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Communications in Soil
Science and Plant Analysis
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Correlations between two
soil extractants and corn
leaf potassium contents
from Hungarian field trials
Peter Csathó a
a Research Institute for Soil Science and
Agricultural Chemistry , Herman O. út. 15.
(H‐1525 Budapest, P. O. Box 35), Budapest,
H‐1022, Hungary
Published online: 11 Nov 1998.
To cite this article: Peter Csathó (1998) Correlations between two soil
extractants and corn leaf potassium contents from Hungarian field trials,
Communications in Soil Science and Plant Analysis, 29:11-14, 2149-2160, DOI:
10.1080/00103629809370099
To link to this article: http://dx.doi.org/10.1080/00103629809370099
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COMMUN. SOIL SCI. PLANT ANAL., 29(11-14), 2149-2160 (1998)
CORRELATIONS BETWEEN TWO SOIL EXTRACTANTS AND
CORN LEAF POTASSIUM CONTENTS FROM HUNGARIAN FIELD
TRIALS
Peter Csathó
Research
Institute
for Soil Science and
Agricultural
Chemistry,
H-1022 Budapest,
Herman O. út. 15. (H-1525 Budapest, P. O. Box 35), Hungary
ABSTRACT
Corn (Zea mays L.) leaf weight, leaf potassium (K) content at the flowering stage,
and ammonium lactate (AL)- and neutral normal ammonium acetate (NH4Ac)-
extractable K were determined in a network of 27-year-old long-term Hungarian field
trials ("OMTK trials") with different K fertilization rates on nine locations repr-
esenting various agro-ecological and soil conditions of the country. Corn leaf weights
at the flowering stage were affected less by soil-extractable K than by the different
agro-ecological conditions. Corn K contents, however, were much more affected by
K rates than leaf weights. The additional effect of the higher K rate, however, was
not significant. Leaf K contents were affected by site also. There was no significant
correlation between corn leaf K content and leaf weight. Above 1.5% K leaf content,
however, leaf weights did not increase. Corn leaf weight increased together with soil
test values up to 150-160 mg kg-1 soil-extractable K. There was a poor linear
correlation between soil-extractable K and leaf weight (r = 0.40**). There was a
significant quadratic polynomial correlation between soil-extractable K and leaf K
content (R = 0.60***). The lower limit of good K supply, indicated by leaf K content
at flowering (1.5% K), was usually reached when the soil-extractable K level reached
150 mg kg-1. The most significant linear correlation was found between NH4Ac- and
AL-extractable K (r = 0.91***). Both the AL and NH4Ac methods identied the
different soil K levels similarly. As a first attempt, new NH4Ac-extractable K supply
categories were established for Hungarian conditions. Soil and plant K analysis data
proved to be useful tools in adapting the results from long-term field trials for
improved fertilizer recommendations.
INTRODUCTION
Potassium, the seventh most common element in the earth's crust, is essential for
both animal and plant growth. As a plant macronutrient, this element plays an
important role as an enzyme catalysis, plant and cellular structures, photosynthesis,
respiration, protein and oil metabolism (Beringer and Nothdurft, 1985; Blevins,
1985,
Csathó, 1991,1997; Huber, 1985; Liebhardt and Murdock, 1965; Suelter,
1985;
Weber, 1985). Potassium also is known to increase plant resistance against
disease and frost (Huber and Arny 1985; Kádár, 1992). Most soils have relatively
2149
Copyright © 1998 by Marcel Dekker, Inc.
www.dekker.com
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2150 CSATHÓ
TABLE
1.
