Download - Effectiveness of Sidedressed Fluid Potassium …...Effectiveness of Sidedressed Fluid Potassium Fertilizer in Corn and Soybean Antonio P. Mallarino Department of Agronomy Iowa State

Effectiveness of Sidedressed

Fluid Potassium Fertilizer

in Corn and Soybean

Antonio P. Mallarino

Department of Agronomy

Iowa State University

Extension and OutreachIOWA STATE UNIVERSITY


Plant Roots and P - K Uptake

• P and K are much less mobile than nitrate,

need to reach roots by diffusion from a

very short distance

• Actively growing root systems with fine

roots is key for uptake of both, and P is

especially needed for early growth

• Banding could help with

- High soil “fixing” capacity

- Soil conditions limiting root/seedling growth

- Cold, compaction, root diseases or insects


Preplant K Placement in Corn & Soybean

• Iowa research since the 1960s has shown

no difference between K fertilization

broadcast, banded preplant, or banded

with the planter with few exceptions

• Deep banding (4 to 6 inches)

- Ridge-till, a must for corn, also found by G.

Rehm in MN in late 1980s and early 1990s

- No-till and strip-tillage, sometimes for corn,

mainly with dry topsoil June to early July IF

there is moisture in the band zone, doubtful

payback


Not Surprising with Iowa Soils & Climate

• Little or no P or K “fixation”; retention of P

and K by soil doesn’t mean fixation

• Good soils allow for large root systems with

many fine roots for P and K uptake

• Usually humid spring weather

• Cold/wet soil early but,

- Need to plant so early?

- Starter P in-furrow or 2x2” is a cost-effective fix,

complements broadcast preplant application


Sidedressing for P and K?

• Fluid N sidedressing for corn is common

- Complements preplant fertilization

- Much research has been conducted

• Sidedressing of P fertilizer, fluid or dry, is

unlikely to work, crops need P very early

- Cell multiplication and division

- New and more leaves

- Grain sink is determined early


Sidedressing for K?

• Doubts, scarce research without irrigation

or with different preplant K application rates

- Not much K needed early, large uptake later on

- Not much K leaching except in sandy soils

- No “true” starter K effect, as it is with N and P

• As a split application can be helpful in some

conditions or serve as a rescue option

- Need soil moisture for uptake, injecting fluid K

with relatively new low-salt potassium acetate

may be the best option


Trials and Soils

• Twelve 2-year trials with corn-soybean

rotations

- One no-till, others tillage for corn

- Six began in 2017 and six in 2018

• Six soil series

- Central, N, NE, S, SE, SW Iowa

- Poorly drained to well drained

- Texture loam, clay loam, or silty clay loam

- Organic matter 3.2 to 4.5%

- pH 5.8 to 6.7


Trials and Treatments

• Five preplant K treatments in large plots,

two K sidedress treatments in subplots,

four replications in blocks

• Used established trials, each with useful

similar previous management except for K

fertilization

• Each block (replication) had four large low-

testing plots (no K application for 6-8 years)

and one high-testing plot with history of

annual K applications


Potassium Treatments

• Preplant K treatments only to corn (1st year)

- 4 broadcast rates (0, 45, 90, 135 lb K2O/acre)

2-3 weeks before planting randomized to the

four large low-testing plots of each block

- No K to the high-test plot of each block

• Sidedress K treatments to both crops

- No/Yes fluid potassium acetate (0-0-24)

- 45 lb K2O/acre at the V5-V6 stage injected

between the rows (30-inch spacing) to a

depth of 3 to 4 inches


Crop and Soil Measurements

• Soil-test K, 6-inch sampling depth

- Initial of low-testing and high-testing plots

- After corn harvest (before soybean) of plots

that didn’t get sidedressed K

• Leaf K concentrations

- Corn ear-leaf blades at R1 stage (silking)

- Top soybean trifoliate leaves at R2-R3

• Grain yield, K concentration and removal


Corn 2017 Leaf K Concentration

SITE 1 - Central Iowa

0 45 90 135 HSTK

Le

af

K C

on

ce

ntr

atio

n (

%)

