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

Soil and Tissue Analysis for Corn Potassium Management

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

Craig StruveSoil View, 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.

Gerwing, Gelderman and Bly, 2003

Miller 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

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.

STK 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 Plant Analysis

Show

Concentration of Nutrient in Tissue (dry basis)

Gro

wth

as P

erce

nt o

f Max

imum

(%)

80

20

40

60

Deficient zone(symptoms)

Transition zone(symptoms or no symptoms)

Adequate Toxic

Critical ConcentrationDefined by Experimentation

0

Deficiency High Marginal

Modified from Reuter and Robinson, 1997.

Plant nutrient critical ranges

100

Miller et al, 2019

NutrientDeficiency threshold 1 Percent of samples deficient 2

< Less Than 2010 2011 2012 2013 2014 2015

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

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

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

S (%) < 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 threshold 1

Percent of samples deficient 2013 – 2015 2

< Less Than Nebraska Wisconsin Minnesota

N (%) < 2.90 42.9 31.1 40.4

P (%) < 0.30 28.6 24.4 31.5

K (%) < 1.90 32.5 53.8 54.5

S (%) < 0.16 16.7 3.6 11.7

Zn (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 unless you know its cause.

Robert Lustig UCSF, CA

SoilFertility

Grain Yield

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 lb

s/ac

GDD

Corn Yield: 314 bu/ac

Potassium accumulation: Karlen et. al. 1988 1

1 Calculated from: Karlen and Flannery. 1988. Agron J. 80:232-242.

*above ground

68% of Total Uptake

Miller et al, 2019

Total lbs/ac

N 348K 330P 62S 32

-2

0

2

4

6

8

10

12

14

Days After Planting

K lb

s/ac

/day

K UptakePeaks

*above ground

1 Calculated from: Karlen and Flannery. 1988. Agron J. 80:232-242.

Corn potassium accumulation rate 1

www.udel.edu

Miller et al, 2019

lbs/ac/day

N 7 - 8

P 0.9 – 1.1

K 13 – 15

Corn Yield: 314 bu/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

Leached K

Primaryminerals(feldspars, micas)

Soil solution K

Depth of bioavailable K

DissolutionTime 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 K

Soil 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.

KRx Site STK (ppm) 2

0 - 8” 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

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Miller, et al., 2019

KRX Project

KRx project was launched in 2011 to evaluate grain yield response to applied K across the Midwest based on the 4Rs approach, using spoke injection.

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

K Deficiency Winchester, Indiana, 2012 - Dave Taylor

Rates: 0, 50 and 100 lbs K/ac

KRX corn yield response

Site STK Check +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

KRx project results 2012, NE, IA, IL and IN. Applied V3-V5 rate 50 lbs K / ac

Check

+ K

K effect on ear size

K increased yield on a soil STK > 300 ppm ?

134

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

Miller et al, 2019

KRX STK vs corn yield – five years

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

Probability of yield response

A K application1 improved grain yield at 33 of 82 locations over 5 years.

Yield increase8 - 33 bu/ac

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

Drought sites, yield < 140 bu/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 increase in leaf K with an application1 of 100 lbs/ac K side dressed at GS V3-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 soil test K influence yield? Ear leaf K?

Does ear leaf K impact yield?

Due Soil factors (pH, SOM. CEC etc.) effect leaf K nutrition?

STK vs corn yield

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Miller et al, 2019

2011-2015, 82 site studies were conducted in grower corn fields across 8 states. Check plot data: soil (pH, P, K, Ca, Mg, SOM, CEC - 0-8”); ear leaf R1-R2 nutrients1; population, grain yield; replicated. 2016 - 2019, 116 observation sites were added. Cluster analysis and regression modeling.

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

KRX Research database

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

Minimum Maximum

pH 4.9 7.6STK ppm 71 605SOM % 1.1 5.4CEC cmo/kg 2.6 32.0

15 ft

40 ft

Check plot diagramFour per site

Ear LeafTissuen = 30

Grain HarvestArea

1 Data 2016-2019 sites, eight states.

Miller et al, 2019

2014, 16 observation sites, 5 states. Data collected on STK, ear leaf nutrients and yield, STK sorted low to high.

1 Cluster analysis contrasting five lowest sites and five highest sites for Mehlich 3 K 0-8” response variable grain yield, 8 reps per site.

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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 whisker plot STK cluster1 comparisonsvariable grain yield, 3 years.

