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Home > Agronomic Practices > Fertigation
Fertigation

Sugarcane being a giant crop producing huge quantity of biomass generally demands higher amounts of nutrient elements. A large number of research experiments have clearly demonstrated that for producing higher cane and sugar yields on a sustainable basis application of adequate amounts of fertilizer nutrients viz., N, P and K is essential.

 

At the same time the cost of chemical fertilizers have increased and there is a need to improve fertilizer use efficiency for more benefits. The best answer to this challenge is "Fertigation", where both water and fertilizers are delivered to crop simultaneously through a drip irrigation system. Fertigation ensures that essential nutrients are supplied precisely at the area of most intensive root activity according to the specific requirements of sugarcane crop and type of soil resulting in higher cane yields and sugar recovery.

 

Fertigation Offers Several Distinct Advantages in Comparison to Conventional Application Methods:

 

  • Distribution of plant nutrients more evenly throughout the wetted root zone resulting in increased nutrient availability & uptake contributing to higher crop growth rates and cane yields
  • Supply of nutrients incrementally according to the crop developmental phases throughout the season to meet the actual nutritional requirements of the crop
  • Careful regulation and monitoring the supply of nutrients
  • Application of nutrients to the soil when crop or soil conditions would otherwise prohibit entry into the field with conventional equipment
  • Minimal nutrient losses through consumption by weeds, leaching and runoff
  • No damage to the crop by root pruning, breakage of leaves, or bending of leaves, as occurs with conventional fertilizer application methods/equipment
  • Less energy is expended in application of the fertilizer
  • Usually less labour & equipment are required for application of the fertilizer and to supervise the application
  • Soil compaction is avoided because heavy equipment never enters the field
  • No salt injury to foliage
  • Allows raising of crop on marginal lands, where accurate control of water and nutrient ion in the plant's root environment is critical

 

Nutrient Uptake by Sugarcane

 


 Absorption of macronutrients by the variety CB41 - 76 (Malavolta, 1982)

 

 

fig. shows the accumulation of macronutrients by the variety CB 41-76 under Brazilian conditions. Several works have indicated that there is a close relationship between increase in stalk production and accumulation of N and K, which suggests that these two elements "go together" in the nutrition and fertilization of the sugarcane plant. The maximum rate of uptake of macronutrients by plant cane and first ratoon in the period of higher growth rate is given in

Table 11.

 

 

Table 11. Maximum Rate of Uptake of Nutrients by Plant Cane and Ratoon Cane (Malavolta, 1994)

 

Element

Plant cane

Firfst ratoon

kg ha-1 day-1

Nitrogen

0.59

0.73

Phosphorus

0.08

0.11

Potassium

0.71

0.95

Calcium

0.45

0.33

Magnesium

0.24

0.26

Sulphur

0.16

0.31

 

Generally speaking, the content of the macro and micronutrients in the plant obeys the following decreasing order:

 

Kgt; Ngt; Pgt;Cagt;Sgt;Mggt;Clgt;Fegt;Zngt;Mngt;Cugt;Bgt;Mo

 

Further most of the published data on the mineral requirements of sugarcane refer only to the above ground parts, which are stalks and leaves. Table 12 is an attempt to show the quantities of macro and micronutrients contained in the entire plant cane.

 

Table 12. Quantity of Macro and Micronutrients in the Below Ground and Aerial Parts of Plant Cane

 

Element

Roots

Millable stalks

Leaves

Total

Kg/ha

Nitrogen

8

83

77

168

Phosphorus

1

15

8

24

Potassium

4

109

105

218

Calcium

2

30

45

77

Magnesium

1

29

18

48

Sulphur

2

25

22

49

Chlorides

--

--

1

1

Silicon

--

98

150

248

g/ha

Boron

34

214

144

392

Copper

13

201

105

711

Iron

4900

3800

7900

16600

Mangnese

84

1170

1981

3235

Molybodynum

--

4

10

14

Zinc

72

437

336

845

Catani et al. (1959), Orlando Filho (1978), Haag et al. (1987),

Sampaio et al. (1987), Korndorfer (1989)

