Desenvolvimento inicial de Ricinus communis L. com substratos de torta de mamona e cascalho de perfuração de poços de petróleo

Abstract

The drill cuttings is a residue of the oil industry produced during the drilling of onshore and offshore wells. Their mineralogical characteristics depend on the geological formation present along the perforation. Upon reaching the surface, it is impregnated with drilling fluid used during the process. The use of this waste in soils has been discussed as it has limitations per se (e.g. high content of Fe, Mn, Zn, Cu) as a consequence of the drilling process (e.g. Ba, Na and hydrocarbons - HTP). The purpose of this study was to investigate the decrease of salinity after the application of gravel with castor cake to the substrate and using the castor bean BRS- 149 cv. Nordestina, as plant indicator, to infer about limitations on the combined use of these wastes. Pots were used (8 dm3) with proportional doses of gravel (control, 5, 15, 30, 45 and 60 Mg ha-1) associated with castor cake (control, 2, 4, 8, 16 and 32 Mg ha-1) in a factorial design with three replications for 97 days after planting (DAP). Improvements were observed in the morphological development of castor bean plants, with the application of 60 Mg ha-1 gravel associated with 16 Mg ha-1 of castor cake. However, the dose of 60 mg ha-1 of gravel caused stress due to accumulation of Na in leaves, the same for the 45 mg h-1 dose. The best ratio of gravel and pie in this respect was of 15 and 32 mg h-1, respectively. After the initial cultivation of castor bean plants, it was found that the application of 30 Mg ha-1 of gravel was sufficiently capable to neutralizing the toxic Al3+; raising the pH to values around 6.5 and thus making the nutrients more avalilable to the crop. Also, there was a marked HTP decomposition (above 92%) from the substrate metabolical microbiological increase, with the pie addition. It was therefore concluded that the use of gravel must follow specific guidelines especially due to salinity, to avoid possible impacts caused to the environmental and the crop (castor bean).