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Cocos nucifera L.

Arecaceae
Coconut, Narel

Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.

  1. Uses
  2. Folk Medicine
  3. Chemistry
  4. Description
  5. Germplasm
  6. Distribution
  7. Ecology
  8. Cultivation
  9. Harvesting
  10. Yields and Economics
  11. Energy
  12. Biotic Factors
  13. Chemical Analysis of Biomass Fuels
  14. References

Uses

Coconut is one of the ten most useful trees in the world, providing food for millions of people, especially in the tropics. At any one time a coconut palm has 12 different crops of nuts on it, from opening flower to ripe nut. At the top of the tree is the growing point, a bundle of tightly packed, yellow-white, cabbage-like leaves, which, if damaged, causes entire tree to die, but if tree can be spared, this heart makes a tasty treat, a 'millionaire's salad'. Unopened flowers are protected by sheath, often used to fashion shoes, caps, even a kind of pressed helmet for soldiers. Opened flowers provide a good honey for bees. A clump of unopened flowers may be bound tightly together, bent over and its tip bruised. Soon it begins to 'weep' a steady dripping of sweet juice, up to a gallon per day. It contains 16-30 mg ascorbic acid/100 g. The cloudy brown liquid is easily boiled down to syrup, called coconut molasses, then crystalized into a righ dark sugar, almost exactly like maple sugar. Sometimes it is mixed with grated coconut for candy. Left standing, it ferments quickly into a beer with alcohol content up to 8%, called 'toddy' in India and Sri Lanka; 'tuba' in Philippines and Mexico; and 'tuwak' in Indonesia. After a few weeks, it becomes a vinegar. 'Arrack' is the product after distilling fermented 'toddy' and is a common spirituous liquor consumed in the East. Nut has a husk, which is a mass of packed fibers called coir, which can be woven into strong twine or rope, and is used for padding mattresses, upholstery and life-preservers. Fiber resistant to sea water and is used for cables and rigging on ships, for making mats, rugs, bags, brooms, brushes, and olive oil filters in Italy and Greece; also used for fires and mosquito smudges. If nut is allowed to germinate, cavity fills with a spongy mass called 'bread' which is eaten raw or toasted in shell over fire. Sprouting seeds may be eaten like celery. Shell is hard and fine-grained, and may be carved into all kinds of objects, as drinking cups, dippers, scoops, smoking pipe bowls, and collecting cups for rubber latex. Charcoal used for cooking fires, air filters, in gas masks, submarines, and cigarette tips. Shells burned as fuel for copra kilns or housefires. Coconut shell flour used in industry as filler in plastics. Coconut water is produced by a 5 month old nut, about 2 cups of crystal clear, cool sweet (invert sugars and sucrose) liquid, so pure and sterile that during World War II, it was used in emergencies instead of sterile glucose solution, and put directly into a patient's veins. Also contains growth substances, minerals, and vitamins. Boiled toddy, known as jaggery, with lime makes a good cement. Nutmeat of immature coconuts is like a custard in flavor and consistency, and is eaten or scraped and squeezed through cloth to yield a 'cream' or 'milk' used on various foods. Cooked with rice to make Panama's famous 'arroz con coco'; also cooked with taro leaves or game, and used in coffee as cream. Dried, desiccated, and shredded it is used in cakes, pies, candies, and in curries and sweets. When nuts are cut open and dried, meat becomes copra, which is processed for oil, rich in glycerine and used to make soaps, shampoos, shaving creams, toothpaste lotions, lubricants, hydraulic fluid, paints, synthetic rubber, plastics, margarine, and in ice cream. In India, the Hindus make a vegetarian butter called 'ghee' from coconut oil; also used in infant formulas. When copra is heated, the clear oil separates out easily, and is made this way for home use in producing countries. Used in lamps. Cake residue used as cattle fodder, as it is rich in proteins and sugar; should not give more than 4-5 lbs/animal/day, as butter from milk will have a tallow flavor. As cake is deficient in calcium, it should be fed together with calcium rich foods. Trunk wood used for building sheds and other semi-permanent buildings. Outer wood is close-grained, hard, and heavy, and when well seasoned, has an attractive dark colored grain adaptable for carving, especially ornamentals under the name of 'porcupine wood'. Coconut logs should not be used for fences, as decayed wood makes favorable breeding places for beetles. Logs are used to make rafts. Sections of stem, after scooping out pith, are used as flumes or gutters for carrying water. Pith of stem contains starch which may be extracted and used as flour. Pitch from top of tree is sometimes pickled in coconut vinegar. Coconut leaves made into thin strips are woven into clothing, furnishings, screens, and walls of temporary buildings. Stiff midribs make cooking skewers, arrows, brooms, brushes, and for fish traps. Leaf fiber used in India to make mats, slippers, and bags. Used to make short-lived torches. Coconut roots provide a dye, a mouthwash, a medicine for dysentery, and frayed out make toothburshes; scorched, used as coffee substitute. Believed to be antiblenorrhagic, antibronchitis, febrifugal, and antigingivitic. Coconut palm is useful as an ornamental; its only drawback being the heavy nuts which may cause injury to man, beast, or rooftop when they hit in falling (Duke, 1972).

