Cultural Management
(from:http://bicol.da.gov.ph/Opportunities/sugarcane%20profile/topic13.html)
Propagation
Sugarcane is propagated commercially by asexual method, which involves the planting of immature portions of the cane stalks. The planting material is known as canepoint, seedpiece, seed or sett. The quality of prepared seed for planting influences the germination, growth and germination of the plant. Seedpieces must be taken from vigorous cane plants free from pests and diseases. It may be sourced out from cutbacks, usually taken from a nursery; top points taken from the young tops of the matured canes; from micro-propagated plantlets developed through tissue culture or whole stalks from cane plants about 5-6 months and preferably erect.
Climatic Adaptation
Sugarcane is widely adapted to a wide range of tropical aqnd semi-tropical climate, soils and cultural conditions. It grows well in the Philippines or in the subtropics when temperatures are modified by warm bodies of water. Survival is possible for all temperature above freezing , but growth ceases anytime the minimum temperature is below 12C.
Optimum temperature for germination of stem cuttings ranges from 32 to 38 C. Growth is optimum when the mean daily temperature is anywhere between 22 C and 35 C. The minimum temperature for active growth is about 20 C. For ripening, relatively lower temperature, in the range of 10 to 20 C are desirable since these have noticeable influence on the reduction of growth rate. The ideal climate for sugarcane consists of 4-5 months of a temperature range of 30-35 C for a one-year crop followed by a six to eight weeks of cooler temperatures to enhance the maturation and sucrose accumulation prior harvest.
Land preparation
There are two important considerations to remember in preparing the land for sugarcane production. First, sugarcane is a fairly deep-rooted plant and second, the germination of the seedpieces is favored by a well prepared land therefore, when preparing the land, the aim should be to attain a soil environment that will favor rapid germination of the cane points as well as deep root penetration. Other good reasons why land should be prepared thoroughly are;
1). To produce soil of good tilth;
2). To mix the residues of the previous crop with the land;
3). To control the growth of weeds;
4). To make the growth of succeeding ratoon crop easier;
5). To increase the aeration and water holding capacity of the soil.
It is also important at this stage, to collect soil samples for laboratory analysis to have a basis for determining the kind and amount of fertilizers to use during that particular cropping season.
When to prepare the field
The best time to prepare the field is during dry season when it has just the right amount of moisture. To know if the field is ready for plowing, get a handful soil, hold it firmly then drop it to the ground. If the soil crumbles to pieces when it strikes the ground, then the soil is ready. This operation is usually undertaken starting from November until May, when harvesting has just finished and plenty of planting materials are available in the field.
Practices in Land Preparation
Plowing and harrowing are two important field operations employed in preparing the land for sugarcane planting. These are normally done deep enough with the use of a moldboard plow or disc plow pulled by a tractor to break the hard soil stratum to improve soil aeration and water holding capacity.
For bigger farms with facilities (35-38 HP tractor), deep plowing and harrowing at 18-24 inches can easily be done on slightly clay to clay soil.
Small farmers on the other hand, make use of native plows and carabao in preparing the land. On new land however, it is advised to use machinery for economical reason and convenience.
There are several factors to consider in preparing the land as follows;
1. Depth of plowing
Depth of plowing differs depending upon the depth of soil surface and structure. For deeper surface soil, plowing must be done deep enough, about 45 to 90 cm depth to enable the roots to penetrate deeply for better absorption of available food and water in the soil particularly during the dry months. Also, deep-rooted system sugarcane crop is more resistant to withstand drought and strong wind compared to shallow-rooted.
For shallow surface soil and where there is a hard pan layer underneath, depth of plowing must be from 15 to 20 cm or only up to where the hard pan layer is located. Deep plowing on this type of soil is being discouraged because the infertile and difficult to pulverized soil is turned on top hence, it may hinder and stunt the growth of sugarcane crop.
2. Sub-soiling
Sub-soiling is a process by which the hard pan layer or compacted layer of the soil is broken without turning over the infertile subsoil to the top. This process is usually done with the use of a tractor drawn sub-soiler to a depth of at least 50 to 175 cm. Depending upon the soil type and degree of compaction, one or two passing is necessary with the last passing criss-crossing the first and if possible, slightly overlapping each other to allow easier and deeper root penetration. The best time to carry out this activity is when the soil is relatively dry so that the hard pan will shatter or crack. As it loosens the hard pan layer of the soil, it offers the following advantages; a) facilitates downward movement of water; b) enhance good drainage; and, c) induce deep penetration of the roots.
