http://gmoanswers.com/sites/default/files/corntatt.jpg/

Soil and Tissue Analysis for Corn Potassium Management

Robert O. Miller Tim m J. Smith Colorado State University Fort Collins, CO Crop Smith Inc. Monticello, IL

Craig g StruveSoil

gil il View

ggwww, gww,w Paulina, IA

South Dakota Agronomy Conference Sioux Falls, SD December 11, 2019

My background

5th Generation farm family in eastern Nebraska – 500 acres corn and soybeans

Affiliate Professor Colorado State University. - Extension Soil Specialist UC Davis - Ph.D. Montana State University

Direct the Agricultural Laboratory Proficiency (ALP) Program, 138 labs. Conduct Regional Research in Soil Sampling, Soil Fertility, Lab Analysis and Crop Nutrition.

Miller, 2010

Nutrient management

Miller, 2011

An evaluation of nutrient availability based on the probability of crop yield response utilizing a laboratory chemical extraction. It has little to do with total nutrient uptake or crop requirement.

Soil

Soil testing

Tissue testingIs an assessment of leaf/plant nutrient concentration based on a standard norm and historical observations.

Gerwingng, Gelderman and Bly, 2003

Miller, 2011Miller et al, 2019

Overview

• Potassium trends: soil and tissue

• Corn K nutrition

• Field K studies

• STK, ear leaf K and Yield

• Fertility management

Miller et al, 2019

Changes in STK North America

Observations

http:////soiltest.ipni.net/maps/Median

Miller et al, 2019

sssssssObsssssssssssssssssbssssssssssssssssssssssssssssssssssssssss rververververververerererererrrererrererrereeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee atiatiatiatiatitiiatiiiiiiiiiiationsonsonsonsonsonsssssssssssssssssonsssooooooooooooooooooooooooooo

US Maize ProductionSoil test K – South Dakota

Miller et al, 2019

0

100

200

300

400

500

600

700

800

900

25 75 125 175 225 275 325 375 425 475 525

Freq

uenc

y

Soil Test K (ppm)

1 Source: Ag Lab Express, Sioux Falls, SD, 2019, 8740 samples.

ppm %

<< 90 1.3<< 120 11.2<< 150 36.8<< 175 62.4>> 200 20.1

One third of sites have high probability of K response, based on LGU recommendations.

What Does What Does Plant Analysis ant Analy

Show

Concentration of Nutrient in Tissue (dry basis)

Grow

th a

s Per

cent

of M

axim

um (%

)

80

20

40

60

Deficient zoneDeficient zone(symptoms)

Transition zoneTransition zone(symptoms or (symptoms or no symptoms)

Adequate Toxic

Critical ConcentrationCritical ConcentrationDefined by Experimentation

0

Deficiency High Marginal

Modified from Reuter and Robinson, 1997.

Plant nutrient critical ranges

100

Miller et al, 2019

NutrientDeficiency Deficiencthreshold

cycy d d 1 Percent of samples deficient t 2

< Less Than 2010 2011 2012 2013 2014 2015

N N (%) < 2.90 9.7 8.9 41.3 18.0 23.6 51.4

P P (%) < 0.30 8.3 12.1 49.2 15.3 8.1 36.5

K K (%) < 1.90 41.5 30.8 67.0 32.0 36.2 16.7

SS (%) < 0.16 0.5 0.2 8.1 2.4 3.7 30.1

1 Critical Nutrient level based on: https://www.extension.purdue.edu/extmedia/AY/AY-9-32.pdf Extension Bulletin E-2567 (New), July 1995

Ear leaf R1-R2, 3670 samples, six years

2 Corn ear leaf GS R1-R2.

37.4 %

25.5 %

Six year Average

Source: Betsy Bower, Ceres Solutions, Lafayette, IN

Corn nutrient deficiencies - Indiana

Miller et al, 2019

NutrientDeficiency Deficiencthreshold

cycy d d 1

Percent of samples deficient nt of sam2013

sam3 3 –

ples dempm– 2015 5 5 2

< Less Than Nebraska Wisconsin Minnesota

N N (%) < 2.90 42.9 31.1 40.4

P P (%) < 0.30 28.6 24.4 31.5

K K (%) < 1.90 32.5 53.8 54.5

SS (%) < 0.16 16.7 3.6 11.7

Zn n (ppm) < 20 49.3 7.0 51.1

1 Critical Nutrient level based on: https://www.extension.purdue.edu/extmedia/AY/AY-9-32.pdf Extension Bulletin E-2567 (New), July 1995

Ear leaf R1-R2, 25,432 samples, three years, upper Midwest

2 Corn leaf GS R1-R2.

46.9 %

38.1 %

Three year Average

Corn nutrient deficiencies

Miller et al, 2019

Corn K fertility

You can’t resolve a problem You can t resolve a problemunless you know its cause

mlemsese.

