K Nutrition in the NGP

8/8/2019 K Nutrition in the NGP

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Potassium Nutrition in theNorthern Great Plains


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Photo courtesy of Lyle Cowell, SWP

Outline: Potassium (K)Nutrition in the NorthernGreat Plains

Role of K in crop production

Soil K and soil test levels

Crop uptake of K

K deficiencies

Crop responses to K

Chloride (Cl) response

Fertilizer K


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What Is the Role of Kin Plants?

K activates enzyme reactions K controls water uptake and transpiration

K influences energy production in photosynthesis andrespiration

K supports photosynthate transport K fosters nitrate-nitrogen (N) uptake and protein

synthesis

K is required for starch synthesis in seeds


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Soil Water

K+

K+K+

K+

K+ K+ K+K+

K+ K+ K+K+Trapped K

K

K K

K

Soil Minerals(feldspar, mica)

SoilColloid

Soil Colloid

Soil Colloid

K

Unavailable (90 to 98%)

Slowly available (1 to 10%)

Readily

available

(0.1 to

2%)

Soil K


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Soil Testing Methodsfor K

Most soil tests for K are based on either an ammoniumacetate extraction or a similar extraction

In some regions with low CEC soils, K rates are oftenbased on the ratio of K relative to other bases, such as

Ca and Mg Ion exchange membranes which measure the soilsupply rate of K


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Median Ammonium AcetateEquivalent Soil Test K Levels,2005


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Median Ammonium AcetateEquivalent Soil Test KLevels, 2005

2005

ND

SK MBAB

MT

207

259 265

201

254

North American-wide

154 ppm


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K Deficient Areas onCanadian Prairies

May be deficient in K

May need K for irrigated crops


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Potassium Soil Test Ratingand Recommendations

Yield Soil test K, ppm

bu/A 0-40 41-80 81-120 121-160 161-200 201-250 251-750 +750

Fertilizer K recommendation, lb K2O/A

30 35 30 20 10 10 10 10 0

40 50 40 30 15 10 10 10 0

50 65 50 35 20 10 10 10 0

60 75 60 40 25 10 10 10 0

70 90 70 50 30 10 10 10 0

Wheat K2O recommendations using band application (Agvise Labs)

- Soil test recommendations vary among labs.

- Most labs use a set of regional crop response data to develop

fertilizer recommendations based on a K soil test. An example:

Wh t A th K


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What Are the KRequirements of Cropsthroughout the Season?

Photo courtesy of Lyle Cowell


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K Uptake of Wheat Duringthe Growing Season

Jacobsen et al., 1992 (graphic from Korb et al., 2002)


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Crop Uptake of K

K uptake in

Crop Yield/A total crop, lb K2O/A

Wheat 40 bu 80 (19)*

Canola 35 bu 89 (20)Peas 50 bu 150 (39)

Barley silage 4.5 tons 132

Alfalfa 3 tons 180

*K removed in grain in parenthesis.


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Potassium DeficiencySymptoms in Barley

11

38

49

58

0 60 120 2400

10

20

30

40

50

60

Barley

grainyield

,bu/A

K2O rate in lb/A

i d i h


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Potassium Budget in theNorthern Great PlainsRegion, 2000-2001

-544-5571352609North Dakota

-301-310942352Montana

-195-2404592332Manitoba

-538-5814359640Saskatchewan

-343-479136128607Alberta

--------------------- K2O, million lb ---------------------

F+M-RF-R(M)(F)(R)

BalanceRecoverable

Manure

Fertilizer

Applied

Crop

Removal

State or

Province


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K Deficiency Symptoms


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K Deficiency Symptoms


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Plant Tissue K Guidelines forCrops An Example

3.9 4.72.5 3.81.8 2.4


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Crop Responses to K

While many northern Great Plains soils have abundantK, the region also has areas with very low soil K

It is not uncommon to find areas of Saskatchewan and

Alberta with soils testing 30 to 50 ppm K/A

Crops respond to K application in these low K soils


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Barley Response to Soil KLevels and Fertilizer K2O

N and P added to soil test recommendation D. Walker, Lacombe, AB

Soil K 50-75 ppm/A

Soil K 75-100 ppm/A

Soil K 25-50 ppm/A

010

20

30

4050

60

70

80

0 12 24

Added K, lbs K2O/A added to seed row

%

Gra

inYield

Incre

ase


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Barley, Wheat, and CanolaResponse to K

N and P added to soil test recommendation Henry and Halstead, 1968

72 ppm K/A

33 ppm K/A

30 ppm K/A

50 ppm K/A

36 ppm K/A

Canola

Wheat

Barley

010

20

30

40

50

60

70

0 100 200 400

Added K (lb K 2O/A Broadcast + Incorp)

Grainyield,

bu/A

K Benefits Crop Growth and


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K Benefits Crop Growth andYield Longevity of AlfalfaStands

K increases carbohydrate in the crown roots ofalfalfa during fall growth to increase

- Winter hardiness

- Early spring re-growth


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Manitoba - Soil K 116 ppm/A (0 to 6 in.)

100 lb K2O/yrNo K100

Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7

0

20

40

60

80

S

tandd

ensity ,%

Plant counts in May as % of those the previous September

K Helps Reduce Winterkillin Alfalfa


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Crop Response onHigh K Soils

Yield increases often occur from potash applied on soilsnot deficient in K. Why?