0.5

1.0

1.5

2.0

2.5

0 K sidedress45 K sidedress

SITE 2 - Southern Iowa

0 45 90 135 HSTK

0.5

1.0

1.5

2.0

2.5



0 45 90 135 HSTK

0.5

1.0

1.5

2.0

2.5


SITE 4 - Northeast Iowa

Broadcast K Rate (lb K2O/acre)

0 45 90 135 HSTK

Le

af

K C

on

ce

ntr

atio

n (

%)

0.5

1.0

1.5

2.0

2.5


SITE 6 - Southwest Iowa


0 45 90 135 HSTK

0.5

1.0

1.5

2.0

2.5


SITE 5 - Northern Iowa


0 45 90 135 HSTK

0.5

1.0

1.5

2.0

2.5


Initial Soil-Test K Very Low

Initial Soil-Test K Low Initial Soil-Test K VL-Low

Initial Soil-Test K Low Initial Soil-Test K Low Initial Soil-Test K Low


Corn 2017 Grain Yield


0 45 90 135 HSTK

Gra

in Y

ield

(bu/a

cre

)

125

150

175

200

225

250

275



0 45 90 135 HSTK

125

150

175

200

225

250

275



0 45 90 135 HSTK

125

150

175

200

225

250

275




0 45 90 135 HSTK

Gra

in Y

ield

(bu/a

cre

)

125

150

175

200

225

250

275




0 45 90 135 HSTK

125

150

175

200

225

250

275


SITE 6 - Southeast Iowa


0 45 90 135 HSTK

125

150

175

200

225

250

275


Initial Soil-Test K Very Low

Initial Soil-Test K Low Initial Soil-Test K VL-Low

Initial Soil-Test K Low Initial Soil-Test K Low Initial Soil-Test K Low


Corn 2018 Leaf K Concentration


0 45 90 135 HSTK

Le

af

K C

on

ce

ntr

atio

n (

%)

0.5

1.0

1.5

2.0

2.5

3.0



0 45 90 135 HSTK

0.5

1.0

1.5

2.0

2.5

3.0



0 45 90 135 HSTK

0.5

1.0

1.5

2.0

2.5

3.0




0 45 90 135 HSTK

Le

af

K C

on

ce

ntr

atio

n (

%)

0.5

1.0

1.5

2.0

2.5

3.0




0 45 90 135 HSTK

0.5

1.0

1.5

2.0

2.5

3.0




0 45 90 135 HSTK

0.5

1.0

1.5

2.0

2.5

3.0


Initial Soil-Test K Very Low Initial Soil-Test K Low-Optimum Initial Soil-Test K Low

Initial Soil-Test K Very LowInitial Soil-Test K Low Initial Soil-Test K Low


Corn 2018 Grain Yield

SITE 7 - Southern IA

0 45 90 135 HSTK

Gra

in Y

ield

(bu/a

cre

)

100

125

150

175

200

225

250



0 45 90 135 HSTK

100

125

150

175

200

225

250


SITE 9 - Northeast IA

0 45 90 135 HSTK

100

125

150

175

200

225

250


SITE 10 - Northern IA

Broadcast K Rate (lb K2O/acre)0 45 90 135 HSTK

Gra

in Y

ield

(bu/a

cre

)

100

125

150

175

200

225

250


SITE 11 - Southeast IA


100

125

150

175

200

225

250


SITE 12 - Southwest IA


100

125

150

175

200

225

250


Initial Soil-Test K Very Low Initial Soil-Test K Low-Optimum Initial Soil-Test K Low

Initial Soil-Test K Very LowInitial Soil-Test K Low Initial Soil-Test K Low


Soybean 2018 Leaf K Concentration


0 45 90 135 HSTK

Lea

f K

Conce

ntr

ation (

%)

0.5

1.0

1.5

2.0

2.5

3.0



0 45 90 135 HSTK

0.5

1.0

1.5

2.0

2.5

3.0



0 45 90 135 HSTK

0.5

1.0

1.5

2.0

2.5

3.0




0 45 90 135 HSTK

Lea

f K

Conce

ntr

ation (

%)

