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INTRODUCTION ΔNH OAc-K vs Kfix (FM)Change in Kfix and NH OAc-K with Air DryingINTRODUCTION
Potassium fixation has been identified as a possible source 60
ΔNH4OAc-K vs Kfix (FM)
300
Change in Kfix and NH4OAc-K with Air Drying
Potassium fixation has been identified as a possible source
of concern for managing fertility in granitic soils in the San
Joaquin Valley of California. Previous work in our lab has 20
40
K (
mg
/kg
)
300
Field MoistJoaquin Valley of California. Previous work in our lab has
demonstrated that vermiculite in the silt and fine sand
fraction is predominantly responsible for observed K
fixation in these soils, and that air-drying of soil materials
0
20
-400 -200 0 200 400 600 800
OA
c-K
(m
g/k
g)
250
Field Moist
Air Dry
fixation in these soils, and that air-drying of soil materials
after the application of K in solution results in an increase in
K fixation potential relative to samples maintained moist. It -40
-20
-400 -200 0 200 400 600 800
ΔN
H4O
Ac
200
K (
mg
/kg
)
Air Dry
Increase in Kfix and
NH4OAc-KK fixation potential relative to samples maintained moist. It
has also been observed that less exchangeable K is usually
extracted from field-moist samples than from air-dried
-60
-40
Kfix (FM) (mg/kg)150
OA
c-K
(m
g/k
g)
NH4OAc-K
Increase in Kfix,
Decrease in NH4OAc-Kextracted from field-moist samples than from air-dried
samples.1Fig. 6 Change in NH4OAc-K with drying as a function of Kfix.
NH4OAc-K increase for most K-fixing soils.
100
NH
4O
Ac
Decrease in NH4OAc-K
Decrease in Kfix and
NH4OAc-K
In order to better understand the effects of drying on K
fixation potential, we measured K fixation potential (Kfix) 60
ΔNH4OAc-K vs NH4OAc-K (FM)100 NH4OAc-K
Decrease in Kfix,
Increase in NH4OAc-Kfixation potential, we measured K fixation potential (Kfix)
and ammonium acetate-extractable K (NH4OAc –K) on field-
moist and air-dried soil material representing a range of K-40
60
K (
mg
/kg
)
50Increase in NH4OAc-K
moist and air-dried soil material representing a range of K-
fixing and non-K-fixing soils.
0
20
-K (
mg
/kg
)
0
-250 -50 150 350 550
Fig. 1 Relationship between NH4OAc-K and Kfix for field-moist and air-dried samples, with arrows representing METHODS-20
0
0 50 100 150 200 250 300 350
NH
4O
Ac--250 -50 150 350 550
Kfix (mg/kg)
Fig. 1 Relationship between NH4OAc-K and Kfix for field-moist and air-dried samples, with arrows representing
the direction and magnitude of change in both values with drying. (Faded, dashed arrows indicate no
significant change with drying for either variable)
METHODSSoils
• 29 soil samples collected from 15 locations in wine grape vineyards
and almond orchards in the Central Valley of California-60
-40
ΔN
H
and almond orchards in the Central Valley of California
• At collection, field-moist soil samples sealed in Ziploc bags followed
by storage under refrigeration350
NH4OAc-K - Field Moist vs Air Dry 700
Kfix - Field Moist vs Air Dry
-60NH4OAc-K (FM) (mg/kg)
Fig. 7 Change in NH4OAc-K with drying as function of NH4OAc-K
by storage under refrigeration
• Subsamples removed and air dried
• NH4OAc-K and Kfix measured on field-moist and air-dried samples
300
350
1:1500
600
700
1:1 DISCUSSION & SUMMARY• NH4OAc-K and Kfix measured on field-moist and air-dried samples
Ammonium acetate-extractable K2 (NH4OAc-K)
• 2.5 g soil saturated and extracted overnight with 1 M NH4OAc
y = 0.8684x + 23.094
R² = 0.9321200
250
K (
AD
) (m
g/k
g)
y = 0.9796x + 54.897
R² = 0.9741300
400