3. Number of times to plow and harrow
The number of times to plow and harrow depends on soil type. Heavy soils like clay and clay loam require more plowing and harrowing than light soils of sandy loam type. It must be remembered that good land preparation does not always mean thorough pulverization of the soil. Therefore, harrowing which normally follows after plowing should be stopped as soon as favorable soil tilth is achieved.
For delayed planting, it is necessary that a disk or tooth harrow should pass across the field to break the capillary movement of soil water and thereby preserving soil moisture.
4. Direction
Many farmers do not pay particular attention in choosing the right direction in plowing, harrowing and in laying out the furrows for planting. Perhaps they are not aware that doing said operations in the correct direction will reduce cost of farm operation and may increase crop yield. This happens because it minimizes problems on soil erosion and loss of fertilizer and irrigation water due to surface water run-off.
The choice of direction differs according to slopes and shapes of the field. For squares and nearly level field, the decision is not as criticial as in the rectangular and rolling fields. A rectangular field should be plowed and harrowed in a direction that will allow greater efficiency and convenience while in the rolling fields, it should follow the general contour of the land to prevent serious soil erosion.
5. Cost of preparing the land
Cost of preparing the land varies depending on the size, kind of farm (whether new or old), practice followed and implements used.
The UP College of Agriculture at Los Banos conducted a related study to determine the time required to plow a hectare of land using different kind of instrument as follows;
The cost of plowing the field is done by multiplying the hours required to plow a hectare with the kind of plow used by the minimum wages in the locality. Harrowing, on the other hand requires 50 to 75% of the time required to plow the same field depending upon the kind of harrow one is using.
Planting
Planting practices affect to considerable degree the germination of the seed pieces and subsequent growth of the plant. Good planting practices do not only mean rapid germination but also fast growth of the crops. It is therefore important to know when and how to plant good seed pieces.
Planting in sugarcane farming is consist of the following operations;
a. Selection of seedpieces
In selecting the seedpieces or cane point, the following characteristics of a good planting material must be considered be it taken from the nursery or plantation;
" Should contain three well-developed and viable buds or eyes and should not include the central growing point or "ubod".
" Must come from a healthy plants and disease and pest free plantation or nursery.
" Must be about 30 cm long and prepared in such a way that there is about three to five cm clearance from the nodes at both ends.
" If taken from the nursery, must not more than six months of age and the cane points obtained from the top half must be separated from the bottom half of the stalk and plant them separately in the field to obtain uniform germination.
Before planting be sure to remove the leaf sheath covering the buds of the selected cane points to prevent delay of shoot emergence and horizontal growth of buds before it can fully emerge to the top. Also, cane points must be planted immediately after cutting because their germination capacity reduces gradually up to five days and rapidly thereafter.
b. Soaking of the seed pieces
Soaking of cane points in water is another common practice in sugarcane farming. Usually, the cane points are soaked in running water for about 48 hours to hasten germination. Generally, this is carried out when there is no enough moisture in the soil that could induce germination of the cane points after planting.
Some planters prefer to soak the cane points in fungicide solution to protect them from fungal infection. The most common practice is to dip the cane points in Mercuric Chloride solution for about a minute. This is normally prepared by dissolving about 125 grams of 6% Agallol per 100 liters of water.
c. Incubation of the seed pieces
After soaking, the seed pieces are incubated for about 2 days by placing them under the shade and covering with moist rice straw or any similar materials. Incubation must be done with proper precautionary measures to ensure higher number of developed stalks. Prolonged incubation may cause the buds to over swell thus it would require careful handling during planting time so as not to destroy the swelled buds.
d. Making the furrows
Furrows should be made only when there are already available cane points for planting to take advantage of the available soil moisture. Making the furrows several days ahead of planting time can result to drying up of soil and planting with this soil condition will result to delayed and poor germination.
e. Distribution and laying out of the seed pieces
Distribution of prepared sugarcane seedpieces must be done immediately after making the furrows to take advantage of the available soil moisture.
f. Planting
Planting should be done immediately after making the furrows for higher percentage germination. Planting position varies depending on the season. During dry season, cane points must be laid flat in the furrow with the eyes on both sides and covered with two inches pulverized soil. Planting the cane points this manner enables them to take advantage of the soil moisture and prevent from rapid drying.
