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Introduction
- The inorganic constituents of the tobacco plant range
from 15 to 25% of its dry matter, the distribution being about
50% in the leaf, 30% in the stem and 20% in the roots.
- The mineral content varies widely, depending on soil and climatic
conditions, in different types and varieties of tobacco.
- The major nutrients essential for growth and development of
tobacco plant are nitrogen, phosphorus, potassium, calcium,
magnesium and sulphur.
- The minor elements equally essential but in micro-quantities
are boron, manganese, iron, zinc, molybdenum and copper.
- Chlorine is also recognized as an essential micro nutrient
for tobacco.
- When the supply of these elements become limited, the plants
exhibit characteristic symptoms of deficiency.
- A tobacco crop yielding about 1000 kg/ha removes approximately
90-22-120 kg NPK/ha.
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Nitrogen
- Nitrogen plays a key role in the production of tobacco.
Nitrogen requirement for different types of tobacco varies
widely. It is 20 kg N/ha for FCV tobacco on black clayey soils,
180 Kg N/ha for bidi-tobacco and 200 Kg N/ha for chewing tobacco
in sandy clay loam soils.
Nitrogen deficiency results in
- Progressive loss in green colour starting in the older leaves.
- Reduction in growth resulting in the stem with pale, small
leaves which grow upright.
- Maturity is delayed and cured leaf is thin, pale and lacks
in texture with much lower nitrogen and nicotine contents
and lower yields.
Excess of nitrogen, results in
- Large, dark-green leaves.
- Profuse sucker-growth and higher proportion of stalk of leaf
and midrib to lamina.
- Ripening is delayed.
- Cured leaf is dark, trashy, thick and immature, with high
nicotine and nitrogen and low sugars, though the yields are
increased.
- Tobacco plant can utilise both the forms of nitrogen, depending
on the soil conditions.
- While alkaline reaction, presence of bicarbonate and non-sterile
conditions favour NH4-N, (Ammoniacal nitrogen) acidic reaction
and sterile conditions favour NO3-N (Nitrate nitrogen)
- Plants supplied with nitrogen in NH4- form were found to contain
less K in the leaves compared with plants supplied with nitrogen
in NO3- form.
- Addition of nitrate to the soil, as and when the crop needs,
is beneficial to the crop as it becomes quickly available
to the plant, encourages uptake of potassium and favourably
influences the concentration of organic acids in the plant.
- Ammonical nitrogen decreases the uptake of potassium and increases
in the nicotine content of leaf.
- Application of organic manures in the form of FYM, filter-press
cake or pig manure to supply 20 Kg N/ha is found to give good
yield without affecting quality.
- Groundnut cake, though increases the yield, had a depressing
effect on bright grades as well as quality.
- Organic nitrogen is considered to prevent tobacco from ripening
too rapidly by maintaining a more uniform nitrogen level.
Dosage
Dosage also depends on the type of tobacco
|
Type of tobacco
|
Nitrogen (kg/ha)
|
| Flue-cured Virginia in
heavy soils of Andhra Pradesh |
40-45 |
| Flue-cured Virginia of
light soils of Andra Pradesh |
40-70 |
| Natu tobacco of Andra Pradesh |
44 |
| Bidi in Karnataka |
45 (as Ammonium sulphate) |
| Bidi in Gujarat |
90 (as Ammonium sulphate) |
| Chewing in Tamil Nadu |
100 (as Ammonium sulphate) |
| Cigars and cheroot in Tamil
Nadu |
50 (As Ammonium sulphate) |
| Chewing in Bihar |
56 (As Ammonium sulphate) |
| Hookah and chewing tobacco
in Uttar Pradesh |
150 |
| Wrapper tobacco in West
Bengal |
125 |
Methods of application
- For majority types of tobacco nitrogen is applied as basal
i.e. 1st week before planting.
- But for FCV tobacco grown in light soils of Andhra Pradesh,
Cigar, chewing and cheroot tobacco in Tamil Nadu and for chewing
tobacco in Bihar, nitrogen is applied in two equal splits.
- 50% of the N is applied on 45th day and the remaining 50%
at 60th day after transplanting.
- In Tamil Nadu, application of half of the recommended N through
foliar spray of urea at 2% (20g / lit) concentration three
times at an interval of 10 days starting from 60th day increases
the cured leaf yield by 6-12%.
- By seedling dipping and soil application of azospirillum,
about 25% of recommended N can be saved.
- Experimental results at Agricultural Research Station, Bhavanisagar
revealed that application of 50% recommended N either as poultry
manure or neem cake or enriched coir pith and top dressing
the remaining 50% recommended N as urea in two equal splits
on 45th and 60th day after transplanting recorded 25 –
30% higher yield over 100% N as urea alone.
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Phosphorus
- The requirement of phosphorus by flue-cured tobacco is
generally low.
- It ranges from 20 to 40 kg/ha. Only 10% of the applied phosphorus
is recovered by the tobacco crop.
