In this essay we will discuss about:- 1. Origin and Distribution of Sugarcane 2. Area and Production of Sugarcane 3. Ratoon Management 4. Harvesting.
Origin and Distribution of Sugarcane:
Sugarcane (Saccharum sp) is the world’s most important sugar crop. Globally, 60 per cent of white crystal sugar comes from sugarcane and 40 per cent from sugarbeet. Sugarbeet is confined to temperate regions while sugarcane has pre-eminent position in tropics and subtropics. India is one of the major producers of sugarcane and sugar in the world.
In India, sugar industry is one of the largest processing industries, next to cotton textiles. There are around 450 sugar factories in India with an average milling days of 135. The annual product value of this crop is estimated at INR 5 billion.
Its contribution to Indian exchequer by way of excise duty is INR 0.8 billion. The per capita consumption of white sugar is 14.2 kg and that of gur and khandasari is 18.2 kg. The domestic sugar consumption is 13.5 M t with an export around 1.0 M t.
The cultivated canes belong to two main groups thin hardy north Indian types S.barbera and the Chinese S.sinense and thick juicy noble canes S.officinarum. Highly priced cane is S.officinarum. S.robustum is the closest wild relative of S.officinarum. The origin of S.officinarum is the Indo- Myanmar China border with new Guinea as the main center of diversity.
The officinarums are called noble canes due to thick juicy, low fibered canes of high sucrose content. The process of nobilisation in sugarcane is the modified backcrossing of wild cane S.spontaneum with S.officinarum and a repeat backcrossing to the noble parent S.officinarum. However, by 1975, the noble cane era ended due to serious diseases like mosaic, smut and red rot.
It is stated that the cradle of cultivated sugarcane is the region where two wild species S.spontaneum and S.robustum are found. The S.robustum is derived from natural crossing between S.spontaneum and Miscanthus floridulus and the origin is New Guinea. The origin of S.spontaneum in subtropical India.
The origin of S.barbara is northern India. These are thin canes with narrow leaves and tolerate adverse climatic conditions. The chunnee canes are represented by this group. The origin of S.sinense is China and is represented by panasahi clone. Both the Chinese and Indian canes were carried by Arab traders to Persia, Syria, Cyprus, Malta and Sicily in Mediterranean.
Alexander the Great took this honey reed to Africa after the conquest of India. By the fifteenth century, it reached Europe via Egypt and Morocco and in the seventeenth century it moved to the Caribbean and northeast Brazil.
Besides India, important sugarcane producing countries include Brazil, Cuba, Pakistan, Thailand, Philippines, Argentina, Colombia, Indonesia, South Africa and Egypt. In India, Uttar Pradesh is the major sugarcane growing state. Other cane growing states are Karnataka, Maharashtra, Andhra Pradesh, Tamil Nadu and Bihar.
Area and Production of Sugarcane:
Sugarcane is grown in 101 countries world over in diverse agroecological conditions. Globally, sugarcane is cultivated in 19.37 M ha (2000) with a production of 1278.09 M t and productivity 65.98 t ha-1. Brazil is the largest producer of sugarcane in the world.
It produces 17.5 per cent sugar and its share in sugar export market is around 40 per cent. Sugarcane growing countries with average cane productivity more than 100 t ha-1 are: Peru (130), Ethiopia (121), Senegal (109), Zambia (106), Malawi (105), Swaziland (103) and Burkina Faso & Guatemala (100).
Top ten sugarcane producing countries during 2008 (FAOSTAT) are indicated below:
India ranks first both in area and production of sugarcane in the world. The area under sugarcane increased from 1.7 M ha in 1950-51 to 4.17 M ha in 2009-10 and the corresponding cane production from increased from 57.1 to 277.0 M t and yield from 33.40 to 66.0 t ha-1.
The UP accounts for about 50 per cent of sugarcane area and 45 per cent of the cane production in the country. Production is highest (108.74 M t) in UP followed by Maharashtra (56.55 M t). Yield is highest (108.60 t ha-1) in TN followed by Karnataka (89.30 t ha-1). Productivity of cane should be raised to 100 t ha-1 by 2020 to obtain 415 M t of sugarcane to meet the sugar needs of the country.