Folk Medicine

According to Hartwell (1967-1971) coconuts are used in folk remedies for tumors. Reported to be anthelmintic, antidotal, antiseptic, aperient, aphrodisiac, astringent, bactericidal, depurative, diuretic, hemostat, pediculicide, purgative, refrigerant, stomachic, styptic, suppurative, and vermifuge, coconut, somewhere or other, is a folk remedy for abscesses, alopecia, amenorrhea, asthma, blenorrhagia, bronchitis, bruises, burns, cachexia, calculus, colds, constipation, cough, debility, dropsy, dysentery, dysmenorrhea, earache, erysipelas, fever, flu, gingivitis, gonorrhea, hematemesis, hemoptysis, jaundice, menorrhagia, nausea, phthisis, pregnancy, rash, scabies, scurvy, sorethroat, stomach, swelling, syphylis, toothache, tuberculosis, tumors, typhoid, venereal diseases, and wounds (Duke and Wain, 1981).

Chemistry

Per 100 g, the kernel is reported to contain 36.3 g H2O 4.5 g protein, 41.6 g fat, 13.0 g total carbohydrate, 3.6 g fiber, 1.0 g ash, 10 mg Ca, 24 mg P, 1.7 mg Fe, and traces of beta-carotene (C.S.I.R., 1948-1976). Per 100 g, the green nut is reported to contain 77-200 calories, 68.0-84.0 g H2O, 1.4- 2.0 g protein, 1.9-17.4 g fat, 4.0-11.7 g total carbohydrate, 0.4-3.7 g fiber, 0.7-0.9 g ash, 11-42 mg Ca, 42-56 mg P, 1.0-1.1 mg Fe, 257 mg K, trace of beta-carotene, 0.4-0.5 mg thiamine, 0.03 mg riboflavin, 0.8 mg niacin, and 6-7 mg ascorbic acid (Food Composition Tables). Coconut oil is one of the least variable among vegetable fats, i.e. 0.2-0.5% caproic-, 5.4-9.5 caprylic-, 4.5-9.7 capric-, 44.1-51.3 lauric-, 13.1-18.5 myristic, 7.5-10.5 palmitic-, 1.0-3.2 stearic-, 0-1.5 arachidic-, 5.0-8.2 oleic-, and 1.0-2.6 linoleic-acids (C.S.I.R., 1948-1976). Following oil extraction from copra, the coconut cake (poonac) contains 10.0-13.3% moisture, 6.0-26.7% oil, 14.3-19.8% protein, 32.8-45.3% carbohydrates, 8.9-12.2% fibers, and 4.0-5.7% ash. The so-called coconut water is 95.5% water, 0.1% protein, <0.1% fat, 0.4% ash, 4.0% carbohydrate. Per 100 g water, there is 105 mg Na, 312 K, 29 Ca, 30 Mg, 0.1 Fe, 0.04 Cu, 37 P, 24 S, and 183 mg choline. Leaves contain 8.45% moisture, 4.282 ash, 0.56% K2O, 0.25 P2O5, 0.28 CaO, and 0.57% MgO.

