Nitrogen, Potassium and Calcium in Potatoes Barry Bull, Hydro Agri Specialities September 2003
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