Influence of Different Organic-Based Fertilizers on the Phytoremediating Potential of Calopogonium mucunoides Desv. from Crude Oil Polluted Soils

Abstract

A greenhouse experiment was conducted to investigate the growth of Calopogonium mucunoides in soils contaminated by various concentrations of crude oil with a view of assessing its phytoremediating potential when different organic-based fertilizers were applied. The crude oil prepared at different concentrations of 0.0, 2.5, 5.0, 10.0 and 20.0% (v/v) acted as contaminants on 3 kg each of the air-dried soil collected from exhaustively cropped farm. Each treatment was replicated thrice in complete randomized design with four different fertility management levels, namely: 8t ha -1 compost organic fertilizer (CM); 8t ha -1 neem fortified organic fertilizer (NM); control 1 , without fertilizer application (C1) and Control 2 , where no fertilizer and no crop but crude oil was applied (C2). Significantly (p<0.05) highest total petroleum hydrocarbon (THC) uptake (10 -2 mg kg -1 ) of 1.08, 0.52 and 0.21; 1.01, 0.51 and 0.11 in the roots and shoots for CM, NM and C1 treatments respectively were obtained at 2.5% contamination. Also, significantly (p<0.05) higher values of (10 -2 mg kg -1 ) 2.57, 1.49 and 0.37; 3.02, 0.98 and 0.58 for Pb in the roots and shoots with CM, NM and C1 treatments respectively were phytoremediated at 5.0% contamination. Lower values of Cd were removed at different contamination levels and fertilizer treatments. With increased contamination, there was a reduction in the uptake of THC and Cd, while higher Pb bioaccumulated. The study concluded that C. mucunoides plant could be effectively used in the phytoremediation of crude oil contaminated soil when compost organic fertilizer is applied.