Effect of Pig Dung (Organic Manure) Application to Crude Oil Polluted Soil on Maize (Zea mays) Growth and Soil Properties

The pot experiment was conducted in the Soil Science Departmental Screen-house in the Faculty of Agriculture Teaching and Research Farm, University of Benin, Benin City, to remediate crude oil-polluted soil with pig dung. The effects of crude oil and pig dung on soil properties and maize (Zea mays L.) growth were investigated. Forty-eight perforated pots were filled with 15 kg of surface soils (0-15cm). The soils were polluted with four levels of crude oil (0, 7.5, 15, 22.5ml) and were amended with pig dung two weeks after pollution at four application rates (0, 500, 550, 600kg/ha) before planting. The results of the experiment indicate that soil properties and maize growth showed a dose-dependent response to crude oil-polluted, pig-dung-amended soils. Reduction in soil properties and plant height (102.1cm), leaf area (337.4cm²), number of leaves (9.33) due to effect of different levels crude oil pollution were significantly different (P<0.05) compared to their control (108.6cm, 413.4 cm²,10) but were significantly increased when amended with pig dung (139.1cm, 508.7cm², 13) respectively. The total hydrocarbon content also decreased significantly in amended treatments, while total organic carbon, Nitrogen, potassium, pH, and phosphorus content were increased. Most of the highest results were recorded for treatments 15ml/550kg and 22.5ml/550kg across various analyses, amongst others. The microbial population was lowest in the polluted soil (4.34 x 10^{^6}) in the 22.5 ml/0 kg treatment, but increased to 13.20 x 10^6 cfu in the 0ml/600kg treatment. Thus, pig dung (organic manure) is effective in ameliorating crude oil-polluted soil.