Robert t t Lustigigig UCSF, CA

SoilSoilFertility

Grain Grain Yield

Corn

S

CornNutrition

Root Cause Analysis

Miller et al, 2019

Plant potassium nutrition

Crop Demand Soil Supply

• Plant Nutrition

• Phenology of Uptake

• Plant Population

• Soil Chemistry

• Nutrient Transport

• Stratification

Miller et al, 2019

0

50

100

150

200

250

300

350

K

K lb

sbsb/a

c

GDD

Corn Yield: d: 314 4 buubu/ac

Potassium accumulation: Karlen et. al. 1988 1

11 Calculated from: m: Karlen and d Flannery. 1988. . Agronn J. 80:23232-2-242.

*above ground

68% of Total 68% of TotaUptake

Miller et al, 2019

Total Tolbsotal otalbsbs/ac

N 348K 330P 62S 32

-2

0

2

4

6

8

10

12

14

Days After Planting

K

K lb

sbsb/a

c/da

y

K UptakeK UptakePeaks

*above ground

11 Calculated from: m: Karlen and d Flannery. 1988. . Agronn J. 80:23232-2-242.

Corn potassium accumulation rate 1

www.udel.edu

Miller et al, 2019

lbsbs/ac/day

N 7 - 8

P 0.9 – 1.1

K 13 – 15

pCorn Yield: d: 314 4 buubu/ac

Population and soil rooting volume

1988 root soil volume per plant

24,000 plts/ac

2019 root soil volume per plant

34,000 plts/acIncreasing plant population from 24,000 plts/ac to 34,000 plts/ac results in:

- a 30% decrease in soil rooting volume per plant1.

- an increase in total corn K uptake of 60-80 lbs/ac.

Thus higher population requires 42% more K from a 30%smaller soil rooting volume.

Impact of Population over 30 years

1 Based on data Doberman et al, 2003. Miller et al, 2019

Plant potassium nutrition

Crop Demand Soil Supply

• Plant Nutrition

• Plant Population

• Phenology of Uptake

• Soil Chemistry

• Nutrient Transport

• Stratification

Miller et al, 2019

Non-harvested K Plant K

Interlayer KExchangeable K

Soil surface

ant K

Leached K

Primaryminerals(feldspars, micas)

Soil solution K

Depth of bioavailable K

Dissolution

Exchangeable KSoil solution K

Time scale: a cropping seasonSpatial scale: cumulative rhizosphere

volume for a crop(rooting zone)

K losserosion

runoff

Harvested K

Plant-available K

http://www.ipni.net/article/IPNI-3396 (modified)

Added KSoil root zone K transport

Root Interception

Mass Flow

Diffusion

Direct root contact with soil K, 1-2% of total uptake.

Soil solution K acquired through mass flow of soil water to plant root, 10-20% of total.

K movement down the concentration gradient from bulk soil to root surface, explains 70-80% of uptake. Decreases with lower soil moisture.

1 Jungk and Claassen, 1986. Z. Pflanzenernaehr. Bodenk

http://plantsinaction.science.uq.edu.au/sites/plantsinaction.science.uq.edu.au/files/4.1-Ch-Fig-4.3.png

Miller et al, 2019

STK root zone stratification

Miller, 2015

Decreased tillage has resulted in consistent STK stratification at surface, 96% of sites.

Standard soil sampling, provides no information on root zone K stratification.

0-2” 242

2-4” 126

4-6” 78

6-8” 48

8-12” 32

FRI-15 Depth STK (ppm)

1 Source: KRx research site Hubbard, IA, 2014.

KRxx Site STKK (ppm) ) 2

0 00 -- 8” 2 2 -- 8”

Monroe, SD 224 136

O’Neil, NE 84 60

Pipestone, MN 182 982 KRx research sites 2016-2019, limited tillage.

