Effect of different organic nutrient supplements on the total heterotrophic counts and diesel oil degradation in diesel polluted soil

The effect of graded quantities of different organic nutrient supplements on the total heterotrophic counts and diesel oil degradation in diesel-polluted soil was studied. Soil samples were mixed with different volumes of diesel to obtain heavy and moderate pollution, which was subsequently amended with different quantities of organic nutrient supplements. Total heterotrophic counts were determined at two weeks intervals for 16 weeks and the oil and grease content were determined at the beginning and at the end of the study. The result showed a general increase in microbial count with increase in the quantities of supplement. Poultry waste-amended samples had the highest count in all the samples followed by pig waste and cow dung-amended samples. Diesel oil degradation followed the same order with the highest percentage oil degradation obtained in poultry waste-amended samples. It therefore, showed that poultry waste is the best organic waste to be appliedin a biodegradation process.Keywords: Diesel oil, organic nutrients, biodegradation, heterotrophic microorganisms