Terminology:
Adsali:
One and a half year crop planted in July/August and harvested in December-February in the next year, common in Maharashtra, AP and TN.
Autumn planted crop:
Sugarcane crop from setts planted in October.
Bagasse:
Part of sugarcane left after the juice is extracted in rollers.
Dead leaf cane (DLC):
Lower part of the cane with dead dry leaves, relatively mature part of the cane.
Detrashing:
Removing dry/dead leaves from the cane, usually, by hand.
Fluff/fuzz:
True seed of sugarcane produced after hybridation.
Green leaf cane (GLC):
Top part of the cane with green or half green leaves, normally enclosed in leaf sheath. It is relatively immature part of the cane.
Water shoots:
Late shoots, which become relatively thicker than the tillers produced earlier. They may be good planting material but leads to processing and sugar recovery problems, if milled.
Late shoots:
Tillers produced after normal tillering phase.
LTM:
Last transverse mark leaf; used as an index tissue. It is also called TVD.
Millable cane:
A fully developed tiller, which after being crushed, juice extracted gives sugar/ jaggery in an economic way.
Mother-shoot:
The first shoot coming out of the planted bud from the lower buds of which other tillers emerge.
Phosphatation:
Use of phosphoric acid from P2 O5 for clarification. In general, 300 mg P2O5 is required per liter of juice. It adds to clarification by precipitating part of colloids and colouring matter.
Plant crop:
Sugarcane crop raised by planting the seed cane.
Ratoon crop:
Crop raised from shoots emerging from subterranean buds of stubbles left in the field after harvesting plant crop.
Rayungan:
In standing crop, top 7-10 cm of cane is cut and the buds in subtending part sprought. The upper 30-45 cm of top cane with 3-4 leaves sprouts are cut. It is called rayungan. It is a good planting material.
Seed cane:
Sugarcane intended for planting. It could be a full cane or 1,2,3 bud setts or even pre germinated setts.
Seedling/settling:
A newly developing plant coming out of the true seed is seedling; where as the one coming out of the planted bud is called settling.
Spring planted crop:
Crop planted in mid-February/March.
Stale cane:
Sugarcane, which is not processed immediately after harvest, undergoing deterioration.
Sugar year:
In India, it is from October of an year to September of next year.
Suru:
One-year crop in Peninsular India.
Tassel/arrow:
Inflorescence of sugarcane.
Theoretical maximum yield of a cane:
Total dry biomass of 470 M t ha-1 year-1.
TVD leaf:
Transverse visible dewlap leaf. LMT and TVD are same; in crop, at a time, LTM leaves have nearly same physiological age.
Ratoon Management of Sugarcane:
Sugarcane ratoon occupies about 50-55 per cent of the total cane area in India. However, its contribution to total cane production varies from 30-35 per cent only. There is an average gap of 20-25 per cent between plant and ratoon yield especially in subtropical states of India.
In major cane growing countries, two or more ratoon crops are common. In Hawaii, Mauritius, Philippines and Cuba, 4 to 6 ratoons are quite common. In India, only one or sometimes two rations are taken in spite of the experimental findings that ratoons are quite profitable.
Benefits of Ratooning:
1. Ratoons are economical by 25-30 per cent in operational cost because of saving in seed material and preparatory tillage.
2. Since ratoons mature earlier than plant cane, they can be harvested easily (labour) and the field will be available for crops in intensive cropping systems.
3. Early supply of cane is assured because of shorter duration of ratoon sugarcane.
4. Ratoons often give better quality cane with improved sugar recovery.
5. Cost of production per tonne of ratoon crop is less than the plant cane.
Varieties:
Generally, early maturing varieties are poor ratooners than mid-late or late varieties. Varieties with high yields as plant crop are also better ratooners with high yield.
Following are the good varieties for ratooning:
Early varieties:
CoS 92254, CoS 95255. Co 87263.
Mid-late varieties:
CoLk 8102, CoS 91269, CoSe 92423, Co Pant 84212.