Miller et al, 2019

Impact on corn K nutrition

Miller, 2015

A corn plant population of 34,000 with a yield goal of 250 bu/ac will have a K uptake1 of 280 lbs/ac, of which 190 lbs is accumulated during GS V4-V12.

Thus soil K diffusion (estimated 80%) must provide a max 7 - 9 lbs/ac/day from a stratified root zone. Limited soil moisture reduces K diffusion, and uptake.

2 Calculation based on data of Karlen et al (1987) and estimates of soil diffusive supply.

-2

0

2

4

6

8

10

12

14

Miller et al, 2019

Miller, et al., 2019

KRRRX X Project

KRxx project was launched in 2011 KKKRxx project was launched in 2011 pto evaluate grain yield response to ttto evaluate grain yiapplied K across

eld responsen yiss the Midwest

e to nsestst based on aaapplied K

the 4Rs acrosss he Midwesth st nased onbad K

ss approach, using spoke injection.

Assess STK, ear leaf nutrient and K AAAssess STK, ear leaf nufertilizer on grain yield.

K Deficiency Winchester, Indiana, 2012 2 -- Dave Taylor

Rates: 0, 50 and 100 0 lbss K/ac

KRRRX X corn yield response

Site STK Check +K K 1 IncreaseCty / State ppm bu/ac

Merrick, NE 151 169 170 + 1Cherokee, IA 290 218 227 +9Piatt, IL 305 141 154 + 13*Sullivan, IN 116 94 110 + 16*Warsaw, IN 198 73 67 - 6

KRKRxx project results 2012, NE, IA, IL and jpIN. Applied V3V3V3-

,33-V5 rate 50

,0 0 lbs

,,ss K / ac

Check

+ K

K effect on ear size

K increased yield on a K increased yieldsoil STK > 300

d on a yield0 0 ppm ?

134

1641 Yield significant at the 0.10 level, corn 15.5% moisture.

Miller et al, 2019

KRRRX X STK vs s corn yield d –– five years

STK 75 to 150 - 56% STK 150 to 200 0 0 - 50%STK 200 to 300 0 0 - 36%STK 300 to 600 0 0 - 14%

Probability of yield response

A K applicationn11 improved grain yield A K aat A K a

t t 33 appa3 333 of

ationn mproved grain yieliiplicapf fofof 82 locations over 5 years.

Yield d increaseYield8

Yield8 8 -

deldd-- 33

crin33 bu

sereacruububu/ac

1 Yield increase to side dress application of 50 lbs/ac K at V3-V5.

Drought ht sites, s, yield < 140 0 buubu/ac-15

-10

-5

0

5

10

15

20

25

30

35

40

0 100 200 300 400 500 600

Incr

ease

d Yi

eld

(bu/

ac)

STK (ppm)

20112012201320142015

Miller et al, 2019

Impact of applied K on ear leaf K

Number of sites where ear leaves shown a significant Number of sites where ear leaves showincrease in leaf K with an applicationnn1

wn a signow11 of 100

sign0 0 lbs

cant nificnbsbsbb /ac K increase in leaf K with an

side dressed at GS V3h anV3V3-

appn an33-V4.

1 K applied as KCl, KSO4 ,or K acetate using spoke wheel applicator, 3 inches off row at 3 inch depth.

90% of sites show no increase of ear leaf K with applied K fertilizer.

Question did fertilizer correct a corn K deficiency?

Year SitesNumber of sites

with an increase of ear leaf K from fertilizer

2011 24 1 2012 22 3 2013 18 2

2014 16 2

2015 8 0

Miller et al, 2019

Questions

Does s soil l test K K influence yield? Ear r leaf f K?

Does s ear leaf K impact yield?

Due e Soil factors ( (pH, SOM. . CEC etc.) effect leaf f K nutritionn?

