Everything you need to learn about sugarcane cultivation, harvest and growth.
Introduction to Sugarcane (Akh, Ganna):
Sugarcane (Saccharum officinarum L.), the main source of sugar in India, is believed to have originated in south-eastern Asia or Indonesia. It is probable that the plant has been grown in India for about 3000 years. Sugarcane is now cultivated in an area of about 3.37 million hectares in the country and this accounts for about 2 per cent of its total cultivated area. The quantity of white sugar produced in India in 1988-89 was approximately 8.8 million tonnes.
The sugarcane crop is cultivated in India in both sub-tropical and tropical regions. In the former, states of UP, Bihar, Haryana, Punjab, Rajasthan, West Bengal and Assam are important, and in the latter, Maharashtra, AP, Tamil Nadu, Karnataka and Gujarat are important.
While UP has the largest area under the crop, more than half the total acreage in the country, the production per hectare is very much higher in Karnataka, Maharashtra and AP. Besides India, Pakistan, Bangladesh, Cuba, Brazil. Mexico, West Indies and Australia are the other important sugarcane producing countries.
Saccharum officinarum L. belongs to the family Gramineae. It is a tall, erect and unbranched plant; culms about 2.6 m high, glabrous or with appressed hairs below the panicle and waxy below the nodes; culm solid with tough rind and numerous fibrous strands and sweet, sugary juice.
Leaves are long, flat, and linear-lanceolate, with thick midrib, scabrous above and on margins; sheath pubescent on the throat; ligules are very short, membranous and ciliate. Inflorescence is a large spreading panicle, dense, silvery silky. Spikelets are paired, linear and oblong, the primary one pedicelled and the secondary sessile, awnless with short callus covered with long hairs.
Florets 2; the lower reduced to an empty lemma and the upper hermaphrodite. Glumes equal, 3.5-4 mm long, lower with inflexed margins in sessile spikelet, papery, membranous and acute and entire; upper glume membranous and acute. Lemmas hyaline, as long as the spikelet in the lower empty floret, lanceolate, acute and membranous; lemma of upper hermaphrodite floret very reduced or absent; palea lanceolate, acute, and ciliate at the apex. Lodicules 2 are cuneate. Stamens 3 is Ovary superior, 1-celled with one ovule. Styles 2 laterally exserted. Stigmas plumose. Caryopsis is oblong.
Climate Required for Sugarcane Cultivation:
Sugarcane does best in tropical humid regions, where the temperature ranges between 25° and 50° C and the rainfall between 750 and 1200 mm. Temperatures higher than 50°C arrest the plant-growth and those lower than 20°C reduce its rate considerably. Severe frosts cause death of the plant.
The sugarcane crop can also be grown in sub-tropical areas, but, in case of extreme climate, when the dry season is long, the growth period is very much reduced and the yields are lower. In areas, where the rainfall is somewhere between 1200 and 1500 mm, as in parts of UP, Bihar, Orissa, W. Bengal and Assam, the crop does not need irrigation.
The crop requires a cool, dry season for ripening. If the rainfall is too heavy and prolonged, the quality of juice is poorer. Sugarcane is a sun-loving plant and light affects tillering profoundly. Of the different sugarcane-growing tracts, Maharashtra, parts of Karnataka and the Telengana areas of AP have ideal climatic conditions for the sugarcane crop.
Soil Required for Sugarcane Cultivation:
The crop can be grown on different types of soil, but it does best on medium heavy soils. It is cultivated in northern India largely on loams and clay loams, and, in Peninsular India, on brown or reddish loams, laterites and black cotton soils. Many heavy soils, which may have been made unfit for growing sugarcane by water-logging or alkalinity, are provided with proper drainage facilities to enable resumption of cultivation of the crop on them.
In areas, where the soils are heavy, addition of 70 to 100 cartloads of sand or red earth per hectare improves the texture. On the other hand, addition of tank silt increases the water- holding capacity of sandy soils.
Sugarcane is grown in rotation with wheat, cotton, gram, maize, jowar, etc., in northern India and mostly with paddy in eastern India. In southern India also, it is generally rotated with paddy. In many areas, sugarcane is grown in rotation with garden crops, like potatoes, chilies, sweet-potato, ginger, onion, turmeric, etc.