Time of Ratoon Initiation:
Moderate temperature (25°-30°C) is most conducive for stubble sprouting. In tropical belt, December-March harvested crop gives best ratoon, where as in subtropical belt, spring harvested crop (February-March) give good ratoon. Piece-meal harvesting throughout the crushing season (November-May) should be discouraged.
Harvesting the plant crop close to the ground level is most important for good ratooning. Above the ground level harvesting not only affect the succeeding crop yield but also the plant cane yield.
Stubble Shaving and Off-Barring:
After the harvest of cane crop, stubble shaving should be done to ground level either by using sharp blade or stubble shaver. This is done to facilitate healthy underground buds to sprought and establish a deeper root system in the ratoon crop.
If the above ground buds are allowed to germinate, sproughting would be inadequate to establish adequate crop stand. Deep root system is necessary for nutrient and water absorption from deeper layers besides minimising crop lodging.
Soil compaction is one of the major causes affecting ratoon growth. To improve the soil physical conditions, off-barring and ridge flattening is necessary wherein ridges are broken and cut on either side. This operation improves soil organic matter through decay of old root mass and promote quick emergence of new roots from the stubble. This operation can be carried out by ridger like implements or tractor drawn shaver.
Gaps and Plant Population:
Intensity of gaps in ratoon crop varies from 10 to 30 per cent. A good ratoon crop should have not more than 15 per cent of gaps of the total clump population (27,000-33,000 clumps ha-1). Ratoon registering gaps beyond 15 per cent need gap filling. The total gaps found in ratoon crop, nearly 50 per cent, are contributed from plant crop itself. Therefore, gap felling or replanting should be taken care from plant crop itself.
Gap filling in ratoon crop may be with young sprouted material raised either in polybags or in nursery. Material for gap filling should be at least 30-35 days old. Material for gap filling can also be obtained from spots where excess sprouting is observed in the same field.
After the harvest of sugarcane crop, about 7-10 t ha-1 of trash (dry leaves) is left in the field. Generally, farmers burn the trash as it is in the field, particularly in scale-infested areas. Trash mulching to sugarcane crop not only suppresses the weed growth but also aids in soil moisture conservation besides increasing fertiliser use efficiency.
Trash mulching between cane rows (5-8 cm thick) stimulates bud sproughting of winter harvested plant crop by regulating rhizospearic thermal regime. Trash mulching also contributes towards organic matter and nutrient status of soil.
Fertiliser Management:
Shallow root system, immobilisation of nitrogen by soil microbes, decaying of old root mass and sproughting of stubble buds put heavy demand on fertiliser nitrogen in ratoons. Therefore, 25 per cent more nitrogen than plant crop is recommended. The recommended rate varies from 150 to 350 kg ha-1 in different states.
Experiments conducted in Uttar Pradesh revealed that 112 kg N ha-1 increased the yield of first, second and third ratoons by 109, 131 and 161 per cent and of sugar by 111, 135 and 146 per cent respectively over control. Ratoon cane yields increased at the rate of 247 kg kg-1 N applied at Kalai, 164.4 kg at Shahjanpur and 160 kg at Muzaffarnagar. At Punjab, 140 kg ha-1 is optimum.
At Anakapalli (AP), 50 per cent more nitrogen was optimum for ratoon crop in comparison to plant crop. At Caddalore (TN), 337 kg N ha-1 was optimum both for plant and ratoon crops. At Mandya (Karnataka), 1.0 kg nitrogen resulted in an average response of 0.136 t ha-1 at 400 kg N ha-1.
Response of ratoon cane to phosphorus application was more consistent than in plant crop and 1.0 kg P2O5 resulted in a response of 0.035 to 0.075 t kg-1 at 100 kg P2O5 ha-1. Response to potassium was observed to be more pronounced in case of ratoon crop in comparison to plant crop in red and black soils. However, the response was marginal in alluvial soils. The response was only around 0.1 t ha-1 at 100 kg K2O ha-1. Results of experiments at Anakapalli (AP) indicated necessity for double the dose of nitrogen recommended for plant crop along with 100 P2O5 and 120 K2O kg ha-1.