During wet season or when soil is extremely wet, cane points are planted at an angle position about 45 degrees, eyes on their sides also and allow the cane point to protrude 3-5 cm. from the surface of the soil. Pointing the cane points this way is necessary to ensure uniform germination and development of strong tillers. In addition, this will also prevent the buds from injury by the movement of machinery or any heavy object on top.
Planting materials requirement to plant a hectare plantation varies depending on the season. During wet season planting and early planting when conditions are favorable, rate of planting is usually 30,000 cane points per hectare or 3 "lacsas". Roughly, this amounts to planting three cane points for every linear meter of the furrow with one meter distance between furrows.
However, when planting towards the dry season, the rate may be increased up to 45,000 cane points per hectare to give allowance to seed pieces that may not germinate. Under favorable condition, germination will take place 5 to 10 days after planting.
Replanting
Replanting of vacant hills must be done immediately and within 30 days after planting. Delayed replanting results to non-uniform crop stand and uneven crop maturity.
Cultivation
Cultivation in sugarcane farming is loosening of the soil to provide aeration thereby increasing the supply of oxygen needed by the plant roots and by the soil organisms thus, ultimately enhances microbial activity in the decomposition of organic matter.
Cultivation Practices
Cultivation practices employed in the farm with the use of animal-drawn or tractor-cultivators are ridge busting and alternate off barring and hilling-up.
The first operation is shallow breaking of the ridge called ridge busting. It is usually done 3-4 weeks after planting by passing the cultivators between furrows to bring part of the soil to the furrows. It must coincide with the first fertilizer application so that this, at the same time cover the fertilizer applied and the exposed portion of the seed pieces. This is followed by the first off barring operation three weeks later or 7 weeks after planting then by the first hilling-up and second off-barring when the plant is about two months or 3 months old, respectively.
The second hilling-up is the last cultivation operation, hence, the closing operation. It is done to cover the second dose of applied fertilizer and to suppress late tillering and formation of floating stool. Floating stools are undesirable growth that dries and dies easily during hot months thus results to low tonnage so must be suppressed to minimize hills in the succeeding ratoon crop and increase yield.
The time of last hilling-up significantly influence sugarcane yield. Phil 56226 and Phil 7544 produced high sugar yield when last hilling-up was done 4-5 months after planting while Phil 6607 was favored by the early plowing field operation. Leaf canopy of Phil 6607 closes in two and half months while Phil 56226 and Phil 7544 closed at 3-4 months after planting. (Dosado, V. G. and Miayo, 1993; Samiano, 1986). This suggests that time of last hilling-up demands upon the time when a variety canopy closed.
Weed Control
Weeds are considered major constraints to higher yields in sugarcane production because it can reduce potential sugar yield by 25 to 93% as well as a loss of significant quantities of nutrients. Thus, it is important to keep the field clean during the first 3-4 months of cane or active tillering stage. Presence of weeds at this period will greatly affect tiller growth, number and development of millable stalks and will compete with sugarcane for sunlight and nutrients.
Experiments conducted at the La Granja Experiment Station, SRA showed improvement in yield due to significant weed control, ranging from 17 to 195% which means that two-thirds of the crop may be lost when weeds are not controlled (Aurelio and Ascalon, 1976). Weeds act as alternate hosts for pests and diseases and can contribute to an increase in the cost of sugarcane production.
Methods of Weed Control
Following are the recommended methods of controlling weeds to minimize yield losses in sugarcane plantations;
1. Cultural
Cultural method is controlling weeds with the use of any of the following cultural practices;
a) Use of fast-growing varieties. It is recommended to use sugarcane varieties that are high tillering and fast growing to shorten the critical period of competition. These varieties compete better with weeds than the slow-growing types. Phil 56-226, a slow growing variety takes four months to close its leaf canopy, while Phil 6607, a fast starter and fast grower, covers the inter-rows three months after planting (De la Cruz, 1983)
b) Use of trash mulch. Every other row should be mulched with trashes during ratooning to reduce weed control operations by 50%. Trashes are confined along the alternate inter-rows to allow weeding and cultivation in the inter-rows without trashes. Trash mulching suppresses weed growth, conserves, moisture, and reduces surface run-off and soil erosion during heavy rains.
c) Use of intercrop. Leguminous crops are planted to take advantage of available space in-between rows during the early growth period. This will suppress weed growth and generate additional income. Intercropping with leguminous crops reduces hand weeding cost by 28% and is a cheaper and easier way of controlling weeds in sugarcane fields (Mercado et al., 1976)
d) Maintenance of complete stand. Seedpiece selection is necessary to attain high germination percentage. Missing hills will promote weed growth and can be remedied by replanting.
