.3 6.1 6.4 6.2
Pewamo NO. 1 7.5 7.5 7.4 7.6 7.7 7.5 7.6 7.4
Pewamo No. 2 7.5 7.3 7.4 7.4 7.6 7.4 7.6 7.6
Plainfield 6.0 6.3 6.1 6.3 6.2 6.0 6.3 6.1
Spinks No. l 6.4 6.7 6.8 6.6 6.6 6.4 6.7 6.7
Spinks No. 2 6.6 6.8 6.6 6.6 6.7 6.5 6.9 6.7

Edt. Clair 7.5 7.5 7.4 7.6 7.7 7.5 7.4 7.6

-323-

Table 6. Continued

.No.4 No.5 ' No.6 Heans and Determination
7.2 7.2 6.9 7.2 7.1 7.1 Standgfg9D1768154ns (SD)
8.1 8.0 8.0 7.8 7.9 7.9 7.99 1 0.122
7.9 7.7 7.7 7.8 7.8 8.0 7.84 1 0.185
8.2 7.9 8.3 8.1 7.9 8.1 8.11 1 0.155
7.8 7.6 7.8 7.6 7.9 7.7 7.76 1 0.144
5.7 5.9 5.7 5.6 5.6 5.6 5.68 1 0.125
6.5 6.5 6.7 6.5' 6.8 6.6 6.65 1 0.122
6.3 6.3 6.1 6.1 6.4 6.2 6.22 1 0.122
7.0 6.9 7.0 6.8 7.1 7.1 7.01 1 0.099
7.4 7.2 7.3 7.3 7.4 7.5 7.35 i 0.096
7.1 6.9 6.9 6.7 7.1 6.9 6.91 1 0.144
7.6 7.7 7.7 7.9 7.7 7.6 7.72 1 0.104
6.4- 6.2 6.5 6.3 6.3 6.1 6.31 1 0.122
'7.6 7.6 7.5 7.3 7.5 7.3 7.50 1 0.119
7.5 7.7 7.7 7.5 7.5 7.3 7.50:0-119

(5.0 6.3 6.3 6.0 6.0 6.1 6.14 1 0.169
6.4 6.5 .6-7 6.5 6.7 6.7 6.601O.127
5.5 6.7 6.7 6.9 6.9 6.7 6.70 1 0.131
7.65 7.6 7.7 7.5 7.4 7.5 7.54 1 0.110

Combined SD 00138

-33...

Summary
On the basis of the above. it is evident that pH mea-

surements made on a particular soil sample varied when mea-
sured under the different conditions stated above (Tables 3,
4, 5 and 6 and Figures 1, 2). The greatest variations of
soil pH values occurred under those conditions where measure-
ments were not always made with the same pH meter and by the
same Operator on the same date, Table 3. However, in most
instances the standard deviations of pH values measured on
the same soil samples under the various conditions were ap-
proximately 1 0.15 pH unit or less (Tables 3, 4, 5 and 6 and
Figure 2).

Therefore, a variation of 10.3 pH unit is considered
necessary to be certain of a probable significant difference
'between individual soil pH measurements. This range of var-
iability satisfactorily includes the errors encountered in
the individual measurements of the pH's of the soils used
111 this study. However, when mean soil pH values of a group
of Inapresentative observations are compared than differences

greater than 10.15 pH unit may be significant, Table 3.

Influence of moisture conditions and
suspending media on seasonal varia—

bility of soil pH values

Data on soil pH's determined at two moisture conditions

witfli the Truog kit, and at three moisture conditions and in

-34-

several suspending media with the glass electrode are pre-

sented in Table 7 in the Appendix. for each of the sites on
each sampling date. Statistical deductions for these data

are presented in Figures 3. 4 and 5.

Ten of the nineteen soil sites used in this study were
sampled for five months. May through September. and the other
sites were sampled for four months. June through September.
0n the nine sites sampled for only four times the seasonal

trends were similar to those of the other ten sites during

that period.

Inf1uence of mo1sture condition on seasonal

vaziabilitv Of soil pH values measured in
water and in 0.0MCaC12 with the_glass electgode

 

 

The field moist soil pH data showed a continuous decrease
in values as the season progressed. Figure 3. Because of the
lower pH's observed on the standard laboratory samples below
3 H 6.5 after August 15. as shown in Figure 1. the pH readings
on the field moist and oven dry samples measured in H20 were
corrected by adding 0.1 pH units to the September readings
that were below pH 6. 5. Soil pH values measured at this
moisture condition in water and in 0.01MCaClz were 0.81 and
0.1V? pH units lower. respectively. at the end of the season.
1J1 September than at the beginning of the season. in May.

(n1 the other hand. the air dry and oven soil pH values tended

to show a cyclic seasonal trend.

Differences between average soil pH values at the three

 

-35-

moisture conditions were 0.08 pH unit or less in both water
and 0.01MCaC12 at the end of the season. Figure 3. These
differences are not significant. However. differences be-
tween soil pH values measured at the three moisture condi-
tions are significant at certain times during the earlier
part of the season. The calculated L.S.D. at the 5% level
is equal to 0.1 pH unit. Figure 3. This calculation was
based on a site by time by moisture condition interaction.

During this period. the air dry and oven dry soil pH
values measured in water were as much as 0.55 and 0.88 pH
units lower than the corresponding field moist pH values.
respectively. Figure 3A.. Similarly. the air dry and oven
dry soil pH's measured in 0.01MCaCl2 were as much as 0.28
and 0.34 pH units lower than the corresponding field moist
pH values. respectively. Figure 3B.

During the season, there were no consistent significant
differences between the air dry and oven dry soil pH values
:measured in either of the two suspending media. Figure 3.

Chi the average. the oven dry soil pH values were less than
(3.1 pH unit lower than the air dry soil pH values measured
111 either water or 0.01MCaC12. The average of the 0.01MCaC12
pfli's were lower than the mean pH values measured in water at
tine following moisture conditions by the following amounts:

field moist; 0.85 pH unit; air dry: 0.60 pH unit; and oven

dry; 0.61 pH unit.

-35-

Figure 3. Average pH's of ten soil sites measured at

7.0

6.8

6.6

6.4-

I 6.2

6.0

5.8

5.6

5.4

three moisture conditions and in two sus-
pending media from May through September.

