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Abstract
Petroleum pipeline vandalism along the Warri–Kaduna trunk line, which transits Edo State’s Etsako and Orhionmwon axis, has produced recurring crude oil spillage incidents. Remediation of the resulting contaminated soils has relied almost entirely on conventional physical clean-up rather than on nature-based, low-cost alternatives. This greenhouse-based experimental study evaluated the phytoremediation potential of four plant species widely available in Edo State guinea grass (Panicum maximum), carpet grass (Axonopus compressus), Siam weed (Chromolaena odorata), and tiger nut sedge (Cyperus esculentus) against crude oil-contaminated soil at two contamination levels (2% and 4% w/w) using a completely randomized design with an unplanted control. After ninety days, all planted treatments significantly reduced total petroleum hydrocarbon (TPH) concentrations relative to the unplanted control. Carpet grass achieved the highest mean TPH reduction (58.4%), followed by guinea grass (54.1%), tiger nut sedge (51.7%), and Siam weed (46.3%), compared with 22.8% in the unplanted control. Plant growth and survival were higher under moderate contamination, with carpet grass and guinea grass showing the greatest tolerance. Soil pH and organic carbon improved under planted treatments. The findings identify carpet grass and guinea grass as the most effective, readily available species for low-cost phytoremediation of oil-spilled soils in Edo State and support their inclusion in post-spill response protocols