500
(AD
) (m
g/k
g)
1:1 DISCUSSION & SUMMARY
1. Effect of drying on Kfix (Figs. 2, 4, 5)• 2.5 g soil saturated and extracted overnight with 1 M NH4OAc
(pH 7) using a mechanical vacuum extractor
• K determined by flame emission spectrometry
R² = 0.9321
150
200
-K (
AD
) (m
g/k
g)
R² = 0.9741
100
200
300
(AD
) (m
g/k
g)
1. Effect of drying on Kfix (Figs. 2, 4, 5)
• Kfix increased with drying for all K-fixing soils
• Average increase was about 55 ppm• K determined by flame emission spectrometry
K fixation potential3 (Kfix)
• 3 g soil shaken in 30 mL of 2 mM KCl for 1 h
100N
H4O
Ac-
0
100
-400 -200 0 200 400 600 800
Kfi
x(A
D)
(mg
/kg
)
• Average increase was about 55 ppm
• For non-K-fixing soils, change in Kfix was not
consistent • 3 g soil shaken in 30 mL of 2 mM KCl for 1 h
• Extracted for 30 minutes with 10 mL 4 M NH4Cl, and centrifuged
• K measured by flame emission spectrometry 0
50
NH
-200
-100-400 -200 0 200 400 600 800 consistent
• There was no discernible relationship
between Kfix values and the magnitude of • K measured by flame emission spectrometry
• K fixation potential was calculated as the difference between a blank
and the measured K solution concentrations Fig. 3 Air-dried (AD) vs field-moist (FM) NH OAc-K values
0
0 100 200 300 400NH4OAc-K (FM) (mg/kg)
Fig. 2 Air-dried (AD) vs field-moist (FM) Kfix values.
-300Kfix (FM) (mg/kg)
between Kfix values and the magnitude of
change
• Change in Kfix did not correlate with
Table 1. Soil properties
and the measured K solution concentrations
• Values less than or equal to zero indicate no K fixation potential.
Fig. 3 Air-dried (AD) vs field-moist (FM) NH4OAc-K valuesFig. 2 Air-dried (AD) vs field-moist (FM) Kfix values.
Regression for Kfix>0 only.
• Change in Kfix did not correlate with
NH4OAc-K values
• Effect of drying may be a function of
Table 1. Soil properties Depth Kfix Kfix NH4OAc-K NH4OAc-K
Field Moist Air Dry Field Moist Air Dry
Code Soil/Classification (cm) (mg kg-1) (mg kg-1) (mg kg-1) (mg kg-1)
• Effect of drying may be a function of
mineralogy (vermiculite in K fixing soils)
ΔKfix vs Kfix (FM) Code Soil/Classification (cm) (mg kg-1) (mg kg-1) (mg kg-1) (mg kg-1)
VSS E San Joaquin silt loam 0-20 177 279 59 66
Abruptic Durixeralf 100-120 613 642 51 81
KTR B Columbia sandy loam 0-20 1 82 123 120
2. Effect of drying on NH4OAc-K (Figs. 3, 6, 7)
• Change in NH4OAc-K was small (less than 20 80
100
120
ΔKfix vs Kfix (FM)
KTR B Columbia sandy loam 0-20 1 82 123 120
Aquic Xerofluvent 120-140 523 604 51 65
VSN C Redding gravelly loam 0-20 87 143 74 72
40-60 499 526 50 54
4
ppm) for most samples
• High NH4OAc-K samples were less likely to
show a large change20
40
60
80
(mg
/kg
)
Abruptic Durixeralf 40-60 499 526 50 54
KTR H Sailboat silt loam 0-20 39 67 113 114
Aquic Xerofluvent 40-60 406 473 72 84
show a large change
• Drying increased NH4OAc-K for most low
NH OAc-K soils and most K-fixing soils-40
-20
0
20
-400 -200 0 200 400 600 800ΔK
fix
(mg
/kg
)
Aquic Xerofluvent 40-60 406 473 72 84
DH 2 Guard clay loam 0-20 17 104 157 160
Duric Haplaquoll 40-60 282 365 81 103
KTR C Sailboat silt loam 0-20 5 38 125 121
NH4OAc-K soils and most K-fixing soils
• Change in NH4OAc-K was less consistent for
non-K-fixing soils-80
-60
-40
Kfix (FM) (mg/kg)
REFERENCES
KTR C Sailboat silt loam 0-20 5 38 125 121
Aquic Xerofluvent 120-140 324 325 65 96
KIMB 219 Kimberlina fine sandy loam 0-20 -103 -159 213 214
40-60 262 278 68 86
non-K-fixing soilsKfix (FM) (mg/kg)
Fig. 4 Change in Kfix with drying as a function Kfix.