In general, 200 N, 60 P2O5 and 60 K2O kg ha-1 are recommended for a good ratoon crop, based on experiments at different sugarcane ecosystems in India. However, each state has its own location specific recommendations.
Time of Application:
In north India, where relatively lower doses of nitrogen (120-200 kg ha-1) are used, entire dose has to be applied at the initiation of ratoon, immediately after plant cane harvest. In areas where irrigation facilities are not adequate, two split applications of nitrogen, half at harvest of plant crop and the remaining half when irrigation water is available have given the best results.
At Anakapalli (AP), two equal split applications at ratooning and 45 days later appears to be ideal. In Tamil Nadu, nitrogen is applied in two splits at first irrigation and 60 days after ratoon initiation.
General recommendation to the country is that nitrogen should be applied in two splits at ratoon initiation and 60 days after ratoon initiation. Entire recommended dose of phosphorus and potassium should be applied only at the ratoon initiation.
Water Management:
Ratoon crop has shallower root system than the corresponding plant crop, hence are less tolerant to drought. Ratoon crop transpire relatively less water than plant crop, but utilise more per unit of cane and sugar production. This indicates relatively lower water use efficiency of ratoon crop as compared to plant crop.
Ratoons require more frequent irrigations than plant crops because of shallower root system. In general, irrigation at 40 per cent DASM is ideal for ratoon crop as against 60 per cent DASM for plant crop. Therefore, irrigations at 12-15 days interval are required in subtropics and at 8-10 days interval in tropics. Irrigation requirement in tropics is 3-4 times higher than subtropics depending on soil and climatic conditions.
Earthing Up and Propping:
Earthing up or moulding up is done to check excessive tillering, to prevent the crop against lodging, to facilitate the water flow in furrows and also to manage weeds. This operation is done before onset of monsoon at the crop age of 3-4 months.
At some places, ratoons need this operation twice, first before onset of monsoon to check emergence of excessive late litters and the second at the start of monsoon. This operation is usually done by manual labour with spades in small farm holdings. Ridge maker drawn by tractor or animal power is, generally, used in relatively bigger farms.
To prevent the crop against lodging due to heavy winds and to keep the crop field open for better aeration, propping is done by tying the canes together using the dry leaves and bottom green leaves. Usually, the trash is twisted to form a sort of rope and cane stalks are tied together. This is known as trash twist propping. In many areas where cane growth is heavy, bamboo poles are used as support. These earthing up and propping operations are followed for plant crop also.
Late shoots (water shoots or balas) are often thick and succulent. They appear later when early tillers are fully developed. Retention of these shoots under late harvest (April-May) of plant cane gives good quality ratoon crop.
Crop Protection:
Due to piece-meal harvesting in subtropics, weed growth continues in patches till the entire field is harvested. PRE application of Atrazine (1.0-1.5) followed by one hoeing 45 days after ratoon initiation is effective and economical. Manual hoeing and weeding at 0,45 and 90 days after ratoon initiation is more effective in controlling weeds.
Insect pests specific to ratoon are shoot, root and top borers, pyrilla, black bugs, white fly, scale insects and mealy bugs. Scale insects can be controlled by drenching Malathion (1.5 kg ha-1) in 800 1 of water. For top borers, Carbofuran (1.0 kg ha-1) soil application before onset of monsoon is quite effective. Black bug can be controlled with Endosulfan (1.0 kg ha-1) in 1200 1 of water.
Diseases associated ratoons are smut, grassy shoot disease (GSH) and ratoon stunting disease (RSD), which can be controlled by heat therapy.
Ratoon under Low Temperature:
In subtropics, sprouting of stubble buds is poor during winter due to low temperature. Trash mulching, intercropping and frequent irrigations are effective in promoting sprouting and also in protecting sprouted buds from low temperature damage. Application of Cycocel (CCC) or Etheral to foliage before 30 days of cane harvest can promote bud sprouting in ratoon crop.
Harvesting of Sugarcane Crop:
Harvesting of the crop at proper time depends on value of the crop in respect of tonnage and recovery percentage from it. Immature crop gives lesser sugar per cent and low yield. It is, therefore, advised that cane crop should be harvested at proper time of maturity.
