Effects of red guinea corn and soybean plants growing on diesel polluted soil on the total heterotrophic and diesel degrading microbes

Effect of red guinea corn and soybean plants growing on diesel-polluted soil on the total heterotrophic and diesel degrading microbes were studied. Soil sample was collected from the Federal Polytechnic Nekede Owerri school farm with the aid of a spade and transported to the preparation ground in clean plastic buckets where it was sun-dried for 3 days. 3kg each of the sun-dried loamy soil sample was weighed out in triplicates and each set was mixed with 30ml, 150ml and 300ml of diesel to obtain 1% (set 1), 5% (set 2) and 10% (set 3) pollutions, respectively, which were dispensed into perforated plastic buckets. Each of these polluted soil samples was planted with the seeds of Red Guinea Corn and Soybean plants. Controls were also set up. Each sample was set up in duplicates. During the first and second week of the plant’s growth, total heterotrophic count, total diesel-utilizing microbes, and rhizosphere enumeration were carried out. The results showed that the total heterotrophic count and the hydrocarbon-utilizing microbes increased with increasing concentration of the diesel oil mixture (10%>5%>1%) in both the polluted soil planted with Red Guinea Corn and Soybeans. Similarly, the rhizosphere effects on both diesel degrading microbes and total heterotrophic bacterial counts were found to have increased with increase in percentage of diesel concentrations for both plants. The microbial population and rhizosphere effects were more in the polluted samples than in unpolluted ones. This implied that by encouraging these plants to grow on diesel oil polluted soils, conditions for microbial degradation of the contaminants can be enhanced and can increase the microbiota of the soil.