In certain localities near large towns, onion, radish, coriander, green cucumber and other quick-growing-vegetables are raised as companion crops on ridges or in interspaces, when the sugarcane crop is young. Growing of potato, dwarf wheat, sugar-beet, toria, berseem and turnip as companion crops in the interspaces of autumn-planted sugarcane is now becoming common in the northern parts of country.
Cultivation of Sugarcane:
The preparation of land has to be very thorough and clean. Soils, in which sugarcane is raised in Peninsular India, are mostly clays and clay loams and they are prepared by one or two deep ploughings and one cross-ploughing, preferably with a mouldboard plough.
These are followed by clod crusher. In the alluvial loams of the north, land preparation is usually done after winter rains. A preparatory irrigation is necessary before ploughing if these rains fail. At the right stage of moisture, a desi plough is used to prepare the land thoroughly and bring the soil to a fine tilth.
Cattle manure, compost and other organic manures are usually incorporated into the soil much before planting is done. If green-manuring is done, the leguminous crop is ploughed under about a month before sugarcane is planted.
Sugarcane is propagated by setts (also known as seeds) obtained by cutting the cane stalks. Before planting, the leaves of the stalks are removed, taking care not to damage the buds, and then the stalks are cut into 30 to 50 cm long pieces, each with 3 buds. The stalks selected for the purpose should be free from diseases and pests.
The top one-third to half of a cane, which is comparatively immature and has buds with good viability, should preferably be used as setts or seeds. In order to prevent rotting and infection of setts with diseases, which is common in Peninsular India under irrigated conditions, the setts should be dipped into a suitable fungicide before planting.
Use of 0.5 percent mercuric choloride or 0.25 per cent Aretan or Agallol solution or 1 kg of Perenox in 400 litres of water is recommended in this connection. Aretan along with gamma BHC is also used in northern India. In areas, where termite attack is serious, gamma BHC is sprinkled on the setts in furrows in proper concentration.
Although the number of setts required for one hectare of land depends on the distance between the rows of planting, usually 25 to 35 thousand 3-bud setts are considered enough.
In northern India, sugarcane planting is usually undertaken as soon as the warm weather begins and it is completed much before the onset of summer. Earlier planting is suitable for the eastern tracts. Whereas the first fortnight of March is the optimum time for planting in Punjab and Haryana, it is February in UP and January-February in Bihar. In northern India a part of the planting is also done in October-November. In Tamil Nadu and AP, planting is done between December and February.
Three different methods are adopted for planting sugarcane, namely:
i. Flat-planting,
ii. Fur- row-planting,
iii. Trench-planting.
i. Flat-Planting:
Shallow furrows, about 25 cm deep, are made with a desi plough, the distance between adjacent rows being 80 to 100 cm. The setts of sugarcane are placed end to end and covered with 5 to 7 cm of soil. Levelling of the field is then done with a heavy plank. Many cultivators follow their own methods, which, though a little different, are essentially the flat method.
ii. Fur-Row-Planting:
A ridger is used to make furrows about 10-15 cm deep in northern India and about 20 cm deep in Peninsular India. The setts are then placed end to end or otherwise in the furrows and covered with 5 to 7 cm of soil in such a way that the upper portion of the furrows is left unfilled. Immediately after these operations, water is let into the furrows.
In heavy clay soils of some parts of Tamil Nadu, water is first allowed to get into the furrow and soak its bed thoroughly, after which the setts are pressed into the mud in the furrow by foot. In the case of planting during the monsoon, precaution is taken against damage to the buds by the stagnant water in the furrow by placing the setts inclined on the side of the furrow instead of placing them flat at its bottom.
iii. Trench-Planting:
In this method of planting, trenches having depths of 20 to 25 cm and rectangular or trapezoidal in section are made either manually or with a tractor-drawn ridger. The bottom of the furrow is then dug up and the soil made loose. After making shallow furrows in the bed of the trench, the setts are placed in them end to end or otherwise and covered as in flat-planting. This is followed by making water available to the setts by letting it into the trenches.
A sugarcane-planter developed at the Indian Institute of Sugarcane Research, Lucknow, which is drawn by a tractor, is very suitable for planting cane in trenches. All the operations relating to sugarcane planting, namely, trench-making, sett-planting, application of fertilizers and pesticides and covering setts in the trenches can be done simultaneously with this planter.
Sugarcane setts may be planted dry or wet. In the former case, irrigation is not necessary at the time of planting or immediately after that, so that the setts germinate in the comparatively dry soil. In the other case, the field is irrigated either just before or after planting or at both times so that germination of setts takes place in wet soil.
