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bioweb.sungrant.org » Technical » Biomass Resources » Agricultural Resources » New Crops » Oilseeds » Castor

Castor	Printer Friendly

Castor (Ricinus communis), a member of the spurge family, is a semitropical plant thought to be native to Africa. The seeds contain 35-55% oil, composed of hydroxyl fatty acids. Castor oil is currently used to make high quality lubricants for heavy equipment and jet engines, and could be used to produce biodiesel and other biofuels. The endosperm of the seeds contain ricin and RCA120, chemicals that are highly toxic to humans and animals, but concentrations of these compounds are very low in other parts of the plant and in the oil. All tissues of the castor plant contain ricinine, a protein that can cause allergic reactions in some people. Castor was produced in the southern United States until the 1970s, but production was discontinued due primarily to economic competition from other countries. Today, the U.S. annually imports about 41,000 metric tons of castor oil from Brazil and India at a cost of around $100 million. The world market for castor oil is estimated to be 1 billion pounds annually.   In the tropics, castor is a perennial and can grow to 30-40 feet tall. It is grown as an annual in temperate regions and grows up to 5 feet tall. The growing season is 140-180 days and germination is slow (10-21 days after planting). Potential production regions in the U.S. include southeastern Kansas, Missouri, southern Illinois and Indiana, parts of Oklahoma and Texas, and the Southeast.   Castor is planted in early May on disked or plowed sites at a depth of 1.5 to 3 inches. Seeding density is 10-14 lbs/ac. Castor is planted at row widths of 38-40 inches and within row spacing of 8-12 inches. Nitrogen application rates depend on existing soil organic matter levels, with higher nitrogen (up to 100 lbs N/ac) required on sites with little organic matter (less than 2%) and lower rates (about 40 lbs N/ac) on sites with high organic matter (greater than 10%). Approximately 20 lbs P2O5/ac and 40 lbs K2O/ac are applied on soils with high phosphorus and potassium levels (i.e. 6-10 ppm P; 81-100 ppm K). Higher levels (an additional 5 lbs P2O5 and 20-30 lbs K2O/ac) should be applied for soils low in P and K. Excessive application of phosphorus can reduce yields.   Due to its slow emergence, castor seedlings are not competitive with weeds and so weed control is essential. Castor is harvested annually and should begin within two weeks following the first killing frost. Combines should be adjusted to account for the tendency of castor to crack during harvest. Seed yields of 2,200 lbs/ac have been achieved in U.S. tests.   Attempts to rid castor from ricin and allergens using traditional breeding methods have had moderate success. The use of biotechnology approaches (i.e., development of antisense genes) by the USDA Agricultural Research Service have reduced the levels of toxins and allergens, but have not resulted in the development of commercial varieties.  Texas Tech University has developed a partnership with Brazil to share and exchange Castor germplasm.

References
Lowery, C.; Auld, D.; Rolfe, R.; McKeon, T.; and Goodrum, J. (2006 Draft). Barriers to commercialization of a Castor (Ricinus communis L.) cultivar with reduced concentration of ricin. Texas Tech University, Plant and Soil Science Department. Oplinger, E.S.; Oelke, E.A.; Kaminiski, A.R.; Combs, S.M., Doll, J.D.; and   Schuler, R.T. (1990, May). Castorbeans. (Alternative Field Crops Manual). University of Wisconsin Extension Service. Wood, M. (2001, January). High-tech castor plants may open door to domestic production. Agricultural Research Magazine. U.S. Department of Agriculture, Agricultural Research Service.