Efeitos dos diferentes níveis e combinações de nitrogênio e potássio no teor de óleo da semente da mamona (Ricinus communis L.) irrigada com esgoto sanitário tratado e água bruta

Abstract

The castor bean (Ricinus communis Linn) is a plant well adapted to conditions of semi-arid and is considered a great economic potential for the Northeast Region. Irrigation with treated domestic sewage is also considered an alternative for those areas with water shortages due to be a source of water for these areas, while providing savings in fertilizer. The oil extracted from the seeds of the castor oil, after the process of esterification, can be used as biodiesel. The aim of this study was to evaluate the potential use of treated sewage into the stabilization ponds for irrigation of castor oil, using different levels and combinations of nutrients (nitrogen and potassium) fertilizer applied in, and check the oil content in seeds produced. The experiment was conducted in an area annexed to the treatment of sewage from the city of Aquiraz, in the metropolitan region of Fortaleza. A cultivar of castor oil was the BRS Nordestina 149, which was irrigated with well water and domestic sewage treated by the stabilization ponds, and micro system. The experiment lasted for 8 (eight) months from January to August 2007. Were implanted two distinct areas: area for irrigation with water from pool (1.320m2), and area for the irrigation with treated sewage (1277.25 m2). Each area had 04 blocks, 04 repetitions. The repetition appeared on 17 plots, with 06 plants. The plots are numbered from 1 to 17, indicating the type of fertilizer to be applied. The fertilization of the treatments varied according to the quantities of nitrogen (00, 30, 60, 90 kg / ha) and potassium (00, 30, 60, 90 kg / ha). The influence of irrigation with treated domestic sewage on productivity and production of oil in various treatments. Overall, there were no significant differences. The yield was influenced by nitrogen fertilization, in which the greatest yields were obtained for the treatment N2K2. The highest percentage of oil during irrigation with treated effluent were 60.78 and 61.22%, obtained respectively, for treatments N1K2 and N3K2, while for the treatments irrigated with water the highest percentages of oil were 61.27 and 60.89, obtained respectively, for treatments N0K2 and N2K2.