Irrigation:
It is essential to maintain optimum conditions of soil-moisture during the entire period of crop growth if high yields are to be obtained. The crop should, therefore, be grown in areas, where the rainfall is well-distributed or irrigation is assured and adequate. In order to help germination of setts and establishment of seedlings, the planting of setts is usually followed by one or two irrigations at intervals of three or four days.
If rains are absent, the crop is irrigated every 10 to 12 days during its growing period. In areas, which are dry, more frequent irrigations may be necessary. The frequency is reduced with the approach of harvesting time and irrigation is stopped a month before harvest.
In northern India, the summer is drier and hotter than in southern India and, therefore, the crop needs water more frequently. In areas, where proper irrigation facilities are not available in summer, trash- mulching is sometimes done in the spaces between the rows of cane for conserving soil- moisture.
Interculture:
The crop is weeded and hoed for the first time three to four weeks after planting. In northern India, certain weeds come up rapidly and, therefore, it may be necessary to give one hoeing within the first one or two weeks. Two or three more hoeing and weeding’s may be necessary during the first three months after planting, which will depend on the conditions of the field and frequency of irrigation.
When furrows or trenches are made for planting, they are gradually filled up during intercultural operations. In order to cut down the cost of interculture, like mulching, weeding, earthing up and covering the fertilizers, bullock- drawn implements are used.
It is usual to earth up the standing crop in the rows and the final earthing-up has to be completed before the start of the monsoon rains. Irrespective of earthing-up of the crop, it is necessary to tie up the canes in order to prevent them from swaying and lodging during the winds. This is commonly done by bringing the stalks of adjacent rows together and tying them with their own Crash and old leaves.
Manuring and Fertilization:
If high yields are to be obtained, the crop must be manured adequately. At present, only a small percentage of the sugarcane crop in the country is manured and, in most cases, it is done inadequately.
The requirement of nitrogen for sugarcane varies considerably in different regions and depends on conditions of soil and climate. Whereas in Punjab, Haryana, UP and Bihar, it is about 150 kg per hectare, in Tamil Nadu, it is 220-280 kg, in Karnataka, 185-250 kg, in Gujarat, 250 kg, in AP, 220-400 kg (in coastal areas, only 112 kg), and in Maharashtra, 250-400 kg.
It is considered desirable to apply half to two-thirds of the total quantity of nitrogen in the form of bulky organic manures, as’ farm-yard manure, compost, green manure, etc., and the remainder as ammonium sulphate or oil-cakes or both. The bulky organic manures are ploughed into the soil much before planting, oil-cakes are applied at the time of planting and ammonium sulphate at the time of planting or tillering or earthing up.
The requirement of phosphate is also quite different in different states. While in Punjab, it is determined on the basis of results of soil tests, in Haryana, UP and Bihar, it is 45-50 kg per hectare, in Tamil Nadu; it is 62 kg, in Karnataka, 75-124 kg, in AP, 112 kg, and in Gujarat and Maharashtra, 115-170 kg. So far as potash is concerned, response has been observed in certain areas only. In Bihar, the requirement of potash is 50 kg per hectare and in Tamil Nadu, Gujarat and Maharashtra; it varies from 112-170 kg.
Ripening:
In northern India, the sugarcane crop normally ripens by early December. However, the content of sugar in the juice continues to increase till the end of March, after which the canes in the field gradually dry up on account of high temperature. In contrast, the crop in the south remains fresh for a longer period since the climatic conditions continue to be favourable.
At maturity, the lower leaves of the plant gradually dry up and only a few green leaves remain at the top. If a ripe cane is cut across with a sharp knife and exposed to sunlight, a slight sparkling is seen in the flesh, which is in contrast to an unripe cane, the latter having a more watery cut surface. Confirmation of the proper stage of maturity can be done by trial boiling of the juice and a satisfactory setting of gur. Testing of the maturity of cane can be done easily by using a hand sugar refractometer.
Harvesting and Yield:
After digging down the ridges formed by earthing up, the stalks are cut at the ground level and dry leaves are removed. The stalks are then topped at the uppermost mature internode. The canes are afterwards tied in bundles for despatch to the market for direct consumption or to the sugar mills for the manufacture of gur and sugar. The harvested canes have to be processed quickly, more particularly in late season and in tropical areas.