 

Role of Nutrients

Nitrogen

  1. N constitutes only a fraction of 1.0% of the total dry weight of mature cane
  2. Key element influencing growth, yield & quality
  3. Adequate and timely supply promotes - Tillering, Canopy development, Stalk formation & stalk growth [internode formation, elongation, increase in girth & weight
  4. Root penetration and proliferation
  5. Deficiency of N causes chlorosis, early leaf senescence, thinner & shorter stalk and longer and thinner roots
  6. Excess N prolongs vegetative growth, delays maturity and ripening; increases reducing sugar content in juice and thus lowering juice purity, and increases soluble N in juice affecting clarification; makes crop susceptible to lodging and pest and disease attack

 

Phosphorus

  1. Requirement is relatively less than N and K
  2. Vital for plant metabolism and photosynthesis
  3. Essential for cell division and thus indispensable for crop growth & development
  4. Promotes tillering, canopy and stalk development
  5. Promotes root penetration and proliferation
  6. Adequate P [ 3-4mg/liter ] in cane juice is necessary for proper clarification
  7. Phosphorus deficiency causes - Poor tillering & reduction in internodal length, Delay in canopy closure and Reduction root surface area

 

Potassium

  1. Required for several plant activities - Photosynthesis, carbon assimilation & translocation of carbohydrates
  2. Promotes sugar synthesis & its translocation to storage tissue
  3. Imparts resistance against pests & disease attack and lodging
  4. Regulates stomatal opening & closing and thus maintains turgor pressure under unfavourable soil moisture conditions
  5. Luxury consumption adversely affects the crystallization of sugar & higher sugar losses in molasses
  6. Deficiency of K affects growth by reducing internodal length, sugar synthesis and recovery

 

Causes of Nutrient Deficiency Symptoms

When a given nutrient is not present in the soil solution in a concentration sufficient for normal growth and differentiation, visual symptoms of malnutrition may eventually show up. The shortage of nutrients, which translate into symptoms of deficiency, could be due to several causes as shown in Table 13. It is clear that the three chief causes are low reserves to begin with, as it is the case of old weathered soils in the tropical regions, decrease in availability, and absence or lack of the element in the fertilizer programme at the rates it is applied.

 

Table 13. Main Causes of Deficiency Symptoms in the Sugarcane Plant 

Element

Cause

Any

  • Low soil reserve
  • Absence or inadequate quantity in the fertilization or liming programme

Nitrogen

  • Low organic matter content
  • High acidity (lack of mineralization)
  • High rainfall (leaching)

Phosphorus

  • High acidity and high sexquiooxides (fixation)
  • Excess liming (lower availability)

Potassium

  • Excess liming (competition for uptake)
  • High rainfall (sandy soils, leaching)

Calcium & Magnesium

  • Excess K in the fertilizer programme (competition)

Sulphur

  • See nitrogen
  • Use of "concentrated" fertilizers

Boron

  • See nitrogen
  • Excess nitrogen ("dilution" or inhibition in uptake)
  • Excess liming (loss in availability)

Copper

  • Excess P in the fertilization programme(inhibition  in uptake)
  • Excess liming (loss in availability)

Iron

  • High organic matter and moisture (loweravailability)
  • Excess liming (loss in availability)

Manganese

  • High organic matter, Excess liming (loss in availability)

Molybdenum

  • High acidity (lower availability)
  • Excess sulphate (inhibition in uptake)

Zinc

  • Excess liming (loss in availability)
  • High P in fertilizer programme (inhibition uptake)

Source: Malavolta (1994)

 

Fertilizer recommendations in different states

Sugarcane being a heavy feeder requires very large quantities of nutrients for growth and yield, accounting for 20 to 25% of the total cost of the production. The fertilizer recommendations for sugarcane in different countries are given in Table 14.