STK vs corn yield

ww

w.h

ear.o

rg/s

tarr

/imag

es/im

age/

?q=0

8091

4-99

18&

o=pl

ants

Miller et al, 2019

20111-1-2015, 5, 82 2 site studies were conducted in 20111 015202 5, 2822 te studies wsigrower corn fields across

es wss 8

ere condwes w88 states.

ducted in ondCheck plot grower c

data: cornwer c

:: soil cornilil (

fields acrossn orn((pH, P, K, Ca,

88 tates.stsss 8a,a Mg, SOM

heckCs.MM, CEC

eckCC -

ck- 0k k0000-

ot lopl0000-8”);

t ); ); ear data

leaf ta:

afaf R1so11RR -

loisoi11-R2

H, P, K, C( HpHp22 nutrients

,ss1 Css11;

Mg, SOMMaa, C;; population

CEC, C C 0000 )88 );OMM,ononn, grain yield; leaaf R1R1 2RR2 utrientnu

replicated. 2016 ent66 -

s ; opulatiopo on grain yield; , gsssnt- 2019, 116 observation sites were replicated. 2016

added. Cluster 2019, 116 observation sites were22166

r r analysis and regression modelingewere

gg.

Sites diverse in soil types, properties, hybrids, Sites diverse in soil types, properties, hybrids, management, crop history, irrigation and weather.

KKRX Research database

1 Lab Analysis: Ward Labs, LGI, Solum Laboratory and Sure Tech Labs.

Minimum Maximum

pH 4.9 7.6pSTK K K ppm 71 605ppp

SOM M MM % 1.1 5.4CEC C C cmoo/kg 2.6 32.0

15 5 ft

40 0 ft

Check plot diagramheck plot diagraFour per site

Ear LeafEar LeafTissueTissueTissuen = 30

Grain Harvestain HarveArea

1 Data 2016-2019 sites, eight states.

Miller et al, 2019

2014, 16 6 observation sites, s, 5 5 states. Data collected on n STK, K, ear 2014, 166 bservation sitesobleaf nutrients and yield,

ss, 55 tates. Dstites, STK sorted

Data cos. Ddd low to

ollectea cooo high.

1 1 Cluster analysis contrasting five lowest sites and five highest sites for Cluster aCMehlich

analyer ahh 3 K

nalyKK 0

aly00-

siysly00----8”

contrasting five lowes ci ”” response variable

est sites and five highest sitowee e grain yield, 8 reps per site.

ww

w.h

ear.o

rg/s

tarr

/imag

es/im

age/

?q=0

8091

4-99

18&

o=pl

antsCluster analysis: STK vs grain yield

STK (ppm) Yield (bu/ac)90 161

100 234116 222122 162126 208128 131139 174141 183146 182151 188158 187163 128186 199187 237187 219189 235

Lowest

Highest

STK Yield

Mean 111 197Stdev 16 34

STK Yield

Mean 182 204Stdev 11 45

STK Cluster

1 2

Yiel

d (b

u/ac

)

120

140

160

180

200

220

240

260

Low High

111mg kg-1

182mg kg-1

2014 Soil STK

Box Whisker Plot

mean

10th perc

90th perc

median

75th perc

25th perc

Miller et al, 2019

STK Cluster

1 2

Yie

ld (b

u/ac

)

160

180

200

220

240

260

280

300

Low High

STK Cluster

1 2

Yie

ld (b

u/ac

)

100

120

140

160

180

200

220

240

260

Low High

STK Cluster

1 2

Yie

ld (b

u/ac

)

80

100

120

140

160

180

200

220

240

260

Low High

Box x whisker r plot STK clusterer1r1 comparisonsBoxx whiskewvariable

er pliskee e grain

t STK clusteerrlotpln nn yield, 3 years.

1 1 Cluster analysis contrasting five lowest sites and d highest sites Cfor

ster anaClusCr r Mehlich

alysis coanahh 3 STK

s coKK 0

co00-

tno00--8”

sting five lowest sites andrast”” in response variable grain

ghesthindd hn n yield.

160mg kg-1

231mg kg-1

2013 3 Soil il STK2012 Soil il STK

130mg kg-1

350mg kg-1

Cluster r analysis: STK and grain yield

2016 6 Soil il STK

102mg kg-1

342mg kg-1

Miller et al, 2019

Soil STK Cluster1 2

Leaf

K (%

)

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

Low High

Soil STK Cluster1 2

Leaf

K (%

)

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

Low High

Soil STK Cluster1 2

Leaf

K (%

)

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

Low High

Cluster r analysis: : STK vs s ear leaf f K Box x whisker r plot soil il STK K clusterer1r1 comparisons forBoxx whiskew r lot soipl il TKSTK lustecl err cccvariable ear leaf K for three years.