The amount
of K
applied
to
the experiments,
kg
K2O
/ha
K-level Period
1968-71 1972-87 1988-94 1968-94
Added K2O
for
com, kg/ha/year
KO
Kl
K2
KO
Kl
K2
0
100
200
0
330
660
0
100
100
Total added K2O, kg/ha/period
0
1600
1600
0
200
250
0
1100
1450
0
129
154
0
3030
3710
large amounts of total K but relatively small amounts of plant-available K. Potassium
is found as a component of several minerals that release K into soluble and
exchangeable forms by weathering at greatly differing rates. Any soil test that
accurately reflects the K available to a crop in a growing season must measure that in
solution plus what is capable of being released into the soil solution and eventually
taken up by the crop during the growing season (McLean and Watson, 1985). Both
the AL method (Egner et al., 1960) and NH4Ac method (Wanasuria et al., 1981)
extract exchangeable and water-soluble K soil fractions. The AL method has been
widely used in the Scandinavian, Baltic, Middle European countries and in Portugal,
while the NH4Ac method is used in the Western European countries and the United
States for determining soil test K levels needed for basing fertilizer K recommenda-
tions. Soil "available" nutrient content data as well as young crop analysis data taken
for diagnostic purposes can be used in fertilizer recommendation techniques only if
the methods are calibrated. Corn and winter wheat are the two main crops grown in
Hungary, occupying together more than 50% of the arable land. Corn proved to be
the most K-demanding crop in the Hungarian field trials (Csathó, 1997; Debreczeni
and Debreczeni, 1994; Kádár, 1992; Kadlicskó et al, 1988; Lásztity, 1989).
Correlation between soil available K, corn leaf K content, and leaf weight taken from
a network of long-term field trials at nine sites were evaluated in this study.
MATERIAL AND METHODS
The Hungarian field trial network called Long-term Fertilization Field Trials
(known by its Hungarian acronym "OMTK") were established at 26 different sites,
representing the main agro-ecoregions of the country. However, due to the lack of
financial sources, only nine sites have been continued. The trials were started in the
autumn of 1967 in a rotation of winter wheat-corn-corn-peas. These trials consist of
increasing nitrogen (N), phosphorus (P), and K rates and combinations of these
mineral fertilizers. From the original 20 .treatments with four replications, five
treatments were selected for this evaluation from each site: N2P1K0; N2P2K0;
N2P1K1;
N2P2K1; and N4P3K2.
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TABLE 2. Soil properties of the nine sites of the long-term field experiment network "OMTK"
PropertiesNH*ntBIExperimental sites
KO KA PUKEHBMOReferences
O
z
3
o
50
oo
Soil type (FAO)
Soil type (USDA)
Soil texture
SoilOM,%
SoilpHKCi
CaCO3,
%
yj,
me/100 g
Calcaric
Phaeosem
Mollisol
loam
2.7
7.2
6.0
-
< 0.01 mm particles, % 38
Clay % (<0.002 mm)23
Calcaric
Phaeosem
Mollisol
loam
2.4
7.4
8.0
-
36
24
Clay mineral composition in the clay fraction, %
Mite
Kaolinite
Smectite
Vermiculite
Mite-
Smectite
Mite-
Chlorite
47
-
16
.
5
3
Mite-
Vermiculite
Total K% in the clay fraction
(HF digestion)n.d.
50
8
_
10
2
-
1.6
Luvic
Phaeosem
Mollisol
loam
1.9
5.6
-
45
33
45
.
17
6
10
3
.
2.5
Haplic
Phaeosem
Mollisol
clay loam
2.6
3.9
-
19
58
46
27
20
37
.
10
6
-
2.1
Luvic
Phaeosem
Mollisol
clay loam
2.7
4.7
-
24
59
45
56
.
7
3
11
5
1
3.0
Ochric
Luvisol
Alfisol
clay loam
2.0
3.9
-
16
49
31
33
14
27
.
19
-
2
1.8
Eutric
Cambisol
Alfisol
sandy loam
1.7
5.9
traces
-
37
22
59
10
6
.
9
3
-
2.1
Luvic
Phaeosem
Vertisol
clay
3.5
6.1
traces
-
53
36
29
.
47
6
5
3
3
2.0
Calcaric
Fluvisol
Vertisol
loam
1.7
7.4
21.0
-
35
25
48
_
16
_
7
-
2.7
SÁRDI& NÉMETH 1993
NÉMETH 1995
SARKADI
1994
DEBRECZENI &
DEBRECZENI 1994
DEBRECZENI &
DEBRECZENI 1994
DEBRECZENI &
DEBRECZENI 1994
DEBRECZENI &
DEBRECZENI 1994
DEBRECZENI &
DEBRECZENI 1994
STEFANOVITS &
DOMBÓVÁRI 1994
STEFANOVITS &
DOMBÓVÁRI 1994
STEFANOVITS &
DOMBÓVÁRI 1994
STEFANOVITS &
DOMBÓVÁRI 1994
STEFANOVITS &
DOMBÓVÁRI 1994
STEFANOVITS &
DOMBÓVÁRI1994
STEFANOVITS &
DOMBÓVÁRI 1994
STEFANOVITS &
DOMBÓVÁRI 1994
STEFANOVITS &
DOMBÓVÁRt1994
* Experimental sites: NH: Nagyhörcsök; IR: Iregszemcse; BI: Bicsérd; KO: Kompolt; KA: Karcag; PU: Putnok; KE: Keszthely; HB: Hajduböszörmeny;
MO:
Mosonmagyaróvár.