1 Cluster analysis contrasting five lowest sites and highest sites for Mehlich 3 STK 0-8” in response variable grain yield.

160mg kg-1

231mg kg-1

2013 Soil STK2012 Soil STK

130mg kg-1

350mg kg-1

Cluster analysis: STK and grain yield

2016 Soil 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 analysis: STK vs ear leaf K Box whisker plot soil STK cluster1 comparisons forvariable ear leaf K for three years.

1 Cluster analysis contrasting five lowest sites and highest sites for Mehlich 3 K 0-8” response variable corn ear leaf K R1-R2.

102mg kg-1

342mg kg-1

2016 Soil STK

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2011 Soil STK

134mg kg-1

331mg kg-1

111mg kg-1

182mg kg-1

2014 Soil 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 leaf nutrients cluster analysis

Box whisker plot nutrient cluster1 comparisonsVariable grain yield – 2014, 16 sites, cluster size 5 sites each

1 Cluster analysis based on five lowest sites and highest sites for each test parameter (Leaf N, K and K:Mg), response variable grain yield, 8 reps per site.

Leaf K

1.60 %

2.17%

Leaf N

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2.52%

3.30%

Leaf 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 Data: Betsey Bower Ceres Solutions, IN, 2011 ear leaf GS R1-R2, 851 samples, data sorted by K, uncertainty K ± 0.05%.

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

K deficiencies during stalk development results in supra–optimal ear leaf Mg and a low K:Mg ratio, < 8, normal is 10 - 14.

K:Mg ratios concur with those of Elwali et al. (1985) Agron J. for corn in the southeastern US and decreased grain yields.

Miller et al, 2019

Year Mean Ear Leaf Low K cluster 1

Mean Ear Leaf High K cluster

K % K:Mg K % K:Mg

2011 1.77 * 5.9 * 2.64 11.1

2012 1.52 3.2 * 1.91 6.7

2013 1.67 3.0 * 1.95 8.3

2014 1.60 * 4.8 * 2.17 10.2

2015 - - - -

2016 2 1.47 * 3.6 * 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 leaf K cluster analysis131 sites, 2011 – 2016 cluster mean comparisons

45.2 Five year 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 Difference

Bu/ac

40.5

58.2 *

34.6

49.5 *

-

44.1 *

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 analysis soil properties 2016Box whisker plot soil test parameters1 comparisonsVariable ear leaf K, cluster size - 8 sites each

1 Cluster analysis contrasting eight lowest sites and highest sites for soil variables 0-8” depth, response variable ear leaf K R1-R2. (CEC by summation).

2.01 % 4.53 %

SOM-LOI 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 Sat. cluster analysis

Variable1 Soil K Base Saturation (%)

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. cluster comparisons - 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 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 Sat. Ranges 2016

Soil K Base Sat. 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 corn K availability, K Base Sat is a 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, 2019

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

Yield difference 28.1 bu/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 - nutritionEar leaf K < 2.0 % and K:Mg < 8, K deficient. Track four grid points/field, assess Mgt.

Stalk analysisStalk K < 1.5%, corn K deficiency.

SoilFertility

Grain Yield

CornNutrition

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 GS V5-V10 will decrease K diffusion > 80%, facilitating Mg uptake.

Soil Analysis

K Base< 2.5%

No Yes

High Probability of Leaf K

Deficiency

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

- Broadcast and incorporation, required.

- Deep banding, 2x2, 2x4 at 50-100 lbs K/ac.

- Side dress shallow banding, 50 lbs K/ac

- Irrigation, 10-15 lbs K /ac per circle, GS V4-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, Students and Staff who have assisted with this project.

Research continues in 2020

Miller et al, 2019

Sponsors

Mike Lindaman, LGI Lab, IA retiredTom McGraw, MISS, MN retiredBetsey Bower, Ceres Solutions, INLarry May, Lincoln, NERandy Brown, Winfield United, NEGreg Binford, Wilbur Ellis, INJodi Jaynes, Sure-Tech Laboratories, INNick Koshnick, Climate Corp, CADave Mowers, Consulting, ILRobert Beck, Winfield United, IL retiredTommy Roach, Nachurs, TXTim Eyrich, Agri-Trend, SCRay McDonald, Can Grow, ONScott Fleming, Rock River Labs, WI

Acknowledgements

Thank you for your time and attention

E-mail:rmiller@colostate.edu