sugarcane cultivation |
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Introduction |
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Sugarcane, Saccharum officinarum L., an old energy
source for human beings and, more recently, a replacement of fossil fuel
for motor vehicles, was first grown in South East Asia and Western
India. Around 327 B.C. it was an important crop in the Indian
sub-continent. It was introduced to Egypt around 647 A.D. and, about one
century later, to Spain (755 A.D.).
Global Distribution of Sugarcane (Click to Enlarge)
Since then, the cultivation of sugarcane was extended to
nearly all tropical and sub-tropical regions. Portuguese and Spaniards
took it to the New World early in the XVI century. It was introduced to
the United States of America (Louisiana) around 1741.
Botanically, sugarcane belongs to the Andropogonae tribe
of the family Gramineae, order Glumiflorae, class Monocotyledoneae,
subdivision Angiospermae, division Embryophita siphonogama. The subtribe
is Sacharae and the genus, of course, Saccharum, derived from the
Sanskrit "sarkara = white sugar", a reminder that the plant reached the
Mediterranean region from India.
Sugarcane growing countries of the world lay between the
latitude 36.7° north and 31.0° south of the equator extending from
tropical to subtropical zones. This map depicts the distribution of
sugarcane in the world.
Worldwide sugarcane occupies an area of 20.42 million ha
with a total production of 1333 million metric tons (FAO, 2003).
Sugarcane area and productivity differ widely from country to country
(Table 1). Brazil has the highest area (5.343 million ha), while
Australia has the highest productivity (85.1 tons/ha). Out of 121
sugarcane producing countries, fifteen countries (Brazil, India, China,
Thailand, Pakistan, Mexico, Cuba, Columbia, Australia, USA, Philippines,
South Africa, Argentina, Myanmar, Bangladesh) present 86% of the area
and 87% of production (Table 1). Out of the total white crystal sugar
production, approximately 70% comes from sugarcane and 30% from sugar
beet.
Table 1. Sugarcane In The world: Area, Production And Productivity
Country
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Area
(million ha)
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Production (million tons)
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Productivity
(Tons/ha)
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Brazil
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5.343
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386.2
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72.3
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India
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4.608
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289.6
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62.8
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China
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1.328
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92.3
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65.5
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Thailand
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0.970
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64.4
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66.4
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Pakistan
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1.086
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52.0
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47.9
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Mexico
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0.639
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45.1
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70.6
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Colombia
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0.435
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36.6
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84.1
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Australia
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0.423
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36.0
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85.1
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USA
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0.404
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31.3
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77.5
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Philippines
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0.385
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25.8
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67.1
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Indonesia
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0.350
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25.6
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73.1
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Cuba
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0.654
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22.9
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35.0
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South Africa
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0.325
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20.6
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63.4
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Argentina
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0.295
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19.2
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65.2
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Myanmar
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0.165
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7.5
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45.4
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Bangladesh
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0.166
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6.8
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41.2
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WORLD
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20.42
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1333.2
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65.2
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Sugarcane is a renewable, natural agricultural
resource because it provides sugar, besides biofuel, fibre, fertilizer
and myriad of by products/co-products with ecological sustainability.
Sugarcane juice is used for making white sugar, brown
sugar (Khandsari), Jaggery (Gur) and ethanol. The main byproducts of
sugar industry are bagasse and molasses.
Molasses, the chief by-product, is the main raw
material for alcohol and thus for alcohol-based industries. Excess
bagasse is now being used as raw material in the paper industry.
Besides, co-generation of power using bagasse as fuel is considered
feasible in most sugar mills.
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For higher sugarcane yields, providing
optimum soil environment is an essential pre-requisite since the crop
remains in the field for about 5 to 6 years due to the practice of
raising several ratoon crops.
Good Land Preparation
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Improper Land Preparation
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Further intense mechanization involving traffic of heavy
machinery from planting to harvesting and transporting to the sugar
mill or distillery, can cause the deterioration of soil physical
conditions. This translates into soil compaction with a cohort of
harmful side effects viz., reduction in storage & movement of air
and water, mechanical difficulty for root growth and difficulty in
absorption of nutrients from the soil itself and from the fertilizer.
Therefore a through land preparation every time a new
crop is planted is absolutely essential to bring the soil to fine tilth
for proper germination of the sets and field emergence and root growth.
Tillage is the physical manipulation of the soil with appropriate implements to loosen the surface soil layer.
