Crop description. Shorea robusta Gaertn. f.—commonly known as sal, shal, saragi, sakhu, sakher, shaal, ral, gugal, mara, sagua, salwa, sakwa, kandar, and kung—is a large tree belonging to the family Dipterocar — paceae (see Fig. 4.23). The tree is native to southern Asia, ranging south of the Himalayas, from Myanmar in the east to India, Bangladesh, and Nepal. It grows in dry tropical forests, in a well-drained, moist, sandy loam soil. This tree can attain heights up to 35 m. The seeds of sal are an important source of edible oil. The seed contains around 20% of oil [183, 184].

Main uses. Although sal is a highly valued timber species, it is also used for house construction, and as poles, agriculture implements, fuelwood, fencing, leaves for cups and plates, and compost [185]. The oil is used for lighting and cooking purposes, and as a substitute for

Figure 4.23 Shorea robusta Gaertn. f. (Photo courtesy of Dr. Mike Kuhns [http: / / extension. usu. edu/forestry/ UtahForests/TreeID/Assets/ Images/sal-1.3.jpg].)

cocoa butter in the manufacture of chocolates. It is suitable for soap making after blending with other softer oils. The oil cakes that remain after oil extraction contain 10-12% protein and about 50% starch, and are used as cattle and poultry feed. However, the oil cake contains 5-14% tannin; consequently, not more than 20% is concentrated for cattle without detrimental effects. As the protein remains completely undigested, the oil cake yields energy only. Sal resin is burned as incense in Hindu ceremonies. It is also used for varnishes, for hard­ening softer waxes for use in the manufacture of shoe polishes, and as cementing material for plywood, asbestos sheets, and so forth. The resin is used in an indigenous system of medicine as an astringent and detergent [184]. No references about its use as a biodiesel source have been found so far.