Studies on organic and in-organic biostimulants in bioremediation of diesel-contaminated arable soil

In this study, use of inorganic fertilizer (N.P.K) was compared with organic manure (compost) in the bioremediation of diesel-polluted agricultural soil over a two-month period. Renewal by enhanced natural attenuation was used as control. The results revealed that total petroleum hydrocarbon removal from polluted soil was 71.40 ± 5.60% and 93.31 ± 3.60% for N.P.K and compost amended options, respectively. The control (natural attenuation) had 57.90 ± 3.98% of total petroleum hydrocarbon removed. Experimental data fitted second order kinetic model adequately for compost amended option. The fertilizer amended option was found to be 1.04 times slower (k2 = 4.00 ± 1.40 × 10−7gmg−1d−1, half-life = 28.15 d) than compost amended option (k2 = 1.39 ± 0.54 × 10−5 gmg−1d−1, half-life = 8.10 d) but 1.21 times (20.6%) faster than the control (k2 = 2.57 ± 0.16 × 10−7 gmg−1d−1, half-life = 43.81 d). The hydrocarbon utilizers isolated from the diesel contaminated soil were: Bacillus nealsoni, Micrococcus luteus, Aspergillus awamori, and Fusarium proliferatum. The phytotoxicity test showed that germination indices for natural attenuation (control), fertilizer (NPK) and compost amended options were 34%, 56%, and 89%, respectively.