0.5

1.0

1.5

2.0

2.5

3.0




0 45 90 135 HSTK

0.5

1.0

1.5

2.0

2.5

3.0




0 45 90 135 HSTK

0.5

1.0

1.5

2.0

2.5

3.0


Rates Before Previous CornRates Before Previous Corn Rates Before Previous Corn

Rates Before Previous Corn Rates Before Previous Corn Rates Before Previous Corn


Soybean 2018 Grain Yield


0 45 90 135 HSTK

Gra

in Y

ield

(bu

/acre

)

40

45

50

55

60

65

70

75



0 45 90 135 HSTK

40

45

50

55

60

65

70

75



0 45 90 135 HSTK

40

45

50

55

60

65

70

75




0 45 90 135 HSTK

Gra

in Y

ield

(bu

/acre

)

40

45

50

55

60

65

70

75




0 45 90 135 HSTK

40

45

50

55

60

65

70

75


SITE 6 - Southeast Iowa


0 45 90 135 HSTK

40

45

50

55

60

65

70

75





Soybean 2019 Leaf K Concentration


0 45 90 135 HSTK

Le

af

K C

on

ce

ntr

atio

n (

%)

0.5

1.0

1.5

2.0

2.5

3.0



0 45 90 135 HSTK

0.5

1.0

1.5

2.0

2.5

3.0



0 45 90 135 HSTK

0.5

1.0

1.5

2.0

2.5

3.0




0 45 90 135 HSTK

Le

af

K C

on

ce

ntr

atio

n (

%)

0.5

1.0

1.5

2.0

2.5

3.0




0 45 90 135 HSTK

0.5

1.0

1.5

2.0

2.5

3.0




0 45 90 135 HSTK

0.5

1.0

1.5

2.0

2.5

3.0





Soybean 2019 Grain Yield


0 45 90 135 HSTK

Gra

in Y

ield

(b

u/a

cre

)

40

45

50

55

60

65

70

75

80



0 45 90 135 HSTK

40

45

50

55

60

65

70

75

80



0 45 90 135 HSTK

40

45

50

55

60

65

70

75

80




Gra

in Y

ield

(b

u/a

cre

)

40

45

50

55

60

65

70

75

80




40

45

50

55

60

65

70

75

80




40

45

50

55

60

65

70

75

80





Corn Yield, 45-lb Preplant vs Sidedress

2017 - Averages of 6 Sites

Broadcast K Rate (lb K2O/acre)0 45 90 135

Gra

in Y

ield

(b

u/a

cre

)

170

180

190

200

210

220


Broadcast K Rate (lb K2O/acre)0 45 90 135

Gra

in Y

ield

(b

u/a

cre

)170

180

190

200

210

22045 K

2O sidedress

45 K2O sidedress

No K sidedressNo K sidedress


Averages for 2nd-Year Soybean


Broadcast K Rate for 1st-YearCorn (lb K2O/acre)

0 45 90 135

Gra

in Y

ield

(b

u/a

cre

)

50

55

60

65


Broadcast K Rate for 1st-YearCorn (lb K2O/acre)

0 45 90 135

Gra

in Y

ield

(b

u/a

cre

)

50

55

60

65

70

45 K2O sidedress to

corn and soybean

45 K2O sidedress to

corn and soybean

No K sidedress

No K sidedress


Conclusions

• Sidedressing liquid K fertilizer doesn’t

increase corn yield with recommended

preplant broadcast K fertilization rates

- Less efficient than a preplant similar rate

- Good rescue option with insufficient

preplant K

• I doubt will get different results but:

- Different sidedress K rates?

- Dribbling to inter-row or with Y-drop?

- Sidedressing N and K together?


[email protected]

www.agronext.iastate.edu/soilfertility/

THANK YOU

Funding by- Fluid Fertilizer Foundation

- Pioneer (Corteva Agriscience)

In-Kind Contributions- The Andersons (2017)

- Nachurs (2018, 2019)

Download - Effectiveness of Sidedressed Fluid Potassium …...Effectiveness of Sidedressed Fluid Potassium Fertilizer in Corn and Soybean Antonio P. Mallarino Department of Agronomy Iowa State

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