Biostimulation of Crude Oil-contaminated Soil Using Plantain (Musa paradisiaca) Pseudo-stem Residues: Effects on Total Petroleum Hydrocarbon Degradation and Soil Physicochemical Properties

The Niger Delta of Nigeria faces a major environmental problem: crude oil pollution. Agricultural soils have been adversely affected by many years of petroleum activities. The study examined the potential of plantain (Musa paradisiaca) pseudo-stem residues as a low-cost biostimulant for the restoration of crude-oil-contaminated loam soil. Ten treatments, including an unamended control, were incubated for 56 days in a Completely Randomized Design with dry pseudo-stem (DPS), fresh pseudo-stem (FPS), and the combination (DPS + FPS) added to soil spiked with 18,920 mg/kg total petroleum hydrocarbons (TPH). Soil pH, electrical conductivity (EC), moisture, organic matter, nitrogen, phosphorus, potassium, and residual TPH were analysed at 14-day intervals. Degradation kinetics, ANOVA, and Pearson correlation analysis were used to evaluate the treatment effects and relationships among variables. TPH removal was better in pseudo-stem amendments compared to natural attenuation (F(3,6) = 15.79, p = 0.003). The joint application of 500 g DPS + 500 g FPS (T10) achieved TPH removal of 83.4% (3,150 mg/kg) with a degradation constant of 0.025349 day-1 and a half-life of 27.34 days, whereas 21.0% removal and a half-life of 218.4 days were recorded for the control. Amendments also improved soil quality by increasing the pH from 3.92 to 6.03 and decreasing EC from 6,590 to 115 µS/cm in T10, while N, P, and K increased with amendment dosage. There was a positive correlation between the concentrations of nutrients and TPH removal (N: r=0.748; P: r=0.793; K: r=0.769; p<0.05). These results suggest that plantain pseudo-stem residues, in particular DPS and FPS combination, are an efficient and sustainable strategy for petroleum hydrocarbon remediation in tropical soils.