1 1 Cluster analysis contrasting five lowest sites and highest sites for Cluster aCMehlich

analyer ahh 3 K

nalyKK 0

aly00-

siysly00--8”

contrasting five lowest sites and higs ci”8” response variable corn ear leaf K

d higK K R1

gheg11RR -

st sitesghe11-R2.

102mg kg-1

342mg kg-1

2016 Soil il STK

ww

w.h

ear.o

rg/s

tarr

/imag

es/im

age/

?q=0

8091

4-99

18&

o=pl

ants

2011 Soil il STK

134mg kg-1

331mg kg-1

111mg kg-1

182mg kg-1

2014 Soil il STK

Miller et al, 2019

Leaf N Cluster1 2

Yie

ld (b

u/ac

)

120

140

160

180

200

220

240

260

Low High

Leaf K Cluster

1 2

Yie

ld (b

u/ac

)

120

140

160

180

200

220

240

260

Low High

2014 Ear r leaf nutrients cluster analysis

Box x whisker r plot nutrient clusterer1r1 comparisonspVariable grain yield d d –

p– 2014, 16 sites, cluster size 5 sites each

1 1 Cluster analysis based on five lowest sites and d highest sites s for each test Cluster analysis based on Cparameter (Leaf N, K and

five loon d d K:Mg

ve loMgMg),

west sites aowlo), ) response

andd ghest sitehies aee variable grain

ess or each test fositen n yield, 8 reps per site.

Leaf K

1.60 %

2.17%

Leaf N

ww

w.h

ear.o

rg/s

tarr

/imag

es/im

age/

?q=0

8091

4-99

18&

o=pl

ants

2.52%

3.30%

Leaf f K:Mg

0.22 %

0.38 %

Leaf K:Mg Ratio Clusters

1 2

Yie

ld (b

u/ac

)

120

140

160

180

200

220

240

Low High

4.3 11.1

Miller et al, 2019

R² = 0.992

0.00

0.10

0.20

0.30

0.40

0.50

1.0 1.5 2.0 2.5 3.0

Mea

n Ea

r Lea

f Mg

(%)

Ear Leaf K (%) 1

Stdev

Corn ear leaf K vs Mg

1 1 Data: Betsey Bower Ceres Solutions, IN, N, 2011 1 ear leaf af GS DR1

DR1R1-

a: BetaDatD11--R2,

etsey: Be2, 2 851

y Bower Ceres tsey11 samples, data

Solutions, INN, 01120 1 ar leaeares a a sorted by K, uncertainty K

leaK K ±

SGf aaf±± 0.05

S0505%.

An extensive six year survey of Midwest corn An extensive six year survey of Midwest coear leaves shows as ear leaf K decreases ear leaves shows as ear leaf K decreabelow 2.0 %, ear leaf Mg increases below 2.0 %, eaexponentially.

K deficiencies during stalk development K deficiencies durresults in supra

durrara–

ng stalk development riduraa–optimal ear leaf Mg and a results in suprraa ptimal ear leaf Mopo

low K:Mg ratio, < 8, normal is 10 f M0 0 -

g andMgM-- 14.

K:Mg ratios concur with those of of Elwalili et al. K:Mg rati(1985)

ios conrati5)5) Agron

ncur with those oof waEl li t al. econnn J. for corn in the southeastern (19855) gronAg n . for corn in the soJ.

US and decreased grain yields.

Miller et al, 2019

Year Mean Ear Leaf Mean Ear Leaf Low K cluster r r 1

Mean Ear Leaf Mean Ear Leaf High K cluster

K % K:Mg K % K:Mg

2011 1.77 7 * 5.9 9 * 2.64 11.1

2012 1.52 3.2 2 * 1.91 6.7

2013 1.67 3.0 0 * 1.95 8.3

2014 1.60 0 * 4.8 8 * 2.17 10.2

2015 - - - -

2016 6 2 1.47 7 * 3.6 6 * 2.93 14.21 Check plot clusters comparisons five sites in 2011, 2012 and 2014; four in 2013; and eight 2016. Insufficient data 2015, five sites. * values are significant at the 0.05 level.

