Nitrogen, Potassium and Calcium in

PotatoesBarry Bull,

Hydro Agri SpecialitiesSeptember 2003

TuberSize

TuberNumber

TuberQuality

Skin Finish

StorageQuality

N

P

K

Ca

Mg

S

Mn

B

Zn

Role of nutrients

in Potatoes

Nitrogen

Nitrogen

Nitrogen and tuber sizeNitrogen and tuber size

Hydro funded trials12

uFor yieldumore nitrogen uhigher yieldsulower bulk density

Nitrogen

uFor qualityuhigh nitrogenusplit potatoesupoor cooking qualityubrown stains in crispsuslow skin-set

Sidedressing nitrogen

uSplit applications with one sidedressu2/3 N applied at seedingu1/3 N applied around tuber initiation

Apply N when ‘hilling up’

uMore applications are better

Splitting Nitrogen Applications

Suecia 1988CNTC

Total N Appl. Split t/ha0 0 39.6

60 60 47.930+30 52.2

90 90 55.360+30 58.6

30+30+30 61.8120 120 56.3

90+30 61.760+30+30 61.9

150 150 61.1120+30 59.0

90+30+30 66.1

Effect of Nitrogen form & rate:

Tuber yield in South Africa (cv. UTD)

0,60,65

0,70,75

0,80,85

0,90,95

1R

ela

tiv

e Y

ield

Total N 120kg/ha

Total N 180kg/ha

Total N 240kg/ha

80% NH4 / 20% NO350% NH4 / 50% NO320% NH4 / 80% NO3

Ref: O. Achilea et al., 2000

Nitrogen - source

u Ammonium nitrogenu Excess NH4

+ is toxic and reduces yieldu NH4

+ Cannot be storedu NH4

+ must be detoxified

u Nitrate nitrogenu not toxicu efficientu potatoes prefer nitrate

CN vs. AN

Potassium

Potassium

u Increases tuber number

uDecreases tuber bruising

uDecreases enzymatic discolouration during cooking

uAnti Stress Element

Field trials - results Bulgaria 1996

22

23

24

25

26

27

28

29

KNO3 K2SO4 KCl

MT/ha

33,9

2826 24,7

20

25

30

35

40

0 50 100 150 200 250

kg K per ha

% d

am

ag

ed

tu

be

rs

Effect of K on % damaged tubers

Source: Hunnius und Bachthaler - IPI

Mc Cains - Trial UK ‘97

Trial: Basedresser based on KCl just before plantingTopdressing: with KNO3 217 kg/ha <-> AN

130

140

150

160

170Number of

tubers bruised

(SAC damage barrell)

No KNO3 +KNO3

Trial Mc Cains ‘97 - UK

Number of peels, necessary to completely remove the bruise

700

800

900

1000

1100

Number of Peels

No KNO3 +KNO3

Potassium and Tuber Quality

Effect of Potassium on discoloration

Mondy & Munshi 1993

Potassium as Anti stress element:stomata regulation

Stomata CO2H2O TRA

NSP

IRA

TIO

NST

OM

ATA

OPE

NIN

G

CONTENT OF K (mg/g)

1.5

1.0

0.5

0.5

1.0

1.5

2.0

2.5

01 2 3 4

50

40

30

20

Wat

er T

rans

pira

tion

g/g

DM

/day

1 2 3 4

50

40

30

20

% K in DM

Source: Blanchet et Al., 1962

K effect on Low Temperature Tolerance

Grewal and Singh .1980 . Plant Soil.

0

50

100

5.9

6.7

7.1

30

16

7

K applied (lb/A)

Yield(tons/A)

Foliage Damagedby Frost (%)

Calcium and heat stress

Potato is a cool season cropHot dry weather is not beneficialLow levels of calcium in the leaf make the

plant susceptible to foliar damage from heat stress.Calcium is important for the active transport

of K for the regulation of stomatal openings.Low calcium levels in leaf means poor control

of the stomata even with high K levels.

Calcium & heat stress

Biotron studies from Wisconsin University show that:

Plants with Ca produced 1.0 kg of tubers / plantPlants without calcium were heat stressed and produced 0.7 kg of tubers / plant

A yield reduction of 30%

Calcium & crop stress

The full study showed nitrogen during the stress helped but Ca & N was better.

Fert applied Yield N only before stress 100 %N only during stress 117 %Ca & N during stress 167 %

Calcium nitrate relieves heat stress in potatoes

Calcium and Potato Disease

Calcium & Erwinia

uCa improves tolerance to disease

Peel Ca Surface area

decayed0,1 % 90 %0.2% 50 %0.3% 20 %0,5 % nil

Calcium & Erwiniau Increasing calcium in cortex (red) & periderm (blue)uDeceases soft rot (yellow)

S o ft R o t

*B acteria lU n ivers ity o f W I

0

0.2

0 .4

0 .6

0 .8

0

1 .2

% C

a

50%

40%

30%

20%

10%

%W

t. Lo

ss Fro

m S

oft R

ot

1 .

