Potato
Potato

Its scientific name is Solanum tuberosum L. belonging to the Solanaceae family.

Potato is an herbaceous annual plant which has a fibrous and branching root system, with superficial roots concentrated in the first 60 cm of the soil. It develops stolons (subterraneous lateral stems) originated in the basal nodes near the soil surface. These stolons or modified stems are converted in tubers in their extremes, presenting these the same structures than the stolons (lenticels, internodes and scamiform leaves).

Even though potato can be reproduced by seeds, actually, the reproduction is always vegetative, performed by mean of tubers, which produces sprouts in the buds.

This crop is grown in a wide rage of soil types, being well adapted in acid soils. Prefer soils for potato cultivation are with light texture, sandy or loam, well drainage and high in organic matter content. Heavy soils can limit tuber development and prevent the absorption of some nutrients such potassium.

The optimum pH varies between 5.0 and 6.5; outside this range some elements usually became less available for the plant. Potato is moderately tolerant to salinity, being 1.7 dS/m the maximum for good yield; above this, the yield decreases.

The ideal storage temperature for potato is 4°C, since at this temperature the later sprouting will be more rapid. The tuber initiation requires temperatures between 18° to 20°C and in the growing phase these should be between 18° to 20° C during the days and lower at night (12° to 14° C). With day temperatures over 25° C the respiration rate increases substantially and decreases the net assimilation rate, affecting the photosynthetic process.

Day light hours influence the tuber filling rate, consequently this rate is maximum in temperate zones (away for the Equator) since they have greater light hours during the day.

It is important to avoid drastic variation in the soil humidity levels during the crop growing period, particularly at the phase of tuber initiation, when good humidity level should be constant. This will influence the increment of stems, foliar area, dry weight and tubers´ number. A 40 kPa tension at the tuberization moment produce high yields. The water consumption could vary between 4,000 to 6,000 m3 of water/ha/season, depending on the variety, climatic conditions, soil texture, etc. Maintaining adequate water levels during the tuberization phase, disease risks such as common scab (Streptomyces scabies) could be minimized. Besides, approaching harvest, an excess of water should be avoided to prevent skin scab and lenticels.

Among potato varieties, there are with short cycle (between 120 to 150 days from planting to harvest) and long cycle varieties (between 180 to 210 days), and according to their use, they can identify as varieties for fresh market, for seed production and for industry (potato chips and crisp).

Main Nutrients
The application of balanced nutrition aims to ensure adequate aerial and root growth to store as much carbohydrate in specialized organs. Adequate nutrition of the crop is a key factor in obtaining good harvests.

To achieve an appropriate nutrition plan in potato is necessary to know the nutrient demand in quantity and type of nutrient. It is also important to know the role of each nutrient for crop growth, yield and quality of production.

Figura 1. Growing stages of the potato crop.
 Figura 1. Growing stages of the potato crop.

The time required for sprouting initiation will depend on the tuber quality as seed, when this was harvest and its storage conditions. After the emergence, the areal part and roots will simultaneously develop, the foliage continues growing until before flowering (Figure 2).

Figure 2. Foliage, roots and tubers rate of growing.

It is important to consider when the simultaneous growth of roots and areal part occur, there is a competition for nutrients in the plant, and then the nutritional strategy must be oriented to assist both types of growing. This period begins between 20 and 30 days after planting and can be prolonged for about 4 weeks.

Tubers growth can happen 2 to 4 weeks after the emergence. The tuberization process occurs between 10 and 30 cm of soil depth. In this stage, carbohydrates produced by the foliage are utilized for developing stolons and tuber initiation. The tuber rate growth varies according to the crop development, and could reach more than a ton/ha/day in fresh weight gain of the tubers. Consequently, in this stage sources of rapid assimilation fertilizers are required, such as potassium, calcium and manganese nitrates, together with an adequate water supply.

Figure 3 presents that the mayor absorption rate happens between the 30 and 80 weeks after emergence, which produces the higher tuber growth rate. This coincides with the minimum growth rate of foliage and roots.

Figure 3. Tuber growth and nutrient absorption.
 Figure 3. Tuber growth and nutrient absorption.

Figure 4 shows the tuber’s proportion requirement of macro-nutrients. The tuber takes a mayor quantity of potassium, then nitrogen and finally magnesium.

Figure 4. Absorption of macro-nutrients by the tuber.
 The following table presents yield parameters and/or quality that are influenced by determined presence of nutrients.