PFieId moist
H654)” °\
7 A)pHSintbO
_ . I 1.3.0.05
7A” dry o/0

(e. we .\

Oven dry \:\: é:
-m.2me°

Field moist\

(5. 79)¢°
P 7:\° B) pHs in
"Airdry / \ O.O|MC0C|2
l' (570”, /°8\\O\
-0ven dry 0 /8 \
__(5.63)¢ §g
*- 4} mean pH value

 

May June July Aug Sepi
Time

_37_

Comparison of the variability of the air dry
pH's of soil samples collected from May through
September when measured in H20. in 0.01MCaC12
and in_110NKCl with the glass electrode.

The average air dry soil pH values measured in water.
in 0.01MCa012 and in 1.0NKC1 showed a cyclic seasonal trend
in the pH's of the ten sites studied for five months. Figure 4.
The May pH values were lower, on the average. than the June
pH values for the ten sites.

The average pH values measured in water were the high—
est at all times during the season and the 1.0NK01 pH's were
lowest for the entire season. On the average. pH's measured
in 0.01MCa012 and in 1.0NKCl were approximately 0.6 and 1.0 pH
units lower. respectively. than pH's measured in water. How—
ever. the 0.01MCaCl2 pH's were 0.5 pH lower than the water
pH's at the more alkaline and of the pH scale and 0.8 pH unit
lower at the more acid end of the pH scale. Similarly the
1.0NKCl pH's were 0.9 and 1.1 pH units lower than the water
pH's at the more alkaline and acid ends of the pH scale. re-
spectively.

There were no significant differences between the sea-
sonal variability of the average air dry pH values measured
in water and in 0.01MCaC12. Figure 4. This is contrary to
the proposal of Schofield et. a1 (66) who have indicated that
air dry soil pH values measured in 0.01MCaC12 show less sea-
sonal variability than the corresponding pH values measured

in water. However. the 0.01MCaC12 solution did reduce the

Figure he

6.8
6.6
6.4
6.2
6.0

255.8

5.6

5.4

5.2

5.0

 

~38-

Variability of air dry pH's of ten
soil sites measured in three suspend-
ing media from May through September.

\< H20
y 646 (0.077)X
(6.3l la><°

0.0|M
\\ COCIZ

\>. y=5.85-(0.076) x
0
(5.70) “/0.\\

(5.3l)‘:f y=5.34"(0.0|9)X

a mean pH value

I l l l l J

May June July Aug Sepl
Time

-39-

seasonal variability of field moist pH values compared to
those measured in water. Figure 3. The field moist soil pH
values measured in water and in 0.01MCaCl2 were 0.81 and O.h7
pH units lower at the end of the season (September) than at
the beginning of the season (May). respectively.

pH values measured in 1.0NKCl showed the least seasonal
variability. Figure h. This is in agreement with the find—
ings of many EurOpean workers who have reported that soil
pH values measured in 1.0NKCl are less influenced by changes
in biological and meteorological conditions and reflect a

more intrinsic characteristic of the soil than soil pH values

measured in water (59).

gemeerison of the seasonel variability of field

moist and air dgy soil p§_yalues measured with

the Truog kit and with the glass electrode
On the nineteen soil sites sampled four times. the field

moist and air dry soil pH values determined with the Truog
.kit showed seasonal trends similar to those of the correspond-
ing pH values measured with the glass electrode. Figure 5.
On.the average. air drying lowered the field moist soil pH
'values determined with the Truog kit approximately 0.3 pH
‘unit during the season. The Truog kit showed less seasonal
'variability in pH's. on the average. than the glass electrode.
particularly on field moist soil samples.

On the average. differences between the field moist
soil.pfliva1ues measured in water with the Truog kit and with

‘17!

Figure 5.

7.0

6.8-

6.6

6.4

6.8
6.6
3; 6.4

5.2

 

 

-uo-

Comparison of average field moist and air dry
pH values of nineteen soil sites measured with
the Truog Kit and in water with the glass elec-
trode from June through September.

A) Field Moist pH's

\/
. \\ T .
o ruog klt

“° (6.85)“

O

\ Glass Electrode
° (6.70)”

a mean pH value

I I 1

June July Aug Sept

8) Air Dry pH's

0

\\\\\‘° Truog kH
\0/0 (6.58)“

/

o____..—o Glass Electrode
(6.42)it

a mean pH value

I 1 J

June July Aug Sept

Time

-41-

the glass electrode increased as the season progressed to a

maximum difference of approximately 0.3 pH unit at the end

of the season, Figure 5A. Figure 5B shows that the air dry

soil pH values measured with the Truog kit during the sea—

son were approximately 0.2 pH unit higher, on the average,

than the corresponding pH values measured in water with the 3
glass electrode. The air dry pH values showed an upward trend

in September with the Truog and glass electrode methods, in-

dicating a cyclic trend back toward the higher pH values early .
l

in the season.

Summary
Regardless of suspending media, the field moist soil

pH’s showed a steady decrease in values as the season pro-
gressed, and the ovaidry and air dry pH's showed a cyclic
seasonal trend, Figures 3 and H. However, it is apparent that
soil pH measurements are influenced by the moisture condition
of the sample and the suspending media.

At the beginning of the season, in May, the oven dry
pfli's measured in water were as much as 0.88 pH unit lower than
the corresponding field moist pH values. Differences between
the mean of the air dry and oven dry pH values measured in
‘wateI'eum.in 0.01MCaC12 were not significant. At the end of
time season, there were also no significant differences between

pfli'values measured at the three moisture conditions in water

or 111 0.01MCaC12, Figure 3.

-u2_

Field moist pH values measured in 0.01MCaCl2 showed less
seasonal variability than the corresponding pH's measured in
water. However, the oven dry and air dry pH's measured in
O.OlMCaC12 were Just as variable as the corresponding pH's
measured in water, Figure 3. The air dry pH's measured in
1.0NKC1 showed less seasonal variability than the corres- h

ponding pH's in water or in 0.01MCaC1 Figure h.

2'
The 0.01MCaC12 pH's were lower than the mean pH values

measured in water at the following moisture conditions by

,5 u

the following amounts: Field moist, 0.85 pH unit; and oven k
dry, 0.61 pH unit. The air dry pH's measured in 0.01MCaCl2
and in 1.0NKC1 were 0.6 and 1.0 pH unit lower, respectively,
than the corresponding pH's measured in water, Figure b.
On the average the field moist pH values determined
with the Truog kit were as much as 0.3 pH unit higher than
the correSponding pH values measured in water with the glass
electrode at the end of the season, in September, Figure 5A.
However, on the average, the air dry pH's determined with
the Truog kit were 0.2 pH unit higher than the pH values

measured in water with the glass electrode, Figure 5B.