Objectives of Land Preparation
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To prepare a seed bed which permits optimal soil water air relations
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Good physical conditions for early root penetration and proliferation
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To incorporate preceding crop residues and organic manures
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To destroy weeds and hibernating pest & disease organisms
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To facilitate proper soil chemical and microbial activity
Tillage operations through tractor drawn implements are
most ideal and quick. For initial ploughing use either mould board
plough or disc plough. Whenever, soil turning is desired, a mould board
plough should be used.
On the other hand when the soil is hard, uneven and
composed of crop stubbles, a disc plough is preferable. Ploughing at
optimum soil moisture content is very essential to achieve tilth. Too
wet soil interrupts movement of machinery and causes destruction of soil
structure.
On the other hand too dry soil will not allow tynes to
penetrate deep and results in frequent mechanical breakdowns, increased
power requirement and cloddy soil surface affecting soil water air
relations.
Without Subsoiling
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With Subsoiling
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The secondary tillage operations are carried out using
disc harrows, tyned harrows or rotavator. The rotavator is a very useful
multi purpose implement, which cuts the crop residues, shred them and
incorporates in the soil in one pass. Use mechanical methods (subsoiling
or chiseling or deep ploughing) or biological means (green manuring
between last ratoon harvest and start of a new crop) to destroy the
compacted layer and to allow roots to develop normally. Subsoiling was
also shown to reduce fuel consumption, working time and facilitate
optimum plant population.
Steps in Land Preparation Involve the Following:
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Subsoiling or chiseling to a depth of 50 to 75 cm to break hard compact sub-pan layer
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Ploughing to incorporate previous crop's crop residues and organic manures
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Discing to break clods
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Land shaping to provide the required gradient for draining excess water during rainy season
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Field layout - Construct ridges & furrows and
shape them. Depth of furrows should be 25 cm. The furrow bottom should
be loosened to about 10 cm.
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Provide drainage channels, which are deeper than the
furrows along the field borders as well as within the field at regular
intervals. Drainage channels are particularly important in the high
rainfall areas to drain the excess water during rainy season.
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Table 7 summarizes the power requirement and output during land preparation.
Table 7. Sugarcane: Power Requirement and Work Ouput for Land Preparation
Operation
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Power requirement/ha
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Output (ha/hr)
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kWatts
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Diesel (Litres/ha)
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Pre-discing
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125
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18
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2.5
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Ripping
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165
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48
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0.5
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Ploughing
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165
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24
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1.7
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Post-discing
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125
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18
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2.5
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Land leveling
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125
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7
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3.5
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Ridging
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70
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16
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0.5
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Planting Material |
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Sugarcane is vegetatively propagated for commercial
cultivation. Different kinds of planting materials viz., cane setts;
settlings and bud chips are used for raising sugarcane crop.
Cane Setts
Stem cuttings or sections of the stalks are called
"setts" or seed pieces. Each sett contains one or more buds. Always use
fresh, genetically pure, pest and disease free setts as seed material.
Generally, three bud setts are used for planting throughout the world,
while in some areas two-bud setts are also used.
Three Bud Sett (Source: Verma, 2004)
Experimental evidence shows that germination percentage
of 3-bud setts is higher than the setts having more or less than 3-buds.
The middle bud of a 3-bud sett has the highest germinating capacity
followed by top end bud and the bottom end bud, respectively (Verma,
2004). The middle bud has an advantage in germination because, as a
non-terminal bud having nodes on either side, its moisture resources are
better protected than those of the terminal buds.
Middle bud showing the highest germinating capacity in 3-Bud Sett
(Source: Verma, 2004)
Germination capacity of single-bud sett is very poor due
to loss of moisture from cut ends on either side. Further the plants
arising from single-bud setts also lack vigour and yield low as compared
to those from three-budded setts. Thus the preference given to
three-budded setts over single-bud setts is partly based on germination
capacity and partly on initial vigour of the germinated plants and cane
yield.
If whole cane stalk is planted without being cut into
setts, usually few buds at its top end germinate and the lower end buds
remain inactive due to top dominance. The effect of top dominance is
eliminated when stalk is cut into pieces.
Settlings
Cane setts with roots and shoots are known as settlings.
Settlings can be raised either in nursery beds or in polythene bags.
Single node settlings are used as a planting material in spaced
transplanting technique of raising sugarcane crop.