Cane Supply in the Factories:
The present system of sugarcane supply in the two major sugar producing states (UP and Bihar) in north India is by issue of harvesting challans to cane growers at least three days in advance during the expected running of the factory on equitable distribution basis. This system is good provided the cane has uniform maturity throughout the entire season but it is defective when the cane crop has a variable maturity period in the season, as is often the case.
Maharashtra and other southern states draw their cane supplies on the basis of date of planting of the crop. Date of planting is only one of the factors affecting maturity of the cane crop and it does not cover all other factors. As such, the date of planting has limited bearing on the maturity of cane crop. Maturity of crop could be perfectly judged by recording brix values with the help of hand refractometer and a puncturing needle.
The quality of sugarcane is estimated by commercial cane sugar (CCS). Quality is given by pol ratio (t cane/t sugar, TC/TS). Lower the ratio better is the quality. The values of pol ratio range from 5 to 15.
CCS = Sucrose % cane – ½ impurities % cane
Impurities = Brix – pol
Brix = Total soluble solids
Sucrose = Pol
Note:
1. Brix represents the apparent solids in sugar solution as determined by Brix hydrometer.
2. Pol = polarimetrically determined sucrose.
3. Purity = pol/corrected Brix; correction is for the temperature of juice standardised in tropics at 27.5°C.
Before cutting the cane, it is customary to give the cane field a good irrigation. Stalks are cut at ground level, preferably after digging down the earthed up ridges. Dried leaves are stripped off from topmost mature internode where the stalk usually breaks easily. Harvested canes should always be processed quickly to avoid postharvest sugar losses.
Postharvest Sugar Losses:
The average sugar recovery in subtropical cane growing belt hovers between 8.0 and 9.5 per cent during peak crushing season, which is extremely low. The low recovery is largely due to absence of a scientific harvesting cum-crushing schedule leading to enormous loss in plant genetic potential.
In the present supply system of cane, kill-to-mill delay of 3 to 10 days or more is quite common which aggravates deterioration process in harvested cane due to inversion, respiration and development of acid, alcohol and polysaccharides producing microorganisms.
The following constraints seem to operate and affect the quality of raw material and consequently recovery:
1. Absence of proper varietal balance and scientific harvesting schedule based on cane maturity
2. Extension of milling period during summer when ambient temperature is more than 40°C
3. Harvesting sugarcane crop 5 to 10 days before its supply to mills
4. Limited crushing capacity of mills resulting into stalling of cane at mill yard/cane centers
5. Inordinate delay in transport of harvested cane from field to mills
6. Week end shut down and other unforeseen circumstances
7. Lack of understanding regarding cane and mill sanitation programme.
Causes for Postharvest Losses:
There are two areas of postharvest quality loses leading to low recovery: sucrose inversion process following harvesting of sugarcane and subsequent delay in delivery of cane to factory and factory loss due to inversion, dextrin, alcohol and acid formation in extracted juice incident to inefficient and unhygienic processing.
Weather is the prime importance in determining the rate of deterioration. Higher the temperature and humidity and wetter the weather, the greater is the deterioration. The rate of inversion in harvested green cane increase during late crushing period (April to June) because of high temperature (>45°C) and low relative humidity (25-35%).
Invertage activity and increased microbial population increase to level of reducing sugars, which has a detrimental effect on sucrose recovery. Level of maturity, burning of the cane before harvest, method of harvest and cane variety are the other factors affecting cane deterioration. On an average, Indian sugar mills lose 10 to 15 kg of sugar per tonne of cane ground.
Crushing and Gur Making:
Three-roller iron crushes operated with bullocks, oil engines or electric motors extract 60 to 70 per cent of the juice from the canes and are in common use. Crushing should be done in the cool hrs of the morning and the extracted juice should be boiled without delay. Metal vessels are preferable as containers for the juice. Bagasse and trash are almost the universally used fuel. But this fuel is often supplemented with sticks of cotton, pigeonpea or castor.