2. Mechanical and manual
Mechanical weed control is carried out to some extent through cultivation operations during hilling-up and off barring in the early part of growing canes, usually 3-4 weeks after planting with the use of either animal drawn plow or tractor drawn cultivator. As this control only weeds growing in between rows, if still needed, manual weeding must be done within the row by pulling the weeds by hand or with the use of grab hoes.
3. Chemical weed control
Chemical weed control is controlling of weed with the use of herbicides. This method offers many advantages as follows;
a) Greatly helps offset the growing scarcity and increasing cost of farm labor in many sugarcane farms
b) Provides sure control and longer residual effect
c) Sometime economical
The rate of acceptance however, is low because they are expensive and only, large-scale plantations can afford. Besides, herbicides are difficult to apply. It has to be applied at a precise amount and rate, thus skilled applicator are needed for effective application. This also demands careful application so as not to affect plants in adjacent farms.
4. Combination of manual and chemical weed control
Wise combination of this method is often the best and most economical way to control weeds. A study conducted in 1985 by delos Santos showed that the combination of Diuron followed by 2, 4-D and hand weeding effectively controlled weeds by 83.5%. Also, Ametryn, followed by 2,4-D and hand weeding gave 65.5% result.
Several factors affect the use of herbicides as weed control as cited by Obien and Baltazar (1979) as follows;
a) Soil type and land preparation. Best results are obtained when the soil has been worked to a fine tilth because such operation which aerates the top soil layer will favor the germination of weeds seeds and eventually increase herbicide activity.
b) Rainfall/Weather condition. Herbicide use is also chosen in relation to weather conditions prevailing or expected during the season when the chemical is applied. Chemical 2,4-D can be applied during dry periods of the year while herbicides of low solubility such as Diuron and Ametryne would be justified during rainy season because of its water residual effect.
c) Sunlight
d) Temperature
e) Soil microorganisms
f) Kind of weeds - The kind of weeds also determines the herbicide treatment. Annuals are controlled better with pre-emergence treatments using residual herbicides such as the substituted ureas and trizine, rather than the soluble 2,4-D and MCPA. Perennial weeds are best controlled with herbicides at different stages of growth. Generally, plants at 2 to 3 leaf stage is very susceptible to leaf absorbed and contact herbicides.
g) Varietal response
h) Crop tolerance
Liming
Liming is necessary to correct the moderately and strongly acidic soils (pH 4-6) of most of the sugarcane plantations in the country. However, this is not commonly practice by planters.
Strongly acidic soils when not corrected cause toxicity to plants because iron, aluminum and manganese become readily available. It also hampers the efficiency of applied N, P and K fertilizers and affects the growth of beneficial soil microorganisms thus affects the growth and yields of sugarcane.
Application rate
Lime requirement as determined by lime titration method in a laboratory varies depending on soil type. Clayey soils have higher lime requirement than sandy soils because of the buffering capacity of clayey soils. A typical clay loam soils need about 3 t/ha of agricultural lime to correct soil reaction from pH 5 to 6.2, while sandy loam soils need about 2 t/ha of agricultural lime at similar range of soil pH.
Following is the recommended lime requirement of sugarcane at varying soil pH and textural classes expressed in ton per hectare.
Method and frequency of lime application
For higher efficacy of lime, it is recommended to use only quality agricultural lime with at least 95% neutralizing value and fine enough to pass through a 20-mesh sieve.
Application should be done at least one month before planting to allow sufficient time for the lime to react with the soil. It is better applied by manual spreading or through a mechanical lime spreader. It should be plowed-under or disked to incorporate thoroughly with the soil so lime will immediately react and correct soil acidity effectively.
In case of delayed arrival of lime, it should be spread along the furrows after planting or on the inter-row spaces after stubble shaving of ratoons. Precautionary measures should be observed to avoid the lime from getting in contact with fertilizers, as this will cause unfavorable chemical reactions such as volatilization of N from urea and phosphate fixation.