 

Table 14. Sugarcane: Recommended Nutrient Doses in Different Countries

 

Country

Crop

Nutrients (kg/ha)

Remarks

N

P2O5

K20

Argentina

--

100

Adapt to requirement

--

Australia

Plant cane

Ratoon

56

78

25-80

--

75-150

--

In addition to Bureau mixture

Bangladesh

--

120

85

110

--

Brazil

North East

South East

Central West

South

Plant cane

Ratoon

Plant cane

Ratoon

Plant cane

Ratoon

Plant cane

Ratoon

60-80

60-80

50-90

50- 90

30-40

40- 60

40-100

20-40

80- 180

20-100

50-110

25-50

30-120

15-60

0-120

20-60

30-120

40-140

20-120

10-80

30-120

20-90

30-120

0-60

N - 2/3 side-dressed

P & K according to soil analysis

P & K according to soil analysis

As above

As above

As above

British Guyana

--

65-90

50-100

60-150

--

Colombia

Plant cane

Ratoon

50-70

50-100

50-100

60-120

60-150

60-150

N - Side dressed according to leaf analysis

P & K rates depending upon soil analysis

Costa Rica

Plant cane

Ratoon

80-200

100-250

60-200

50-200

80-200

80-250

--

Cuba

Plant cane

Ratoon

0

35-150

0-50

0-50

0-120

0-150

P & K rates depending upon soil analysis and yield level

Ecuador

Plant cane

Ratoon

120

90

75-135

--

75-195

--

N-1/3 side dressed

P & K rates according to soil analysis

India 

--

SEE NEXT TABLE

--

Indonesia

--

120

--

--

P & K rates according to soil analysis

Jamaica

--

80-160

--

--

P & K rates according to soil analysis

Mauritius

--

100-125

--

--

2 - 1 -1 mixture

Mexico

--

120-180

0-150

0-150

Most frequent rates: 120 N+60 P2O5+60 K2O

Pakistan

--

90-160

--

--

--

Philippines

VMC District

Luzon

Puerto Rico

--

125

120-140

135-200

120

--

62

180

--

112

--

South Africa

Coastal Lowland

Natal Midland

Lowveld

Plant cane

Ratoon

Plant cane

Ratoon

Plant cane

Ratoon

100-120

140

80

120

120

100

40

20

60

40

30

10

100

150

125

175

125

175

N and K2O for plant cane in 2 split applications

Hawaii (USA)

Irrigated

Rainfed

Plant cane

Plant cane

400

300

280

280

400-450

400-450

N in 2 split applications

 

 

Leaf Analysis

Leaf analysis may be considered a method, which evaluates the soil supply of available elements using the plant itself as an extracting agent. A general representation of the relationship between leaf concentration and cane yield is presented in fig.

 

Relationship Between Leaf Concentration and Cane Yield

(Prevot & Ollagnier, 1956)

 

The picture describes several situations, which may occur. Clockwise the following segments are shown:

 

  • Curve in "C" - Yield is increased but leaf level is reduced; this happens when the rate of dry matter production is higher than the velocity of uptake or transport of the element into the leaf tissue which causes its dilution
  • Zone Of Deficiency Or Adjustment - Only in this section is the relationship between leaf level and growth or yield is observed, and very often there is a linear relationship between increase in leaf concentration and yield;
  • Lower Critical Level - Usually a narrow band below which yield is reduced due to a shortage of the element
  • Zone Of Luxury Consumption - It is wider in the case of macronutrients like K, and much shorter in other cases such as that of B; leaf level increases wheras production remains constant, there is therefore, a waste of fertility or fertilizer;
  • Upper critical level - A zone which separates the yield plateau from the toxicity zone;
  • Zone of toxicity - Leaf content increases even further and yield drops, either as consequence of a toxic effect of the element, or as a result of unbalance among

 

In the agricultural practice, the goal is not the maximum physical production but rather the realization of the maximum economic yield (MEY). For this reason the concept of critical level or lower critical level was redefined with the introduction of an economical component: it is the range of an element in the leaf below which production is restricted and above which fertilizer application is no longer economical.