K-fixing soils uniformly showed an increase in Kfix. REFERENCES
1. Mallarino, A.P., P.A. Barbagelata, and D.J. Wittry. 2004. Soil-test potassium
Typic Torriorthent 40-60 262 278 68 86
KTR A Columbia sandy loam 0-20 -60 -31 160 156
Aquic Xerofluvent 40-60 244 266 111 107ΔKfix vs NH4OAc-K (FM)
K-fixing soils uniformly showed an increase in Kfix.
1. Mallarino, A.P., P.A. Barbagelata, and D.J. Wittry. 2004. Soil-test potassium
field calibrations for soybean Iowa interpretations and research update.
North-Central Extension-Industry Soil Fertility Conf. Proceedings. Vol. 20.
2.Soil Survey Staff. 2004. Soil Survey Laboratory Methods Manual – Soil Survey
Aquic Xerofluvent 40-60 244 266 111 107
CM F Montpelier-Cometa complex 0-20 13 34 80 80
Xeralfs 40-60 54 159 37 59
DON A Archerdale clay loam 0-20 -98 -81 244 25080
100
120
2.Soil Survey Staff. 2004. Soil Survey Laboratory Methods Manual – Soil Survey
Investigations Report No. 42. Version 4.0. USDA-NRCS. Lincoln, NE.
3.Murashkina, M., R. J. Southard, and G. S. Pettygrove. 2007. Potassium fixation
in San Joaquin Valley soils derived from granitic and nongranitic alluvium. Soil
DON A Archerdale clay loam 0-20 -98 -81 244 250
Pachic Haploxeroll 40-60 110 155 39 90
RM X Redding gravelly loam 0-20 -24 -46 93 89
40-60 -2 26 37 4020
40
60
80
Kfi
x (
mg
/kg
)
in San Joaquin Valley soils derived from granitic and nongranitic alluvium. Soil
Sci. Soc. Am. J. 71:125-132.Abruptic Durixeralf 40-60 -2 26 37 40
CM N Montpelier-Cometa complex 0-20 -24 -48 137 124
Xeralfs 40-60 -102 -6 166 118-40
-20
0
20
0 50 100 150 200 250 300 350ΔK
fix
(m
g/k
g)
ACKNOWLEDGEMENTS
Research was made possible by grants from the Lodi Winegrape
Xeralfs 40-60 -102 -6 166 118
Dougan Vina fine sandy loam 0-20 -98 -126 247 257
Pachic Haploxeroll 40-60 3 -36 68 116
KIMB 198 Kimberlina sandy loam 0-20 -169 -174 318 303
-80
-60
-40
NH4OAc-K (FM) (mg/kg)Research was made possible by grants from the Lodi Winegrape
Commission and the California Department of Food & Agriculture.
KIMB 198 Kimberlina sandy loam 0-20 -169 -174 318 303
Typic Torriorthent 40-60 -29 -54 106 149
RVB Nord fine sandy loam 0-10 -206 -233 270 259
Fig. 5 Change in Kfix with drying as a function of NH4OAc-K
NH4OAc-K (FM) (mg/kg)
Cumulic Haploxeroll