- The content of phosphorus in tobacco leaf ranges from 0.5
to 0.9%, which under deficient supply goes down to 0.3%.
Available phosphorus is abundantly needed in the early stages
of growth.
- The plant absorbs 50 per cent of the requirement, when only
20% of the growth has occurred. Phosphorus application was
found to hasten the growth and bud initiation.
- The tobacco plant depends mostly on the applied fertilizer
for its phosphorus requirement in the initial stages of growth.
- It is reported that 40-90% of the phosphorus requirement of
the plant is met with by applying fertilizer four weeks after
the transplanting.
- Response to phosphorus was not observed in black cotton soils
in India. This was attributed mainly to the fixation of phosphorus
as calcium phosphate.
Deficiency symptoms
- Plants were very much stunted in growth.
- Deficient phosphorus supply tend to produce dark colours of
dull luster in the cured leaf.
- Phosphorus in general improves the colour of flue-cured tobacco.
- In moderate quantities, phosphorus hastens the growth, maturity
and improves the quality of tobacco.
- But at higher doses, yields get reduced, leaves get undesirably
thickened and produce a black ash.
- Phosphorus is positively related to sugar content.
- Better utilization of phosphorus takes place when applied
along with nitrogen and particularly when the fertilizers
are applied as a band at a depth of 15 cm.
Dosage
- 30 kg/ha for FCV tobacco grown in Heavy soils of Andhra
Pradesh
- 60-80 kg/ha for FCV tobacco grown in light soils of Andhra
Pradesh
- For chewing tobacco in Tamil Nadu 100 kg P2O5 /ha as super
phosphate in conjunction with sieved farm yard manure (FYM)
or night soil compost (NSC) at 1:4 ratio, i.e. 625 kg super
phosphate + 2500 kg FYM or NSC is recommended as basal application
at transplanting.
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Potassium
- Potassium is essential for the normal and healthy growth
of tobacco plant.
- Potassium content as potassium (K2O) ranges from 2.5 to 7.0%
in the leaf. When it falls below the range of 0.5 to 2.5%,
deficiency symptoms appear on the plant.
Deficiency symptoms
- Yellow mottling on leaf just before maturity which spreads
inwards from the tip and later from the sides of the leaf.
- Rim-firing and stunted growth in case of severe deficiency.
- Potassium deficiency may be accentuated by excess nitrogen,
particularly in ammonical form, and by high levels of magnesium
or sulphur.
- The quality parameters that are related to potassium are physical
appearance and burning quality.
- As the rate of available potassium is increased, the potassium
content of cured leaf increases and the concentration of calcium
and magnesium generally decreases.
- Among the different sources of potassium, potassium sulphate
or potassium nitrate are preferred but not potassium chloride.
Dosage
- For chewing, cigar and cheroot tobacco in Tamil Nadu -
applied in two equal split doses along with N at 45 and 60
days after planting.
- For FCV tobacco grown in heavy soils of Andhra Pradesh –
50 kg/ha
- For Hookah and chewing tobacco in West Bengal – 80 –
100 kg/ha
- For Wrapper tobacco in West Bengal – 112-125 kg/ha
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Micronutrients
- Micronutrients such as Boron, Manganese, Iron, Zinc, Copper,
Molybdenum and Chloride are considered important in influencing
the yield and quality of tobacco.
- Micronutrients play a significant role in influencing the
yield and quality of tobacco.
- Micronutrients act as co-factors in several enzyme systems
(like catalases, peroxidases, polyphenol oxydases etc.) that
bring about certain vital transformations during curing effecting
the final quality of the leaf.
- Micronutrients when present in toxic or deficient quantities
change the quality of the tobacco leaf. Gray tobacco is attributed
to the toxic leaves of Fe, Mn and Zn.
- Copper deficiency causes metabolic changes in leaf at maturity,
resulting in low total sugars and high total and protein nitrogen
which leads to poor quality.
- Boron deficiency is considered injurious to leaf quality as
it hinders the translocation on carbohydrates.
- Micronutrient status of tobacco growing areas in India revealed
that the soils in general are having available micronutrients
higher than the critical limits except zinc in southern light
soils and boron in northern light soils.
- In some areas of northern light soils, Zn content of soil
is marginally lower than the critical limits. In traditional
black soils it is higher than the critical limits.
- In spite of low levels of micronutrients in some areas, the
leaf analysis showed sufficient quantities of micronutrients.
Chloride
- Chloride is an essential micro-nutrient for tobacco which
plays an important role in influencing the leaf quality and
leaf burn.
- One of the principle effects of chloride in growing leaf is
to increase water content and turgor, which inturn tends to
produce a larger, smoother and thinner leaf.
- When present in small quantities, it improves the yield and
certain quality factors like colour, moisture content and
keeping quality.
- Larger amount of chloride produces cured leaves of muddy and
uneven colour with excessive hygroscopicity and poor burn
and such leaf is commonly known as saline leaf.