Element

Tuber Size

Tuber Number

Tuber Quality

Skin Quality

Quality and Storage

N

+

 

+

 

 

P

+

+

+

 

 

K

+

+

+

 

+

Ca

 

 

+

+

+

Mg

+

 

+

+

 

S

 

 

 

+

 

Mn

+

 

+

+

 

B

+

 

+

+

+

Zn

 

 

+

+

 

Las recomendaciones en la tabla son generales: Ellas pueden variar por diversos factores, condiciones, criterios y objetivos. Pregunte a su asesor o distribuidor por su programa de cultivo específico o por cualquier otra información acerca del uso del rango de nutrición de productos Speedfol™.
Nutritional Recommendation
An adequate supply of nutrients to plants should incorporate both macronutrients and micronutrients. SQM in the selection of specialty plant nutrition (SPN) that offers the following alternatives available according to the route of application (fertigation, soil or foliar):

It is very important to perform a soil and water analyses previous to formulating a precise nutritional plan for the present conditions. Then, during the crop, a foliar or of petiole analysis is recommended to help to correct any eventual nutritional problem.

The nutrition in the potato crop can be performed the following ways: only with granular products, only with granular and soluble products, only with granular and foliar products, with granular, foliar and soluble products, only with soluble products, with soluble and foliar products.

The following table shows the principal nutrients for the potato crop, their roles in the plant, nutrient sources, variable to be considered and indications for their application.

Remoción de macronutrientes de frutos de paltos (Kg/ha) con rendimiento de 10 ton/ha.

Nutrient

Principal source

Characteristics

Nitrogen

Nitric-N
Ammonia-N
Urea

Role: It is important for foliar and tuber growth. The mayor part of nitrogen is translocated from the leaf to the tuber while this is growing. The application must be controlled since an excess can generate a delay tuberization, favor the incidence of hollow or black hart and tuber deformation.

The Nitrogen form to be applied will depend on the crop phenological stages, such as the tuber filling stage and the competition among ions.

Sources and variable to be considered: Among the nitrate sources are: Potassium nitrate, Calcium nitrate, Magnesium nitrate and NH4+ nitrate. In case of applying ammonia or ureic sources (urea, ammonium sulphate, ammonia and ammonium nitrate), it must consider the climatic conditions and the soil pH.

Application: Granular application: 2 applications: one at planting with nitric and ammonia sources (50% from total) and 2nd application 30 days after emergence (initial tuber growth) with nitric sources.

Application via fertirrigation: At post-emergence between 15 to 90 days (short cycle varieties).

Role: Incentive roots´growth and tubers´formation. The plant needs P during the entire developing period; even though, during the first growth stages it is consumed in larger quantities. It must be applied very near the roots to make possible the absorption by the plant.

Phosphorus

Diammonic phosphate
Monoammonic phosphate
Triple super phosphate
Simple duper phosphate
Urea phosphate
Monoamonic phosphate technical grade
Monopotasic phosphate
Phophoric acid

Sources and variables to be considered: Soil pH (acid soil: super-phosphate is recommended; for alkaline pH: Monoammonic phosphate or diammonic).

Application via: Via irrigation: Monoammonic phosphate (technical grade), urea phosphate, phosphoric acid, and monopotasic phosphate (alkaline pH) and monoammonic phosphate (technical grade) and monopotasic phosphate (acid pH). Soluble NPK is appropriate for any type of water.

Application: The total amount is provided, at planting, in the 1th nutrition application. It is recommended to reinforce with soluble Potassium, from the 3er week until the 6th o 7th week. This reinforcement must be accompanied with Boron and Zinc to improve cellular division of the developing tubers.

Later foliar applications of Phosphorus are possible after the 10th week of post-emergence.

Potassium

Potassium nitrate
Potassium sulphate
Potassium chloride

Role: It is very important for obtaining large productions, due its role in the sugar and starch synthesis. It helps to the starch translocation toward the tubers. It reduces frost damage, protects plant tissues against drought, assuring constant sugars and starch generation. It influence potato texture, coloration and flavor, as well as conservation, providing skin strength and resistant to blows.

Sources and variables to be considered:Potassium nitrate is the source readily available for the plant; consequently it is used during the tuber growth stage.

Other sources are recommended in moderate quantities and only at the initial crop development stage to be available for the plant at required moments. These have the following disadvantages: potassium sulphate has less solubility than the nitrate. Chloride is toxic, competing with other anions, increasing salts quantities in the soil, producing water absorption problems for the plant and causing storage fungi diseases.