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TABLE 3. The effect of 27 years of K fertilization on NH,OAc- and AL-extractable K. OMTK field trial network, 1994.
K-level
KO
Kl
K2
LSD5o/o
Mean
Kl-KO
K2-K1
KO
Kl
K2
LSD5o/o
Mean
Kl-KO
K2-K1
NH*
102
232
306
48
213
130
74
73
191
223
19
162
118
32
re
99
165
198
17
145
66
33
99
166
211
13
158
67
45
BI
225
264
249
62
245
39
-15
146
190
201
32
182
44
11
KOExperimental sites
KA PUKE
NH4OA0 extractable K, mg/kgsoil
171
317
359
59
267
146
42
170
283
290
41
239
113
7
150
212
256
40
196
62
44
105
149
158
12
133
44
9
AL-extractable K, mg/kgsoil
173
298
285
46
252
124
-13
154
259
258
18
224
105
-1
148
240
247
43
212
92
6
110
170
180
20
153
60
10
HB
ni
142
144
15
130
31
2
91
118
124
26
111
27
6
MO
60
143
197
13
121
83
54
45
105
137
18
96
70
32
66
53
49
36
Mean
133
212
240
17
195
79
28
115
193
207
20
172
78
17
• Experimental sites: see in Table 2.
n
1
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X
•z
o
TABLE
4. The
effect
of 27
years
of
network,
1994.
K-level
KO
Kl
K2
LSD5%
Mean
Kl-KO
K2-K1
KO
Kl
K2
LSD5o/o
Mean
Kl-KO
K2-K1
NH*
69.1
77.0
69.0
8.1
71.7
7.9
-8.0
0.62
1.42
1.66
0.22
1.23
0.80
0.24
IR
70.6
73.2
72.3
4.1
72.0
2.6
-0.9
0.98
1.97
2.11
0.27
1.60
0.99
0.14
K fertilization on the flowenng stage com-leaf weight and leaf-K concentrations. OMTK field trial
BIKOExperimental sites
KA PUKEHB
Corn-leaf weight at flowering, g/ 20 leaves (air-dry)
75.8
84.3
84.8
6.7
81.0
8.5
0.5
1.07
1.69
1.74
0.19
1.45
0.62
0.05
97.4
97.4
87.8
13.0
95.5
0.0
-9.6
72.2
72.9
72.9
11.2
72.9
0.7
0.0
94.0
82.5
95.0
10.9
89.6
-11.5
12.5
78.6
83.1
86.5
3.9
82.0
4.5
3.4
Corn-leaf K% at flowering, (air-dry)
1.65
1.92
2.12
0.26
1.85
0.27
0.20
1.79
1.96
2.19
0.67
1.94
0.17
0.25
1.05
1.70
1.84
0.17
1.52
0.75
0.14
0.74
1.92
1.86
0.14
1.44
1.18
•0.06
75.4
82.7
77.8
8.7
78.8
7.3
4.9
0.75
1.53
1.69
0.16
1.25
0.78
0.16
MO
68.6
70.2
69.2
9.3
69.3
1.6
-1.0
1.32
1.9S
1.98
0.35
1.70
0.63
0.03
LSD5%
8.0
7.0
0.20
0.18
Mean
78.0
80.4
79.5
4.0
79.3
2.4
-0.9
1.11
1.80
1.91
0.10
1.61
0.68
0.12
*
Experimental
sites:
see in
Table
2.
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2154CSATHÓ
• KO P1/P2
N2
• K1 P1/P2
N2
• K2 P3
N4
100
—i
90
—
'S
a
o
<u
70
—
60
—I
•
•
•
'A
A
•
A
•
# •
•
A
y
=
0.0501
x + 70.3
r
=
0.399
**
(n
= 44)
T
' I ' T
100 200 300
NH4OAc extractable K, mg/kg
400
FIGURE
1.
Correlation between NH4OAC extractable
K
and flowering stage
com
leaf weights.
