African oil palm
Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.
Two kinds of oil are obtained from this palm, Palm Oil and Palm Kernel Oil. Palm oil is extracted from the fleshy mesocarp of the fruit which contains 45-55% oil which varies from light yellow to orange-red in color, and melts from 25° to 50°C. For edible fat manufacture, the oil is bleached. Palm oil contains saturated palmitic acid, oleic acid and linoleic acid, giving it a higher unsaturated acid content than palm kernel or coconut oils. Palm oil is used for manufacture of soaps and candles, and more recently, in manufacture of margarine and cooking fats. Palm oil used extensively in tin plate industry, protecting cleaned iron surfaces before the tin is applied. Oil also used as lubricant, in textile and rubber industries. Palm kernel oil is extracted from the kernel of endosperm, and contains about 50% oil. Similar to coconut oil, with high content of saturated acids, mainly lauric, it is solid at normal temperatures in temperate areas, and is nearly colorless, varying from white to slightly yellow. This non-drying oil is used in edible fats, in making ice cream and mayonnaise, in baked goods and confectioneries, and in the manufacture of soaps and detergents. Press cake, after extraction of oil from the kernels, used as livestock feed, containing 5-8% oil. Palm wine made from the sap obtained by tapping the male inflorescence. The sap contains about 4.3 g/100 ml of sucrose and 3.4 g/100 ml of glucose. The sap ferments quickly, and is an important source of Vitamin B complex in diet of people of West Africa. A mean annual yield per hectare of 150 palms of 4,000 liters is obtained, and is double in value to the oil and kernels from same number of palms. Central shoot or cabbage is edible. Leaves used for thatching; petioles and rachices for fencing and for protecting the tops of retid walls. Refuse after stripping the bunches used for mulching and manuring; ash sometimes used in soap-making.
According to Hartwell (1967-1971), the oil is used as a liniment for indolent tumors. Reported to be anodyne, antidotal, aphrodisiac, diuretic, and vulnerary, oil palm is a folk remedy for cancer, headaches, and rheumatism (Duke and Wain, 1981).
As oil is rich in carotene, it can be used in place of cod liver oil for correcting Vitamin A deficiency. Per 100 g, the fruit is reported to contain 540 calories, 26.2 g H2O, 1.9 g protein, 58.4 g fat, 12.5 g total carbohydrate, 3.2 g fiber, 1.0 g ash, 82 mg Ca, 47 mg P, 4.5 mg Fe, 42,420 ug ß-carotene equivalent, 0.20 mg thiamin, 0.10 mg riboflavin, 1.4 mg niacin, and 12 mg ascorbic acid. The oil contains, per 100 g, 878 calories, 0.5% H2O, 0.0% protein, 99.1% fat, 0.4 g total carbohydrate, 7 mg Ca, 8 mg P, 5.5 mg Fe, 27,280 ug ß-carotene equivalent, 0.03 mg riboflavin, and a trace of thiamine. The fatty composition of the oil is 0.5-5.9% myristic, 32.3-47.0 palmitic, 1.0-8.5 stearic, 39.8-52.4 oleic, and 2.0-11.3 linoleic. The component glycerides are oleodipalmitins (45%), palmitodioleins (30%), oleopalmatostearins (10%), linoleodioleins (6-8%), and fully saturated glycerides, tripalmatin and diapalmitostearin (6-8%).
Tall palm, 8.3-20 m tall, erect, heavy, trunks ringed; monoecious, male and female flowers in separate clusters, but on same tree; trunk to 20 m tall, usually less, 30 cm in diameter, leaf-bases adhere; petioles 1.3-2.3 m long, 12.5-20 cm wide, saw-toothed, broadened at base, fibrous, green; blade pinnate, 3.3-5 m long, with 100-150 pairs of leaflets; leaflets 60-120 cm long, 3.5-5 cm broad; central nerve very strong, especially at base, green on both surfaces; flower-stalks from lower leaf-axils, 10-30 cm long and broad; male flowers on short furry branches 10-15 cm long, set close to trunk on short pedicels; female flowers and consequently fruits in large clusters of 200-300, close to trunk on short heavy pedicels, each fruit plum-like, ovoid-oblong to 3.5 cm long and about 2 cm wide, black when ripe, red at base, with thick ivory-white flesh and small cavity in center; nuts encased in a fibrous covering which contains the oil. About 5 female inflorescences are produced per year; each inflorescence weighing about 8 kg, the fruits weighing about 3.5 g each.
