Effect of petroleum crude oil on mineral nutrient elements and soil properties of jojoba plant (Simmondsia chinensis)

This study evaluated the effect of petroleum crude oil contaminated soil on the mineral nutrient elements, soil properties and bacterial biomass of the rhizosphere of jojoba plant (Simmondsia chinensis). Malondialdehyde (MDA) concentration increased in jojoba leaves when grown in petroleum oil polluted soil especially at 2% and 3% crude oil. It was noted that Na, Mg and Ca decreased, while K increased in shoots of jojoba. In roots Na and Ca increased, however K and Mg decreased with increasing crude oil concentration in the soil. Heavy metals, Cu, Mn, Cd and Pb increased in both shoot and root with increasing crude oil concentration, while Zn decreased comparing with the control. In soil, N and K decreased, meanwhile Cu, Fe, Mn and Zn as well as organic matter increased with increasing crude oil concentration. Soil was free from P, while the addition of inorganic fertilisers improved P content. Bacterial account was significantly increased at the end of the experiment at 1% and 2% crude oil, especially after addition of inorganic fertilisers. The electrical conductivity and MDA of the leaves increased with increasing crude oil concentration in the soil. The addition of inorganic fertilisers to crude oil contaminated soil decreased the electrical conductivity and MDA comparing with crude oil only