The effectiveness of lime may last for three to five years, depending on soil texture, rainfall, application rate and kind of material applied. Frequent light applications in sandy soils is recommended while for clayey soils, it must be less often. Whether reliming is necessary, soil testing must be done to determine its necessity.
Fertilization
As sugarcane is a long-term crop that has to be grown continuously in the same area for a minimum of 2-3 cropping years, the fertility level of the soil is usually depleted and somehow the pH balance is destroyed. For the sugarcane to be productive, supplementation of any organic or inorganic material of natural or synthetic origin is necessary to improve the soil fertility level required by the crop. Right kind, amount and time of application is important for higher efficiency and effectiveness of fertilizer materials applied. The general principles on the amount and kind of fertilizer to use have to be guided by economic principles in the context of soil fertility, climate, plant uptake and adaptable technology available. Following are the basic guide on fertilization;
1. Know the nutrients requirements of sugarcane - The optimum level of fertility being recommended by SRA soil testing laboratories is 200-600-400 kg/ha of N, P2O5 and K2O, respectively. This was based from fertilizer experiments conducted in the different sugarcane growing areas, which were subjected to economic analysis.
2. Know the amount of fertilizers to apply - Fertilizer rate is usually expressed in kilograms nitrogen (N), phosphoric acid (P2O5) and water-soluble potassium (K2O) per hectare. Farmers should be able to compute and calibrate the fertilizer need of his sugarcane plantation.
3. Choose the right kind of fertilizers to apply - Choice should be based upon; a) the nutrient contents of fertilizer materials, b) nutrients needs of the soil, and; c) comparative costs.
4. Proper placement and timing of application - Maximum efficiency of the applied fertilizers can be attained when placed in the root zone with adequate soil moisture.
Method of Fertilizer Application
Fertilizers can be applied in any of the following manner depending on the existing condition in the field and the kind of fertilizer to use;
1. Broadcasting
Broadcasting is employed when heavy application of ground rock phosphate, lime, dolomite or organic fertilizer is applied. When the cane rows are closely spaced and the root system has permeated the whole volume of soil, nitrogen and potassium fertilizers can be broadcasted in the inter row space, provided, there is enough moisture in the soil.
2. Furrow or basal application
The fertilizer is applied in the furrows at planting time. The applied fertilizer shall be covered with a thin layer of soil before planting the cane points to avoid injury to the buds. Direct contact of chemical fertilizers on cane points has direct effect on the percentage germination of the seed pieces as reflected in the following;
3. Side-band application
The fertilizer is applied in band to one or both sides of the seed piece or cane row. A mechanical fertilizer applicator can effectively apply the required fertilizers through this method after proper calibration to ensure uniform distribution. If done by hand, a shallow cut is first made by a plow along the cane rows before the fertilizer is applied in band manually and then covered by soil to avoid loss of nitrogen due to volatilization.
4. Side or Top dress application
Fertilizers are applied into or between sugarcane rows either by hand or with a wooden or steel drill. This must be followed immediately by simultaneous plow cultivation to cover the applied fertilizer with soil. This method is commonly practiced in the second dose of nitrogen and potassium.
5. Foliar spraying
This method is used extensively in the correction of trace elements. The fertilizer materials is dissolved in water at certain concentration and applied by spraying to cane plants. Supplemental N and K can be applied by spraying solutions of urea and muriate of potash on the canes. Studies showed the following effect on sugarcane yields, which varies depending on the time of application;
Calibration
Equal distribution of the applied fertilizer is necessary to ensure uniform growth of the cane plant. Mechanical fertilizer applicator should be properly calibrated prior to using the implement. Manual applied by hand can be calculated as follows;
1) Calculate the quantity of fertilizer per hill. Assuming that there are 30,000 cane plants per hectare to be fertilized with 215.02 kg. Urea, 228.26 kg 18-46 and 166.67 kg muriate of potash, the amount of the fertilizer mixture is equivalent to 609.95 kg/30,000 plants or 20.33 gram per hill.
2) Weigh 20.33 g of the fertilizer mixture and place in a scoop or cup. Mark the level with pen or fill-up the extra space with melted paraffin.