Reported from the African Center of Diversity, the African oil palm or cvs thereof is reported to tolerate high pH, laterite, low pH, savanna, virus, and waterlogging (Duke, 1978). Cultivars are said not to occur (Reed, 1976), but Ehganullah (1972) published on oil palm cultivars. African Oil Palm is monoecious and cross-pollinated, and individual palms are very heterozygous. Three varieties are distinguished: those with orange nuts which have the finest oil but small kernels; red or black nut varieties have less oil, but larger kernels. Sometimes oil palms are classified according to the fruit structure: Dura, with shell or endocarp 2-8 mm thick, about 25-55% of weight of fruit; medium mesocarp of 35-55% by weight, but up to 65% in the Deli Palms; kernels large, 7-20% of weight of fruit; the most important type in West Africa; the macrocarya form with shells 6-8 mm thick forms a large proportion of crop in western Nigeria and Sierra Leone. Tenera, with thin shells, 0.5-3 mm thick, 1-32% of weight of fruit; medium to high mesocarp 60-95% of weight of fruit; kernels 3-15% of fruit; larger number of bunches than Dura, but lower mean bunch weight and lower fruit to bunch ratio. Pisifera, shell-less, with small kernels in fertile fruits, fruits often rotting prematurely; fruit to bunch ratio low; infertile palms show strong vegetative growth, but of little commercial value, but has now become of greatest importance in breeding commercial palms. Deli Palm (Dura type) originated in Sumatra and Malaya, gives high yields in the Far East, but not so good in West Africa. Dumpy Oil Palm, discovered in Malaya among Deli Palms, is low-growing and thick stemmed. Breeding and selection of oil palm has been aimed at production of maximum quantity of palm oil and kernels per hectare, and resistance to disease. Recently, much attention has been directed at cross-breeding with E. oleifera for short-trunk hybrids, thus making harvesting easier. Zeven (1972) elucidates the center of diversity, and discusses the interactions of some important oil palm genes.(2n = 32,36)
Center of origin of the oil palm is in the tropical rain forest region of West Africa in a region about 200-300 km wide along coastal belt from Liberia to Angola. The palm has spread from 16°N latitude in Senegal to 15°S in Angola and eastwards to the Indian Ocean, Zanzibar and Malagasy. Now introduced and cultivated throughout the tropics between 16°N and S latitudes. Sometimes grown as an ornamental, as in southern Florida.
Occurs wild in riverine forests or in freshwater swamps. It cannot thrive in primeval forests and does not regenerate in high secondary forests. Requires adequate light and soil moisture, can tolerate temporary flooding or a fluctuating water table, as might be found along rivers. Ranges ecologically from savanna to rain forest. It is slightly hardier than coconut. Native to areas with 1,780 to 2,280 mm rainfall per year. Best developed on lowlands, with 2-4 month dry period. Mean maximum temperature of 30-32°C and mean minimum of 21-24°C provide suitable range. Seedling growth arrested below 15°C. Grows and thrives on wide range of tropical soils, provided they have adequate water supply. Waterlogged, highly lateritic, extremely sandy, stony or peaty soils should be avoided. Coastal marine alluvial clays, soils of volcanic origin, acid sands and other coastal alluviums are used. Soils with pH of 4-6 are most often used. Ranging from Subtropical Dry (without frost) through Tropical Dry to Wet Forest Life Zones, oil palm is reported to tolerate annual precipitation of 6.4 to 42.6 dm (mean of 27 cases = 22.7), annual temperature of 18.7 to 27.4°C (mean of 27 cases = 24.8), and pH of 4.0 to 8.0 (mean of 22 cases = 5.7) (Duke, 1978, 1979).