Several factors influencing the

seasonal variability of soil_pH values

The field moist pH values, measured in water, of all the
nineteen soil sites studied showed seasonal variability (Table 7),

as illustrated in Figure 3 for the ten sites. However, only

 

mar-Lu a

-43-

fourteen of the sites showed seasonal variability of soil pH
when the air dry pH's measured in water were considered,
Table 7. Variations of the pH's of the other five sites
(Chelsea, Hillsdale No. 2, Houghton, Oakville and Pewamo

No. 1) measured during the season fell within the range of

the experimental error, i 0.3 pH unit, deduced in this study. ?
Even though differences between the pH values for each of 2
these five sites measured during the season were not signif- E
icant, it appears that there may be a seasonal trend similar 2

L

to that illustrated in Figure h, as shown in Figure 6.

Seasonal variations of the field moist pH values meas-
ured in water ranged from 0.5 pH unit for Chelsea to 1.6
pH unit for Pewamo No. 1, Table 7. The seasonal variations
of the corresponding air dry soil pH values ranged from 0.5
pH unit for Nekoosa No. l to 0.9 pH unit for Pewamo No. 1,
Table 7.

Tohelp explain these seasonal variations in soil pH
measurements the field moisture content, the total exchange-
able metallic cations, the electrical conductivity and the
organic matter content were determined on each sample col-
lected from each site during the season. These data for
each site and for each month are presented in Table 8
in the appendix.

In addition, the cation exchange capacity of each site

was determined on one of the samples from each site. The

Figure 6 e

6.2

5.8

 

-4n-

Variability of the air dry pH's
of five soil sites measured dur-
ing the season.

I l 1

June July Aug Sept
Time

 

-45-

percent base saturation and the exchange acidity were cal—
culated using the cation exchange capacities and the ex—
changeable metallic cations. It was assumed that there
were no changes in the cation exchange capacity of each
site during the season. The cation exchange capacity, the
calculated percent base saturation and the calculated ex-
change acidity for each site are shown in Table 8B in the
appendix.

Statistical analyses of these data were made under
the supervision of Dr. C. E. Cress in the Crop Science De-
partment with the assistance of Mrs. N. Galuzzi and the Com-
puter Laboratory. The resulting significant correlations
between the pH's and these soil prOperties are shown in
Table 9.

Electrical conductivity and organic matter percentage
were negatively and positively correlated, respectively,with
soil pH's, Table 9. The negative correlation shows that
the increase in electrical conductivity, due probably to the
presence of soluble salts, is associated with decreases in
soil pH values. There is also a significant increase in
field moist soil pH's with an increase in the moisture per-
centage. These two relationships may thus be direct corollaries
of increasing the salt concentrations and diluting their in-

fluences on soil pH's, respectively.

-46-

Table 9 Significant simple correlations between_sea-
sonal variability of soil pH and field moisture
percentage, base saturation percentage, elec-
trical conductivity and organic matter content.

Correlation of field moist pH's measured in water with:

Field mOiSture percentage eoeeeeeooeeeeoe r
Base saturation percentage eeoeeeeeeeeeee r
Electrical COHdUCtiVity eeeeeeeeeeeeeeeee r
Organic matter content eeeeeeeeeeeeeeeeee r
Base saturation and organic matter
percentages ........................... r

Correlation of air dry pH's measured in water with:

Ease saturation percentage .............. r
EleCtrical condu0t1v1ty eeeeeoeeeeeeeoeee r
Organic matter content eeeeeeoeeeeeeeeeee r

Correlation of field moisture percentage with:

EleCtrical condUCtiVity eeeeoaeeeeeoeeeoe r
Organic matter percentage eeeeeeoeeeeeoee r

*Significant at 5% level

+0.285*
+0.493*
-0.336*
+0.592*

+0.638*

“—1- r-' w.

 

-47-

Seasonal variations of electrical conductivity and or-
ganic matter content were highly correlated with field mois-
ture percentage, Table 9. This helps to explain why organic
matter gave the highest correlation between seasonal varia-
bility of the field moist soil pH values and the lowest cor-
relation between the seasonal variability of theedr dry soil
pH values. This is due to the fact that organic matter in-
fluences the amount of moisture present at the field moist
condition and to the dilution effect of increased moisture
on the soluble salts present.

The relatively low correlation between seasonal var-
iability of soil pH values and percent base saturation may be
partially due to the presence of soluble salts which will be
counted in the exchangeable cations but will tend to decrease
rather than increase the pH. However, the air dry pH's of
eight of the sites (Blount, Ceresco No. l, Colwood No. 2,
Hillsdale No. l. Nekoosa No. l, Pewamo No.1, Plainfield and
Spinks No. 2) also showed seasonal variability when measured
in 0.01MCaClé, Table 7. Two of the sites, Blount and Hills-
dale No. 1, showed seasonal variability even when measured in
1.0NKC1, Table 7. These indicate that other factors besides
electrical conductivity are responsible for the observed
variations in the measured pH values of some soils. However
electrical conductivity, believed to be largely a reflection

of salt content, is responsible for most of the seasonal

-48—

variability of the pH's of most of the soil sites used in
this study.

It was assumed that there were no significant season-
al variations in the cation exchange capacities. However,
there were variations of as much as ten percent, in the or-
ganic matter percentages during the season. Therefore, it
is possible that the cation exchange capacities also varied
seasonally. Seasonal variability of the cation exchange

capacities may partially account for the relatively low cor-

r” ‘* “a“ :;_:..;'_:v

relation between seasonal variations of soil pH values and

the base saturation percentages, as calculated in this study.

Seasonal variability

of lime requirement

The variation of lime requirement was evaluated on air
dry samples collected from eleven sites by the following
three methods: pH plus texture, SMP or buffer and exchange
acidity. Lime requirement was determined on all air dry
soil samples with pH values less than 6.5 when measured in
‘water with the glass electrode. These data are presented in
TableJED and the variations of the average lime requirements
for four months (June through September) are illustrated in
Figure 7.

