Effect of Untreated Petroleum Refinery Effluent on Bacterial and Fungal Population of Soil and Seedling Growth of Maize (zea Mays L.) in an Ultisol.

This trial was conducted to investigate the effect of applying untreated petroleum refinery effluent on bacterial and fungal population and seedling growth of maize in an utisol. 2 kg of soil from an uncultivated land was measured into 12 pots which were then polluted with untreated refinery effluent at the rate of, 0, 50, 100, 150 milliliters, these treatments were replicated three times and laid out in a Completely Randomized Design (CRD). Two weeks after pollution, the pots were seeded to maize. The variables measured were plant height, number of leaves, leaf area, leaf nutrient concentration, bacterial and fungal count in the soil. The agronomic data collected were subjected to Analysis of Variance (ANOVA) with the means separated using LSD(0.05) while the changes in the microbial population were analyzed using simple descriptive statistics. The results obtained at the end of the experiment showed that untreated petroleum effluent had impeding effluence on the growth of maize plant, population and growth of soil microorganisms (bacteria and fungi). The bacteria and fungi strain in the soil mostly affected by the untreated petroleum effluent were Pseudomonas spp and Trichoderma spp., respectively. Also, leaf area and leaf nutrient concentration were observed to increase with an increase in the quantity of effluent applied. The heavy metal content in the soil was discovered to increase with increasing rate (T150 > T100 > T50 > T0) in effluent applied and the values obtained for Ni, Pb, Cd and Cr all exceeded the permissible limit of 0.3mgkg-1 as stipulated by World Health Organization (W.H.O).