In wild areas of West Africa the forest is often cleared to let 75 to 150 palms stand per hectare; this yields about 2.5 MT of bunches per hectare per year. Normally oil palms are propagated by seed. Seed germination and seedling establishment are difficult. Temperature of 35°.C stimulates germination in thin shelled varieties. Thick-walled varieties require higher temperatures. Seedlings are outplanted at about 18 months. In some places, seeds are harvested from the wild, but plantation culture is proving much more rewarding. In a plantation, trees are spaced 9 x 9 m, a 410-ha plantation would have about 50,000 trees, each averaging 5 bunches of fruit, each averaging 1 kg oil to yield a total of 250,000 kg oil for the 410 ha. Vegetative propagation is not feasible as tree has only one growing point. Because oil palm is monoecious, cross-pollination is general and the value of parent plants is determined by the performance of the progeny produced in such crosses. Bunch-yield and oil and kernel content of the bunches are used as criteria for selecting individual palms for breeding. Controlled pollination must be maintained when breeding from selected plants. Seed to be used for propagation should be harvested ripe. Best germination results by placing seeds about 0.6 cm deep in sand flats and covering them with sawdust. Flats kept fully exposed to sun and kept moist. In warm climates, 50% of seed will germinate in 8 weeks; in other areas it may take from 64-146 days. Sometimes the hard shell is ground down, or seeds are soaked in hot water for 2 weeks, or both, before planting. Plants grow slowly at first, being 6-8 years old before the pinnate leaves become normal size. When planting seedlings out in fields or forest, holes are dug, and area about 1 m around them cleared. Young plants should be transplanted at beginning of rainy season. In areas where there is no distinct dry season, as in Malaya, planting out may be done the year round, but is usually done during months with the highest rainfall. Seedlings or young plants, 12-18 months old, should be moved with a substantial ball of earth. Ammonium sulfate and sulfate or muriate of potash at rate of 227 g per palm should be applied in a ring about the plant at time of planting. Where magnesium may be deficient in the soil, 227 g Epsom salts or kieserite should be applied also. In many areas oil palms are intercropped with food plants, as maize, yams, bananas, cassava or cocoyams. In Africa, intercropping for up to 3 years has helped to produce early palm yields. Cover-crops are often planted, as mixtures of Calopogonium mucunoides, Centrosema pubescens and Pueraria phaseoloides, planted in proportion of 2:2:1 with seed rate of 5.5 kg/ha. Natural covers and planted cover crops can be controlled by slashing. Nitrogen dressings are important in early years. Chlorosis often occurs in nursery beds and in first few years after planting out. Adequate manure should be applied in these early years. When nitrogen fertilizers, as sulfate of ammonium are used, 0.22 kg per palm in the planting year and 0.45 kg per palm per year until age 4, should be sufficient. Potassium, magnesium, and trace element requirements should be determined by soil test and the proper fertilizer applied, according to the region, soil type and degree of deficiency.
First fruit bunches ripen in 3-4 years after planting in the field, but these may be small and of poor quality. Often these are eliminated by removal of the early female inflorescences. Bunches ripen 5-6 months after pollination. Bunches should be harvested at correct degree of ripeness, as under-ripe fruits have low oil concentration and over-ripe fruits have high fatty acid content. Harvesting is usually done once a week. In Africa, bunches of semi-wild trees are harvested with a cutlass, and tall palms are climbed by means of ladders and ropes. For the first few years of harvesting, bunches are cut with a steel chisel with a wooden handle about 90 cm long, allowing the peduncles to be cut without injuring the subtending leaf. Usually thereafter, an axe is used, or a curved knife attached to a bamboo pole. A man can harvest 100-150 bunches per day. Bunches are carried to transport centers and from there to the mill for oil extraction.
Yields and Economics
According to the Wealth of India, the oil yield of oil palm is higher than that of any other oilseed crop producing 2.5 MT oil per ha per year, with 5 MT recorded. Yields of semi-wild palms vary widely, usually ranging from 1.2 to 5 MT of bunches per hectare per year. One MT of bunches yields about 80 kg oil by local soft oil extraction, or 180 kg by hydraulic handpress. Estate yields in Africa vary from 7.5-15 MT bunches per hectare per year; in Sumatra and Malaya, 15-25 MT, with some fields producing 30-38 MT. Estate palm oil extraction yield rates vary accordingly: Dura, 15-16% oil per bunch; Deli Dura, 16-18%; Tenera, 20-22%. Kernel extraction yields vary from 3.5-5% or more. Palm oil is one of the world's important vegetable oils. United States imported nearly 90 million kg in 1966, more than half of it as kernel oil. Recently palm oil commanded $.31 per kg, indicating potential yields of about $1400 per ha. In 1968 world producing countries exported about 544,000 long tons of oil and 420,000 long tons of kernels. Main producing countries, in order of production, are Nigeria, Congo, Sierra Leone, Ghana, Indonesia, and Malaysia. United Kingdom is the largest importer of oil palm products, importing about 180,000 T of palm oil and 243,000 T of palm kernels annually. Japan, Eastern European and Middle East countries also import considerable quantities of palm oil and kernels. Some palm kernel oil extraction is now being done in the palm oil producing countries. Previously, most of the kernels had been exported, and the oil extracted in the importing countries.