On the average, the pH plus texture method showed the
maximum seasnnal variability of lime requirement, which was

approximately 1.0 ton per acre, Figure 7. The maximum average

-49-

variations in lime requirements by the buffer method during
the season were more comparable to but greater than those

in the exchange acidity method, Figure 7. The pH plus tex-
ture and S.M.P. buffer methods showed a cyclic seasonal trend

in lime requirement, with the maximum in mid-summer (July),

Figure 7. Contrary to these the lime requirement evaluated T}
by the exchange acidity method tended to fluctuateless during i
the season.
Seven of the eleven soil sites with evident lime re- :5
. 3‘

quirement had zero lime requirement at the beginning of the
season or in May, Table 10. However, each of the eleven
sites exhibited maximum lime requirement in July or in August.
The maximum difference in lime requirement evaluated by the
pH plus texture method was 2.5 tons per acre for Hillsdale
No. 2. Similarly, the maximum difference in lime requirement
determined by the S.M.P. buffer method was 2.3 tons per acre
for Pewamo No. 1. However, the maximum seasonal difference
in lime requirement for any soil studied was with use of
the exchange acidity method on samples collected from Pewamo
No. 1. Here the lime requirement varied from 0.0 early in
the season to 4 tons per acre in July, Table 10.

Thus, it is concluded that the seasnnal variability of
lime requirement should be considered when lime recommenda-

tions are made.

-50-

Figure 7. Seasonal variability of average lime
requirement determined by three methods.

 

\o s M P Buffer

L4 - /°\ opH plus Texture

l.2r

|,o - cfExchange Acidity
r /

0.8 - ° 0

0.6-

Average Lime Requirement- Tons/acre.

I J

 

 

June July Aug Sept
Time

-51-

SUMMARY AND CONCLUSIONS

A study of the seasonal variability of the pH's and lime
requirements of several soils in Southern Michigan was con-
ducted. The experimental errors in pH determinations were
evaluated. Results of chemical and physical soil analyses
were studied and correlations of those results with pH dif-
ferences were calculated to determine the relationship of
several soil prOperties to the seasonal variability of soil
pH values.

The results of this study are summarized as follows:

1. To be reasonably certain of a significant dif-
ference between individual soil pH values, a varia—
tion greater than i 0.3 pH unit is necessary. How-
ever, when mean soil pH values of a representative
number of observations are compared, differences
greater than i 0.15 pH unit are likely significant.

2. Field moist soil pH values measured in water usually
showed marked seasonal variability. A maximum vari-
ation of 1.6 pH units was observed, and the average
seasonal variation was approximately 0.8 pH unit.
The highest and lowest pH values were early in the
season and at the end of the season, respectively.
The correlation between organic matter content and
season variability of these pH values was the high-
est of the correlations with the soil factors

studied. This is probably due to the combined

‘7ZLJ

a.

 

-52-

effects of the relationships of organic matter
content to field moisture content, and field
moisture content to electrical conductivity.

On the average, during the wetter portion of the

season, the air dry and oven dry pH values measured

‘-
. +-

in water were approximately 0.5 and 0.8 pH unit

lower, respectively, than the corresponding field

‘Md —--

moist pH values. During the drier part of the

season, differences between average pH values

‘rn— .. .—‘—-I~« .hk-
V‘ .s .

measured at the three moisture conditions were
less than 0.1 pH unit and non-significant. Air
dry and oven dry pH values measured on samples
collected during the drier portion of the season
may be better expressions of the pH in the field
than the corresponding pH values measured on
samples collected during the wetter part of the
season. Therefore, when soil pH values are in-
terpreted for various purposes the moisture con-
ditions and the time of collection of the soil
samples should be considered.

Only four of eleven soil sites exhibited a lime
requirement during the early part of the season,
based on air dry samples, but each of the eleven
sites showed a lime requirement during the middle
of the summer. A maximum seasonal variation of

4 tons per acre was observed for an individual site,

-53..

using the exchangeable hydrogen method for lime
requirement. Therefore, the time of sampling and
the method for estimating lime requirement are
factors that should be considered in making lime
requirements recommendations.

The relative magnitude of the seasonal variability
of soil pH values, measured in both water and in
0.01MCaC12, at the three moisture conditions is as
follows: field moist>oven dry "1 air dry. Drying
soil samples in an oven facilitates the time and
space necessary for drying. Therefore, it appears
that oven dry soil samples are best adapted for
routine pH determinations.

On the average, 0.01MCaC12 and 1.0NKC1 lowered air
dry soil pH values measured in water approximately
0.6 and 1.0 pH unit, respectively. The relative
order for the seasonal variability of air dry pH's
measured in the three suspending media is as
follows: H20) 0.01MCaClZ> 1.0NKC1. However, for
some soils the 0.01MCaC12 pH's were just as variable
as the pH's measured in water.

Field moist soil pH values determined with the
TruOg kit showed less seasonal variability than
the corresponding pH values measured in water with
the glass electrode. However, on the average, the

Truog pH values were higher than the pH values

444!

9.’

-54-

measured in water with the glass electrode. 0n
the average field moist and air dry soil pH values
determined with the Truog kit were not more than
0.3 and 0.2 pH unit higher, respectively, than the
corresponding glass electrode pH values. The
Truog kit is also well adapted for field work,
especially soil survey. Therefore, the Truog

kit, as it is commonly used by soil surveyors in
Michigan, appears to be a satisfactory field kit
for pH determinations.

Soil pH values measured in 1.0NKC1 were the least
variable during the season and appeared to reflect

an intrinsic characteristic of the soil. There-

fore, these pH values may be very useful in reseasch

work and soil classification, especially in classi-

fying soils at the family level in the 7th approx-
imation. These pH values may also aid in making
lime requirement recommendations that are rela-
tively free of seasonal influences.

Seasonal variability of air dry soil pH values

measured in water were negatively and highly cor-

related with electrical conductivity of the samples.

Also, most of the soil sites exhibited no seasonal
variability of soil pH values when measured in
1.0NKC1. This indicates that soluble salts are

probably responsible for most of the observed

 

10.

-55-

seasonal variability of soil pH values. However,
two of the nineteen soil sites showed seasonal
variations even when measured in 1.0NKC1, so
soluble salts cannot explain all of the seasonal
variations in pH's.

Further study is needed to determine what and
how other soil properties influence the seasonal
variability of soil pH values and lime require-

ments of soils.

a7

.“4‘.

.. ———.‘—~ .n'.

‘ry m. . .-.. m.
.p‘.
—- u..—

10.

11.

12.

LIST OF BEFEEENCES

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”;;7

..A'.‘

Arrhenius, O. The potential acidity of soils. Soil
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Bailey. E. H. The effect of air drying on the hydro- L?

gen ion concentration of the soils of the United in
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Bates. R. G. Electrometric pH Determinations. John
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Bowser, w. E. and Leat, J. N. Seasonal pH fluctuations
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Bradfield. R. The effect of the concentration of
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Burgess, P. S. The hydrogen concentration of soils
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Fisher, R. A. Statistical Methods for Research Work-
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Gardner, F. D.. and Brown, B. E. The lime requirement
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.

a...