Single bud settling (Source: Verma, 2004)
Bud Chips
Little portion of stem with one bud
is known as bud chip. Bud chips are used to raise settlings in nursery.
They were found to produce a good crop when transplanted in main field.
The principal advantage of bud chips is substantial saving in seed
material. Seed requirement is reduced to less than one ton per ha.
Adopting the following procedure raises settlings from bud chips:
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Prepare the bud chips from whole cane using a sharp edged knife in such a way that each bud has a little portion of stem
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Plant the bud chips on raised nursery beds adopting a inter-row spacing of 7.5 cm at the rate of 300 buds/m2
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Alternatively nursery can be raised in polybags of 15 cm x 10 cm size
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Fill the polybags with homogeneous mixture of equal quantity of soil, sand and well rotten compost
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Plant the bud chips in polybags with the bud facing upwards and cover with soil mixture to avoid drying of the bud
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Bottom of the bags should have holes to facilitate drainage
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Ensure regular watering of bags or nursery area
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Settlings are ready in 5 - 8 weeks for transplanting in the main field
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Under good management conditions establishment of transplanted seedlings in the main field is high (90-100%)
Raising of Seed Cane Crop
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normal practice in many parts of the world is to use commercial crop of
sugarcane for seed purposes. Characteristics for good seed are seldom
taken into consideration. Many growers do not care for seed quality and
many of those who do, select the seed only at the sett cutting and
planting stage. This is not enough. If a grower wants to be sure of
getting good and disease free seed cane he should raise the seed crop
separately. This crop should be kept completely free from pests and
diseases by constant field scouting from the very beginning.
Moreover, seed quality is not merely a matter of pest
and disease freedom. Seed has to be in high water content and of good
nutritional status. Neglect in raising good seed crop is one of the
major defects in sugarcane cultivation all over the world. (In the picture above: Bud Chip)
Use of sugarcane seed from the commercial crop has been
responsible for rapid multiplication of a large number of diseases like
red rot, wilt, smut, ratoon stunting and grassy shoot which adversely
affect the cane yield and quality. It is, therefore, raising of healthy
and vigorous sugarcane crops for seed purpose is essential and
recommended.
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Select an upland field for raising seed crop with no
soil problems (soil salinity, acidity, waterlogging etc) and adequate
irrigation facility
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Prepare the soil thoroughly and incorporate 20-25 tons/ha of FYM 15 days before planting
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Provide field channels and field drains to prevent rain water traversing from adjoining field to check spread of red rot disease
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Select seed material from previously raised seed
nursery crop and prepare the setts. Use only sterilized setts to avoid
transmission of certain diseases like RSD and GSD
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Give heat treatment (heat therapy) to eliminate seed
borne diseases and organomercurial treatment to protect the setts from
soil borne diseases to ensure better germination
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Adopt narrow spacing of 75 cm to obtain higher yield of setts per unit area
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Use 25% higher seed rate than normal cane crop
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Apply higher nutrient dose of 250 kg N + 75 kg P2O5 + 125 kg K2O/ha
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Irrigate the crop at optimum levels to avoid any water
stress during crop life taking in to account evaporative demand of the
atmosphere (ETo) and Crop characteristics (Kc) at different crop growth stages
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Provide weed free environment for better growth of the crop and also to avoid infestation of pests and diseases
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Adopt field scouting for timely control of pests and diseases
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Rouge out the affected clumps and plants of other varieties
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Protect the crop from lodging, binding and propping
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Crop is ready in 7 - 8 months. Setts obtained from
such crop contain healthy and sound buds, higher moisture content,
adequate nutrients, higher amounts of reducing sugars, therefore,
establish quickly and grow vigorously thus ensuring a good commercial
main field crop.
Preparation of Setts for Main Field Planting
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Harvest the seed crop one day before planting to obtain higher percentage and uniform germination.
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Prepare the setts always one day before planting by giving sett treatment.
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Planting material or seed cane should be free from aerial roots and splits.
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Avoid damage to buds while cutting setts.
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Change the seed material after every two to three
seasons. In case if it is inevitable to use mature cane as seed, the top
one-third portion can be used satisfactorily.
Ideal Seed Cane
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Always use seed cane obtained from a seed crop of 7-8 months
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Free from disease and pest infestation like red rot, wilt, smut, ratoon stunting disease etc
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Possesses healthy buds without any damage in handling and transport.
