Efeito do uso de torta de mamona do processo de produção de biodiesel direto da semente em solo da Chapada do Apodi - RN

Abstract

In search of alternatives sources of energy production, and to replace current energy matrix, based on consumption of fossil fuels such as petroleum, biodiesel shows to be a promising option in reducing environmental impacts, for example, lowest emissions of gases to atmosphere. However, through the production of biofuels, wastes are generated such as the castor bean residue, produced directly from seed (PDS cake), an industrial patent of Petrobras/CENPES. Thus, it required the use or re-use of the residue, to complete the production chain of this biodiesel, and following the protocols for maintenance of natural resources. The castor bean cake is an organic residue with great potential in providing nutrients and as a soil conditioner. However, its usage should be studied before application in agriculture, as any other waste. This study aimed to evaluate the characteristics and effects of usage of this material in cultivation of oilseeds plants in an alkaline substrate. Castor oil cake (PDS), obtained by Petrobras processing method in 2008, was characterized and its parameters compared to the 2007 produced cake (PDS of 2007), and a commercial castor bean cake from conventional method (CEASA cake). There were promising aspects and limitations in the usage of the castor oil cake, based on the ABNT/NBR 10.004:2004 and Ministry of Agriculture standards. As well as, the chemical characteristics variability of seed and cakes obtained in 2008 year. The results showed sodium values above the limits allowed by the standard, and this was the main limiting factor. Thus, methods to reduce sodium content in the cake were tested, by washing it with water and KCl solution in different proportions and concentrations. In addition, the evolution of CO2 from the respiration of micro-organisms was estimated. The rate of release of nutrients by the cake was highest by the seventh day of incubation, with greatest influence of the cake doses added to the substrate. Castor bean (Ricinus communis L.) and sunflower (Helianthus annuus L.) plants were grown in the greenhouse, under increasing doses of non treated cake and treated with water cake. The highest cake dosages showed higher and proportional gain for most of the studied variables.