Description

Palm to 27 m or more tall, bearing crown of large pinnate leaves; trunk stout, 30-45 cm in diameter, straight or slightly curved, rising from a swollen base surrounded by mass of roots; rarely branched, marked with rings of leaf scars; leaves 2-6 m long, pinnatisect, leaflets 0.6-1 m long, narrow, tapering; inflorescence in axil of each leaf as spathe enclosing a spadix 1.3-2 m long, stout, straw or orange colored, simply branched; female flowers numerous, small, sweet-scented, horne towards top of panicle; fruit ovoid, 3-angled, 15-30 cm long, containing single seed; exocarp a thick fibrous, husk, enclosing a hard, bony endocarp or shell. Adhering inside wall of endocarp is testa with thick albuminous endosperm, the coconut meat; embryo below one of the three pores at end of fruit, cavity of endosperm filled in unripe fruit with watery fluid, the coconut water, and only partially filled.when ripe. Fl. and fr. year round in tropics.

Germplasm

Reported from the Indochina-Indonesia and Hindustani centers of origin, coconut has been reported to tolerate high pH, heat, insects, laterites, low pH, poor soil, salt, sand, and slope. Many classifications have been proposed for coconuts, none is wholly satisfactory. Variations are based on height, tall (27 m or so) or dwarf (2 m); color of plant or fruit; size of nut (some palms have very large fruits, others have large numbers of small fruits); shape of nuts, varying from globular to spindel-shaped or with definite triangular sections; thickness of husk or shell; type of inflorescence; and time required to reach maturity. Many botanical varieties and forms have been recognized and named, using some of the characteristics mentioned above. Cultivars have been developed from various areas. Dwarf palms occurring in India are introductions from Malaysia, live about 30-35 years, thrive in rich soils and wet regions, flower and fruit much earlier than tall varieties, and come into bearing by fourth year after planting. However, dwarf varieties are not grown commercially, and only on a limited scale because of their earliness and tender nuts, which yield a fair quantity of coconut water. They are highly susceptible to diseases and are adversely affected by even short periods of drought. Tall coconuts are commonly grown for commercial purposes, 40-90 years, are hardy, and thrive under a variety of soil, climatic, and cultural conditions, begin to flower when about 8-10 years after planting. 2n = 16.

Distribution

Now pantropical, especially along tropical shorelines, where floating coconuts may volunteer, the coconut's origin is shrowded in mysteries, vigorously debated. According to Purseglove (1968-1972), the center of origin of cocoid palms most closely related to coconut is in northwestern South America. At the time of the discovery of the New World, coconuts (as we know them today) were confined to limited areas on the Pacific coast of Central America, and absent from the Atlantic shores of the Americas and Africa. Coconuts drifted as far north as Norway are still capable of germination. The wide distribution of coconut has no doubt been aided by man and marine currents as well.

Ecology

Ranging from Subtropical Dry to Wet through Tropical Very Dry to Wet Forest Life Zones, coconut has been reported from stations with an annual precipitation of 7-42 dm (mean of 35 cases = 20.5), annual temperature of 21-30°C (mean of 35 cases = 25.7°C) with 4-12 consecutive frost free months, each with at least 60 mm rainfall, and pH of 4.3-8.0 (mean of 27 cases = 6.0).