Partitional Aspect and Timing of Application
Fertilizer should be applied at different stages of growth of the cane plant, which requires most the nutrients to obtain maximum economic returns. Soil texture and available moisture determine whether nitrogen and potassium fertilizer should be applied once or in split dosage. Ordinarily, there is no need of splitting phosphorous because of its well-known laziness in the soil. Application of N and K is split whenever there is likelihood of losses and dissipation due to leaching in light textured soils. When much rainfall is expected, the first dose of N and K along with the full amount of P is better applied after the first weeding. During the dry season or when little rain is expected, the first dose of the required NPK fertilizers may be applied at planting ratoon crop. The last dose of N and K is best applied after the last weeding, before final hilling-up or closing of the field. It should not be applied later than this to avoid unfavorable effect on juice quality.
Harvesting
Harvesting is one of the critical operations is sugarcane farming. Untimely harvesting and improper practices result in the loss of tonnage and sucrose content not to mention the time, capital and efforts in cultural management. Loss of damage range from 6.4 t/ha to 17.5 t/ha (Quiloy, 1982) Sugar loss could be about 12-33 kg/ha.
Harvesting includes cutting, loading and transport of the canes. The first essential is to ensure that the cane is ripe. Determination of ripeness is a combination of experience, visual observation, knowledge of the recent history of the field and a testing of the canes. Weather and soil conditions should enter the planters' decision. Pre-harvest sampling and juice analysis will indicate whether or not a cane is ready for harvest. There are two ways of determining maturity of the canes as follows;
1. Brix Reading by Refractometer
A cane is said to be matured and ready for harvest when the sugar content or juice quality of the upper third portion of the stalk is about the same as or close to that of the lower portion of the stalk. Immature canes will give a much higher brix reading from the base than at the upper portion whereas the over-matured canes have relatively higher reading in the upper than in the lower portion.
2. Visual Observation
A cane field ready for harvest exhibits the following characteristics;
a) Yellowing of the leaves in the whole field is uniform
b) The stalks become yellowish
c) Internodes at the upper portion of the stalk shorten
There are many factors that influence cane maturity as follows;
1. Age of the crop. Chronological age of the plant may not be reliable guide alone in determining cane maturity. Other factors may have a more direct bearing on the real maturity of the crop such as soils and weather condition
2. Cane varieties. Different varieties differ in their ability to mature at different stages. The optimum age to harvest a certain cane will depend on whether the canes are early maturing (Phil 56226, 6723 at 10-12 months), medium maturing (Phil 58226, 6123, 6553, 6607, 7495 at 12 months) and late maturing (Phil 7083 and 6723 at 14 months).
In a study conducted at the Luzon Experiment Station by S. Samiano, the optimum ages to harvest specific cane varieties are the following;
3. Fertilization practices. There are varieties that are sensitive to nitrogen fertilization in relation to maturity. In these varieties, maturity is delayed when excessive nitrogen is applied or when nitrogen is applied late.
4. Weather conditions preceding the harvest period. There is an adverse effect of unfavorable weather conditions on sugarcane plant during harvest season. When rainfall occurs during the ripening periods, it is best that all of the nitrogen has been used up. Any unused nitrogen will stimulate vegetative growth and deterioration of cane sugar results. The stored sucrose is inverted to reducing sugars and the latter is used as energy for continued vegetative growth. Even when there is not much nitrogen present at the time of harvest, it would be better to delay the cutting of canes.
The effects of adverse weather conditions during harvesting season can be counteracted by the application of chemical ripeners. The application of chemical ripener 6-8 weeks before harvest during rainy season increases sugar quality. An average increase in sugar quality of about 20% for Polaris (5kg a.i./ha) was obtained in a study made in Negros Occidental. Any delay in harvesting of the treated canes, however, may lower the sugar content.
Some of the improved harvesting techniques in sugarcane farming include the following:
1. Cutting. Canes should be cut close to the base. Cutting as close as possible to the base/ground level would eliminate waste in terms of sugar left in the field. Studies made by technologies have shown that a 10-12cm length of canes left in the field uncut may mean a loss of about 5 piculs sugar per hectare. O. Quiloy (1985) showed that on a hectare basis, about 3-5 tons sugarcane is left in the field when the canes are cut too high above the ground.
Cutting the cane stalks close to the ground will also reduce the cost of stubble shaving. If harvesting is supervised closely, stubble shaving may even be avoided entirely. In ratooning, the latter practice has a very grave importance. The cost of shaving-off stumps after harvest may be small but the decrease in yield due to the delayed stubble shaving may be substantial. Studies conducted by VICMICO-SRD indicated a 16-44% decrease in yield when stubble shaving was delayed from 6-5 to 20 days after burning the trashes (Fernandez, et al. 1964).