- It has been reported that the burn and keeping quality of
leaf were adversely affected if the leaf chloride exceeds
2.0% and the leaf becomes nearly incombustible if the chloride
content exceeds 2.5%.
- The main sources of chloride supply are soil, fertilizers
and irrigation water. Soils containing > 100 ppm (100 mg
in 1 lit) of chlorides are not suitable for tobacco cultivation.
Irrigation waters containing > 40 ppm (40 mg in 1 lit)
are not suitable for irrigation.
- For chewing tobacco, the irrigation water should have high
potassium and moderate chloride contents.
Calcium
- The actual requirement of Calcium by tobacco plant appears
to be somewhat less than that for K under average conditions,
the content of Ca in the leaf exceeds that of K because of
its more abundant supply.
- The normal range of CaO in the leaf is 3.0 to 7.0% and in
stalk only 0.5 to 1.0%. Deficiency symptoms appear when the
CaO content in the leaf falls below the range of 0.3 to 1.0%
and in stalk below 0.2%.
- Calcium is essential for cell wall structure.
- It is generally present in the plants as insoluble salt.
- Calcium is acting to function as a general regulator of cell
metabolism, it may also function to prevent injury from an
excess of other ions.
Dose
- Normally calcium need not be applied to the crop. However,
it is being supplied with P in superphosphate.
- In acidic soils, liming is found to be beneficial.
Magnesium
- A normal tobacco plant contains MgO to an extent of 0.8%
of dry matter, 1.10% in the leaves and 0.35% in the stalk.
Deficiency symptoms
- Magnesium is a constituent of chlorophyll and Magnesium
deficiency is called as 'sand drown'. Magnesium-deficient
leaf when cured, produces chlorotic area which are relatively
dark and of uneven colour. The leaf tends to be thin, dry
and lifeless. Such a leaf when smoked produces dark coloured
ash.
- It is observed that upto 2% Mg in the leaf improves burn of
cigars and beyond that it has an adverse effect on this character.
- Supplying the soil with MgO fertilizer increases the total
water-soluble carbo-hydrates and decreases the albumins and
nicotine. The yield of dry matter in the leaves is considerably
increased.
- Application of 12-15 kg/ha Magnesium oxide as dolamite is
recommended to safeguard against magnesium deficiency which
may also sometimes occur under repeated irrigation or heavy
rainfall.
Sulphur
- Symptoms of sulphur deficiency are very similar to and
often mistaken for nitrogen deficiency. Deficiencies are most
likely in the early stages of plant growth.
- When the plant is low in available nitrogen, the lower leaves
are paler than the upper leaves and these lower leaves eventually
burn-up.
- However, sulphur deficient plants are pale from top to bottom
and lower leaves do not burn up. Sulphur deficiency can be
partly corrected with side dress application of fertilizers
such as potassium sulphate, magnesium sulphate, and ammonium
sulphate.
- Sulphur deficiency symptoms rarely occur because most of the
fertilizer applied to tobacco (Ammonium sulphate, single super
phosphate and potassium sulphate) contains sulphur.
- Sulphur is highly leachable element and the available sulphur
in soils is released from organic matter with high concentrations
in lower horizons.
- Therefore, sulphur deficiencies are most likely to occur in
the deep, sandy soils, which are low in organic matter.
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Hints For Tobacco Fertilization
- A high yielding variety uses fertilizer more efficiently
than local varieties at any level of fertilization, even in
years of subnormal rainfall.
- Get the soil analysed and apply NPK fertilizers as per requirement
of the crop.
- Complex fertilizers may be used for basal application. Unit
cost of nutrient is less for complexes than for straight fertilizers.
Potash should be applied as potassium sulphate only at all
times of application.
- Use any of the straight 'N' fertilizer for top dressing.
- Nitrogen is best applied in split doses for getting maximum
benefit. If applied at a time, losses due to leaching and
volatilization may be high. Nitrogen is to be applied according
to crop requirement during crop growth.
- Thorough incorporation is most essential when fertilizer is
applied basally.
- In case of light soils, have more split applications under
irrigation.
- Under unirrigated conditions, all fertilizers are to be applied
as basal dose. Proper nutrient balance need to be maintained
in addition to application of N.
- Phosphorus is applied as basal dose. Application of phosphorus
along with organic manure is beneficial.
- In light soils it is beneficial to apply nitrogen in 50 :
50 basis in ammonical and nitrate forms.
- Potash is generally high in black soils and low to medium
in light soils. It is applied in splits in light soils.
- In zinc deficient areas, zinc sulphate should not be applied
with phosphatic fertilizers. It can be applied 2-3 days before
or after application of P.
- In traditional black cotton soils, entire quantity of nitrogen
is to be applied as basal dose in plant row plough furrow.
- In light soils, nitrogen and potash are applied in split doses
and phosphorus as basal dose.
- Application of green manuring in situ or any organic manure
and inorganic fertilizers in 25 : 75% basis is always advantageous
in almost all the tobacco growing soils.
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