All
sites,
1994.
The amount
of K
given
for
different
K
soil levels
are
given
in
Table
1.
Twenty
flowering-stage com leaves opposite
to the cob
together with
20
post harvest
composite soil samples were taken from the plots with different
K
rates
in
1994—the
27th year
of
the trials (Debreczeni and Debrcczeni, 1994). Leaf sampling dates
for
the
flowering stage
of
com were
as
follows: Nagyhörcsök: July
22,
Iregszemcse: July
20,
Bicsérd: July
21,
Kompolt: July
16,
Karcag: July
18,
Putnok: July
Keszthely: July 19, Hajduböszörmeny: July 22, Mosonmagyaóvár: July 20,1994.
Soil properties
of the
nine sites, representing
the
different soil conditions
and
agro-ecoregions
of
Hungary,
are
given
in
Table
2.
After digestion
in
concentrated
sulfuric acid (H2SO4)
+
30% hydrogen perioxide (H2O2) (Thamm, 1973),
the K
content
of
the digest was determined
by
flame photometry. The
AL
method (0. IM
ammonium lactate
+
0.4M acetic acid,
pH =
3.75, soil/solvent ratio
= 1:20,
shaking
time
= 2
hours, Egner
et
al., 1960)
and the
NH4AC method
(IM
ammonium acetate,
pH=
7.0,
soil/solvent ratio
= 1:25 ,
shaking time
= 1
hour, Wanasuria
et al., 1981)
were used
for
extracting soil
K.
Linear
and
polynomial quadratic correlation calculations were calculated
for
determining
the
correlation between soil
K
test and com leaf weight, soil
K
test
and
com leaf
K
content
as
well
as
between com leaf K content and leaf weight.
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O)
'S
O)
20
—
10
—
•
•
/
•
/
/ • *
# KO P1/P2
N2
• K1 P1/P2
N2
• K2 P3
N4
•
y =
-0.000125
xA2 +
0.0878
x + 4.04
•
R =
0.605
***
(n=44)
I
100
200 300
NH4OAC extractable K, mg/kg
400
FIGURE
2.
Correlation between NK,OAc extractable
K and
and flowering stage corn leaf-K concentrations.
All
sites,
1994.
O)
I
300
—
200
—
100
—
KO P1/P2
N2
K1 P1/P2
N2
K2
P3 N4
y
=
O.79O X
+ 14.0
r
=
0.9O7
***
(n
= 44)
100
200 300
NH4OAc extractable K, mg/kg
400
FIGURE
3.
Correlation between NH,0Ac extractable
and AL
extractable
K
values.
All sites,
1994.
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TABLE 5. Corn responses to K application in previous six years in the trials, t/ha grain yields.
(After Debreczeni and Dvoracsek, 1994)
K-level
KO
Kl
LSD!%
Relative yield, %
(100K0/K1)
Yield surplus, t/ha
(K1-K0)
NH*
7.51
7.98
0.32
94
0.47
m
7.08
7.82
0.45
90
0.74
BI
8.38
9.11
0.41
92
0.73
Experimental sites
KO KA
4.90
5.05
0.27
97
0.15
8.40
8.03
0.78
105
-0.37
PU
6.06
6.04
0.28
100
-0.02
KE
6.07
7.33
0.46
83
1.26
HB
9.40
10.96
0.77
86
1.56
MO
7.41
7.68
0.32
97
0.27
Mean
7.24
7.78
0.16
93
0.54
* Experimental sites: see in Table 2.
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TABLE 6. Comparison of K supply categories, as indicated by AL-extractable K, com-leaf K concentrations, as well as by previous
com responses to K application in the „ OMTK" field trial network.
Experimental sites
K-level NH^ K BI KO KA PU KE HB MO
K supply, indicated by AL- extractable K concentration (According to Csathó, 1997)
KO
Kl
K2
KO
Kl
K2
K-supply, indicated by com responses to K application (According to Debreczeni and Dvoracsek, 1994)
KO p-m p p m-g g g vp vp m
* Experimental sites: see in Table 2. ** vp= very poor; p= poor; m= medium; g= good; vg= very good. *** rainfall prior sampling might
cause some leaching of K from the tissues
vp"
vg
vg
vp-p
g
vg
m
vg
vg
g
vg
vg
m-g
vg
vg
m
vg
vg
P
vg
vg
K supply, indicated by com-leaf K concentration (According to Elek and Kádár, 1980)
vp
m
m-g
vp
g
g
m
m-g
g
m-g
g
g
g
g
g
p*»*
g
g
vp
g
g
vp
p
p
vp
m
m-g
vp
P
m
m
g
g
to
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2158 CSATHÓ
TABLE 7. New soil K-supply categories for the Hungarian agro-ecological conditions as indicated by the
neutral NH4OAC- extractable K-concentrations.