The average yield of a crop, 11 to 12 months old, varies from 40 to 50 tonnes of cane per hectare in different states of India, except in Maharashtra, Karnataka, AP and Tamil Nadu, where it varies from 75 to 85 tonnes. The yields in all the states can be increased much by improving the inputs and the management of the crop. The yields of 18-month crops in southern India are usually much higher, 120 to 140 tonnes of cane per hectare, while those in the heavily manured canal-irrigated tracts of Bombay-Deccan are still higher, more than 160 tonnes.
Extraction of Juice and Manufacture of Sugarcane:
The harvested stalks of cane are carried to sugar mills, where they are thoroughly cleaned and cut into small pieces. They are then conveyed by a cane-carrier to a crusher fitted with revolving knives and are cut into much smaller pieces. These are passed through sets of rollers and the juice is gradually extracted, leaving the bone-dry residue, known as bagasse.
Usually about 90-95% juice is extracted from the cane. The raw juice is a dark-greyish, sweet liquid, containing about 15% sucrose and small quantities of glucose, fructose, gums, proteins, mineral salts, organic acids, colouring matter, dirt and particles of bagasse. If the juice remains untreated for some time, fermentation sets in and hence treatment has to be undertaken within a reasonably short time.
Clarification of juice is done by two processes, namely, sulphitation and carbonation. In the former, addition of milk of lime to the juice is followed by treatment with sulphur dioxide; and, in the latter, addition of milk of lime is followed by treatment with carbon dioxide. Sometimes a combination of the two is used to get better results.
The juice is strained for removal of suspended matter and is then treated with 2-3% lime until its pH is 7.2 in the heating tanks. On heating, the vegetable proteins are coagulated and the organic acids are neutralized. The scum formed on the surface when the hot juice is transferred to settling tanks, and also the mud that settles at the bottom are removed with the help of a fitter press and a clear solution is obtained. This defecated juice is taken to special tanks for carbonation or sulphitation.
A current of carbon dioxide, when passed through the juice, removes the excess of lime and decomposes calcium sucrosate. In sulphitation, treatment with sulphur dioxide serves the same purpose and also bleaches the juice and makes its colour much lighter. Further, formation of brown mass by oxidation is prevented and coagulation of gums and albuminoids are more effective. The juice is filtered again for removing the precipitates.
The clear juice obtained is concentrated in a multiple-effect evaporator and sulphur dioxide is again passed through it. Acidity of solution is strictly controlled throughout the process. The syrupy juice is then boiled in a vacuum pan until crystals of sugar begin to form. The contents of the vacuum pan, now sticky syrup, known as massecuite are taken to the crystallizing tank and allowed to cool slowly. The process enables the tiny crystals of sugar to grow in size.
The crystals of sugar and the mother liquor or molasses are centrifuged to remove the latter. A small amount of molasses, which remains adhering to the crystals, is removed by centrifuging again after spraying cold water. A blue colour is added to the crystals, which are then dried with the help of hot air and bagged for being sent to the market.
In many foreign countries, sugar is further refined by dissolving the crystals in hot water, decolorising the solution with animal charcoal or coconut charcoal. The liquid, after filtration, is concentrated under reduced pressure, when crystallization takes place.
Uses of Sugarcane:
The cane sugar has various uses. It is used as an article of food and as a sweetening agent in sweets, jam, jelly, various drinks and also in cooking. The by-products of sugar industry are used commercially for molasses, rum, industrial alcohol, etc. Bagasse, obtained after crushing sugarcane, is used for manufacture of various kinds of paper.
Varieties of Sugarcane:
Since the establishment of the Sugarcane Breeding Institute at Coimbatore in 1912, it played a very important role in developing superior varieties of sugarcane suited to widely different agro-climatic conditions of the country. During the period of over seven decades, many varieties (Co series) possessing desirable characters, mainly, increased yield, superior quality, resistance to various diseases and pests and also to drought, salinity, waterlogging, frost, etc. have been evolved. Some of the varieties like Co 312, Co 419, and Co 740 and Co 1148 have helped to increase the production to a great extent and thus transformed India from a sugar importing country to an exporting one.
With an increase in the area under the crop in India, there has been an increase in the number of breeding objectives. Besides those mentioned above, others considered important are erect habit, synchronous tillering, fast early growth, greater photosynthetic efficiency and low fibre, low non-sugar content in the juice, etc.