 

This means that above this physiological-economical critical level, both yield and leaf content of the element could rise in response to the fertilization. The increase in yield, however, does not pay the additional fertilizer and the cost of its transport and distribution. Thus levels of nutrients considered adequate for economic yield are presented in Table 15 & 16.

 

Table 15. Levels of Macronutrients Considered Adequate for Maximum Economic Yield

 

Country

Crop

% of dry matter

N

P

K

Ca

Mg

S

Australia

Plant

1.90-2.50

0.21-0.30

1.30-2.00

0.20-0.60

0.10-0.30

--

Ratoon

1.90-2.50

0.21-0.30

1.30-2.00

--

--

--

Brazil

Plant

1.90-2.10

0.20-0.24

1.10-1.30

0.80-1.00

0.20-0.30

0.25-0.30

Ratoon

2.00-2.20

0.18-0.20

1.30-1.50

0.50-0.70

0.20-0.25

0.08-0.35

British Guyana

Plant

2.1

0.21-0.35

1.25-2.00

0.15-0.20

0.12-0.18

0.08-0.35

Ratoon

1.9

0.21-0.35

1.25-2.00

0.20-0.24

0.12-0.18

--

Colombia

--

1.80-2.00

0.25-0.35

1.60-1.80

> 0.25

> 0.20

--

India

--

1.96

0.086

1.99

--

--

--

Puerto Rico

--

1.60-2.00

0.18-0.24

1.55-2.00

--

--

0.13

South Africa

--

1.70-1.90

0.10-0.20

1.05-1.10

0.15-0.18

0.08

0.12-0.13

USA

--

1.50-1.75

0.18-0.22

1.25-1.75

0.28-0.47

0.14-0.33

0.13-0.18

Reuter (1986), Malavolta (1986), Evens (1967), Garcia Ocampo (1991), Srivastava (1992),

Samuels (1971), Gosnell & Long (1971), Anderson & Bowen (1990)

 

 

Table 16. Levels of Macronutrients Considered Adequate for Maximum Conomic Yield 

 

Country

Crop

%

B

Cl

Cu

Fe

Mn

Mo

Si

Zn

Australia

--

--

--

2

50

--

--

--

10

Brazil

Plant

9-30

--

8-10

200-500

100-250

0.15-0.30

--

25-50

Ratoon

9-30

--

8-10

80-150

50-125

--

--

25-30

British Guyana

--

2-10

 smaller
than 0.5%

5-100

4-15

20-200

0.08-1.0

--

15-50

South Africa

--

1.6-10

49-915

3-12

15

--

12-25

USA

--

3-8

0.068%

7-600

20-21

14-235

0.05-4

1.5-4%

19-38

Anderson & Bowen (1990), Malavolta (1982), Evens (1967), Wood (1987),

Scroeder et.el (1983), Anderson & Bowen (1990)

 

Fertigation Programme

The aim of the fertigation programme is to cover the difference between requirement and supply, that is:

 

(M) Fertilizer = [M (requirement - supply)] f

 

Wherein M = a macro or micronutrient, f = is a factor higher than 1 destined to compensate for losses due to volatilization, leaching, fixation and immobilization.

 

Whenever the soil supply is lower than the crop requirement, fertilizers have to be added in order to increase and to keep M (in soil solution) at a level compatible with the plant needs. In order to make practical fertilizer recommendations, we have to answer several questions, namely:

 

What? Which Element(s) is (are) Limiting Growth and Production; How Much? What Quantity Has to be Added?

The capacity of the soil to supply nutrients can be evaluated through leaf analysis already dealt with, and more frequently via soil chemical analysis. Further the cation exchange capacity, clay content, efficiency factor etc have to be considered to quantify the nutrient requirement.