K responses as a result of:

- Cold soils in the spring (slow root growth and

nutrient uptake)

- Dry soils (droughty conditions reduce K diffusion)

- Field (landscape) variability

- Cl ion (Cl-

) response


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Barley Response to Starter Kand Seeding Date

Dubbs, Montana State Univ.Soil K levels - High

April 6 May 6 June 3

7 bu

6 bu

3 bu

0

10

20

30

40

50

60

B

arley

Yield

(b

u/A)

Check

20 K2O

Crop Response to Added K


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Crop Response to Added Kin High K Soils in Montana(264 Sites)

36 Expts.

48 Expts.

33 Expts

97 Expts.

0 20 40 60 80

Winter Wheat

Spring Wheat

Feed Barley

Malt Barley (irr.)

Alfalfa

Corn Silage

Potatoes (irr.)

10 Expts.

22Expts.

18 Expts.

5.5 bu/A

4.8 bu/A

3.9 bu/A

9.2 bu/A

0.35 t/A

2.8 t/A

25 cwt/A

Frequency of response, %

Each crop represents 2 to 8 cropping years

Soils testing > 600 ppm (1967-1979)Skogley & Haby 1981


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Barley, oats, and rape 1968-74

Crop Response to Added K inAlberta (548 sites)

Exch. K Total Responsive Average

ppm/A sites sites,% Resp., cwt/A

0 - 50 37 70 6.1

51 - 100 132 73 4.8

101 - 150 115 55 2.5

151 - 200 100 52 2.4

201 - 300 99 46 2.7

301 - 400 37 43 2.4

> 400 28 21 1.9

Lopetinsky 1977

Frequency Distribution


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Frequency Distributionof Soil K on a 220 x 220 ft.Grid at Mundare, AB

Penny et al., 1996

Mean = 135 ppm

Mode = 108 ppm

05

10

15

20

25

30

35

Frequ

ency

(%)

59-101 101-

143

143-

185

185-

227

227-

269

269-

311

Soil K (ppm)

hl id i l


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Chloride---An EssentialPlant Nutrient

The deficiency of Cl in the soil can account for cropresponses to KCl application.

Earliest report of Cl crop response ... table salt (NaCl)in mid 1800s

Recognized as an essential micronutrient since the1950s

Research in the late 1970s revealed insufficient levelsin many areas


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Chloride has been shown to have an effect on: Root rot and foliar diseases in cereal crops

Seed weight at harvest, especially barley, by extending thegrain filling period

Reducing physiological leaf spot in cereal crops on fields

where soil Cl is less than 10 lb/A (24 in. depth) Increasing crop yields

Crop Responses to Chloride

Ph i l i l L f S t


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Physiological Leaf Spot onKestrel Winter Wheat

No ChlorideNo Chloride ChlorideChloride


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Chloride May ImproveCrop Yields

~ 200 university trials in KS, MN, MT, ND, SD, MB,and SK have evaluated Cl response in wheat andbarley

Included non-responsive and high Cl sites

Significant yield response in 48% of trials Average yield response of 5 bu/A


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Yield Boost from ChlorideDepends on Wheat Variety

-6

-4

-2

0

2

4

6

8

1012

Yieldrespo

ns

e,

bu/A

Barrie Cora Grandin Karma Kyle

1996 1997 1998


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Fertilizer K Management


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Once in the soil,

all fertilizersources are thesame form as

found in the soil(K+). This is theform taken up by

plants.

K+

KClKCl KK22SOSO44

Wh t H t


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What Happens toFertilizer K in the Soil?

Absorbed by crop in year 1:

20 to 60% of applied K

Highest recovery on low K soils

Slowly available K (future years): Bulk of remaining K in most soil types

Future supply of K

Available K SlowlyAvailable K

Unavailable K


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Fertilizer K Sources

Source Analysis

Potassium chloride, KCl 0-0-60 (62)

Potassium sulfate, K2SO

40-0-50 - 17

Potassium nitrate, KNO3

13-0-44

Potassium-magnesium sulfate,

K2SO

4

.2MgSO4

0-0-22-22-11

Potassium thiosulfate, K2S

2O

30-0-25-17


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Fertilizer K Placement

l Cl


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Barley Response to KClPlacement and Rate

N and P added to soil test recommendation SIP Soil Fertility Rpt, 1968

Broadcast

Side band

Seed row

0

5

10

15

20

25

30

0 15 30 60 90 120 150 180 240

lb K2O/A

GrainYieldI n

creas

e(bu/A)

Safe Rates of Seed Ro K


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Safe Rates of Seed Row Kapplication (Saskatchewan)

Seed row application of K2O should not exceed

(1 in. spread, 6 to 7 in. rows): Cereals 50 lb K2O/A

Canola 20 lb K2O/A

Dry pea 15 lb K2O/A Combined P2O5 and K2O in the seed row should also not

exceed the recommended safe rates for K2O alone

Source: Saskatchewan Agriculture and Food

Potassium Does Not Cause


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Potassium Does Not CauseRoots to Proliferate

Split-root experiment

Percent of the total root

system on the side with

K was the same as that

on the side without K Effects of K on root

growth may not be

localized as is found

with P

Classen and Barber, 1977

Proportion of roots expected for no K effect (%)

0 20 40 60 80 100Proportio

nofrootsobserv

edinKsolution

(%)

0

20

40

60

80

100 Corn 17 days old


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Be Sure and

Use SoilTesting toMonitor Soil K

Supplies

Summary


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SummaryK Nutrition in the NorthernGreat Plains

K nutrition is critical to crop production Most northern Great Plains soils are high in K, allowing

for a net removal of soil K each year

Crops take up as much K as N during growth, with only a

small proportion removed in grain Where deficient, crop response to K is greatest for

barley, followed by wheat and canola

Crop responses to muriate of potash (KCl) can be a Cl

response


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International Plant Nutrition Institute655 Engineering Drive, Suite 110Norcross, GA 30092-2604Phone: 770-447-0335; Fax: 770-448-0439

www.ipni.net

K Nutrition in the NGP

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