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Buds with higher moisture content, adequate nutrients, higher amount of reducing sugars and viability.
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Free from aerial roots and splits.
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Pure in quality.
Seed Cane Treatment
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Objective:
To protect the crop from soil borne diseases causing pathogens, which
usually gain entry into the setts through the cut ends following
planting and cause sett rotting and damage to buds, thus affecting
germination.
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Most farmers don't treat the setts before planting
which results low plant population per unit area consequently reducing
the yield
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Treat the setts soon after cutting in 0.1% (at 1g/liter) Carbendazim solution for 15 minutes.
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Three
important diseases viz., grassy shoot disease, smut and ratoon stunting
disease are carried forward through seed cane material. These diseases
lead to progressive decline in yields and degenerate sugarcane
varieties. For control of these diseases treat the seed material (setts)
with moist hot air at 52°c for 30 minutes.
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To control termites early shoot borer and scale
insects treat the setts in a systematic insecticide viz. Malathion 50EC
(at 2 ml/liter) or Dimethoate 30EC (at 3 ml/liter) for 15 minutes.
In the Pictures above:
Sett treatment with fungicide against soil borne pathogens + moist hot
air treatment of setts against seed borne diseases
In the picture below: Termite damaged setts (Source: Verma, 2004)
Seed Rate
Under
drip irrigated paired-row system of planting [(0.6m + 1.20m) x 0.12m],
about 60,000 two-bud or 40,000 three-bud treated setts would be required
to plant one ha of land. With proper germination of buds, this seed
rate is adequate to give a gapless stand and raise a successful crop.
Nearly 10-12 tons of seed cane
is required to plant one ha of field. However, it is better always to
go by number of setts per ha rather than weight basis as sett weight in
sugarcane varies largely with varieties.
Measures to obtain higher germination
Some important yet simple measures to obtain higher uniform plant population are as follows:
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Using quality setts as seed material obtained from a short seed crop devoid of any primary infection
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Using preferably two eye bud setts instead of three bud setts as seed material
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Careful preparation of setts without damaging the buds or setts
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Using sterilized knives for preparing setts to avoid transmission of root stunting and grassy shoot diseases
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Planting freshly prepared and treated setts
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Giving adequate and frequent irrigation's during germination phase
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Control of weeds through pre-emergence herbicides
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Seed treatment with fungicide and pesticides
Transplanting Technique
Seedlings
are raised in a nursery bed using single bud setts. When the seedlings
are of about 6 week old, they are transplanted in the prepared main
field.
In the pictures on the right and below (Source: Verma, 2004):
Advantages
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Saving in the seed cost as the seed requirement is only about 2-3 tons/ha against the normal seed requirement of 10-12 tons/ha.
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Synchronous tillering leading to uniform growth and maturity of stalk population, which usually gives better yield and sugar recovery.
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Sufficient time for main field preparation
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Saving in water and fertilizer
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Better weed management
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Harvesting Management |
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Harvesting of sugarcane at a proper time i.e., peak
maturity, by adopting right technique is necessary to realize maximum
weight of the millable canes (thus sugar) produced with least possible
field losses under the given growing environment.
On the other hand harvesting either under-aged or
over-aged cane with improper method of harvesting leads to loss in cane
yield, sugar recovery, poor juice quality and problems in milling due to
extraneous matter.
Therefore, proper harvesting should ensure:
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To harvest the cane at peak maturity (i.e., avoiding cutting of either over-matured or under-matured cane)
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Cutting cane to ground level so that the bottom sugar rich internodes are harvested which add to yield and sugar
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De-topping at appropriate height so that the top immature internodes are eliminated
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Proper cleaning of the cane i.e., removing the extraneous matter such as leaves, trash, roots etc.
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Quick disposal of the harvested cane to factory
Several standard analytical methods are available to
determine the peak maturity or quality so that the cane is harvested at
right time. Without such analysis also several farmers take-up cane
harvesting based on crop age and appearance. Sometimes farmers harvest
the crop even before the crop fully matures due to necessity to supply
cane to the mills early.
Likewise delays in harvesting are also quite common,
particularly when there is excess cane area. To avoid such extremes
harvesting should be done at right time employing right method. The
following criteria enable harvesting of cane at right time adopting
proper procedures:
Crop Age
Harvesting is done based on maturity (age) group.
