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