For economy in fuel and efficiency in boiling, improved furnaces such as the Lucknow furace and the improved Meerut and Bilari models are recommended in northern India. The Poona bel, Godavari, Sindewahi and the Pugalur furnaces are popular in various parts of Peninsular India. The principal features of the improved furnaces are heat conservation and fuel economy, a quicker boiling rate, greater facility for working and better control on the striking point.
Much attention is now given to the clarification of gur and its good texture. In northern India, where the juice is usually purer and more nearly neutral, the elimination of acidity with lime is not essential. In southern India, however, the addition of a thin suspension of lime is usually necessary for neutralising the juice; this operation helps the final product to set satisfactorily.
In the north, juice in the course of heating is clarified with the mucilage of bhindi (Abelmoschus esculentus) or with deola (Hibiscus ficulneus) extracted in water. In Punjab, the bark of suklai (Kydia calycina) and in the eastern areas that of semul (Bombax malabricum) is used for clarification.
An emulsion made by crushing castor or groundnut seeds in water is also recommended. The strike stage is reached when the boiling syrup attains a temperature range of 118°C to 120°C. At this stage, if the syrup is dripped from a ladle, it forms fine threads which waft in the breeze. The syrup also readily solidifies when a drop is allowed to fall into a mug of water. At this stage, the syrup is quickly transferred to wooden troughs or moulds of various sizes and shapes.
Addition of Lime:
The pH of fresh juice ranges from 5.2 to 5.4. It needs to be raised to 6.5 to 7.00 to make it alkaline to facilitate the coagulation of suspended impurities of gummy colloidal substances. For this purpose lime water (prepared by dissolving 150 to 200 g lime in 5 liters of water) is added
Stages in Boiling Process:
Removal of first scum:
When the temperature reaches 85°C, which takes about 25 to 30 minutes, the nitrogenous impurities present the juice start to coagulate and float on the surface of scum which are removed with the help of long handled steel strainer and collected in scum strainer.
Addition of vegetable clarificants:
Bhendi extract is added. This extract is prepared by crushing 1.5 to 2 kg bhendi plants (Hibiscus esculantus) added to 15 liters of water. The extract is added to the boiling pan in two to three installments at an interval of 5-10 minutes.
Addition of phosphoric acid:
After removal of first scum, the excess of lime is neutalised by addition phosphoric acid (free from) to adjust the pH of media to about 5.5.
Removal of second scum:
At this stage, golden coloured scum appears on the surface which is removed. When entire scum is removed, boiled juice looks clear, transparent and brownish yellow in colour. Many farmers at this stage use chemical clarificants like hydros powder (Na2S2O4) as a bleaching agent. Excess of hydros powder is injurious to health. Sulphur dioxide (SO2) content should not exceed 70 ppm in the final product. The hydros 35 g (having purity more than 80 %) per 1000 liters of sugarcane juice is recommended as a permissible limit for purification.
Concentration of juice and stirring:
When the temperature raises to about 99 -100°C the juice begins to forth. To avoid excess of forthing and loss of juice due to overflowing, continuous stirring with wooden ladle is necessary. This helps to avoid charring. Heavy forthing causes the juice to bubble. At this stage, the liquid becomes thick. This concentrated juice now is liquid jaggery (kakavi) and is ready for removal between 104 and 106°C temperature.
If the liquid jaggery is collected at lower temperature (less than 105°C), its storability is adversely affected since the product is subjected to microbial growth during storage. If removed at higher temperature (more than 106°C) there is a problem of crystallisation of sucrose during storage. Thus keeping quality depends upon striking temperature of liquid jaggery (105-106°C).
Stages of Boiling of Sugarcane Juice:
Stages of sugarcane juice boiling are summarised below:
Uses of Liquid Jaggery:
1. Excellent as table syrup.
2. Can be consumed directly with chapati, bread and bhakari.
3. Preparation of sudharas for consumption in every day food.
4. Recommended s a sweetener in confectionary for various preparations like cake, biscuits etc.
5. Best sweetener for ice-cream.
6. Advised for jaundice patients in diet as rich source of glucose.
7. Recommended as rich source of iron o anaemic patients.
8. Better syrup for Pharmaceutical formulations.