Farmers who grow a particular variety are usually conversant with the
harvesting time. Even most sugar factories give cutting orders to
farmers based on crop age. This is not a scientific method since,
planting time, crop management practices, weather conditions etc
influences maturity.
Visual Symptoms
Yellowing and drying of leaves, metallic sound of mature
canes when tapped, appearance of sugar crystal glistening when a mature
cane is cut in a slanting way and held against the sun are some of the
visual indices of assessing maturity of cane.
Quality Parameters
Important sugarcane quality parameters for assessing cane maturity are the juice Brix, pol or sucrose percentage and purity.
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Juice Brix:
Juice Brix refers to the total solids content present in the juice
expressed in percentage. Brix includes sugars as well as non-sugars.
Brix can be measured in the field itself in the standing cane crop using
a Hand Refractometer. This is usually referred as a Hand Refractometer
Brix or HR Brix. In the field using a pierce collect composite juice
samples from several canes. Then place a drop of the composite juice
sample in the Hand Refractometer and measure the Brix reading.
The
circular field gets darkened relative to the Brix level, which could be
easily read. The HR Brix meter has graduations from 0 to 32 per cent.
The HR Brix readings can be separately taken from both top and bottom. A
narrow range indicates ripeness of the cane, while a wide difference
indicates that the cane is yet too ripe. On the other-hand if the bottom
portion of the cane has lower Brix value than the top, it means that
the cane is over-ripened and reversion of sugar is taking place.
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Juice Sucrose Or Pol Per Cent:
The juice sucrose per cent is the actual cane sugar present in the
juice. It is determined by using a polarimeter, hence sucrose per cent
is also referred to as pol per cent. For all practical purposes pol %
and sucrose % are synonyms. Now a days an instrument called sucrolyser
is also available for determining sucrose % in juice.
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Purity Coefficient:
It refers to the percentage of sucrose present in the total solids
content in the juice. A higher purity indicates the presence of higher
sucrose content out of the total solids present in juice. The purity
percentage along with sucrose percent aids in determining maturity time.
Purity Percentage = (Sucrose %/HR Brix)100
A cane crop is considered fit for harvesting if it has attained a minimum of 16% sucrose and 85% purity.
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Reducing Sugars:
The reducing sugars refer to the percentage of other sugars
(fructose and glucose) in the juice. A lower reducing sugars value
indicates that much of the sugars have been converted into sucrose.
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Commercial Cane Sugar:
The commercial cane sugar (CCS) refers to the total recoverable sugar
percent in the cane. This could be calculated by the following formula:
CCS (tons/ha) = [Yield (tons/ha) x Sugar Recovery (%)] /100
Sugar Recovery (%) = [S - 0.4 (B - S)] x 0.73
Where, S= Sucrose % in juice and B= Corrected Brix (%)
Manual Harvesting
In
many countries even today harvesting is done manually using various
types of hand knives or hand axes.Among the several tools the cutting
blade is usually heavier and facilitates easier and efficient cutting of
cane.
Manual harvesting requires skilled labourers as improper
harvest of cane leads to loss of cane & sugar yield, poor juice
quality and problems in milling due to extraneous matter. (In the picture: Manual harvesting of sugarcane)
Mechanical Harvesting
Harvesting labour is becoming scarce and costly in view
of diversion of labour to other remunerative work in industry,
construction, business
etc. Mill stoppages because of non-availability of canes are not
uncommon owing to shortage of harvesting labour. And, most of the new
mills are of higher crushing capacity and many are expanding their
crushing capacities. Therefore daily requirement of cane is increasing
and hence greater demand for harvesting labour.
Added to this most of the present day agricultural
labourers are not interested in field operations involving much
drudgery. Thus in years to come, the labour position is likely to
deteriorate further. Therefore mechanization is inevitable and hence,
adoption of mechanical harvesting of cane in future is inevitable.(In the picture: Mechanical harvesting of sugarcane)
In countries like Australia, Brazil, USA, South Africa, Taiwan,
Thailand etc where sugarcane cultivation is highly mechanized huge
harvesters are employed for cane harvesting. In these countries,
sugarcane is grown on large plantation scale in large farms owned by
either mills or big farmers. The field capacity of mechanical cane
harvesters varies with the size (2.5 to 4 ha per day of 8 hours.
The limitation of mechanical harvesters is use of such machines in
small, irregular and fragmented holdings, diversified cropping patterns,
limited resource capacity of small & marginal farmers in several
countries.
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