Summary: Ear r leaf f K K K cluster analysis131 siteses, 2011 1 –– 2016 cluster mean comparisons

45.2 Five year r average

Cluster comparisons show mean leaf K and K:Mg ratios are different.

Cluster yield differences were consistent.

2 2016 Data based on 46 sites, seven states.

Yield YieldDifference

Bu/ac

40.5

58.2 2 *

34.6

49.5 5 *

-

44.1 1 *

Miller et al, 2019

Soil SOM-LOI1 2

Leaf

K (%

)

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

Low HighSoil CEC

1 2

Leaf

K (%

)

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

Low High

Soil K Base Sat.1 2

Leaf

K (%

)

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

Low High

Cluster r analysis soil properties s 2016Box x whisker r plot soil test parameterss1s1 comparisonsBoxx whiskew r lot soilplVariable ear leaf K,

l test pasoilK,K cluster

aramepar r size

ameee -

tersss comparccetme- 8 sites each

1 1 Cluster analysis contrasting eight lowest sites and highest sites for soil variables 0000-

luCC000-8”

ter analysis contrasting eight lowest siteustlu”” depth, response variable ear leaf K R1

siteR1R1-

s and highest sites for soil esite11-R2. (CEC by summation).

2.01 % 4.53 %

SOMM-M-LOI I 2 CEC

8.0cmol kg-1

24.6cmol kg-1

K Base Sat.

1.2 % 6.8 %

http://corn.agronomy.w

isc.edu/Managem

ent/L011.aspx

2 Regression of CEC = 5.6 x (SOM-LOI) - 1.0, R2 0.864

mean meanmean meanmean mean

Miller et al, 2019

Soil K Base e Sat. cluster analysis

Variablee1 Soil K Base Saturation n (%)

Low Cluster High Cluster

Mean Mean

K Base Sat (%) 1.2 6.8 *

CEC (cmol kg-1) 23.4 11.7 *SOM (%) 4.28 2.40 *Soil K:Mg (meq) 0.05 0.43 *

K Base Sat.t. cluster r comparisons s -- 2016 Sites

1 Forty-six sites across seven states, K base sat cluster size eight sites each.2 * Mean values are significant at the 0.05 level.

Leaf K (%) 1.50 2.62 *Leaf K:Mg 4.6 13.2 *Stalk K (%) 0.97 2.51 *

Grain (bu/ac) 202 240

Cluster analysis of soil K Base Sat. shows significant differences for soil CEC, SOM, K:Mg ratio.

Low soil K Base Sat. was associated with low leaf K, low K:Mg, low stalk K and lower grain yields.

Grain yield, although associated with higher leaf K, is a function of factors impacting grain fill (moisture, N, Pest, Temp etc).

http://extension.missouri.edu/explore/im

ages/ipm1007crabgrasslarge01.jpg

Miller et al, 2019

Soil K Base e Sat. vs STK

Soils with STK of 190 ppm with a CEC > 30 cmol/kg are highly probable to have ear leaf K deficiency, < 2 %.

Whereas, soils with 90 ppm K with CEC of 5-6 cmol/kg have low probability of ear leaf K deficient, < 2 %.

< 1.5% 1.5 – 2.0%2.0 – 3.0%

3.0 – 5.0%

> 5.0%

1 2016, 46 field sites, each K base sat range represent 7-9 observations sites, soil sample 0-8” depth collected spring 2016, ear leaves collected at GS R1-R2.

Miller et al, 2019

Soil K Base e Sat. Ranges 2016

Soil K Base Soil K BaseSat. Range Parameter

(%) Percent of ear leaves < 2.0% K

Average grain Yield (bu/ac)

< 1.5 100 % 2051.5 – 2.0 70 % 2222.0 – 3.0 54 % 2363.0 – 5.0 33 % 244

> 5.0 12 % 2451 2016, 46 field sites, each K base sat range represent 7-9 observations sites, soil sample 0-8” depth collected spring 2016, ear leaves collected at GS R1-R2.

Cluster analysis of soil K Base Sat. shows significant impact on ear leaf K concentration and average grain yield.