(x 10 -1)C o rtex P erid erm

Calcium & Internal Rust Spot

uCa improves tolerance to diseaseCa IRS Peel Canil 60 % 0,11 %84 37 % 0,13 %

252 17 % 0,15 %

Calcium & Internal Brown Spot (IBS)

Ca in the inner part of tubers: Slight variations can make the difference

0102030405060

0,0050 0,0070 0,0090 0,0110 0,0130 0,0150

Ca in tuber flesh (% of DM)

% of IBS

Tuber flesh, Site 1 Tuber flesh, site 2

Ca in tubers & Internal Brown Spot (IBS)

R2 = 0.5701

0102030405060

0.0050 0.0070 0.0090 0.0110 0.0130 0.0150

Ca (% of DM)

% of IBS

R2 = 0.1851

0102030405060

0.035 0.055 0.075 0.095 0.115

Ca (% of DM)

% of IBS

Tuber flesh, Site 1Tuber flesh, site 2Tuber fleshLinear (Tuber flesh)

Tuber skin, Site 1Tuber skin, site 2Linear (Tuber skin)

Pulp

Skin

•% of IBS

Calcium and Potato Skin Finish

Calcium – Skin finish

Calcium and skin finish

uTubers need at least 0.15% Ca in peelu0.2% is better for disease tolerance.

Ca & tuber storageCa in the outer skinConfers resistance against pressure

0,0400

0,0450

0,0500

0,0550

0,0600

0,0650

0,0700

4100 4200 4300 4400 4500 4600 4700Resistance against pressure (g)

Calcium (% DM)

1 year trial, 2001Germany

CooperationHydro Agri /

Uni. Goettingen / Bahlsen

Ca & tuber bruising

Ca @ 165 kg/haCombination of CN & CaCl

05

10152025

303540

45

Atlantic Snowden Burbank Superior Norland

Incidence of Bruising (%)

Amm Nit

CN.CaCl

0

50

100

150

Atlantic Snowden Burbank Superior Norland

Amm Nit

CN.CaCl

200

250

300

350

Tuber Calcium levels (ppm)All varieties increased in calciumAll varieties had less bruising

Karlsson & PaltaUni. Of Wisconsin

2001

Does it work?

u Example : In Australia - average peel analysis.u Ca ranged from 0.07 to 0.11%u Desired level at least 0.15%

u CN rates usedu 125 kg/ha solid when tubers 25mmu 25 kg/ha/week fertigated for 6 weeksu Total 275 kg/ha CN

u Farmer increased his Ca levels to 0.15%u Skin blemishes decreased from 16% to 8%

u Cost / Benefitu Cost Aus $192.5/hau Benefit Aus $1088/ha

Calcium and Potato Yield

The importance of calcium in potato nutrition is demonstated in an experiment where seed potatoes were grown with and without calcium.

Crops grown with these seed pieces showed substanial differences.

Calcium nitrate improves subsequent yieldof seed potatoes.:

7170Superior

5462Norland

4773 Atlantic

- Calcium+ Calcium

+ Ca = Calcium nitrate+ Ca = Calcium nitrate

-- Ca = Ammonium nitrateCa = Ammonium nitrate

Minituber production using hydroponics

Calcium nitrate removedTuber skins cracked and peeledInternalbreakdown.

Calcium uptake in tubers

Most Calcium absorption occurs from tuber initation and throughout tuber bulking

Planting

TuberInitiation

Suberization VineKill Harvest

StolonGrowth

Bulking

CalciumApplication

Calcium uptake is through stolon and tubers

Ca % DMStolon/tuber Main root Peel Tissue

100 100 0,09100 3000 0,09

3000 100 0,270,08

Ca applied ppm

Field grown

Main Roots

u (dyed water travels up to stem not into stolons and tuber)

Stolon - tuber connection

Stolons pick up dyed water

dyed water travels into tuber

Moving Ca into potatoes

Stolon and tuber roots

take in Ca for the tubers

Soil Ca moves upwards into the

leaves

Foliar Ca remains in the leaf

Tuber initiation

Varies with variety - digging is the best way to see

Applying CN

Through watering system

Dry apply and incorporate

Both ways are effective in moving Ca over the tubers

Apply in time for rapid cell division.

Calcium Analysis

Tissue analysis:

Calcium levels in the leaf at start of flowering should be between 1 & 2 %If below these levels – yield will be lower.Leaf analysis is not a good indicator of

tuber Ca levels.

Tuber analysis:

Tubers need higher levels of Calcium.Calcium levels are 3 to 5 times higher in

peel than whole tuber.0.15% Ca in peel will give better skin

finish0.2% Ca in peel gives good disease

tolerance

Calcium in potatoes improves:

Tolerance to heat and cold stressTolerance to diseases

Less internal tuber breakdownBetter skin finish

Yield: where soil Ca levels lowwhere heat or cold stress results from low Ca levels

Calcium is vital to potatoes

TuberSize

TuberNumber

TuberQuality

Skin Finish

StorageQuality

N

P

K

Ca

Mg

S

Mn

B

Zn

Role of nutrients

in Potatoes

Is it worth the effort?Australian example – sandy soilIncreased in program

NitratesCalcium Magnesium

Yield: no differenceQuality - Packout

major improvement

Cost: extra $A 290.00Return: extra $A 3995.45

Nutrition is vital to potatoes