Cultivation

Propagated by seedlings raised from fully mature fruits. Seeds selected from high-yielding stock with desirable traits. Yield of copra is final criterion, based on size and number of nuts per palm. Seednut trees should have straight trunk and even growth, with closely spaced leaf-scars, short fronds, well oriented on the crown, short bunch stalks, and from palms growing under normal rather favorable conditions. Also the inflorescence should bear about 100 female flowers, and the crown should have a large number of fronds and consequently of inflorescences. Seednuts should be medium-sized and nearly spherical in shape; long nuts usually have too much husk in relation to kernel. Because male parent is unknown and because female parent is itself heterozygous, seednuts from high-yielding palms do not necessarily reproduce same performance in progeny; so that character alone has limited value. Records are kept of fruits harvested from each mother palm, such as number of bunches, number of nuts, weight of husked nuts, estimated weight of copra (about one-third weight of husked nuts being considered favorable). After fully mature nuts are picked, and not allowed to fall, they are tested by shaking to listen for water within. Under-ripe, spoiled, those with no water, or with insect or disease damage are discarded. Nuts are planted right away in nursery or stored in a cool, dry, well-ventilated shed until they can be planted. Seeds planted in nursery facilitate selection of best to put in field, as only half will produce a high-yielding palm for copra. Also, watering and insect control is much easier to manage in nursery. Soil should be sandy or light loamy, free from waterlogging, but close to source of water, and away from heavy shade. Nursery beds should be raised about 22 cm, and long, separated by shallow drains to carry away excessive water. In preparation of nursery beds, they should be dug and loosened to a depth of 30 cm. Loosened soil mixed with dried or rotten leaves and ash from burnt fresh coconut husks at a rate of 25 lbs. of husk-ash per 225 sq. ft. Nuts spaced in beds 22 x 30 cm, a hectare of nursery accomodating 100,000 seednuts. Nuts planted horizontally produce better seedlings than those planted vertically. The germinating eye is placed uppermost in a shallow furrow, about 15 cm deep, and soil mounded up around, but not completely covering them, leaving the eye exposed. Soaking nuts in water for 1-2 weeks before planting may benefit germination; longer periods of soaking are progressively disadvantageous. Bright sunlight is best for growing stout sturdy seedlings. Regular watering in nursery is essential in dry weather, amount and frequency depending on local conditions. Mulching sometimes used to preserve moisture and supress weeds. Paddy straw, woven coconut leaves, and just coconut leaves are used; howevers they might encourage termites. Potash fertilizer helps seedling growth, and probably do not need other fertilizers as nut provides most of needed nutrition. About 16 weeks after nut is planted, the shoot appears through the husk, and at about 30 weeks, when 3 seed-leaves have developed, seedlings should be planted out in permanent sites. Rigorous culling of seedlings is essential. All late germinators and very slow growers are discarded. Robust plants, showing normal rapid growth, straight stems, broad comparatively short dark-green leaves with prominent veins, spreading outward and not straight upward, and those free of disease symptoms, are selected for planting out. Best spacing depends upon soil and terrain. Usually 9-10 m on the square is used, planting 70-150 trees/ha; with triangular spacing of 10 m, 115 palms/ha; and for group or bouquet planting, 3-6 palms planted 4-5 m apart. Planting holes of 1 m wide and deep should be dug 1-3 months before seedlings are transplanted. In India and Sri Lanka, 300-400 husks are burned in each hole, providing 4-5 kg ash per hole. This is mixed with topsoil. Two layers of coconut husks are put into bottom of hole before filling with the topsoil mixed ash. Muriate of potash, 1 kg per hole, is better than ash, but increases cost of planting. The earth settles so that it will be 15-30 cm below ground level when seedling is planted. In planting, soil should be well-packed around nut, but should not cover collar of seedling, nor get into leaf axils. As plant develops, trunk may be earthed up, until soil is flush with general ground level. Usually 7-8 month old seedlings are used for transplants. In some instances plants up to 5 years old are used, as they are more resistant to termite damage. If older plants are used, care must be taken not to damage roots, as they are slow to recover. Desirable to transplant in rainy season. In areas with only one rainy season per year, it is simpler to plant nuts in nursery in one rainy season, and transplant them a year later. Young plantation should be fenced to protect plants from damage from cattle, goats, or other wild animals. Entire areas may be fenced in, individual trees, or, as in Sri Lanka and southern India, piles of coconut husks are placed around tree. At end of first year after transplanting, vacancies should be filled with plants of same age held in reserve in nursery. Also any slow-growers, or disease damaged plants should be replaced. During first 3 years, seedling should be watered during drought, an application of ca 16 liters/tree twice a week being recommended. Keep trees clear of weeds, especially climbers. Usually a circle 1-2 m in radius should be weeded with mattock several times a year, the weeds left as mulch. Cover-crops, as Centrosema pubescens, Calopogonium mucunoides, or Pueraria phaseoloides, are used and turned under before dry season. Catch-crops as Cassava (Manihot utilissima), and green gram (Vigna aureus) and cowpea (Vigna unguiculata), bananas and pineapples, may be used. Sometimes bush crops, in addition or instead of, ground covers are used as green manures, as Tephrosia candida, Crotalaria striata, C. uraramoensis, C. anagyroides, all fast growers. Gliricidia sepium and Erythrina lithosperma may be grown as hedges or live fences, their loppings used as green manure. Usually the cheapest form of fertilizer materials for a given area are used. General fertilizer recommended, used with suitable local modifications, would consist of 230-300 g N, 260-460 g P2O5, and 300-670 g K2O per palm. Application of lime is not generally recommended. There is no evidence that salt is beneficial as is sometimes claimed. They can withstand a degree of salinity, about 0.6%, which is lethal to many other crops. Palms seem to need some magnesium, but are extremely sensitive to an excess. Cultivation depends on soil type, slope of land, and rainfall distribution; often disk-harrowing at end of monsoon rains to control weeds is all that is necessary (Reed, 1976).