 

When? In What Stages Fertilization is to be Done?

As shown in fig. accumulation pattern as a function of crop ontogeny has to be taken in to account for timing of fertilizer application. Both nitrogen and potash fertilizers tend to increase the osmotic pressure of the soil solution which when too high could damage the seed cane or the roots. Nitrogen in mineral forms can be leached from the rhizosphere. The same is true for K in the case of soils with low CEC. These facts seem to point out the need to apply only part of the N requirement at planting and doing the same for potash in sandy soils.

 

Nitrogen requirement of sugarcane is greatest during the tillering (formative) phase. This is required for adequate tiller production and canopy development. Tillering in field grown sugarcane commences around 30 to 45 days after planting. Therefore, adequate N supply should be made available to the crop in the soil from the start of tillering phase. Further, crop requirement for N is higher in early grand growth period.

 

This facilitates cane formation; checks tiller mortality and promote cane growth. Application of more N at later phase of active crop growth period not only promotes late tiller formation, but also affects sugar recovery due to reduced juice sucrose (Pol) percent, increase in soluble N in juice, water shoot formation besides attracting pests and diseases.

 

Phosphorus need of sugarcane is greater in the formative phase of the crop. Thus, the optimum time of P application is during initial stages of crop growth. Therefore, sufficient P must be made available in the soil during formative phase for absorption by the crop.

 

Potassium applications are usually done along with N application. This is because of better utilization of N by the crop in the presence of K; therefore, potassium should be applied along with N. However, late application of K at around six months has also been found to improve sugar recovery.

 

In general all the phosphorus should be applied before 4 months, nitrogen before 6 months and potassium before 7 months period. Relative requirement of NPK (%) at different crop growth stages is shown in Fig.

 

Relative requirement of NPK at different crop growth stages of sugarcane (Bachchhav, 2005)

 

How? What is the Most Efficient Way of Fertilization?

The efficacy of fertilizer depends on several factors, such as: process of contact between the element and the root, distribution of the root system, type of crop (plant crop or ratoon) and spacing, type of fertilizer and application rate. Root interception, mass flow and diffusion make the following percent contributions to the total of the element, which reaches the root surface: N (1, 99 & 0), P (2, 4 & 94); K (2, 20 & 78). While in the case of nitrogen mass flow plays an almost exclusive role for the contact, diffusion is the chief mechanism (94%) for P and for K (78%). It follows therefore that as long as P is placed adequately, both N and K will be taken equally well. Thus from the above it appears that fertigation is the best option of fertilization.

 

With what? Which fertilizers are to be Used?

Table 17 lists the main water soluble fertilizers used in the sugarcane world. It is desirable to use water soluble specialty fertilizers in view of the following features:

 

Table 17. Fertilizers Suitable for Fertigation Via Drip Irrigation System

 

Nutrient

Water soluble fertilizers

Nutrient content

Nitrogen

Urea

Ammonium Nitrate

Ammonium Sulphate

Calcium Nitrate

Magnesium Nitrate

Urea Ammonium Nitrate

Potassium Nitrate

Monoammonium Phosphate

46-0-0 

34-0-0 

21-0-0  

16-0-0  

11-0-0  

32-0-0 

13-0-46

32-0-0  

Phosphorus

Monoammonium Phosphate

Monopotassium Phosphate

Phosphoric Acid

12-61-0 

0-54-32

0-82-0

Potassium

Potassium Chloride

Potassium Sulphate

Potassium Nitrate

Potassium Thiosulphate

Monopotassium Phosphate

0-0-60

0-0-50 

13-0-46

0-0-25

0-52-34

NPK

Polyfeed

19-19-19

20-20-20

Micronutrients

Fe EDTA

Fe DTPA

Fe EDDHA

Zn EDTA

Ca EDTA

Rexolin CXK (B+Cu+Fe+Mn+Mo+Zn+Mg)