Note data is diverse as it represents 46 observations collected across seven states ranging in soil types, weather, management and hybrids.

Miller et al, 2019

STK does not address s corn K availability, K Base Sat is a y,better estimator.

Soil K Base Saturation 2017

TestParameter

STK (ppm)

CEC (cmol/kg)

K Base Sat (%)

Leaf N (%)

Leaf K (%)

Leaf K:Mg

Stalk K (%)

Yield (bu/ac)

KRx Data 2017: Each site four replications, ear leaf samples collected R1-R2. Plant populations and corn maturity identical. All parameters except leaf N significantly different at 0.05 level.

Miller et al, l, 2019

Leaf K:Mg ratio and stalk K are ghighly associated with K base g ysaturation. Kana site ear leaf K < 2.0% and K:Mg < 8.0.

Yield difference e 28.11 bubu/ac

O’ NeilNebraska

682.66.82.452.5416.1 1.48

248.3

SteenMinnesota

161 32.2 1.22.381.482.7 0.42

220.2

Management tools

Soil analysis Assess K Base Sat: < 2.0 %; K:Mg < 0.12

Tissue analysis s -- nutritionEar leaf K < 2.0 % and K:Mg < 8, K deficient. Ear leaf Track

f K <eaf k k four

< 2.0 % and K:Mg < 8, K deficieK <rr grid points/field, assess Mgt.

Stalk analysisStalk K < 1.5%, corn K deficiency.

SoilSoilFertility

Grain GrainYield

CornCornNutrition

Root Cause Analysis

Miller et al, 2019

Ag Lab Express data, Sioux Falls, SD, of 8740 samples in 2019 indicates KBase < 2.0 % occurred on 59 % of soils tested.

Corn potassium nutrition

Drivers of crop K demand

Factors limiting soil K supply

Higher plant populations

Increased nitrogen fertility

High air temperatures, during V4-R1, mean daily > 85F

Low soil K Base Sat.

Low sub soil STK, 2-8”

Limited soil moisture, > 2 bar, ET > Precip.

Miller et al, 2019

A 50% soil moisture deficit during A 50% sGS V5

% sV5V5-

oil moisture deficit duo% s55--V10 will decrease K

ring duKK diffusion GS V

> 805 10 will decrVVS VV55

8080%, facilitating reasecr

g g Mg se KK ffudieas

g g uptake.

Soil Analysis

K BaseK Base< 2.5%

No Yes

High Probability gh Probabilityof Leaf K of Leaf K

Deficiency

- Avoid K surface broadcast on no till. Not effective.

- Broadcast and incorporation, required.

- Deep banding, 2x2, 2x4 at 5050-0-100 0 lbss K/ac.

- Side dress shallow banding, 50 0 lbss K/ac

- Irrigation, 100-0-15 5 lbss K /ac per circle, GS V4V4-4-V12.

Annually assess ear leaf nutrition and fertilizer effectiveness with tissue testing, four grid points per field.

Cost < $0.60/ac for a 160 ac field

Fertility recommendations

Miller et al, 2019

Thanks to our Grower Cooperators, p ,Students and Staff who have assisted with this project.

Research Researchcontinues in 2020

Miller et al, 2019

Sponsors

Mike e Lindaman, n, LGI GI Lab, b, IA retiredTom

,m mm McGraw, MISS, S,S MN

,N NN retired, ,

Betsey Bower, Ceres Solutions, INyLarry

,yy y May, Lincoln, NEyy y, ,

Randy Brown, Winfield d d United, d, NEy , ,Greg Binford, Wilbur Ellis, INgJodi

,gdi di Jaynes, Surerere-

,ee-Tech Laboratories, IN

Nick y ,

k k Koshnick, k, k Climate Corp, p, p CA, pp,Dave Mowers, Consulting, ILRobert

,rt rt Beck, Winfield

g,d d United, IL retired

Tommy ,

y y Roach, h, h Nachurs,

rsrsrs, TXyyTim Eyrich,

,h, h Agri

,grgr -

,riri-ii Trend, SCy

Ray y , ggg ,y

y y McDonald, Can Grow, ONyy , ,Scott Fleming, Rock River Labs, WI

Acknowledgements

Thank you for your time nk you for your tand attention

EE-E-mail:EE mail:mmrmiller@colostate.edu