The Effects of Nitrogen Fixing Tree (Leucaena leucocephala) and Mushroom (Pleurotus tuber-regium) on Spent Engine Oil Polluted Soil

Greenhouse experiment was conducted for four months using leucaena leucocephala and pleurotus tuber-regium to determine their bioremediation potentials. leucaena leucocephala, pleurotus tuber-regium and leucaena leucocephala combined with pleurotus tuber-regium were tested for their ability to improve nutrient (n, p, k, total organic carbon) and reduce heavy metals (zn, ni, pb, cu) of soil polluted with spent engine oil [5% (v/w)] and soil without spent engine oil was used as control. bioaccumulation of nutrients and heavy metals in leucaena leucocephala and pleurotus tuber-regium were also determined. the highest reduction in zn, ni, pb and cu (41%, 48.39%, 61.60 and 52.72% respectively) were recorded in soil remediated with leucaena leucocephala alone, reduction of 30.40%, 26.53%, 48.07% and 39.60% respectively were recorded in soil remediated with pleurotus tuber-regium alone while in soil remediated with combined pleurotus tuber-regium and leucaena leucocephala, reductions of 32.7%, 33.43%, 88.41% and 46.22% respectively were recorded. bioaccumulation of zn, ni, pb and cu in leucaena leucocephala increased by 73.41%, 85.46%, 3366.04% and 125.53% respectively, similarly in pleurotus tuber-regium by 30.16%, 21.67%, 71.11% and 53.21% respectively. these studies have shown that pleurotus tuber-regium and leucaena leucocephala are capable of bioremediating spent engine oil polluted soil although, treatment with leucaena leucocephala alone tends to be most effective of these treatments.