The experimental site was located at 24 75† N latitude and 90 50† E longitude at an elevation of 18 m above sea level. The site falls under Agro-Ecological Zone 9 (AEZ-9) on the river in the Brahmaputra floodplain in Bangladesh (Food and Agriculture Organization of the United Nations 1990). The experimental site is characterized by moderately high temperature, high humidity, and heavy rainfall with occasional gusty winds from April to September, as well as scanty rainfall associated with moderately low temperatures from October to March.
Pit Preparation and Propagation The size of the pits for the plantation of the cuttings was 50 cm · 50 cm. The soil was taken out and dried for 1 week. The pits were refilled with one-third normal soil, one-third sand, and one-third compost, after stones and boulders were removed. There are various methods for the propagation of Jatropha, either generative or vegetative. Although direct seeding generally has a low survival rate, it can be successful under feasible conditions (e.g., optimal soil moisture content and sufficient seed supply per hole). Good survival rates (90%) are normally achieved by directly planting the cuttings or by transplanting methods (Heller 1996). Hence, the direct planting method was applied with the cuttings of the branches were collected from the northern part of Bangladesh. For plantation purposes, branches 30 cm long and 3 cm thick were selected.
Intercultural Operations and Harvesting Fertilizing. About 2 kg of organic manure mixed with fertilizers containing N, P, and K were applied at the time of planting. An admixture of 20 g of urea, 120 g of single super phosphate (SSP), and 16 g of muriate of potash (MOP) were applied after the plant was established. The plants responded well to the addition of fertilizers containing small amounts of calcium, magnesium, and sulfur as well as organic rich nutrition. Pruning. The plants must produce side shoots to maximize flowers and seed (Kumar and Sharma 2008). Pruning was done to ensure proper shape and size when the branches reached a height of 40–60 cm during the first year. The top of the plant was cut to produce 8–12 side branches. Because branches grow near the base, they were removed every year and replanted elsewhere. For easy harvesting, the tree height must be less than 2 m. Hoeing and weeding. It is necessary to hoe and weed Jatropha plants at least twice a year, especially during the establishment period. Weeding was done whenever necessary to keep the plant free from weeds, to facilitate soil aeration, and to break the crust. This also helped conserve soil moisture. Harvesting. The degree of flowering in the Jatropha plant depends upon location and agro-climatic conditions, as fruit can mature in 2 to 4 months. Flowering of the Jatropha began in the middle of May, and the fruit was harvested in July. During the harvesting period, the fruits in their maturity showed characteristic colors and sizes. The ripened fruits were then collected from the branch by hand and stored in dry place.
Processing, Handling, and Storage Once collected, the fruits were dried until they were unfolded. The seeds were separated from the fruits, dried in the shade (to reduce the negative effect of sunlight on seed viability), and sorted according to quality. Only good seeds were used for planting, while others were used for oil extraction. The dried seeds were stored in airtight containers instead.
Chemical Method for Oil Extraction from Jatropha Seed Vegetable oil can be extracted chemically with solvent extracts that produce higher yields. Mechanical extraction is another way that combines several different modes. In addition, the oil from Jatropha seeds can also be extracted by both chemical and mechanical methods. The oil content of the Jatropha seed was determined by the cold percolation method. The word cold in this context implies that extraction proceeds at room temperature without heating.
Preparation of seeds. As the ripe fruits were plucked from the trees, the seeds were sun dried and decorticated manually. For oil extraction, seeds should be solar heated for several hours or roasted for 10 min. This drying process can facilitate the breakdowns of the cells containing the oil to facilitate the liquation.
Equipment and chemicals used. For the experiment, the following items are required: agate mortar and pestle, percolator and sintered glass funnel, 20-mL airtight plastic bottle, 100-mL beaker, sand bath, Mattler balance. In addition, sodium sulfate (Na2SO4 ), carbon tetrachloride (CCl4 ), and crushed glass powder are needed for chemical treatment. Procedure. To begin with, 0.3 g of Jatropha seed powder, 2 g of glass powder, and 2 g of Na2SO4 were put into a mortar. The mixture was ground to a fine size. Then, 10 mL of CCl4 was added into the mortar to make a solution of 20 mL. The solution, contained in a vial, was shaken overnight in a shaker and then filtered with a sintered glass funnel with a percolator. The filtrates (oil + CCl4) were collected in a preweighed beaker with two glass balls. The beaker was then placed on a sand bath to allow for the evaporation of CCl4 at 60–70 C. The oil contained in the beaker was kept in a desiccator for cooling. Finally, the beaker with the oil and glass ball was weighed to compute the weight of the oil.