2. Topping. The usual practice before cutting of the canes is to top or cut the upper portion of the stalk for planting materials. In topping, only the youngest top portion of the stalk should be cut off.
3. Hauling. In hauling canes, include only the millable stalks. Water shoots, bull shoots, very young stalks, dead stalks, etc. should not be included. They should be excluded for the following reasons; a) They contain no sugar; b) They affect milling operations; and c) They provide unnecessary hauling expenses.
4. Milling. Canes should be milled as soon as possible after harvesting or within 48 hours after cutting. Any delay would mean a corresponding percentage loss of sugar.
Some of the practices to avoid in harvesting include the following;
1. Delayed milling
Cut canes should be hauled immediately to the factory. Sugar content decreases when milling is delayed from the time of cutting due to sucrose deterioration and evaporation.
Canes delivered to the mill 2-5 days from cutting showed a 10% decrease in yields compared with that of the fresh canes milled immediately after harvest (Cover, R.)
Rosenfield's study showed that fresh canes cut and left lying in the fields for 8 days have lost weight through evaporation by as much as 11%.
2. Burning of canes before harvest
Except in unavoidable circumstances, canes should not be burned. The death of the cells of the stalks as a result of burning causes the inversion of the sucrose content of the canes into reducing sugars (a sugar form which cannot be crystallized). In cases where burning is unavoidable, burnt canes should be harvested immediately and milled within the shortest time possible. Burnt canes left uncut or standing in the fields will continue to absorb water from the soils. This water cannot be lost through evaporation since the leaves have already been destroyed.
Calma (1944) observed that 5 days after the canes were burned, there was a marked decline in purity of the juice and the loss in weight ranged from 3.5% to as high as 20.5%.
Under Canlubang conditions both burnt chopped canes and green chopped canes showed deterioration 48 hours after harvest. On burnt canes, the rendement showed significant decrease on the 6th day after harvest. The reducing sugar increased significantly on the second day but did not go beyond the standard 1.28% until the 6th day (Hernia and Gregorio, 1984)
Corpuz, et al and Lezarde (1993) stated that canes delivered more than 48 hours after burning tend to contain much non-sugar due to deterioration, making clarification and crystallization difficult.
3. Delayed harvesting after topping
Topping is the removal of the terminal portion of the stalks of the standing canes to secure seed pieces for planting. A long interval between topping and harvesting resulted in sugar losses.
The following data shows the reduction in purity and sugar yields for every day delay in cutting;
In another study conducted by Mercado et al (1984), the following data showed the effect of varying harvesting practices and delays in milling on juice quality.
4. Milling of trashy canes
Another bad practice of sugarcane planters to be avoided is delivering of trashy canes to the mills.
Trash is defined as extraneous materials which form part of the cane delivery consisting of leaves, cane tops, dead, stale and diseased stalks, water sprouts, roots, weeds, soils, etc. These materials contain no sugar. When mixed with a cane stalks during milling, they sponge-up a lot of the cane juice. These will later be thrown out as bagasse thus, it reduce sugar recovery.
The juice from the cane tops contains starch, ash, soluble polysaccharides and reducing sugars. Milling of canes with tops decreases the recoverable sugar per ton cane by the amount of 15.% to 17.2% in relation to the canes without tops. The higher tonnage compensates for this but there is still a decrease by 0.05% to 0.1% in sugar yields.
On the other hand, stale canes and diseased stalks contribute to juice deterioration and poor sugar quality.
Silica content of the leaves increases wear and tear of the mills and therefore lengthen the milling period.
Trash occupies space in transport vehicle thus therefore increased transport expenses.
Compiled results of former PHILSUGIN studies showed the increasing loss in piculs sugar with the increasing percent trash in cane as follows;
A study made by Corpuz and Lezarde (1993) showed that in Don Pedro, the recoverable sugar from trash could have amounted to;
1. In 1990-91, a 2.26% trash meant a loss of 176,458.51 LKG sugar
2. In 1991-92, a 1.96% trash meant a loss of 17,584.28 LKG sugar
If the planters observed a clean cane delivery, these could have been added revenues to both the planters and the millers.
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