Bunch yields may attain 22,000 kg/ha; of which only about 10% is oil, indicating oil yields of only 2,200 kg/ha. Higher yields are attainable. Corley (1981) suggests plantation yields of 2-6 MT/ha mesocarp oil, experimentally up to 8.5 MT/ha. Hodge (1975), citing oil yields of 2,790 kg/ha suggests that this is the most efficient oil making plant species. The seasonal maximum total biomass reported for oil palm is 220 MT wet weight. When replanting occurs, over 40 MT/ha (dry weight) of palm trunks are available, conceivably for energy production, after the 70% moisture from the wet material has been expelled (Corley, 1981). Although annual productivity may approach 37 MT DM/ha, mean productivity during the dry season is 10 g/m2/day (Westlake, 1963). Averaged over the year, oilpalm in Malaysia showed a growth rate of 8 g/m2/day for an annual phytomass production of 29.4 MT/ha (Boardman, 1980). Fresh fruit bunch yields have been increased elsewhere by 2 MT/ha intercropping with appropriate legumes. Estate yields in Africa are 7-15 MT bunches per year, with oil yields of 800-1800 kg/ha, and residues of yields of ca 6-13 MT. It is probable that older leaves, leaf stalks, etc., could be harvested with biomass yield of 1-5 MT/ha. Based on energetic equivalents of total biomass produced, up to 60 barrels of oil per hectare could be obtained from this species. An energy evaluation of all the wastes from the palm oil fruit was made and it revealed that this can satisfy ca 17% of Malaysia's energy requirements. Palm oil could satisfy 20% more (Keong, 1981). An alcoholic wine can be made from the sap of the male spikes, 150 trees yielding about 4,000 laters of palm wine per hectare, per year. Most incredible, and surely worthy of energetic interest is Gaydou et al's (1982) suggestion that the oil palm can yield twice as much energetically as sugar cane, at least based on the Malagasy calculations. I am told that palmoil is already flowing in Malaysian pipelines, but that the palm oil industry is the most serious polluter in Malaysia. Barker and Worgan (1981) report utilization of the effluents. Biomass yields of ca 50 g/100g OM were obtained containing 40% CP with BOD reductions of 85% and COD reductions of 75-80% in batch culture. Supplementation with an inorganic N source was necessary.
Many fungi attack oil palms, but the most serious ones are the following: Blast (Pythium splendens, followed by Rhizoctonia lamellifera), Freckle (Cercospora elaeidis), Anthracnose (Botryodiplodia palmarum, Melanconium elaeidis, Glomerella cingulata), Seedling blight (Curvularia eragrostidis), Yellow patch and Vascular wilt (Fusarium oxysporum), Basal rot of trunk (Ceratocystis paradoxa, imp. stage of Thielaviopsis paradoxa), other trunk rots (Ganoderma spp., Armillaria mellea); Crown disease, rotting of fruit (Marasmius palmivorus). Spear rot or bud rot is caused by the bacterium Erwinia sp., which has devastated entire areas in S. Congo. The following nematodes have been isolated from oil palms: Aphelenchus avenae, Helicotylenchus pseudorobustus, H. microcephalus Hoplolaimus pararobustus, H. sp., Meloidogyne sp., Rhadinaphelenchus cocophilus (serious in Venezuela), and Scutellonema clathrocaudatus (Golden, p.c., 1984). The major pests of oil palm in various parts of the world are the following: Palm weevils (Rhynchophorus phoenicis, R. palmarum, R. ferrugineus), Rhinoceros beetles (Oryctes rhinoceros, O. boas, O. monoceros, O. owariensis), Weevils (Strategus aloeus, Temnoschoita quadripustulata), Leaf-miners (Coelaenomenodera elaeidis, Hispolepis elaeidis, Alurunus humeralis), Slug caterpillar (Parasa viridissima), Nettle caterpillar (Setora nitens), Bagworms (Cremastophysche pendula, Mahasena corbetti, Metisa plana). Rodents may cause damage to seedlings and fruiting palms; some birds also cause damage in jungle areas.
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