13

12

6

15

9.7

---

 

  • Free from chlorides and sodium
  • No salt build up in the crop root zone
  • Contain 100% plant nutrients
  • Fast acting nitrate nitrogen, soluble phosphorus and soluble postassium
  • Completely water soluble with any residues
  • Most of the fertilizers are acidic in nature, hence no special chemical treatment is required to check emitter plugging
  • Maintain optimum soil pH contributing to more uptake of nutrients
  • Most of the fertilizers are blended with micronutrients


Effect on Quality? Not Only Total Tonnage of Millable Stalks are to be Considered, the Effect of the Fertilizer on Sugar Yield Has Also to be Taken into Account:

It is well known that "sugar is made in the field, not in the factory". Sugar formation and accumulation is a function of several variables viz., variety and age or duration of the crop cycle, climatic conditions, soil fertility and fertilization. The effect of fertilization of course reflects to a large extent the role played by the nutrient in the physiological process within the plant, particularly photosynthesis, transport and accumulation of sucrose (the sink source relationship).

 

Increase in the rate of N raises yields of stalk and sugar until yield reaches a maximum. If N is applied in excess of the optimum, sugar production may drop. Timing of N application has a profound influence on sucrose content at harvest. N application at beginning of vegetative growth has no negative effect on sucrose content. However, late application at 10 months caused a decrease in sugar yield of 14 g per stalk when compared to the application before 7 months.

 

Higher rates of P (100 kg P2O5/ha) application can reduce yield, sugar concentration, pol % and purity, particularly in ratoons and in soils not deficient in phosphorus. On the other hand, in P deficient soils higher p levels increase pol % and purity. The amount of P in cane juice has an effect on clarification and should be in the range of 132 to 264 ppm P when lime is used for clarification. Other methods of clarification may need lower values.

 

Potassium application raises millable stalk yield, sugar % of cane and in brix % juice also. K deficiency impairs sucrose transport from the leaf into the stalk (Fig.). There is a positive interaction between N and K - the reduction in sugar content caused by high rates of N is ameliorated by an adequate supply of K. Excessive dosages of K i.e., over and above optimal rates may exert a negative effect on apparent sucrose percent in cane (pol % cane) and may promote an increase in the ash content of juice. Increased ash content in cane juice has a negative influence on sugar quality since K is the main constituent of juice ashes.

 

When k exceeds 1000 ppm in juice it is undesirable and affects manufacturing process. Potassium passes through the clarification process affecting the exhaustion of the final syrup, keeping a certain amount of sucrose in solution. K is a mellassigenic substance because one mol of K holds one molecule of sucrose. The unfavourable effects of K however, should be anticipated only when excessive rates are used; in low potassium soils improvement in cane quality are to be expected, as shown in Fig.

 

Effect of K Supply on Sucrose Yield, Sucrose and Fibre Content 
(Malavolta, 1994)

 

Considering the above factors a model fertigation progremme is given in Table 18 for 12 months crop and Table 19 for 14-16 months crops. This is only a guideline, based on the local soil, variety, climatic and management factors necessary adjustments can be made to the programme.

 

Table 18. Fertigation Schedule for Seasonal (12 months)/Ratoon Sugarcane

 

Days After Planting

Nutrients (kg/ha/day)

N

P2O5

K2O

1-30 Days

1.20

0.10

0.20

31-80 Days

1.50

0.40

0.24

81-110 Days

2.00

1.00

0.40

111-150 Days

0.75

0.30

0.75

151-190 Days

--

1.50

 

Table 19. Fertigation Schedule for Preseasonal (14 to 16 months) Sugarcane

 

Days After Planting

Nutrients (kg/ha/day)

N

P2O5

K2O

1-30 Days

1.5

0.15

0.25

31-80 Days

2.0

0.60

0.30

81-110 Days

2.5

1.50

0.50

111-150 Days

0.75

0.50

1.0

151-190 Days

--

1.80

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