Application: Apply a fraction at planning (40-50%) and the rest, before the crop closes its canopy (foliage).

1th application: At planning. These can be sources of different availability speeds for the crop.

2nd application: Exclusively Potassium nitrate since coincides with tuber development. Both applications can be completed with foliar sprays for assuring a complete tuber filling during its development.

If the application is via irrigation, the supply must be between 15 and 90 days after post-emergence for short cycle varieties.

Calcium

Calcium nitrate
Calcium chloride

Role: High levels in the plant (>0.25% in the skin tuber) diminish disease susceptibility, increase harvest quality and improve storage.

Sources: Calcium nitrate is the faster available source.

Application: Calcium supply must be at the tuber development stage, locating it near the stolons and tubers.

Magnesium

Magnesium nitrate
Magnesium sulphate

Role: Magnesium provides quality to growing tubers. Similarly, being chlorophyll essential component, it has a great importance in the photosynthesis, and consequently to crop production. Photsynthesis should be active long time and Magnesium is an essential contributor. An unbalance in the Potassium, Magnesium and Calcium concentrations produces reduction in the tuber specific weight.

Sources and variables to be considered: Magnesium nitrate is the most soluble source. Also, the one that has better performance at low temperatures. Magnesium sulphate is widely used due to its low cost and affectivity. In fertirrigation, Magnesium nitrate can be mixed with any other macro-nutrient; on the contrary Magnesium sulphate cannot be mixed with Calcium nitrate in high concentrations since they precipitate.

Application: 1th application at planting (35%) and the rest (65%) before the crop closes its foliage (canopy). Via irrigation: between 15 and 90 days after emergence in short cycle variety.

Sulphur

 

It is important for reducing the effect common scab.

Zinc

 

It influences the Nitrogen absorption and in the metabolism for starch formation. Also, in the cellular division and elongation, and auxin promotion.

Boron

 

Boron role: Calcium assimilation, cellular division, sugars transport and carbohydrates metabolism.

Manganese

 

It diminishes the effect of common scab. Also has the function of protecting the chloroplasts, enzymatic synthesis and in the photosynthesis.

The following table shows sources and application period of granular N, P and K in the nutrition.

Souces per Application

N

P2O5 (Soil pH)

K2O

Source

%

Source

%

Planting

NO3

20-35

Según pH

KNO3

40

< 6 = SFT

< 6 - 7,5 = DAP

> 7,5 = MAP

2° Application

NO3

60 - 80

 

KNO3

100

NH4

20 - 35

 

K2SO4

0

Nutritonal programs suggested by SQM.

High Production Level Product / Nutrition

Application Period

Doses (kg/ha)

Nutrients (kg/ha)

N

P2O5

K2O

S

MgO

CaO

B2O3

Qrop™ Mix 7-22-13-5-4-4+B+Zn+Mn

Planting

1.200

84

264

156

60

48

48

7

Qrop™ Mix 14-0-26+10CaO

1th Ridging

600

84

0

156

0

0

60

0

Foliar supply

 

320

39

36

48

0

12

21

0

TOTAL NUTRITION

 

2.120

270

300

360

60

60

129

7


Detail Nutritional Program Compound of 2 Qrop™ Mix.

• 1th application: at planting.
• 2th application: before the crop closes its canopy.

Foliar complement: N-P-K+ME (Speedfol™ 9-45-15+ME), weekly application in a dosis of 20 kg/ha, between the 2nd and 5th week of post-emergence.

Potassium nitrate, Ca nitrate and Mg nitrate, weekly applications in dosis of 10 kg/ha from the 6th until the 13th week.

Granular Nutritional Plan without Foliar Complement

High Production Level Product / Nutrition

Application Period

Doses (kg/ha)

Nutrients (kg/ha)

N

P2O5

K2O

S

MgO

CaO

B2O3

Qrop™ Mix 10-25-15-5-3-3+Zn+Mn+B

Planting

1.300

130

325

195

65

39

39

2

Qrop™ Mix 14-0-26+10CaO

1th Ridging

600

84

0

156

0

0

60

0

TOTAL NUTRITION

 

1.900

214

325

351

65

39

99

2


Detail Nutritional Program: Compound of 2 Qrop™ Mix, 1th application at planning and the 2nd application before the crop closes its canopy.

Soluble Nutritional Plan for Application via Irrigation with Qrop™ mix Base, for Short Cycle Variety.