The State Agricultural Universities have also been intensifying their work on development of improved varieties suited to different agro-climatic zones. Thus, the cooperative research work undertaken by various organisations in the country has brought about significant improvements in sugarcane production. Good deals of changes have occurred in the varietal scene over the decades, starting from the twenties to the eighties.
Some of the more important recommended varieties during the latter period being:
(i) For subtropical zone- Co 1148, Co 1158, Co 7717, Bo 91, Bo 99, CoJ 64, CoS 687, CoS 767
(ii) For tropical zone- Co 419, Co 740, Co 975, Co 62175, Co 6304, Co 6907, Co 7219,CoC671, Co 8021
Jaggery is considered important in the rural economy of the country and therefore, a systematic breeding programme has been undertaken for developing suitable varieties. Certain varieties like Co 313, CoS 570, Co 740, Co 775 and Co 997, which have high sugar content and are preferred by sugar factories, are also good for jaggery production.
A few early maturing varieties like Co 62174, Co 6806, and Co 7201. Co 7314, Co 7704 and Co 671 are suitable for producing jaggery of good quality even at the age of nine months. There are, however, varieties like Co 62175, which are better for jaggery production than for production of white sugar.
Work has also been undertaken to develop short duration varieties, which can mature in eight months and fit into various cropping systems. Six such varieties, namely, Co 8336, Co 8337, Co 8338, Co 8339, Co 8340 and Co 8341, which are moderate yielders, have the potential of high quality. The yield of these varieties can be increased by suitable cultural practices like closer spacing and early application of fertilizers.
Diseases of Sugarcane:
The important diseases of sugarcane are:
(i) Red rot caused by Glomerella tucumanensis (Colletotrichum falcatum), which can be controlled by growing resistant varieties, roguing out affected canes, treating setts with Aretan or Agallol.
(ii) Smut caused by Ustilago scitaminea, which can be controlled by growing resistant varieties, removing diseased clumps and using healthy seeds.
(iii) Wilt caused by Cephalosporium sachari, which can be controlled by growing resistant varieties and using healthy seed.
(iv) Grassy shoot caused by Mycoplasma, which can be controlled by using healthy setts and treating setts with hot water (50°C for one hour).
(v) Red stripe caused by Xanthomonas rubrilineans and Pseudomonas rubrilineans, which can be controlled by growing resistant varieties and removing affected clumps.
(vi) Bunga caused by Aeginetia indica, which can be controlled by removing infected stools along with the parasite and burning the same.
(vii) Eye spot caused by Helminthosporium sacchari, which can be controlled by growing resistant varieties.
(ix) Mosaic caused by virus, which can be controlled by growing resistant varieties.
(x) Gummosis caused by Xanthomonas vasculorum, which can be controlled by using disease-free seed.
Insect Pests of Sugarcane:
The important insect pests of sugarcane are:
(i) Top borer (Tryporyza nivella), which can be controlled by destroying egg masses and affected top shoots, using resistant varieties, applying Carbaryl or Endosulfan granules.
(ii) Early Shoot-boner (Chilotraea infustallus), which can be controlled by practising clean cultivation, planting healthy setts, giving two light earthings during the early stages of the crop.
(iii) Root borer (Emmalocera depressela), which can be controlled by practising deep harvesting to destroy stubble, burning all trash, selecting healthy setts for planting and destroying the rejected ones, and removing weekly all dead-hearts.
(iv) Leaf hopper (Pyrilla perpusilla), which can be controlled by growing resistant varieties, destroying all trash after harvest, destroying egg masses during April-May, and dusting 5% BHC or spraying 0.03% Monocrotophos.
(v) Termites (Odonotermes obesus, 0. assumthi, Microtermes anandi), which can be controlled by using only well-rotted manure, mixing thoroughly 5% Aldrin or Chlordane dust with the soil, and applying Aldrin EC if the standing crop is attacked.
(vi) Scale insects (Melanaspis glomerata, Ceroplastes actiniformis), which can be controlled by destroying infested sheaths, and, if serious, spraying 0.03% Monocrotophos, Dimethoate or Methyl demeton.
(vii) Black bug (Covelerius excavatus), which can be controlled by dusting 5% BHC or spraying 0.1% BHC + 0.1% DDT.
(viii) Mealy bugs (Saccharicoccus sacchari, S. saccharifolii, Ripersia sacchari), which can be controlled as No. (vi) above.