TC?

39-

40.

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1935-

McGeorge. M.T. The determination of soil reaction
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-__-e" '-

 

52.

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Morgan. M.F. Base exchange capacity and related
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7;}

.a"

‘Iflaaaa‘x‘nl ~.'
9

.p-

T&- fl-fi‘. ~13 -

65.

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23152-1590

Trans. of 7th

1960.

......—- .- ._....._—-——-.a-—-
' . o .

APPENDIX

.63_

Table 7 Soil reaction measured at three moisture
conditions and in several suspending
media for each site on each sampling date

May sampling

Field Moist pH's

 

 

Soil Truog Glass Electrode
Site Kit H20 0.01MCaCl2
Blount 6.7 6.8 7.2 7.2 6.4 4.4
Ceresco(No.l) 7.8 8.0 8.0 8.0 7.0 7.0
Hillsda1e(No.1) 6.8 6.7 6.7 6.7 5.5 5.5
Houghton 6.7 6.7 7.1 7.1 6.3 6.3
Lapeer 6.6 6.7 7.5 7.5 6.5 6.5
Nekoosa(no.1) 6.8 6.9 7.1 7.1 6.3 6.3
Oakville 5.9 5.7 6.5 6.5 5.1 5.1
Pewamo(No.1) 6.7 6.7 7.4 7.4 6.5 6.6
Plainfield 5.5 5.4 6.0 6.0 4.8 4.9
Spinks(No.1) 5.8 5.8 6.7 6.7 5.5 5.5
Air Dry pH's
it Truog Glass Electrode

Kit H20 0.01MCaC12 . 1.0NKC1
Blount 6.6 6.6 6.6 6.0 6.0 5.1 5.1
Ceresco(No.1) 8.0 8.0 7.5 7.0 6.9 6.3 6.4
Hillsdale(No.1) 6.0 6.0 6.0 5.3 5.3 4.9 5.0
Houghton 6.8 6.8 6.6 6.0 5.9 5.6 5.7
Lapeer 7.0 7.0 7.2 6.3 6.3 6.0 6.0
Nekoosa(No.1) 6.4 6.4 6.7 6.1 6.1 5.6 5.6
Oakville 5.5 5.6 5.9 4.8 4.8 4.3 4.2
Pewamo(No.1) 6.7 6.5 6.9 6.3 6.3 5.5 5.5
Plainfield . 5.5 5.5 5.5 4.5 4.5 4.2 4.3
Spinks(no.1) 6.0 6.0 5.8 5.2 5.2 4.8 4.9

Oven Dry pH's

H20 Glass EleCtrOdeO.01MCaC12
Blount 6.2 6.2 5.7 5.7
Ceresco(No.l) 7.0 6.9 6.5 6.5
Hillsdale(No.l) 5.8 5.7 5.2 5.2
Houghton 6.1 6.2 5.9 5.9
Lapeer 6.7 6.7 6.0 6.0
Nekoosa(No.1) 6.5 6.5 5.8 5.8
Oakville 5.4 5.5 4.8 4.7
Pewamo(No.1) 6.6 6.6 6.0 6.0
Plainfield 5.1 5.1 4.5 4.5
Spinks(No.1) 5.8 5.8 5.1 5.2

’ J
n
u -
._(_.__
‘

 

Electrode

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£29

A

(

Continued

LA

1:0 11'01 in r
... so“

U

 

Truog hit

 

June

 

Table 7.

 

O
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oil Sit

r:
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. ... In
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2609.88.51. _16.0/5_5_5

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6 75664 55.666.64.664 556

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7.:00 700 756/0 771776 77566 7

10 J20/7/0 20538 28 56 576

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1212 .. 12
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Air Dry_pH's

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orrllellupkk wwaii.
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Table 7. Continued

“- :1 .
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Soil dite Glass Electrode

32g 9:91m0a012
Blount 6.9 6.9 6.4 6.3
Ceresco K0. 1 7.2 7.2 6.6 6.7
Ceresco No. 2 7.1 7.0 6.6 6.5
Colwood No. 1 6.9 6.9 6.3 6.u
Colwood K0. 2 6.9 6.9 6.4 6.4
Cheléea 5.2 5.2 .4.6 4.5
Hillsdale No. l 5.8 5.9 5.3 5.3
Hillsdale No. 2 5.7 5.6 5.0 5.0
Houghton 6.3 6.1 5.8 6.0
Lapeer 6.9 6.7 6.0 6.0
Nekoosa No. 1 6.5 6.5 5.6 5.6
Nekoosa ho. 2 6.8 6.8 6.3 6.3
Oakville 5.5 5.5 4.7 4.7
Pewamo No. 1 7.2 7.2 6.6 6.6
Pewamo No. 2 6.6 6.6 6.0 6.1
Plainfield 5.2 5.3 4.6 4.6
Spinks No. l 6.0 5.9 5.4 5.4
Spinks No. 2 5.9 5.9 5.4 5.4
St. Clair 6.1 6.1 5.5 5.6

3.3

-533-

Continued

Table 7.

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uly 32:.

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Air Dry pH's

 

1
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O
l
e
.0
0
r 2
+Ul
CC .
6 a
10
EMF.
.1.
80
S o
80
1
.G
0
2
H
g
mt
.1
Wyn
I...

915.4 2352 010 704.4 70 060.4

5/0/0o/0/0/04 55/0 504 55.4 555

80441240Qw9/0133/02123

5/0/0/0/0/04 5555/04 5.4/4 55/}

338é258233736715258
o o o o o o o o

66666.4..4. 54.10 564 564 555

54 l 28 3591.40 30/50 71 712

/0 777/0 555/0 70/05/0055/0/0

000007800005nUo74029w37

0888855C C76 750 7550/0

70000509 005055000010

08888 5057.70 75/0/05r3/0/0

12
O.
1212 00 12
.00. KN o. 12 12
0000 00 ..d..
N... bun N..M.flomu
V“ “A
Goddaaao aal i a
tCCOoeddtrSSlOOf381
nSSOOg;::neooimwnkrgv
upwemww.L1flnceAUnvv .Lhum
or.rqi1+eaL1.u“PkTKr.w Wna171 .
leeOOhiioaeeweelppt
.bnvC"UflannuquLHCNnanrp.Sfiacv

Continued

Table 7.

VIC“
#

11
QCHHD ....

A

t

 

. ' '|
Auiug

D.