Harvesting

Trees begin to yield fruit in 5-6 years on good soils, more likely 7-9 years, and reach full bearing in 12-13 years. Fruit set to maturity is 8-10 months; 12 months from setting of female flowers. Nuts must be harvested fully ripe for making copra or desiccated coconut. For coir they are picked about one month short of maturity, so that husks will be green. Coconuts are usually Picked by human climbers, or cut by knives attached to end of long bamboo poles, this being the cheapest method. With pole, a man can pick from 250 palms in a day, by climbing, only 25. In some areas nuts are allowed to fall naturally, and collected regularly. Nuts are husked in field, a good husker handling 2,000 nuts/day. Then nut is split, (up to 10,000 nuts per working day). Copra may be cured by sun-drying, or by kiln-drying, or by a combination of both. Sun-drying requires 6-8 consecutive days of good bright sunshine to dry meat without its spoiling. Drying reduces moisture content from 50% to below 7%. Copra is stored in well-ventilated, dry area. Extraction of oil from copra is one of the oldest seed-crushing industries of the world. Coconut cake is usually retained to feed domestic livestock. When it contains much oil, it is not fed to milk cows, but is used as fertilizer. Desiccated coconut is just the white meat, the brown part is peeled off. It is usually grated, but may be thread or chip. Dried in driers similar to those for tea. Good desiccated coconut should be white in color, crisp, with a fresh nutty flavor, and should contain less than 20% moisture and 68-72% oil, the extracted oil containing less than 0.1% of free fatty acid, as lauric. Parings, about 12-15% of kernels, are dried and pressed for oil yielding about 55%. Used locally for soap-making. The resulting poonac used for feeding draught cattle. Coconut flour is made from desiccated coconut with oil removed, and the residue dried and ground. However, it does not keep well. Coir fiber obtained from slightly green coconut husks by retting in slightly saline water that is changed frequently (requires up to 10 months); then, husks are rinsed with water and fiber separated by beating with wooden mallets. After drying, the fiber is cleaned and graded. Greater part of coir produced in India is spun into yarn, a cottage industry, and then used for rugs and ropes. In Sri Lanka, most coir consists of mechanically separated mattress and bristle fiber. To produce this, husks are soaked or retted for 1-4 weeks, and then crushed between iron rollers before fibers are separated. Bristle fibers are 20-30 cm long; anything shorter is sold as superior mattress fiber. In some areas, dry milling of husks, without retting, is carried on and produces only mattress fiber. The separated pith, called bast or dust, is used as fertilizer since the potash is not leached out. Coconuts may be stored at temperature of 0-1.5°C with relative humidity of 75% or less for 1-2 months. In storage, they are subject to loss in weight, drying up of nut milk and mold. They may be held for 2 weeks at room temperature without serious loss.

Yields and Economics

For copra, an average of 6,000 nuts are required for 1 ton; 1,000 nuts yield 500 lbs. of copra, which yields 250 lbs. of oil. Average yield of copra per ha is 3-4 tons. Under good climatic conditions, a fully productive palm produces 12-16 bunches of coconuts per year, each bunch with 8-10 nuts, or 60-100 nuts/tree. Bunches ripen in about 1 year, and should yield 25 kg or more copra. For coir, 1,000 husks yield anout 80 per year, giving about 25 kg of bristle fiber and 55 kg of mattress fiber. Efficient pressing will yield from 100 kg of copra, approximately 62.5 kg of coconut oil, and 35 kg coconut cake, which contains 7-10% oil. The factor 63% is generally used for converting copra to oil equivalent. Yields of copra as high as 5 MT/ha have been reported, but oil yields of 900-1,350 kg/ha. Pryde and Doty (1981) put the average oil yield at 1,050 kg/ha, Telek and Martin (1981), at 600 kg/ha. World production of coconut oil is more than 2 million tons/year, about half of which moves in international trade. Desiccated coconut produced in countries where palm are grown and the products exported. Sri Lanka, Philippine Islands, Papua, and New Guinea are the largest producers. United States and United Kingdom each import at least 50 million pounds annually. Only about 40% of copra produced is exported, remaining 60% processed into oil in country of origin. United States annually imports 190 million pounds of coconut oil and more than 650 million pounds of copra; some sources state 300,000 tons copra and over 200,000 tons coconut oil annually. Coconut oil ranks third, after soybean and peanut oil, in world production of oils. I predict palm oil (Elaeis) will soon move up.