Development Phase

Number of days

Nutrient

Number of Applications

Application kg/ha

Total kg/ha

Nutrients (kg/ha)

N

P2O5

K2O

S

MgO

CaO

Planting

0 - 20

Qrop™ Mix 7-22-13-5-4-4+B+Zn+Mn

1

700

700

49

154

91

35

28

28

Emergence, vegetative and root development

21-45

Ultrasol® 15-30-15

8

20

160

24

48

24

0

0

0

Magnesium Nitrate

8

20

160

18

0

0

0

24

0

NKS 13-0-45

8

20

160

21

0

72

0

0

0

Tuberization

46 - 65

Calcium nitrate

6

20

120

190

0

0

0

0

31

Magnesium sulphate

6

15

90

0

0

0

12

15

0

B+Zn+Mn

6

1

6

0

0

0

0

0

0

12 - 61 - 0

6

20

120

14

73

0

0

0

0

NKS 13 - 06 - 40

10

20

200

26

12

80

0

0

0

 

Nutrition

184

134

257

25

57

97

Total

233

288

348

60

85

125


Nutritional Recomendation via Speedfol™

Growth stage

Product

Dose/100 l (ml or gr)

Product use/ha (l or kg)

Remarks

Before planting

Speedfol™ Marine SL

2 l

 

Dip the seed potatoes before planting for approximately 5 minutes in a 2% solution.

Leaf emergence

Speedfol™ Amino Starter SC

500 ml

2.0 lz

Speedfol™ Amino Starter SC contains a high P level and auxins for stimulating rooting especially during periods of low soil temperatures and for good crop establishment.

2 weeks later (leaf development and tuber initiation).

Speedfol™ Marine SL

1.000 ml

5.0 l

To promote the vegetative development and tuber initiation. Speedfol™ Marine SL will also help to reduce possible stress coming from herbicide applications.

Speedfol™ Amino Calmag Plus SC

600 ml

3.0 l

Speedfol™ Amino Calmag Plus SC contains calcium for stronger cells and magnesium for improved photosynthetic efficiency.

Speedfol™ B SP

150 g

0.75 kg

To increase the tuber quality.

2 weeks later (leaf development and tuber initiation / filling)

Speedfol™ Amino Vegetative SC

1.000 ml

5.0 l

Speedfol™ Amino Vegetative SC will ensure sufficient leaf mass for the production of sugars for tuber filling.

Inflorescence emergence and tuber filling

Speedfol™ Amino Flower & Fruit SC

1.000 ml

5.0 l

Speedfol™ Amino Flower & Fruit SC to provide the high K requirement of the plant during flowering and tuber development.

Speedfol™ B SP

150 g

0.75 kg

Speedfol™ B SP to increase the tuber quality.

Speedfol™ Amino Calmag Plus SC

600 ml

3.0 l

Speedfol™ Amino Calmag Plus SC to support the foliage with calcium for stronger cell walls and more disease resistance and magnesium for improved photosynthetic efficiency.

Tuber development

Speedfol™ K SL

1.000 ml

5.0 l

To improve tuber quality and post harvest life. Repeat every 7-10 days as required.

Speedfol™ Mg SC

1.000 ml

5.0 l

To maintain the foliage intact and improve the photosynthetic efficiency. Repeat as required.

Nutritional balance
Nutritional balance in crop quality and yield of potato crops

As a basic recommendation for a good nutrition plan, we need as much information as possible. Thus, an analysis of soil (the nutrient solution) and water (when it is irrigated) is essential for good planning. Then during cultivation, foliar or petiole analysis can help to correct any possible nutritional problem.

Specialty Plant Nutrition available to supply the growing needs of the Potato.

The following research was conducted by Knight, FH et al in 2000 in South Africa and shows the relationship between the dose of nitrogen used, the combination of sources (ammonium nitrate) and performance. Where its results can be seen that for the different treatments, the best combination for maximum production was 80% nitrogen nitric and 20% nitrogen ammonia, independent of the total nitrogen amount used.

Relationship between potato yield, source and the nitrogen rate.
Relationship between potato yield, source and the nitrogen rate.

The following table shows the sources and timing of application for the supply of granular soil Nitrogen - Phosphorus - Potassium

The following research was conducted in South Africa in 1983 by Van de Merwe. It can be seen in the ratio of the potassium source used, the dose used and the performance obtained. As can be seen then as the dose is increased used of elemental potassium, also increase yields. Linked to this, it is clear that when the source is potassium nitrate used is obtained consistently better results compared with the use of potassium chloride.
Performance in relation to the source of potassium.
Performance in relation to the source of potassium.

