1. K+S Group
K+S KALI GmbH
How Potassium and Magnesium affect potato yield an quality
Prof. Dr. Andreas Gransee
K+S KALI GmbH
Germany

2. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S Group
Potassium uptake (kg K2O) of potato during the
vegetation period
1
0
50
100
150
200
250
300
350
400
450
500
23. 25. 26. 28. 29. 31. 32. 33. 35. 36. 38. 40.KW
kgha-1
Cilena tubers (430 dt/ha) Cilena leaves/stems
Russet Burbanks tubers (900 dt/ha) Russet Burbanks leaves/stems
K+S KALI GmbH
Source: K+S KALI GmbH field trials, 2004
Cilena: Table potato variety
Russet Burbanks: Processed potato variety

3. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S Group
Nutrient demand of the potato crop
2
K+S KALI GmbH
Average Potato Yield in Kenya (FAOstat): 19 t ha-1
Nutrient Removal Calculation by K+S KALI GmbH

4. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S Group
Nutrient demand of the potato crop
3
K+S KALI GmbH
Average Potato Yield in Germany (FAOstat): 46 t ha-1
Nutrient Removal Calculation by K+S KALI GmbH

5. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S Group
K distribution in potato plants
4
K+S KALI GmbH

6. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S Group
Effect of different doses and forms of K on
yield of potato
34
35
36
37
38
39
40
41
42
43
Yieldt/ha
Control 100 kg K2O/ha as SOP 200 kg K2O/ha as SOP 300 kg K2O/ha as SOP
5
K+S KALI GmbH
Bakum-Lüsche, slight-silty sand
ST (2008): 138 mg K2O/kg soil (CAL) class ‘C’
32 mg Mg/kg soil (CaCl2) class ‘A/B’

7. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S Group
Effect of K on yield and dry matter content of potato
tubers
6
20,49
17,7
26,79
19,5
31,11
21,6
30,37
22,4
0
5
10
15
20
25
30
35
40
T1 T2* T3* T4*
* = significant T1, 2, 3, 4 = 0, 100, 150, 225 kg K2O ha-1
(+ N = 150, P = 100 kg ha-1 each)
Tuber yield (t ha-1) Dry matter content (%)
(average of 10 fields), 1996-97
K+S KALI GmbH

8. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S Group
Relative yield increase as affected by K supply
(Control = 100 %)
7
K+S KALI GmbH
K supply from soil
low middle optimal high
Yieldrelativeto
control(%)

9. K-MA / Prof. Dr. Andreas Gransee, Dr. Hendrik Führs K+S Group
K+S KALI GmbH
Quality parameters for potatoes used in
processing industry
8
Processing
quality
External quality Internal quality
External consitution
• Tuber size
• Tuber form
• Skin firmness
• Eye depth
Internal consitution
• Valuable ingredients (e.g. starch,
vitamins, minerals)
• Turgor and physiological age
External defects
• Damages
• Growth disruptions
• Rot and scurf
• Greening
• Tuber misshaping
Internal defects
• Internal damages
• Internal rot
• Invaluable ingredients (e.g.
nitrate, heavy metals, reducing
sugars, alkaloides, acrylamide
• Black spots
• Hollow centersAccording to Dr. Haase, Max Rubner-Institute (MRI) Detmold, 2010

10. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S Group
Effect of Potassium and magnesium on tuber sensitivity to damages
(No. of damages per 100 tubers)
0
50
100
150
200
250
300
0 120 240 360 240*
damages(n)
2009
2008
9
K+S KALI GmbH
kg/ha K2O as Patentkali®, * as Korn-Kali®
Averages of three trials each, Landwirtschaftskammer Lower Saxony
Varieties: Verdi 2009, Kuras and Saturna 2008
Artificial mechanical impact induced by damage test bench of potato research station
Dethlingen and rating of necrotic tissue according to Bundessortenamt-Index

11. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S Group
K fertilization and K form affect yield and starch
content
10
K+S KALI GmbH
47,5
51,2
57 56,7
58,3
7,7 8,5 9,5 8,5 8,6
16,1
16,5 16,7
15
14,7
13
14
15
16
17
18
0
15
30
45
60
K 0 240 SOP 400 SOP 240 MOP 400 MOP
%
tha-1
K fertilization kg K2O ha-1
Magnesium supply in all variants: 320 kg ha-1 Kieserit gran.
Schuby 2003 K content soil medium Cultivar : Linda
Tuber yield Starch yield Starch content
Source: Landwirtschaftskammer Schleswig-Holstein

12. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S Group
Factors for black spot incidence
in potato tubers
11
Growing conditions:
site, water supply
Variety
Harvest conditions
Post harvest
treatment
Maturity
of tubers
Tuber content:
• free phenolic amino acids
• organic acids (pH)
• other phenolic compounds
• activities of enzymes
Mineral contents (K, Ca, Fe, Mg)
Fertilization
Storage conditions
(After Pawelzik, Delgado 1999)
K+S KALI GmbH

13. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S Group
Black spots as a consequence of K deficiency
12
Deficient K supply
Optimal K supply
K+S KALI GmbH

14. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S Group
Effect of different K supply on black spot incidence
of potato
13
0 102 205 307
0
20
40
60
80
kg K2O/ha as SOP
Black spot incidence (%)
before after storage
Average of 9 trials with increasing K supply on light soils in northern Germany
K+S KALI GmbH

15. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S Group
30
32
34
36
38
40
42
44
controle 100 kg/ha K2O as
SOP
200 kg/ha K2O as
SOP
300 kg/ha K2O as
SOP
300 kg/ha K2O as
SOP
yield(t/ha)
40
45
50
55
60
65
70
blackspotincidence(%)
14
Influence of K and Mg application on yield and
quality of potatoes (variety Premiere)
K+S KALI GmbH
Bakum-Lüsche, silty sand
Soil analysis: Ø 13,6 mg K2O/100 g soilCAL
Ø 3,2 mg Mg/100 g soil CaCl2
+ 400 kg ha-1 ESTA® Kieserit

16. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S GroupK+S Gruppe / 16
Quality parameters Nutrients
N P K Mg Ca
Tuber yield ++ + ++ + +
Starch content - + +/- + +
Protein content ++ ++ +
Ascorbic acid - and citric acid + + ++
Maturation - +
Skin firmness - +
After cooking blackening ++
Storability - + +
Reducing sugars - +
Resistance against:
Damages - + + +
Black spot incidence - ++ +
Discolourations ++
+ = positive effect ++ = very positive effect - = negative effect
Effect of fertilization on quality parameters
K+S KALI GmbH

17. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S Group
Magnesium Deficiency Symptoms
● Interveinal chlorosis on older lower leaves with a marbling effect (leaf veins remain
green)
● Later various shades of red/purple can appear as chlorophyll breaks down leading
eventually to leaf necrosis.
16Photos: K+S KALI GmbH
K+S KALI GmbH

18. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S Group
Potassium Deficiency Symptoms
● Bronzing of leaves and necrosis of leaf margins and
tips.
● Stunted bushy plants with small leaves and very
premature senescence before adequate tuber
bulking.
17Photos: K+S KALI GmbH
K+S KALI GmbH

19. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S Group
Balanced Fertilisation
Crucial for potato yield and quality
18
Potassium and Magnesium
are crucial for high potato
yield and the risk
management in unfavorable
conditions such as drought.
Potassium decreases the
incidence of discolorations
such as internal blackening
and blackspot
Potassium increases citric
acid, vitamin C and starch
content of the tuber
Potassium decreases
reducing sugar content
important for processing
An optimum supply of
potassium improves harvest
and storage characteristics.
This results in a reduced
susceptibility to bruising
Magnesium is essential for
the assimilation of the plant
and affects protein and
carbohydrate synthesis and
their transport and storage in
the tuber
K+S KALI GmbH
Potassium and Magnesium

20. Prof. Dr. Andreas Gransee, K+S KALI GmbH K+S GroupK+S Gruppe / 1
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