 

Oven Dry pH's

Field Moistng'S

 

 

Electrode
O.OlPCaC12

Glass

Electroce
0.01MCaClZ

Glass
H20

Truog
K1 1:

Site

Soil

8 97786 7103926 7:4 500. 37

O
SAW/06 5.4.”. 566 (.7014 5/0.” 554”

2n 110. 0.1326“ 7652 100 l 28 O

/O. 7%7/nw 555666656/0. 56 r) 0

973.4 350013126 75.4840

.<¢b/0A30h~(J<¢OzoAionw(flohmqibxo

37314.4..4/006 299/0 20 322/0

ID 77775566 766 56 75rnW/O/nw

7506nW/thNO.AU.nU.0nU.n/3nu.5ooo

x0 78 7755/hw W7w/.7.u5/nw 7576 7

550505?nU.fiWAU.AU.nU.n/..O..J.O.5OAU.AU.

Km 78 7755/nw 7.7775/nw 757/0. 7

1
2

O.
1212 00 12
00.. NH .0 12 12
0000 00 ..d..
NNNN 88 NN OOloor
11H eNNENN1
ooddaaao aal. 51 a
.tccooeddtrssloofssl
nssoosssheooiwwnckc
ueewwlllWeoow 1mm
orrllell Pkkxwwaii.
leeoohiioaeeweelppt
BCCCCCHHHLNNOPPPSSS

Air D33,QH'S

 

AC1

1 . ON”

Glass Electrode
O.OlI‘f§CaCl2

H20

Truog
Kit

”44.410186071208019?“

o o o . o o o o o o o

3336nw13QU71/nwnw3272081

fibéioAEGhmufiuzaerAfi4a2€fiwqfiuzj

88 78/058 30.30U277hwh58h. O./

56/0/06I4h45/O/05/O.” 5/0.h~. 555

239004u9u8/D76172113

O O O O O O O O O O O O O O O O O O O

{O 7.6 7755566665665666

250 50.400750598083305

6 78 775556 7665665666

AN5nN5nw56550.58/fiw005.405

Aw 7..8 7..75KJS/nw 7/O/O.56 756/06

1
2

C O
1212 00 12
.... NN .. 12 12
0000 o ..d..
NNNN ee KN ooloor
lln eNNeNNi
Goddaaao aal 1 a
luccooeddtr;:3loofssl
mssoosssheooimmnikc
eewwlllgeoow eiMn
orrllellupkkkwweii.
«leeOOh::loaeeap:flppt
BCCCCCHHHLNNOPPPSSS

| able 7.

/ ’3‘9“

Continued

E. September Samgling

 

 

Field hoist pH's

Soil Site Truog Glass Electrode

Kit H20* 0.01KCaC12
Blount 7.0 7.0 7.0 6.6
Ceresco No.1 7.5 7.5 6.8 6.Q
Ceresco No.2 8.0 8.0 7.5 6.6
Colwood No.1 7.5 7.5 7.5 6.7
Colwood No.2 7.2 7.2 7.3 6.6
Chelsea 5.8 6.0 _ 5.9 5.2
Hillsdale No.1 6.7 6.6 5.7 U.8
Hillsdale No.2 6.5 6.# 5.9 5.1
Houghton 6.8 6.9 6.6 6.2
Lapeer 7.0 7.0 6.9 6.2
Nekoosa No.1 6.3 6.5 6.3 5.6
Nekoosa No.2 7.0 7.0 7.1 6.u
Oakville 6.0 5.9 5.6 4.6
Pewamo No.1 6.5 6.5 6.4 5.9
Pewamo No.2 6.9 7.0 6.8 6.3
Plainfield 5.5 5.6 5.2 4.4
Spinxs No.1 6.0 6.2 5.5 4.5
Spinks No.2 6.5 6.5 6.2 5.3
St. Clair 7.0 7.0 6.3 5.8

Air Dry pH's

TruOg Glass Electrode

Kit H20 0.01m0a012
Blount 7.0 7.0 6.9 6.5
Ceresco No.1 7.5 7.5 7.3 6.4
Ceresco No.2 7.5 7.5 7.u 6.5
Colwood No.1..' 7.0 7.0 7.1L 6.6
Colwood No.2 7.0 7.0 7.6 6.5
Chelsea 5.5 5.6 5.u 4.h
Hillsdale No.1 6.3 6.5 5.5 h.8
Hillsdale No.2 6.3 6.4 5.9 5.1
Houghton 6.8 6.8 6.7 6.2
Lapeer 6.5 6.6 6.9 6.1
Nekoosa No.1 6.3 6.h 6.2 5.5
Nekoosa No.2 6.8 6.8 7.1 6.3
Oakville 5.8 5.8 5.6 4.6
Pewamo No.1 6.5 6.5 6.3 5.8
Pewamo F5002 700 6.8 6.7 6.2
Plainfield 5.5 5.5 ,5.3 4.4
Spinks No.1 6.0 6.0 5.9 5.2
Spinks No.2 6.0 6.0 6.1 5.3
St. Clair 6.5 6.5 605 5.8

*Because of the lower pH's observed on the standard laboratory

‘ - . '1 ..
C‘J E ..l QT;

Electrode
0.01KCa312

Glas

d20*

7.0

7.1

7.1

7.4

.7.0

509

5-5

5.9

6.7

6.9

6.4

6.9

5014

6.3

6.8

5-3

5.2

6.1

6.3

l.ONKCl

6.2 6.3
6.3 605
6.3 6.3
6.2 6.2
6.1 6.0
4.0 4.0
u.3 U.O
”.8 [4'09
5.? 5.6
5-9 5.9
5.2 5.1
6.0 6.0
u.3 4.2
50% 501
5. “.9
4.2 L3
5.0 5.1
5.1 5.1
5-3 5-3

T‘T—T ' r1
'-'-Lo- ‘

(Rb) {—‘UIN (DKnbjUil—‘HH (DP-3m O\O\U\O\

\JIKA-P-{I‘O\\J1(:'CT\\JIO\O\UI cC-‘UIONO‘xO‘sO‘xCN

samples below pH 6.5 after August, as shown in Fig.1, the pH

readings on the field moist and oven dry samples measured in H20
were correCted by adding 0.1 pH units to the September readings

that were below pH 6.5.

o v
. o O O c O o
o c I u a I a
o C I a r O o
a n n. a o O l
a a c o o p o

 

 

 

I

-94-

Table 8A Field moisture percentage. total exchangeable
metallic cations electrical conductivity and
organic matter content measured during the
season, for each soil site.