Granular nutritional plan with foliar complement

The following research conducted in India by Grewal and Singh (1980) we can see the relationship between the dose of potassium used and the damage to the tubers as a result of cold, in the image below, according to the results observed, we conclude that increasing applications of potassium result in lower tuber damage by cold effect. Increasing the marketable yield.
Damage leaf with different doses of potassium.
Damage leaf with different doses of potassium.

The following investigation by Karlson and Palta in 2003 in the U.S., where we see the relationship between the damage to the tubers, the type of fertilizer used and the concentration of calcium in the tuber, for different varieties. Here are appreciated calcium levels in the tuber, where you can see that for all varieties, calcium levels are higher when calcium sources are used in nutrition.
Calcium levels in the tuber (ppm).
Calcium levels in the tuber (ppm).

The following image shows that damage to the tubers decreases, as calcium levels are higher in the tuber. The most interesting is that this effect occurs consistently in all varieties treated.
Percentage of damaged tubers.
Percentage of damaged tubers.
Study performed in Mexico
Treatments summary

Treatment

Starting Mix

Doses kg/ha

N

P2O5

K2O

SO4

MgO

CaO

B2O3

1

12

23

17

2

2

0

1,1

1100

2

10

23

15

3

3

4

1,1

1000

3

12

23,5

16

2

1,4

0

1

1000

4

12

23,5

16

3

2,3

3

1

1000


Treatment

Reapplying Mix

Doses kg/ha

N

P2O5

K2O

SO4

MgO

CaO

B2O3

1

13

0

25

1,4

1,2

7,4

0

900

2

18

0

27

0

0

0

0

850

3

16

2

23

3

2

0

0

800

4

16

2

23

3

2

0

0

800


Summary of applied units per treatment

Units / ha

N

P2O5

K2O

SO4

MgO

CaO

B2O3

Treatment 1

249

253

430

43

32

66

12

Treatment 2

253

250

380

33

27

36

11

Treatment 3

248

251

344

50

38

16

10

Treatment 4

248

251

344

53

39

17

10



Results

Treatment

Production kg / ha

Nutritional Cost (US$ / ha)

First

Second

Third

Fourth

Total

1

18.130

13.870

9.617

0

41.617

735

2

16.500

13.870

9.557

0

39.926

623

3

15.652

12.104

7.791

543

36.091

595

4

14.870

10.339

9.557

0

34.765

560


• T1, T2 y T3: To study yield and tuber quality with different K and Ca doses.
• T3 y T4: To compare tuber yield and quality with different K sources.
• For T3 Sulpomag, K suphate and K nitrate were used at planting and K nitrate was reapplied.
• For T4 Sulomag and K chloride were used at planting and K chloride was reapplied.

Comparison of different K sources in the potato crop.
Comparison of different K sources in the potato crop.

Treatments and results: Better yields were obtained with K nitrate.
Comparison of different K doses in the potato crop.
Comparison of different K doses in the potato crop.

Results: Increasing K doses improved yield.

Relation between potato quality and potassium and calcium applied
Relation between potato quality and potassium and calcium applied

Results: Increasing doses of K and Ca generate more yields and better potato quality.

Price / kg (Mexican $US)

Income / ha

Income US$

Nutritional Cost (US$ / ha)

Income US$ (subtracting nutritional cost)

$3,20

$2,50

$2,00

$2,00

Total

First

Second

Third

Fourth

Treatment 1

58.017

34.674

19.235

0

111.926

11.193

735

10.458

Treatment 2

52.800

34.674

19.113

0

106.587

10.659

623

10.036

Treatment 3

50.087

30.261

15.583

1.087

97.017

9.702

595

9.107

Treatment 4

47.583

25.848

19.113

0

92.543

9.254

560

8.694


Cost-benefit Relation (Exchange rate: 1US$ = $10 Mexican pesos).

Treatments and results: T1 was the most expensive nutritional treatment, but it also had the larger net income (greater total production and better quality potato), then the conclusion is that more expenditure in nutrition is a good investment.

In addition, the best net income was obtained with K nitrate as a source of this element.
Phenological Stage


Info by crop:

 
Disclaimer:
All the information is given to the best of SQM's knowledge and is believed to be accurate. Your conditions of use and application of the suggested products and recommendations are beyond our control. There is no warranty regarding the accuracy of any given data or statements. SQM specifically disclaims any responsibility or liability relating to the use of the suggested products and recommendations and shall under no circumstances whatsoever, be liable for any special, incidental or consequential damages which may arise from such use.