Soil texture
Sands
Sandy loams
Loams
Clay loams
Clayey soils
Very poor
<50
<90
<110
<120
<130
K-suppy categories (NH4OA0K,
Poor
51-80
91-130
111-140
121-150
131-160
Medium
81-110
131-160
141-170
151-180
161-190
mg/kg)
Good
111-140
161-190
171-210
181-230
191-250
Very good
14K
191<
211<
231<
251<
RESULTS
The effect of K application on NH4Ac- and AL-extractable K was significant for
the Kl treatment rate as compared to the K0 rate. The additional effect at the K2 rate
was not significant (Table 3). Soil test levels at the KO rate refer to the soil texture
groups, although significant differences can occur within the groups. Neutral
ammonium acetate and AL extracted similar amounts of K, similar to the findings of
Sárdi and Németh, 1993 (Table 3). Corn leaf weights at the flowering stage were
affected less by extractable K concentrations than by the different agro-ecological
conditions. Corn leaf K contents, however, were much more affected by the K
fertilization rates than were leaf weights. The additional effect of the K2 rate,
however, was not significant. Leaf K content was also affected by site (Table 4).
There was no significant correlation between corn leaf K content and leaf weight.
Above a leaf K content of 1.5%, leaf weights did not increase. Com leaf weight
increased together with soil test K levels up to 150-160 mg kg-1. There was a poor
but statistically significant linear correlation between soil K and leaf weight (r =
0.4**)
(Figure 1). There was a highly significant quadratic polynomial correlation
between NH4AOc-soluble K and leaf K content (R =
0.6***)
(Figure 2). The lower
limit of adequate K supply, indicated by leaf K content at the flowering stage (1.5%
K),
was usually reached when NHjAc-extractable K reached 150 mg kg-1.
The most significant linear correlation was found between the NH4Ac- and AL-
extractable K levels (r =
0.9***)
(Figure 3). On the basis of previous calibrations of
the AL method based on the Hungarian field trials (Csathó, 1997) as well as the
findings from this study, a first attempt for this country to establish new NH4Ac-
extractable K supply categories were undertaken for Hungarian agro-ecological
conditions (Tables 5, 6, and 7). These categories vary according to soil texture and
will provide for an environmentally friendly K fertilization practice for corn.
CONCLUSIONS
Both the AL and the NH4Ac extraction methods for determining soil K levels
were well correlated for the soils used in these trials. Soil and plant K analysis data
were found to be useful tools in evaluating the results of long-term field trials for
establishing fertilizer K recommendations. The calibration of extractable K by both
methods with com grain yields based the long-term field trials is essential.
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HUNGARIAN FIELD TRIALS 2159
ACKNOWLEDGEMENTS
The scientific board for planning and development of the the experiments included
Professors G. Lang (chairman), E. Bocz, B. Debreczeni, J. Sarkadi, J. Sváb and P.
Wellish. The Author is much obliged to
Prof.
Katalin Debreczeni, Pannon University
of Agricultural Sciences, Keszthely, head of the network centre, as well as to the
researchers, responsible for the individual trials: Keszthely: Dr. Tamas Kismányoky,
Dr. István Ragasits; Mosonmagyaróvár: Dr. István Késmárky, Dr. Éva Szalka ;
Iregszemcse: Dr. László Takács, Miklós Mihalovics; Bicsérd: Dr. László Takács,
József Ekkert; Nagyhörcsök: Dr. Tamas Németh, Dr. Imre Kádár, Kompolt: Dr.
Sándor Holló; Putnok: Dr. Béla Kadlicskó; Hajdúboszormény: Dr. Mihály Sárvári;
Karcag: Dr. Lajos Blaskó, Dr. György Zsigrai. Without their genuine help this study
could not have been completed. This study was financially supported by the
Hungarian National Scientific Research Fund (OTKA) under Grant No. T 021264.
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