A. May Sampling

Field Total exchange— Electrical Organic
moisture able metallic Conductivity Matter
Soil Site % cations (mhos x10-5/cm) %
(me./1005.)
Blount 16.38 9.49 12 16 5.30
Ceresco No.1 19.58 18.49 20 18 7.80
Ceresco No.2 ---------- -- -- ----
Colwood No.1 ---------- -- __ ---_
Colwood No.2 ---------- -— -- ----
Chelsea ----- ----— -— -- ----
Houghton 73.53 36.29 31 31 92.20
Hillsdale No.1 6.49 2.26 3 12 2.01
Hillsdale No.2 ---------- -— -- -——-
Lapeer 4.93 4.86 14 10 4.70
Nekoosa No.1 1.08 3.22 15 13 1.01
Nekoosa No.2 ---------- __ -- __-_
Oakville 1.79 0.67 0 0 1.02
Pewomo. No.1 16.37 15.69 15 15 6.03
Pewomo No. 2 - ---------- —- -— ----
Plainfield 1.51 0.46 0 0 0.70
Spinks No.1 6.04 2.56 l 3 1.20
Spinks No.2 ---------- -— -— --——
St. Clair ----- ---~- -- —- --—-
13. June 8513;1ng

Blount 16.87 14.2 30 34 5.10
Ceresco No.1 20.83 18.49 18 18 7.90
Ceresco No.2 25.96 19.83 4 2 8.00
Colwood No.1 16.09 19.09 2 8 4.50
Colwood No.2 28.81 15.40 20 20 6.02
Chelsea 6.75 1.29 0 O 1.40
Houghton 71.93 39.96 26 30 91.50
Hillsdale HO.1 14.‘8 2.26 0 0 2.12
Hillsdale K0.2 9.46 2.64 0 0 2.40
Lapeer 10.36 4.8 10 8 4.80
.flekoosa No.1 6.08 1.49 0 0 1.00
IKekoosa No.2 6.26 2.66 10 10 2.00
Cakville 4.93 O.8~ 0 0 1.03
Pewomo No.1 19.73' 16.13 30 26 6.13
.Pewomo No.2 22. 8 15.13 9 13 6.00
Plainfield 4u23 0.81 2 4 Cu81
Spinks No.1 10.96 2.43 5 5 1.23
Spinks No.2 5.71 2.97 3 1 1.13
tSt. Clair 15.33 11.13 12 12 5.12

 

‘rwsm. -
. .DC.

C. .Tuly'iknigliznv

M.

Field Total exchange— Electrical Crgdnic

Koisture able metallic conductivity Latter
Soil Site 5 cations (mhos X1079/cm S

(me./100g.)
Blount 15.17 12.93 32 36 4.90
Ceresco No.1 20.26 19.59 19 19 8.10
Ceresco No.2 23.08 19.3‘ 20 22 8.20
COIWOOd No.1 17.99 19.08 21 18 4.30
Colwood No.2 16.5 15.40 16 20 6.10
Chelsea 9.62 1.29 4 2 1.40
Houghton 75.03 40.93 28 32 92.30
Hillsdale No.1 10.09 2.26 5 5 1.93
Hillsdale No.2 9.93 4.07 8 12 2.41
Lapeer 8.33 4.85 18 16 5.00
Nekoosa No.1 5.65 3.19 11 11 1.11
Nekoosa No.2 8.30 4.43 26 22 2.00
Oakville 4.37 1.56 0 0 0.95
Pewomo No.1 17.46 14.84 30 32 6.52
Pewomo No.2 17.36 14.25 20 24 6.00
Plainfield 3.39 1.62 0 0 1.80
Spinks No.1 9.47 4.05 17 15 .30
Spinks No.2 6.25 2.06 10 10 1.25
St. Clair 11.33 11.13 13 13 5.05
2. August Sajilin;

Blount 15.40 11.28 29 3 4.90
Ceresco No.1 15.73 22.69 21 21 8.00
Ceresco No.2 19.97 22.08 21 23 7.91
Colwood No.1 6.67 17.76 21 27 4.11
COIWOOd No.2 13.4 12.32 22 26 5.94
Chelsea 4.84 1.07 O 0 1.22
Houghton 66.58 40.93 79 81 92.40
Hillsdale No.1 11.15 2.26 2 15 1.88
Hillsdale N0.2 14.09 5.3 18 18 2.39
Lapeer 4.29 4.87 11 17 4.90
Nekoosa No.1 9.29 3.62 8 6 1.21
Nekoosa No.2 6.61 5.76 9 11 1.90
Oakville 4.87 3.34 0 O 0.99
Pewomo No.1 18.29 17.91 32 30 6.58
Pewomo No.2 20.05 19.43 4 6 6.10
Plainfield 2.87 2.33 O O 0.88
Spinks No.1 5.87 5.34 l9 17 1.27
Spinks No.2 5.42 2.04 9 7 1.30
St. Clair 11.93 11.13 19 19 5.18

 

 

\ “JF‘—l. -- -.‘ng—un—-.. . m
. - .
-'- .‘2‘.
l

 

 

 

 

o o
.
v o a o o c o o
o c o O n n . . v .
c O C .
s
I O I I O O c I I O a O c o O o 0 I O l a l a O a I a 0 0 O o o
.
O O O O O O O O O O I U l I o a O I r O 0 O n O O O I Q 0 I O

 

 

-64C-

E. Segtemter Sampliqg

Field Total exchange- Electrical Organic
Moisture able metallic conductivity Matter
Soil Site cations (mhos 110'5/cm) ‘
(me./lOOg.)

Blount 13.89 13.45 34 32 4.80
Ceresco No.1 17.42 21.38 19 17 7.80
Ceresco No.2 16.97 17.67 17 23 7.92
Colwood No.1 17.56 18.64 18 18 4.00
Colwood No.2 18.32 15.30 18 18 5.83
Chelsea 3.31 1.94 12 16 1.31
Houghton 70.07 40.93 52 58 91.60
Hillsdale No.1 3.22 3.17 6 4 1.70
Hillsdale No.2 6.22 4.42 12 18 2.38
Lapeer 3.78 5.85 10 12 4.72
Nekoosa No.1 3.46 2.98 0 0 1.20
Nekoosa No.2 2.76 6.09 4 2 2.10
Oakville 2.92 2.23 0 O 1.10
Pewomo No.1 17.27 15.61 21 19 6.43
Pewomo No.2 29.05 15.11 27 33 6.05
Plainfield 3.19 2.08 0 O 0.77
Spinks 80.1 4.92 2.03 2 2 1.25
Spinks No.2 4.70 ' 2.04 O O 1.28
St. Clair 8.02 11.13 13 15 5.19

. .d'

Table BB. Cation exchange capacity of each site, and
the base saturation percentage and exchange

acidity of each site measured during the season.