Energy

The coconut of commerce weighs 0.5-1.0 kg. According to Purseglove, the average number of nuts per hectare varies from 2,500 to 7,500 indicating yield of ca 1,200 to 7,500 kg/ha. On the one hand, 'Jamaica Talls' fruits average 1.7 kg, nuts 0.7 kg, of which 50% is endosper; on the other, 'Malayan Dwarfs' fruits average 1.1 kg, the nut 0.6 kg, yielding 0.2 kg copra (6,000 nuts/ton copra). Average production yields of copra (3-8 nuts per kg copra) range from 200 kg/ha in Polynesia to 1,200 kg/ha in the Philippines, suggesting coconut yields of 1,000 to 8,000 kg/ha. Since about 60% of this constitutes the inedible fruit husk and seed husks, I estimate the chaff factor at 0.6. Coconut oil, cracked at high temperatures will yield nearly 50% motor fuel and diesel fuel. Coconut destructive distillation is reported to yield 11.5% charcoal, 11% fuel gas, 37.5% copra spirit, 12.5% olein distillate, 1% crude acetate, 0.15% glycerol, and 0.85% acetone plus methanol. As of June 15, 1981, coconut oil was $0.275/lb., compared to $0.38 for peanut oil, $1.39 for poppyseed oil, $0.65 for tung oil, $0.33 for linseed oil, $0.265 for cottonseed oil, $0.232 for corn oil, and $0.21 for soybean oil (Chemical Marketing Reporter, June 15, 1981). At $2.00 per gallon, gasoline is roughly $0.25/lb. Quick (1981) tested linseed oil (Iodine number 180) which cokes up fuel injectors in less than 20 hours and rapeseed oil (Iodine number ca 100) which logs into the hundreds of hours before the onset of severe injector coking. Coconut oil (Iodine number 10) should be a very good candidate from this viewpoint. This could be very important in developing tropical countries where diesel fuel is scarce and often more expensive than coconut oil. One Australian patent suggests that distillation of coconuts at 550° gave 11.5% charcoal, 11% fuel gas, and 37.5% copra spirit, 12.5% olein distillate, 12.5% black oil, 1% crude acetic acid, 0.15% glycerol, and 0.85% (acetone + methanol) which natural fermentation takes to 2.7-5.8% ethanol. Of course, you can't have your coconut toddy and eat or drink or burn it too (Duke, 1977b).

Biotic Factors

Coconuts are subject to numerous fungal diseases, bacterial infections, and the most serious virus-like disease, cadang-cadang. Coconut trees are also attacked by numerous nematodes and some insect pests, the most damaging insect being the black beetle or rhinoceros beetle (Oryctes rhinoceros), which damages buds, thus reducing nut yield, and breeds in decaying refuse. Diseases and pests of a particular area should be considered and local agent consulted as to how to deal with them. Agriculture Handbook No. 165 (1960) lists the following as affecting this species: Aphelenchoides cocophilus (red ring disease), Cephalosporium lecanii, Diplodia epicocos, Endocalyx melanoxthanus, Endoconidiophora paradoxa (leaf-bitten disease, leaf scorch, stem-bleeding), Gloeosporium sp., Pellicularia koleroga (thread blight), Pestalotia palmarum (gray leaf spot, leaf-break), Phomopsis cocoes (on nuts), Phyllosticta sp. (on leaves), Physalospora fusca (on leaves), P. rhodina (on roots and trunk), Phytopthora palmivora (bud rot, leaf drop, wilt), Pythium sp. (wilt).

Chemical Analysis of Biomass Fuels

Analysing 62 kinds of biomass for heating value, Jenkins and Ebeling (1985) reported a spread of 20.05 to 19.02 MJ/kg, compared to 13.76 for weathered rice straw to 23.28 MJ/kg for prune pits. On a % DM basis, the fiber dust contained 66.58 % volatiles, 3.72 % ash, 29.70 % fixed carbon, 50.29 % C, 5.05 % H, 39.63 % O, 0.45 % N, 0.16 % S, 0.28 % Cl, and undertimed residue.

References

Complete list of references for Duke, Handbook of Energy Crops
last update July 8, 1996