 

 

 

 

Cation MAY JUNE
exchange Base Sa— Exchange Base Sa- Exchange
capacity turation acidity turation acidity

Soil 8 te fime./100gm.) #3 (me/100g) _%_, (mellOOfiL
Blount 15.2 ** 1n.7 63.68 5.41 95.5 0.68
Ceresco No.1 24.5 ***25.1 80.8 6.31 80.8 6.31
Ceresco No.2 23.1 ***23.3 ---- 85.7 3.32
Colwood No.1 21.2 *21.7 —--- 89.2 .36
Colwood No.2 25.5 ***25.5 ---- 60.4 10.10
Chelsea 7.2 * 7.01 --—- 18.3 5.77
Houghton 108 ***108 33.6 71.71 37.0 68.04
Hillsdale No.1 6.7 ** 7.1 32.8 4.64 32.8 4.64
Hillsdale No.2 9.2 ** 9.2 ---- 28.7 6.56
Lapeer 8.7 *** 9.2 54.0 4.09 54.2 4.05
Nekoosa No.1 6.5 *** 6.13 50.7 3.09 23.7 4.82
Nekoosa No.2 6.9 *** 7.0 ---- 38.3 4.29
Oakville 4.3 *** 4.4 15.2 3.73 20.5 3.46
Pewamo No. 1 28.3 **29.4 54.4 13.16 55.9 2.72
Pewamo No. 2 32.4 **3l.3 ---- 47.5 16.67
Plainfield 3.5 *** 3.85 12.6 3.21 22.0 2.87
Spinks No. 1 6.5 ** 6.68 38.84 4.03 36.9 4.16
Spinks No. 2 3.98 ** 4.3 ----- 71.8 1.17
St. Clair 15.2 **15.6 ------ 72.3 4.27

1."er

‘FL gnu—..h... .--. _u——..———-...
. .
fl

* Measured on samples collected in July
** measured on samples collected in August
‘*** Reasured on samples collected in September

 

 

 

Table 83 Continued
JULY AUGUdT SEPTEHBNR

Base Exchange Base Exchange Base Exchange

Saturation acidity Saturation acidity Saturation acidity

5 13911003)» 5 12611005) f5 _129/107;)
86.84 2.02 75.26 3.67 89.7 1.50
79.02 5.21 91.5 2.11 86.2 3.42
85.7 3.32 95.2 1.12 76.2 5.53
89.2 2.32 83.0 3.64 87.1 2.76
60.4 10.10 48.3 13.18 60.4 10.20
18.3 15.77 15.2 5.99 27.5 5.12
37.9 68.07 37.9 68.07 37.9 68.07
32.8 4.64 32.8 4.64 45.9 3.73
47.9 5.13 57.8 3.88 47.9 4.73
54.5 4.05 54.7 4.03 65.7 3.05
50.7 3.12 57.5 2.69 47.4 3.33
63.7 2.52 82.9 1.19 86.9 0.86
35.8 2.79 76.7 1.01 51.2 2.12
51.3 14.01 62.2 10.94 54.4 13.24
44.8 17.65 61.1 12.37 47.5 16.69
44.0 2.06 62.9 1.35 56.5 l.’3
61.5 2.54 81.2 1.25 30.7 4.56
49.7 2.03 49.7 2.10 [9.7 “.10
72.3 4.33 72.3 4.27 72.3 4.27

Table 10.

Soil

Site

Blount

Chelsea

Hillsdale
No. 1

Hillsdale
No. 2

Nekoosa No.

Oakville

Pewamo No.

Plainfield

1

Spinks No. l

Spinks No. 2

St.

Clair

1

Seasonal Variability of lime requirement
(Tons/acre) determined by the pi plus tex—

ture, SEE buffer and exchange acidity

methods as determined on air dry samples
from 11 of the sites representing 9 soils.

 

KAY

pH plus SLP exchange

texture Buffer acidity
0.0 0.0 0.0
0.0 0.0 0.0
1.50 1.51 1.58
0.0 0.0 0.0
0.0 0.0 0.0-
1.50 1.15 1.39
0.00 0.00 0.00
1.50 1.15 1.18
1.50 1.27 1.50
0.0 0.0 0.0’
010 0.0 0.0

 

JUNE

pH plus SNP exchev e

tgzture ‘uffer aciditr
0.0 0.0 0.0
1.50 1.51 2.22
1.50 1.27 1.58
2.50 1.51 2.31
0.0 0.0 0.0
1.50 1.27 1.23
0.00 0.00 0.00
1.50 1.15 1.02
0.50 0.96 1.40
0.0 0.0 0.0
0.0 0.0 0.0

—663-

Table 10 Continued

JULY AUGUST
pH plus SNP exchange pH plus SE? exchange
texture buffer acidity texture buffer acidity

0.0 0.0 0.0 2.00 1.51, 0.37
2.00 1.69 2.22 2.00 1.69 2.33
2.50 1.69 1.58 3.00 1.51 1.58
2.50 1.51 1.48 2.50 1.93 1.02
0.50 1.15 0.95 0.0 0.0 0.0

1.50 1.27 0.95 1.50 1.27 0.0

2.00 2.05 4.06 2.00 1.93 2.52
2.00 1.51 0.62 2.00 1.15 0.30
1.50 1.69 0.60 0.50 0.96 trace
0.50 1.15 trace 0.50 0.96 trace
2.00 1.51 0.58 2.00 1.51 0.58

Table 10 Continued

C“ M‘f‘"“"’_"‘1"1
o-L 1.11-5151";

pH plus SKP exchange
Soil Site texture Buffer acidity
Blount 0.00 0.0 0.0
Chelsea 2.00 1.51 1.89
Hillsdale No. 1 2.50 1.51 1.14
Hillsdale No. 2 2.50 1.51 1.48
Nekoosa No. 1 0.51 1.15 0.56
Oakville 1.50 1.51 0.62
Pewamo No. 1 2.00 2.29 3.62
Plainfield 2.00 1.27 0.41
Spinks No. l 1.50 1.69 1.60
Spinks No. 2 0.50 1.51 trace
St. Clair 0.0 0.0 0.0

«5mm,

‘7' ' . ’2'. .t'd-r &'= t!...'
Wag

llHlHlWHllllllllllllllllillll11111111111lllHll

 

3101668188